Browse Topic: Rotary engines

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Design of a Rotary Engine Based High-Power Density Hybrid-Electric Power Generation TestbedF-0078-2022-175325/10/2022
ABSTRACT
Fernandes, Roydon, Shivakumar,  Jayaprakash, Gehrmann, Mariana, Miller, Nicholas, Collins, Kule, Currier, Patrick, Anderson, Richard
Review of Additive Manufacturing for Internal Combustion Engine Components03-13-05-00399/9/2020
With highway vehicles using over 20% of the total energy consumption in the United States, making strides in improving their fuel economy will positively influence the nation’s environmental impact. One methodology to accomplish this outcome is by reducing vehicle weight. In this regard, since the internal combustion (IC) engine is a major contributor to the mass of an automobile, it is an ideal area to target. Prior efforts in this area include using alternative materials (e.g., aluminum or magnesium) to decrease weight. Here, additive manufacturing (AM) is an appealing option due to its freedom from typical manufacturing constraints and the ability to produce highly optimized designs using nonconventional powertrain materials (e.g., titanium). The use of AM has the potential to increase reliability, improve performance, decrease production cost, and possibly minimize the number of parts. Since metal-based AM is a relatively new area of manufacturing for IC engines, its use has been largely limited to research, motorsport, and luxury vehicle activities. Given its potential, this effort provides a review and summary of AM work completed in this field including design optimization, prototyping, tooling and indirect manufacturing, part production, and remanufacturing and repair for IC engine components.
Gray, Jamee, Depcik, Christopher
Non-Contacting Finger Seal Piston for Oil Less Engines2020-01-10964/14/2020
The current quest to reduce CO2 emissions combined to new technologies has sparked an interest in revisiting radically different engine configuration concepts, such as adiabatic and split-cycle engines. To achieve the full potential of both concepts, the combustion chamber must be sealed without lubricating oil. A promising approach that has yet remained elusive, is to lubricate the piston-liner interface with gases. This paper explores the concept of using non-contacting finger seals to seal piston engines combustion chambers. The finger seals, made of a gas-lubricated pad at the end of a flexible beam, are fixed on a rotating piston that uses the centrifugal force to close the piston-liner gap. A physics-based fluid-structure model is developed to predict finger displacements and sealing performances. The model shows that the radial displacement of the fingers naturally creates a convergent profile with the liner that generates sufficient aerodynamic pressure to maintain a micrometer gap that prevents the piston to contact the liner. The results also show that the achievable leakage area would be similar to that of Wankel rotary engine and friction losses would be negligible compared to those of conventional piston rings. On the other hand, the study reveals challenges that will need to be addressed in order that finger seals be practical in engines, such as the finger torsion, dynamic behavior when exposed to bore distortion as well as the manufacturing tolerances required to ensure contact-free operation.
Boudreau, Pascal, Picard, Mathieu
Pre-design Investigation of Resonant Frequency Effects on Gas Exchange Efficiencies of a One-kW Natural-Gas Linear Engine Alternator2020-01-04884/14/2020
Performance of a natural gas two-stroke engine incorporated in a 1-kW free-piston oscillating Linear Engine Alternator (LEA) - a household electricity generator - was investigated under different resonant frequencies for pre-design phase purposes. To increase the robustness, power density, and thermal efficiencies, the crank mechanism in free-piston LEA is omitted and all moving parts of the generator operate at a fixed resonant frequency. Flexure springs are the main source of the LEA’s stiffness and the mass-spring dynamics dominates the engine’s speed. The trade-off between the engine’s performance, mass-spring system limits, and power and efficiency targets versus the LEA speed is very crucial and demands a careful investigation specifically at the concept design stages to find the optimum design parameters and operating conditions. CFD modeling was performed to analyze the effects of resonant frequency on the engine’s gas exchange behavior. To take combustion effects into account, a semi-empirical method was employed to obtain the initial and boundary conditions during the gas exchange from experiments and imported into CFD simulation. The numerical results of the gas exchange were validated at the engine speed of 5400 RPM with the experimental results. The semi-empirical method eliminated the complicated combustion simulation and significantly reduced the computational time and well-matched with experiments within 1 % error. Results showed enhanced trapping efficiency of 7.1% per 1000 RPM, and reduced scavenging efficiencies of 5.5% per 1000 RPM as speed engine’s speed increased. Comparison of the trapping and scavenging efficiencies showed an improved fuel/power efficiency equal to about 1.45 % per each 15 Hz increase in the LEA resonant frequency.
Zamani Meymian, Nima, Darzi, Mahdi, Johnson, Derek, Famouri, Parviz
Initial Investigations into the Benefits and Challenges of Eliminating Port Overlap in Wankel Rotary Engines2020-01-02804/14/2020
The Wankel rotary engine historically found limited success in automotive applications due in part to poor combustion efficiency and challenges around emissions. This is despite its significant advantages in terms of power density, compactness, vibrationless operation, and reduced parts count in relation to the 4-stroke reciprocating engine, which is now-dominant in the automotive market. A large part of the reason for the poor fuel economy and high hydrocarbon emissions of the Wankel engine is that there is a very significant amount of overlap when the ports are opened and/or closed by the rotor apices (so-called peripheral ports). This paper investigates the benefits of zero overlap from a production engine with this characteristic and the effect of configuring a peripherally-ported Wankel engine in such a manner. As discussed in the paper, arranging this condition for peripherally-ported engines unfortunately reduces the trapped compression and/or expansion ratios significantly, such that when naturally-aspirated operation is simulated, a large reduction in performance ensues. In order to demonstrate the potential of zero port overlap in Wankel engines with respect to emissions, a 2007 model year Mazda RX-8 was rebuilt, run-in, degreened, and tested on a chassis dynamometer. As standard, the engine in this vehicle is configured with no port overlap through the adoption of side intake and exhaust ports. This testing was performed in order to see subjectively how successful such an approach could be in controlling emissions. The vehicle easily met Euro 5 limits for all criteria emissions and was even better in terms of hydrocarbon emissions versus Euro 6 on the WLTP cycle, giving the lie to the belief that a Wankel engine can no longer meet current automotive emissions targets. The analytical work reported here studies the result of eliminating overlap on the performance of a peripherally-ported single-rotor Wankel engine using a 1-D model. This was implemented and correlated to the in-production Advanced Innovative Engineering (UK) Ltd 225CS engine used in the UK government-funded ADAPT project. The initial port study focused on advancing and retarding the exhaust and intake port respectively to achieve zero port overlap and then sweeping their zero-overlap positions together around the trochoid housing. The best location for the ports was then identified; this was essentially an “Otto” timing set, with broadly equal compression and expansion ratios. Notwithstanding this, potential performance was found to be severely curtailed, as was to be expected given the marked reduction in trapped compression and/or expansion ratios necessary due to peripheral porting. Countermeasures to this reduction are discussed. Those that will be studied later in the project will be reported in a later publication.
Turner, James, Turner, Matthew, Vorraro, Giovanni, Thomas, Toby
Bitt-rotator rotary engine2019-36-03191/13/2020
This work presents the Bitt Rotator, a recently developed and patented combustion engine. It is a new rotary internal combustion engine, with a distinct conception, durability and performance, possible to be applied to all types of vehicle or industrial equipment.
Bittencourt, Daniel, Fernando Bittencourt, José, Soares, Armando Dias Stamile, Manguino, Jo˜ão L.V., Brand˜ão, Frederico Renan Sim˜ões
A cutting-edge technology to increase the friction coefficient in bolted joints in a simple way2019-36-02361/13/2020
Lightweight vehicles are one of the most efficient solutions to reduce the fuel consumption and the emission of polluting gases, which leads the automotive industry to the constant need to manufacture ever lighter vehicles. Due to these current requirements, there is a general move toward compact and lightweight powertrain system designs. Although more compact, these systems must be able to transmit the same or even higher forces and torques. Dealing with these contradictory requirements adding to the constant request to minimize production and assembly costs is a huge challenge to engineers. One approach is to enhance the coefficient of static friction in friction joints. When friction joints are designed, physical parameters such as overall size and surface pressure usually can only be varied in a tight window. Load transmission capability in friction joints is thus limited by the friction coefficient of the mating materials. An efficient solution for these limitations is to apply a nickel diamond coating either to the actual parts of the joints or to friction shims for installation in the joint. In this context are the 3M™ friction shims, steel foils with a coating of electroless nickel embedded with diamond particles. When the shim is placed between two components in a bolted connection, the diamonds cut into the metal mating surface and create a micro-scale interlock that significantly increases friction between the two parts. This friction shims are thin enough to fit within close engineering tolerances, creating possibilities for lightweight compact design while increasing potential load and peak torque in bolt connections, making them a cutting-edge connection technology capable of transmitting effectively and reliably up to four times higher torques than conventional systems without requiring modifications to the joint design. The objective of the paper is to demonstrate the theory involved in this technology as well as practical evidence through tests performed using friction shims as an alternative to increase the coefficient of static friction in bolted joints.
Souza Valério, Vanessa de, Tamagawa, Rosana Emi, Busiol, Kellen Cristina, Filho, Petrus Lencioni
The Szorenyi Three-Chamber Rotary Engine Concept2019-24-01689/9/2019
Currently automotive engines are reciprocating or Wankel rotary engine types. Reciprocating engines are bulky, heavy and complex, mainly due to the intake and exhaust valves and their associated cam-train. Wankel engines have a low rotor rev limit, and have inefficient sealing of the apex seals leading to poor economy and undesirable emission gases. The Rotary Engine Development Agency (REDA) has designed a new three-chamber rotary internal combustion engine concept using an adaptation of the patented Szorenyi Curve. The new design is an evolution of the design which was the subject of SAE Technical Paper 2017-01-2413 and SAE publication ‘So You Want to Design Engines: UAV Propulsion Systems’. This paper describes the features of the new three-chamber engine concept and includes an analysis of the major shortcomings of the Wankel engine. The Wankel engine’s geometry results in excessive crankshaft deflection at high engine revs due to the centrifugal force of the rotor which is eccentric to the crankshaft. This results in a low rotational speed limit. Analysis of the Wankel design reveals that the rotational speed limit cannot be increased by increasing the diameter of the crankshaft. Also, analysis of the apex seal reveals that the shape of the stator accelerates the seal inwards during the intake and power stroke and, at the same time, the seal experiences a large change in its contact angle with the stator surface. These effects combine to produce poor conditions for sealing the combustion chamber of the Wankel engine. The paper identifies that the Szorenyi three-chamber engine design does not have these same issues because its symmetrical rotor enables a high rotational speed, and its continuously concave stator profile ensures an outward acceleration of the apex seal and much less change of contact angle with the stator surface. The paper concludes that the Szorenyi engine has the potential to replace Wankel and reciprocating engines in a range of applications and is particularly suited to light aircraft.
King, Peter
Long time coming19AUTP06_066/1/2019
After six decades of teasing enthusiasts with intriguing concepts, Chevrolet is launching an all-new Corvette with its engine located where Zora intended-behind the driver. In the Spring of 1957, while pondering the demise of Chevrolet's Corvette Super Sports racer at Sebring's 12-hour endurance race, legendary Corvette godfather Zora Arkus-Duntov concluded, “Heat source must be behind driver.” The official explanation offered for dropping out after 29 laps was a failed rear-suspension bushing-but the actual show-stopper was that driver John Fitch's feet were being cooked by the exhaust-header pipes snaking around the SS's sheet magnesium ‘firewall.’ Sixty-two years later, the Corvette development trek initiated by Arkus-Duntov's brainstorm reached New York's Times Square, when a camouflaged prototype (see cover image) driven by chief engineer Tadge Juechter and with GM CEO Mary Barra as passenger, finally confirmed that the 2020 Corvette will have its engine located behind the driver.
Sherman, Don
Misfire Generator Functional RequirementsJ2901_201904 (Current)4/11/2019
The intent of the specification is to present a functional set of requirements which define the user and hardware interfaces while providing sufficient capability to meet the misfire patterns for compliance demonstration and engineering development. Throughout this requirement, any reference to “ignition or injector control signal” is used interchangeably to infer that the effected spark ignition engine’s ignition control signal or the compression ignition engine’s injector control signal is interrupted, timing phased, or directly passed by the misfire generator. For spark ignition engines, the misfire generator behaves as a spark-defeat device which induces misfires by inhibiting normal ignition coil discharge. It does so by monitoring the vehicle’s ignition timing signals and suspends ignition coil saturation for selected cylinder firing events. The misfire generator will thereby induce engine misfire in spark ignited gasoline internal combustion engines; including rotary engines. For compression ignition engines, the misfire generator behaves as a fuel injection-defeat device which induces misfire by inhibiting the normal fuel injection pulses. It does so by monitoring the injection pulses signal and suspending the injection pulses for selected cylinder firing events. The misfire generator will thereby induce engine misfire in compression ignition engines. This requirement assumes that the user has a fundamental understanding of misfire diagnostics as well as ignition controls. This requirement is not intended to be an introductory misfire guideline or interpretation of regulatory requirements.
Vehicle E E System Diagnostic Standards Committee
Mass Benefit Analysis of 4-Stroke and Wankel Range Extenders in an Electric Vehicle over a Defined Drive Cycle with Respect to Vehicle Range and Fuel Consumption2019-01-12824/2/2019
The gradual push towards electric vehicles (EV) as a primary mode of transport has resulted in an increased focus on electric and hybrid powertrain research. One answer to the consumers’ concern over EV range is the implementation of small combustion engines as generators to supplement the energy stored in the vehicle battery. Since these range extender generators have the opportunity to run in a small operating window, some engine types that have historically struggled in an automotive setting have the potential to be competitive. The relative merits of two different engine options for range extended electric vehicles are simulated in vehicle across the WLTP drive cycle. The baseline electric vehicle chosen was the BMW i3 owing to its availability as an EV with and without a range extender gasoline engine. Two different range extenders were considered; a single rotor Wankel rotary and a 4-stroke reciprocating engine, with the baseline vehicle electric glider mass fixed for all options. Fuel tank capacity was fixed at 9 litres. Baseline EV performance was evaluated on simulated European drive cycles with mass sensitivity conducted before the implementation of each range extender. Potential options for the optimisation of the range extender operation were considered with respect to their impact on vehicle performance. Total combined fuel efficiency was compared and an assessment of maximum range and vehicle performance was also conducted.
Turner, Matthew, Turner, James, Vorraro, Giovanni
Powering back to the FUTURE19AUTP04_044/1/2019
Rotaries, gas turbines, hybrids-even nukes! Propulsion tech from the past, present, and beyond the horizon is revealed at the SAE Mobility History display at WCX'19. Credit Leonardo DaVinci for creating what many historians believe was the first depiction of a self-powered vehicle. It was powered by springs. And in the centuries since then, engineers have found increasingly complex and interesting solutions for vehicle propulsion. Steam came first. Nicolas-Joseph Cugnot's 1769 steam tractor is generally believed to be the first self-propelled road vehicle. By the 1830s, steam carriages carried passengers on roadways in Britain. During this period another technology was emerging: in the 1830s, American blacksmith Thomas Davenport's experiments with electricity and electromagnetism led him to patent an electric motor. When battery technology finally caught up with this vision in the 1880s, the recipe for the first electric cars was born.
Brooke, Lindsay, Anden, Erika
Q&A19AUTP03_193/1/2019
It may be a small OEM, but Mazda has always punched far beyond its weight class in engineering and technology. That point is acknowledged by Masahiro Moro, president and CEO of North American Operations (MNAO) and an officer of the parent Mazda Motor Corp. A 34-year veteran of the company, Moro-san is responsible for all aspects of Mazda operations in the region. He clearly enjoys talking tech, as he'll do on April 11 as part of SAE's Leadership Summit at WCX '19 in Detroit. At the L.A. Auto Show he spoke with Editor-in-Chief Lindsay Brooke to discuss recent developments. Mazda's Skyactiv concept-the holistic combination of light weight, high efficiency, and driver-centric design-resonates with engineers across the industry. They get it.
Mazda details electrification strategy, confirms rotary engine's return18AUTP11_0611/1/2018
In an announcement from Japan in October, Mazda-one of the few established automakers to articulate a comprehensive longterm commitment to hybridization or all-electric vehicle propulsion-said it intends to incorporate some type of electrification in all its vehicles by 2030. Yet in nearly the same virtual breath, the company affirmed its connection to “soulful” forms of internal combustion, including a confirmation that it will renew its longstanding enthusiasm for the rotary engine. In a carefully-worded statement, Mazda reminded that many credible forecasts call for internal combustion to remain the dominant light-vehicle propulsion source for perhaps decades to come, while discretely laying out its plan for electrification-when and where it makes sense for the environment.
Visnic, Bill
Automotive Engineering: November 201818AUTP1111/1/2018
Electrifying the two-wheeler Alta Motors, one of the newest electric motorcycle OEMs, is fueling zero-emission excitement with a passion for product. AV testing is for dummies Rapid development of automated vehicles is driving ATD innovations, as Humanetics' CEO explains. 2019 Yamaha Niken steers a radical path The world's first leaning three-wheel motorcycle is an expression not only of engineering prowess, but of a real passion for riding. Editorial Electrify the U.S. Postal Fleet! SAE Standards News SAE publishes first global standard on shared mobility Supplier Eye Moving the goalposts of emission compliance The Navigator Engineering AVs to 'play nice' with humans What We're Driving Mazda details electrification strategy, confirms rotary engine's return Detecting battery leaks at production speeds Nexteer readies steering technologies for autonomous and mixed-mode driving Nissan's all-new Altima gets variable-compression engine, AWD Lexus soups-up seventh-generation ES sedan Q&A Honda's Noriyuki Sato talks hybrids
Design Parameters for Small Engines Based on Market Research2018-01-17179/10/2018
Small internal combustion engines outperform batteries and fuel cells in regards to weight for a range of applications, including consumer products, marine vehicles, small manned ground vehicles, unmanned vehicles, and generators. The power ranges for these applications are typically between 1 kW and 10 kW. There are numerous technical challenges associated with engines producing power in this range resulting in low power density and high specific fuel consumption. As such, there is a large range of engine design solutions that are commercially available in this power range to overcome these technical challenges. A market survey was conducted of commercially available engines with power outputs less than 10 kW. The subsequent analysis highlights the trade-offs between power output, engine weight, and specific fuel consumption. These engines are analyzed to show the benefits and disadvantages of different engine design parameters including fuel type, number of strokes per cycle, number of cylinders, intake pressure, and cooling strategy. A Pareto frontier analysis is conducted to identify the top performing engines based on the output power and the total power system weight. Recommended designs are presented for different ranges of output powers.
Mittal, Vikram
Analysis of patent deposits and PROCONVE MAR – I in the development sector of agricultural machinery engines2018-36-02719/3/2018
Agriculture is directly associated with climate change issues and is a major source of Greenhouse Gas (GHG) emissions. Part of the emissions are the result of burning fossil fuels such as coal, natural gas and oil in internal combustion engines of agricultural machinery. In addition, because of negative impacts on air quality, human health and climate change, new strategies are being developed to reduce the impacts of GHG emissions. However, it is noted that there is a lack of information that instigates emissions of non-road equipment, such as emissions from agricultural machinery. Thus, in order to achieve climate policy objectives, new trends in agriculture are being adopted. They set emission standards for GHG reductions by agricultural engine engines. In Brazil, the Program for the Control of Air Pollution by Automotive Vehicles (PROCONVE) is responsible for establishing the legal regulations for admissible emissions for the different categories of motor vehicles. In order to control the emission limits of agricultural and road machinery, PROCONVE granted the MAR - I phase (Agricultural and Road Machinery), which came into force in 2015. Brazil, through the regulation of PROCONVE MAR - I, seeks to reduce GHG emissions, which among its guidelines are the improvement of the concepts of agricultural engine engines and their post - treatment technologies, resulting in improvements in the control of atmospheric emissions from exhaust gases. Thus, the article presents an analysis of the deposits in patent bases, through the Questel Orbit Platform, aiming at verifying who are the main manufacturers of the Brazilian market, what are the post-treatment systems for agricultural machinery engines and who are the countries which stand out for developing technologies linked to the reduction of the emission of pollutants. As a result, the main meta specifications structured in agricultural machines in countries with high emission standards include Selective Catalytic Reduction (SCR) for the control of NOx (Nitrogen Oxides), Exhaust Gas Recirculation (EGR) to enable cooling of the NOx formation and the Diesel Particulate Filters (DPF) in the control of PM (Particulate Material). In addition, the Electronic Fuel Injection System also allows a significant reduction in the emission of pollutant gases. As a consequence, research on these results can help to provide new conceptions of products that, besides being functional, have a legal adequacy, thus establishing a connection with PROCONVE MAR - I.
Silveira, Franco da, Ruppenthal, Janis Elisa, Farias, Marcelo Silveira de, Machado, Filipe Molinar, Costa, Marcela Avelina Bataghin, Amaral, Fernando Gonçalves
Performance of a Low-Blowby Sealing System for a High Efficiency Rotary Engine2018-01-03724/3/2018
The X engine is a non-Wankel rotary engine that allies high power density and high efficiency by running a high-pressure Atkinson cycle at high speeds. The X engine overcomes the gas leakage issue of the Wankel engine by using two axially-loaded face seals that directly interface with three stationary radially-loaded apex seals per rotor. The direct-interfacing of the apex and face seals eliminates the need for corner seals of the typical Wankel engine, significantly reducing rotary engine blowby. This paper demonstrates the sealing performance that can be achieved by this new type of seal configuration for a rotary engine based on dynamics models and experiments. The dynamics models calculate the displacement and deformation of the face and apex seals for every crank angle using a time implicit solver. The gas leakage is then calculated from the position of the seals and pressure in the chambers and integrated over a rotor revolution. An “effective leakage orifice” area can be determined, to compare blowby between different engine types. Model results show that the X engine equivalent leakage area could be around 35% that of the leakage area of a similarly sized Wankel engine obtained from the same modeling method, which brings the X engine leakage closer to the piston engine’s leakage range. Initial experimental results support the findings from the model, as the X engine shows an equivalent leakage area of about 65% that of a scaled Wankel engine. This result demonstrates the potential of the X engine to achieve gas sealing improvements through additional seal development.
Leboeuf, Maxime, Dufault, Jean-François, Nickerson, Mark, Becker, Kyle, Kopache, Alexander, Shkolnik, Nikolay, Shkolnik, Alexander, Picard, Mathieu
Development of a LIF-Imaging System for Simultaneous High-Speed Visualization of Liquid Fuel and Oil Films in an Optically Accessible DISI Engine2018-01-06344/3/2018
Downsizing and direct injection in modern DISI engines can lead to fuel impinging on the cylinder walls. The interaction of liquid fuel and engine oil due to fuel impinging on the cylinder wall causes problems in both lubrication and combustion. To analyze this issue with temporal and spatial resolution, we developed a laser-induced fluorescence (LIF) system for simultaneous kHz-rate imaging of fuel and oil films on the cylinder wall. Engine oil was doped with traces of the laser dye pyrromethene 567, which fluoresces red after excitation by 532 nm laser radiation. Simultaneously, the liquid fuel was visualized by UV fluorescence of an aromatic “tracer” in a non-fluorescent surrogate fuel excited at 266 nm. Two combinations of fuel and tracer were investigated, iso-octane and toluene as well as a multi-component surrogate and anisole. The fluorescence from oil and fuel was spectrally separated and detected by two cameras. Both the laser and the cameras were capable of kHz repetition rates. Preliminary studies in a thin-film cuvette investigated the optical properties of tracer/fuel-mixtures and mixtures with a first-fill engine oil and a low-additive surrogate engine oil. In particular, cross-talk by the fuel tracer in the oil channel was low, but signal from oil fluorescence in the fuel channel was significant. Experiments were performed in a research engine with optical access along the entire stroke of the cylinder in fired and motored engine operation. Besides fuel wall wetting, fuel transport across the piston ring pack and the impact on the lubricant conditions in the piston group can be seen in the images.
Mueller, Torben, Wigger, Stefan, Fuesser, Hans-Juergen, Kaiser, Sebastian
Comparison of 1-D Modelling Approaches for Wankel Engine Performance Simulation and Initial Study of the Direct Injection Limitations2018-01-14524/3/2018
Recent interest in the possible use of Wankel engines as range extenders for electric vehicles has prompted renewed investigations into the concept. While not presently used in the automotive industry, the type is well established in the unmanned aerial vehicles industry, and several innovative approaches to sealing and cooling have recently been developed which may result in improved performance for ground vehicle applications. One such UAV engine is the 225CS, a 225 cc/chamber single-rotor engine manufactured by Advanced Innovative Engineering (UK) Ltd. To be able to analyse the parameters, opportunities and limitations of this type of engine a model was created in the new dedicated Wankel modelling environment of AVL BOOST. For comparison a second model was created using the established method of modelling Wankel engines by specifying an ‘equivalent’ 3-cylinder 4-stroke reciprocating engine. The output from both of these models was evaluated using engine test data supplied by Advanced Innovative Engineering (UK) Ltd. The model created in the dedicated Wankel environment was found to fit the experimental data more closely. The model was then used to evaluate the impact on performance and fuel economy of applying direct injection to a Wankel rotary engine. This potential is because the nozzle can be situated in the cold side of the trochoid housing, taking advantage of the longer intake phase of the Wankel in turn permitting lower delivery pressures (the intake ‘stroke’ having 270 degrees of eccentric shaft rotation vs. 180 degrees for the reciprocating engine), plus the fact that the injector can be shielded from combustion pressure and hot burned gases. As it was found to be more accurate, the dedicated Wankel model was used to analyse the interrelationships between injector position, injection pressure and engine speed. Although a number of assumptions were required, and these will affect the accuracy of the model, the results provide a reasonable preliminary assessment of the feasibility of applying direct injection to the 225CS engine. A notable finding was that injection pressures of approximately 4.5 bar should be sufficient to supply fuel at all engine speeds and that the optimum position for the injector (for maximum fuel injection) corresponded to a position defined by the rotor apex tip at 597 degrees of eccentric shaft rotation after top dead centre firing. The advantage of both the injection pressure and injector location suggests a less complex fuel system design (compared to equivalent reciprocating systems) is possible at a reduced cost.
Peden, Michael, Turner, Matthew, Turner, James W G, Bailey, Nathan
Description of a Novel Concentric Rotary Engine2018-01-03654/3/2018
The present work presents the concept of a new rotary engine, and provides first investigations for its implementation in the energy sector. The main focus of this work is to provide a theoretical description of the engine and its differences from the state-of-the-art technologies. Its innovative principle consists of concentric operation, with two pistons of different rotation radius and the addition of a third intermediate chamber between the compression and combustion chamber. A description of the engine’s physical model is provided, followed by an analysis of the selected specific geometrical features. Additionally, a thermodynamic analysis clarifies the operational advantage compared to the existing cycles and, finally, a numerical investigation on the engine’s bulk performance is provided to quantify the anticipated results of the theoretical analysis. The theoretical description concludes that the new rotary engine is characterized by simple design with the minimum possible moving parts that can be easily integrated into hybrid systems or small sized applications. Its anticipated volume and weight is five to six times smaller than that of conventional engines owing to the fact that there is no need for motion conversion system and there is one power stroke in every 180 degrees. Last but not least, its expected thermal efficiency based on Atkinson cycle can theoretically be 15% greater than that of existing engines for the same application.
Savvakis, Savvas, Gkoutzamanis, Vasilis, Samaras, Zissis
Low Volatility Fuel Cold Start Experience with a Stepped Piston UAV Engine to Address Single Fuel Objectives2017-01-92838/1/2017
This paper reports on the research and development challenges experienced from dynamometer testing of a spark ignition UAV engine operating on heavy fuel. The engine is a segregated scavenging two stroke engine with air charge delivery by means of integral stepped pistons overcoming durability issues of conventional crankcase scavenged engines. A key element of the experimental study builds upon performance development to address the need for repeatable cold start on low volatility fuel thereby eliminating gasoline from UAV theatres of deployment. Lubrication challenges normally associated with crankcase scavenged two stroke engines are avoided by the integrated re-circulatory lubrication system. The fuel explored in this study is kerosene JET A-1.
Hooper, Peter R.
Past as prelude to the FUTURE17AUTP04_064/1/2017
SAE's Mobility History Committee brings a trove of knowledge-and cool technology. Engineers who have done patent searches know there's truth in the old saying: Few things are truly new under the sun. First hybrid-electric car? 1899. First autonomous car tests? 1920s. First car with a cast-aluminum body structure? 1946. First aircraft to employ titanium in its initial design phase? 1952. First head-up display in aircraft? 1958. First drivable fuel-cell vehicle? 1966. First composite-plastic truck cab? 1967. The list of such pioneering developments is long indeed and rarely fails to surprise.
Brooke, Lindsay
Development and Application of Ring-Pack Model Integrating Global and Local Processes. Part 1: Gas Pressure and Dynamic Behavior of Piston Ring Pack2017-01-10433/28/2017
A new ring pack model has been developed based on the curved beam finite element method. This paper describes the first part of this model: simulating gas pressure in different regions above piston skirt and ring dynamic behavior of two compression rings and a twin-land oil control ring. The model allows separate grid divisions to resolve ring structure dynamics, local force/pressure generation, and gas pressure distribution. Doing so enables the model to capture both global and local processes at their proper length scales. The effects of bore distortion, piston secondary motion, and groove distortion are considered. Gas flows, gas pressure distribution in the ring pack, and ring structural dynamics are coupled with ring-groove and ring-liner interactions, and an implicit scheme is employed to ensure numerical stability. The model is applied to a passenger car engine to demonstrate its ability to predict global and local effects on ring dynamics and oil transport.
Liu, Yang, Tian, Tian
Development and Application of Ring-Pack Model Integrating Global and Local Processes. Part 2: Ring-Liner Lubrication2017-01-10473/28/2017
A new ring pack model has been developed based on the curved beam finite element method. This paper describes the second part of this model: simulating oil transport around the ring pack system (two compression rings and one twin-land oil control ring (TLOCR)) through the ring-liner interfaces by solving the oil film thickness on the liner. The ring dynamics model in Part 1 calculates the inter-ring gas pressure and the ring dynamic twist which are used in the ring-liner lubrication model as boundary conditions. Therefore, only in-plane conformability is calculated to obtain the oil film thickness on the liner. Both global process, namely, the structural response of the rings to bore distortion and piston tilt, and local processes, namely, bridging and oil-lube interaction, are considered. The model was applied to a passenger car engine. It was found that a net oil scraping by the top ring, as a potential oil consumption source, only occurs with a combination of high bore distortion and local oil bridging. The effect of fuel deposition on the oil film was also investigated.
Liu, Yang, Li, Yuwei, Tian, Tian
Experimental Measurements and Computations for Clarifying Nearly Complete Air-Insulation Obtained by the Concept of Colliding Pulsed Supermulti-Jets2017-01-10303/28/2017
In our previous papers, a new concept of a compressive combustion engine (Fugine) was proposed based on the collision of pulsed supermulti-jets, which can enclose the burned gas around the chamber center leading to an air-insulation effect and also a lower exhaust gas temperature due to high single-point compression. In order to examine the compression level and air-insulation effect as basic data for application to automobiles, aircraft, and rockets, a prototype engine based on the concept, i.e., a piston-less prototype engine with collision of bi-octagonal pulsed multi-jets from fourteen nozzles, was developed. Some combustion results [Naitoh et al. SAE paper, 2016] were recently reported. However, there was only one measurement of wall temperature and pressure in the previous report. Thus, in this paper, more experimental data for pressures and temperatures on chamber walls and exhaust temperatures, are presented for the prototype engine. First, pressure over 0.6MPa was measured on the chamber wall. A nearly complete air insulation effect was presumably obtained based on the experimental data for temperature measured on the chamber wall. The measured exhaust temperature was at an intermediate level around 700K. Experimental data are also presented for the air-insulation effect on a small solid wall located downstream from the collision point of the supermulti-jets. Unsteady three-dimensional computations of compressible flow also indicate that the experimental result of 0.6 MPa at the cylinder wall implies pressure of about 5 MPa at the collision point of the jets. The potential for high thermal efficiency is evaluated on the basis of the data.
Konagaya, Remi, Oyanagi, Susumu, Kanase, Takuto, Tsuchiya, Jumpei, Ayukawa, Ken, Kinoshita, Kodai, Mikoda, Junya, Fujita, Hirotaka, Naitoh, Ken
EDITORIAL: Question mark or exclamation point?17AUTP02_052/1/2017
Editor-in-chief Lindsay's Brooke's illuminating account of the production-readiness of the Achates Power opposed-piston engine (see p. 16) seems an appropriate kind of punctuation mark for the auto industry's current state of developmental and political flux. The problem is, English doesn't have a punctuation symbol that combines exclamation point and question mark-and I think it's time we create one. Consider:
Visnic, Bill
Endurance Testing for Wankel Rotary Engine2017-26-03361/10/2017
VRDE has developed Wankel type rotary engine to achieve high power output & fuel efficiency for indigenization programme of UAVs. This engine is meeting all performance parameters needed for intended aerial vehicle. This paper describes the testing methodology followed by development engineers to prove the endurance and reliability of UAV engine for airworthiness certification. This paper gives the brief about testing carried out on the Wankel engine, failures faced during endurance testing and their rectification to enhance the life of the engine to achieve hundred test cycle mark. This paper also briefs about the test set up, endurance test cycles simulating the practical operating conditions.
Yewale, Ganesh Liladhar, Tapkire, Abhishek, Radhakrishna, D, Shejwal, Popat, Singh, Kaushal, Panchal, Gaurav
Comparative Small Engine Testing Using Hybrid Composite Cylinder Liners2016-32-002211/8/2016
Cylinder liners exert a major influence on engine performance, reliability, durability and maintenance. Various combinations of nonmetallic reinforcements and coatings have been used to improve the tribological performance of sleeves or surfaces used in compressors and internal combustion engines in four stroke, two stroke and rotary configurations. In this paper we report the use of a hybrid composite containing silicon carbide and graphite in an aluminum alloy matrix to improve the performance of various small engines and compressors. Material properties of the base material, as well as comparative dynamometer testing, are presented.
Weiss, David, Beno, Simon, Jordan, Chris, Rohatgi, Pradeep
Development of a flex-fuel rotary engine with variable compression ratio2016-36-021810/25/2016
Energy independence and reduction in pollutant emissions are a center of interest for several researchers and car manufacturers. Renewable fuels have gained in popularity because of their sustainability and, in some cases, lower amounts of greenhouse gases. Moreover, energy diversification is also required by all countries. One possible solution is the use of biofuels such as ethanol, methanol, etc. These biofuels have been shown as good candidates as alternative fuels for vehicles because they are liquid and they have several physical and combustion properties similar to gasoline. Alcohols have also a higher octane number and oxygen content than gasoline. This allows the alcohol engines to have much higher compression ratios (CRs), and thus, better BTE (brake thermal efficiency). Brazilian car manufacturing industry has developed flexible-fuel vehicles, introduced in 2003, which became a commercial success. Flex fuel internal combustion engines (ICEs) can run on any proportion of Brazilian gasoline (E27 blend) and hydrous ethanol (E100), allowing the use of the cheaper fuel available. However, conventional flex fuel engines have a fixed CR, generally between the ideals CRs for gasoline and ethanol, which leads to lower BTE and higher fuel consumption. In order to reduce or eliminate these issues, this paper presents the Kopelrot engine, a flexible fuel rotary engine with dynamically variable compression ratio.
Guarato, Alexandre Z., Ticona, Epifanio M., Braga, Sergio L.
Computations and Experiments for Clarifying Compression Level and Stability of Colliding Pulsed Supermulti-Jets in a Piston-Less Single-Point Autoignition Engine2016-01-233110/17/2016
In recent years, a new type of engine (Fugine) based on the colliding of pulsed supermulti-jets was proposed by us, which indicates the potential for attaining very high thermal efficiencies and also less combustion noise. A prototype engine with eight nozzles for injecting octagonal pulsed supermulti-jets, which was developed with a low-cost gasoline injector and a double piston system, showed high thermal efficiency comparable to that of diesel engines and also less combustion noise comparable to that of traditional spark-ignition gasoline engines. Another type of prototype piston-less engine having fourteen bioctagonal nozzles was also developed and test results confirmed the occurrence of combustion, albeit it was unstable. In this work, time histories of pressure were measured in the combustion chamber of the piston-less prototype engine under a cold flow condition without combustion in order to examine the compression level obtained with the colliding supermulti-jets. Pressure was measured with a piezoelectric sensor. Unsteady three-dimensional computations were also performed and compared with the experimental pressures. The results showed a relatively high pressure level at the cylinder center and low pressure at the walls, which provided evidence of silent autoignition. Moreover, the reason why combustion was unstable in the prototype piston-less engine was also clarified. The data obtained have led to a new technique for improving combustion stability at engine start.
Naitoh, Ken, Tsuchiya, Jumpei, Ikoma, Daiki, Nakai, Takuya, Oyanagi, Susumu, Kanase, Takuto, Okamoto, Takuma, Tanaka, Yoshiaki, Ayukawa, Ken, Konagaya, Remi
Fundamental Combustion Experiments of a Piston-Less Single-Point Autoignition Gasoline Engine Based on Compression Due to Colliding of Pulsed Supermulti-Jets2016-01-233710/17/2016
Computational and theoretical analyses for a new type of engine (Fugine), which was proposed by us based on the colliding of pulsed supermulti-jets, indicate a potential for very high thermal efficiencies and also less combustion noise. Three types of prototype engines were developed. One of them has a low-cost gasoline injector installed in the suction port and a double piston system in which eight octagonal supermulti-jets are injected and collide. Combustion experiments conducted on the prototype gasoline engine show high thermal efficiency comparable to that of diesel engines and less combustion noise comparable to that of traditional spark-ignition gasoline engines. This paper presents some combustion experiments of one of the other piston-less prototype engines having bi-octagonal pulsed multi-jets injected from fourteen nozzles. The purpose of this study was to make clear the level of compressive combustion obtained with the pulsed supermulti-jets and air-insulation effect as basic data for application to automobiles, aircraft, and rockets. A torch system for stabilizing the onset of combustion was important in this study because the engine has no pistons and no homogeneous compression at engine start. By developing and employing the torch system, combustion experiments were performed using the colliding of pulsed supermulti-jets. As a result, very strong combustion light was obtained in nine continual cycles, although start of combustion was not still reliable. Therefore, experiments were carried out with a higher oxygen concentration. As a result, more reliable start of combustion with a higher pressure increase and nearly complete air insulation effect were obtained.
Naitoh, Ken, Ayukawa, Ken, Ikoma, Daiki, Nakai, Takuya, Oyanagi, Susumu, Kanase, Takuto, Tsuchiya, Jumpei
Computations and Experiments of Single-Point Autoignition Gasoline Engine with Colliding Pulsed Supermulti-Jets, Single Piston and Rotary Valve2016-01-233410/17/2016
A new engine concept (Fugine) based on colliding pulsed supermulti-jets was proposed in recent years, which is expected to provide high thermal efficiencies over 50% and less combustion noise. Theoretical analyses indicate a high potential for thermal efficiency over 60%. Three types of prototype engines have been developed. The first prototype engine based only on the colliding of pulsed supermulti-jets with fourteen nozzles has no piston compression, while the second type equipped with a low-cost gasoline injector in the suction port has a double piston system and eight jet nozzles. Combustion experiments conducted on the second prototype gasoline engine show high thermal efficiency similar to that of traditional diesel engines and lower combustion noise comparable to that of traditional spark-ignition gasoline engines. This paper presents the third prototype engine: a single-piston engine having a rotary valve, which induces strong point compression produced by twenty-four pulsed multi-jets injected from suction nozzles. Negative pressure generated by expansion due to piston motion under a closed rotary valve condition results in strong jets going to the cylinder center. This third engine has no compression due to piston motion. Unsteady three-dimensional computations for this engine including spray calculations of liquid gasoline, subsonic and supersonic turbulent flows, and combustion phenomena show the potential for very high combustion efficiency over 95%. Based on the result, combustion experiments of the engine were started. The colliding of the pulsed supermulti-jets causes combustion to occur.
Yamagishi, Kan, Onuma, Yuichi, Ohara, Soichi, Hasegawa, Kenya, Kojima, Kentaro, Shirai, Tomoya, Kihara, Takahiro, Tsuru, Kota, Naitoh, Ken
Steering Mazda's UNIQUE COURSE16AUTP10_0110/1/2016
A chassis engineer at heart, Chairman Kanai challenges his engineers to think differently and embrace the Skyactiv technology that has made Mazda a benchmark. In 1999 Mazda Motor Corp.'s current Chairman, Seita Kanai, had just taken over as program manager for the first-generation Atenza/Mazda6. The new car was a top priority and its success was deemed vital to the Hiroshima-based automaker's survival-this was Mazda's first new product in 18 months. Considered an “engineer's engineer” within a company that prides itself on technical creativity, Kanai was under significant pressure from both Mazda management and from Ford Motor Co., which owned a controlling stake, to deliver an exceptional car. “It was then Kanai-san's dream-and he strongly believed-that Mazda would someday produce a car that would ‘beat up’ the German premium sedans,” recalled Masahiro Moro, the CEO of Mazda North American Operations and good friend of Kanai, who at the time was the young head of product marketing. But in his first benchmarking drive of the incumbent Mazda sedan on the German autobahn, Kanai was shocked.
Yamaguchi, Jack
Low Cost Possibilities for Automotive Range-Extender/Hybrid Electric Vehicles to Achieve Low CO 2 and NVH Objectives2016-01-18416/15/2016
Powertrain system duplication for hybrid electric vehicles and range-extenders presents serious cost challenges. Cost increase can be mitigated by reducing the number of cylinders but this usually has a negative impact on noise, vibration and harshness (NVH) of the vehicle system. This paper considers a novel form of two-stroke cycle engine offering potential for low emissions, reduced production cost and high potential vehicle efficiency. The engine uses segregated pump charging via the use of stepped pistons offering potential for low emissions. Installation as a power plant for automotive hybrid electric vehicles or as a range-extender for electric vehicles could present a low mass solution addressing the drive for vehicle fleet CO2 reduction. Operation on the two-stroke cycle enables NVH advantages over comparable four-stroke cycle units, however the durability of conventional crankcase scavenged engines can present significant challenges. The use of stepped piston charging methods to isolate the crankcase from the scavenging process provides a solution to these challenges with significantly higher durability and lower oil consumption whilst offering specific power per litre levels associated with comparable conventional two-stroke cycle engines. Stepped piston engines have been shown to operate at significantly lower oil consumption under full load operating conditions. This therefore overcomes serious drawbacks associated with conventional two-stroke cycle units. Oil consumption reduction strategies applied to crankcase scavenged engines normally result in durability problems. Design strategies are presented for compact powertrain solutions supported by initial data from computational fluid dynamic modelling using Ricardo WAVE engine simulation software. Details of the thermodynamic model development supported by experimental data are discussed together with design aspects that enable minimum NVH in a compact low mass power plant solution.
Hooper, Peter R.
Application of Rankine Cycle to Passenger Vehicle Waste Heat Recovery - A Review2016-01-01784/5/2016
Rankine cycle (RC) is a thermodynamic cycle that converts thermal energy into mechanical work, which is commonly found in thermal power generation plants. Recently, there are many studies focusing on applying Rankine cycle to recover low-grade waste heat. On-road vehicles, which convert around one third of the fuel energy into useful mechanical energy for propulsion, are moving energy conversion systems that generate considerable waste heat. It was found from many research studies that Rankine cycle has a great potential to be applied to harvest waste heat from automobiles. However, different from other low-grade waste heat sources, vehicles have limited space for the RC system integration and the waste heat is relatively unstable. In the current paper, the efforts in the past few decades related to applying RC to on-road vehicles, specifically passenger cars, are reviewed. Characteristics of the waste heat sources on vehicles and the constraints put on the automotive RC application are identified. Rankine cycle architectures, system components, and working fluids suitable to different vehicle types are summarized to provide a guideline for the future RC system design for automobiles. In the end, an insight into the application of Rankine cycle to vehicle waste heat recovery (WHR) is provided.
Zhou, Feng, Dede, Ercan, Joshi, Shailesh
CAD/CFD/CAE Modelling of Wankel Engines for UAV2015-01-24669/15/2015
The Wankel engine for Unmanned Aerial Vehicle (UAV) applications delivers advantages vs. piston engines of simplicity, smoothness, compactness and high power-to-weight ratio. The use of computational fluid dynamic (CFD) and computer aided engineering (CAE) tools may permit to address the major downfalls of these engines, namely the slow and incomplete combustion due to the low temperatures and the rotating combustion chambers. The paper proposes the results of CAD/CFD/CAE modelling of a Wankel engine featuring tangential jet ignition to produce faster and more complete combustion.
Boretti, Alberto
Two Stroke Direct Injection Jet Ignition Engines for Unmanned Aerial Vehicles2015-01-24249/15/2015
Unmanned Aerial Vehicles (UAV) require simple and reliable engines of high power to weight ratio. Wankel and two stroke engines offer many advantages over four stroke engines. A two stroke engines featuring crank case scavenging, precise oiling, direct injection and jet ignition is analyzed here by using CAD, CFD and CAE tools. Results of simulations of engine performances are shown in details. The CFD analysis is used to study fuel injection, mixing and combustion. The CAE model then returns the engine performances over the full range of loads and speeds with the combustion parameters given as an input. The use of asymmetric rather than symmetric port timing and supercharging scavenging is finally suggested as the best avenue to further improve power density and fuel conversion efficiency.
Boretti, Alberto, Jiang, Shuheng
Simultaneous Observation of Combustion in Optical Rotary Engine by Bottom View and Side View2015-01-18919/1/2015
Combustion behavior in Rotary Engine (RE) is quite different from that in conventional reciprocating engines. Therefore, it is important to observe the combustion in RE. In the previous studies, an optical RE was developed, which enabled the observation of the flame propagation in the rotor rotating direction (side view). In the present study, modification was made to the optical RE so that the observation of the flame propagation in the rotor width direction (bottom view) became possible. By using two high-speed cameras, the combustion in RE was observed by bottom view and side view simultaneously. Consequently, it was found that the flame propagation in the rotor width direction is also important for better engine performance as well as that in the rotor rotating direction.
Karatsu, Yuichi, Minota, Shunki, Hashimoto, Hideki, Moriue, Osamu, Murase, Eiichi, Yun, Jyong-Ho, Kagawa, Ryoji
Modeling of the Rotary Engine Apex Seal Lubrication2015-01-20359/1/2015
The Wankel rotary engine is more compact than conventional piston engines, but its oil and fuel consumption must be reduced to satisfy emission standards and customer expectations. A key step toward this goal is to develop a better understanding of the apex seal lubrication to reduce oil injection while reducing friction and maintaining adequate wear. This paper presents an apex seal dynamics model capable of estimating relative wear and predicting friction, by modeling the gas and oil flows at the seal interfaces with the rotor housing and groove flanks. Model predictions show that a thin oil film can reduce wear and friction, but to a limited extent as the apex seal running face profile is sharp due to the engine kinematics. The seal-housing interface remains between the boundary and mixed lubrication regimes, which leads to large asperity contact pressure and therefore significant wear of the running face, and an effective friction coefficient that varies between 0.03 to 0.11 depending on speed and load.
Picard, Mathieu, Tian, Tian, Nishino, Takayuki
Rotary SI/CI combustion engines: A thing of the future?15OFHP02_012/1/2015
The internal combustion engine enjoys widespread use as an inexpensive and reliable power conversion system. While piston engines date back 150 years, various alternative engine architectures and cycles have been considered. Today's small piston engines can be inexpensive, and have suitable reliability to serve a variety of applications including scooters, motorcycles, ATVs, boats, lawn and garden equipment, and auxiliary power generation, not to mention small aircraft including UAVs. While piston engines enjoy prolific use, their efficiency is remarkably low. The Wankel rotary engine has some advantages that make it a formidable contender for some markets served by reciprocating engines. The piston in a four-stroke reciprocating engine momentarily comes to rest four times per cycle as its direction of motion changes. In contrast, the moving parts in a rotary engine are in continuous unidirectional rotational motion. However, the rotary type engine has some drawbacks, including fuel economy.
Development of a Small Rotary SI/CI Combustion Engine2014-32-010411/11/2014
This paper describes the development of small rotary internal combustion engines developed to operate on the High Efficiency Hybrid Cycle (HEHC). The cycle, which combines high compression ratio (CR), constant-volume (isochoric) combustion, and overexpansion, has a theoretical efficiency of 75% using air-standard assumptions and first-law analysis. This innovative rotary engine architecture shows a potential indicated efficiency of 60% and brake efficiency of >50%. As this engine does not have poppet valves and the gas is fully expanded before the exhaust stroke starts, the engine has potential to be quiet. Similar to the Wankel rotary engine, the ‘X’ engine has only two primary moving parts - a shaft and rotor, resulting in compact size and offering low-vibration operation. Unlike the Wankel, however, the X engine is uniquely configured to adopt the HEHC cycle and its associated efficiency and low-noise benefits. The result is an engine which is compact, lightweight, low-vibration, quiet, and fuel-efficient. Two prototype engines are discussed. The first engine is the larger X1 engine (70hp), which operates on the HEHC with compression-ignition (CI) of diesel fuel. A second engine, the XMv3, is a scaled down X engine (70cc / 3HP) which operates with spark-ignition (SI) of gasoline fuel. Scaling down the engine presented unique challenges, but many of the important features of the X engine and HEHC cycle were captured. Preliminary experimental results including firing analysis are presented for both engines. Further tuning and optimization is currently underway to fully exploit the advantages of HEHC with the X architecture engines.
Shkolnik, Alexander, Littera, Daniele, Nickerson, Mark, Shkolnik, Nikolay, Cho, Kukwon
The Influence of Some Synthetic Fuels on the Performance and Emissions in a Wankel Engine2014-01-261110/13/2014
Nowadays, there is a permanent need to develop alternative fuel production and combustion technologies. The general objective indicated in Directive 2009/28/EC for biofuels in Poland is application in transport 10% of renewable energy by 2020 and 20% by 2030. In Poland, it can be achieved by adding bio-components to liquid fuels. Flexible fuel vehicles are not as popular in Europe as in Brazil, so further ethanol processing is justified. The researched synthetic gasoline was obtained from bioethanol at the Ekobenz Company Ltd. in Poland. In 2008, Sasol launched its 100% synthetic jet fuel produced by CTL (Coal to Liquids). A variety of engine concepts was tested and evaluated in terms of the key criteria for use as a range extender developed by AVL Company. The Wankel engine has been selected for the vehicle prototype as the most compact and of excellent NVH behaviour. The use of this engine in light helicopters is also considered. The paper describes the combustion results of a synthetic fuel produced from bioethanol in the ETG (Ethanol to Gasoline) process. This type of fuel is totally alternative as it has no petroleum additives. The influence of some second-generation biofuels on emissions, fuel consumption and the characteristics of the Wankel engine was described. The combustion results were compared with those of gasoline. The emission test results were also presented for different mixtures of synfuels and gasoline. The tested object was a low intake, 4-stroke XR50 Wankel engine.
Siadkowska, Ksenia, Wendeker, Miroslaw, Majczak, Adam, Baranski, Grzegorz, Szlachetka, Marcin
A Heat Pipe Assisted Air-Cooled Rotary Wankel Engine for Improved Durability, Power and Efficiency2014-01-21609/16/2014
In this paper, we address the thermal management issues which limit the lifespan, specific power and overall efficiency of an air-cooled rotary Wankel engine used in Unmanned Air Vehicles (UAVs). Our goal is to eliminate the hot spots and reduce the temperature gradients in the engine housing and side plates by aggressive heat spreading using heat pipes. We demonstrate by simulation that, for a specific power requirement, with heat spreading and more effective heat dissipation, thermal stress and distortion can be significantly reduced, even with air cooling. The maximum temperature drop was substantial, from 231°C to 129°C. The temperature difference (measure of temperature uniformity) decreased by 8.8 times (from 159°C to 18°C) for a typical UAV engine. Our heat spreaders would not change the frontal area of the engine and should have a negligible impact on the installed weight of the propulsion assembly. We expect our approach could lead to a very significant reduction in thermal stress-induced warping which is primarily responsible for wear and high friction. With reduced friction and wear, the thermal efficiency of the rotary engine is increased, and the durability of the engine would be improved very significantly at the same time. Under proper thermal management, the Wankel engine could be run at a higher rpm to yield a higher specific power. Rotary engines represent a huge emerging market for aerospace as well as a myriad of commercial applications if key issues related to life, combustion efficiency, power density and specific fuel consumption can be improved.
Wu, Wei, Lin, Yeong-Ren, Chow, Louis
Hybrid-Electric, Heavy-Fuel Propulsion System for Small Unmanned Aircraft2014-01-22229/16/2014
A series hybrid-electric propulsion system has been designed for small rapid-response unmanned aircraft systems (UAS) with the goals of improving endurance, providing flexible and responsive electric propulsion, and enabling heavy fuel usage. The series hybrid architecture used a motor-driven propeller powered by a battery bank, which was recharged by an engine-driven generator, similar to other range-extended electric vehicles. The engine design focused on a custom, two-stroke, lean-burn, compression-ignition (CI), heavy-fuel engine, which was coupled with an integrated starter alternator (ISA) to provide electrical power. The heavy-fuel CI engine was designed for high power density, improved fuel efficiency, and compatibility with heavy fuels (e.g., diesel, JP-5, JP-8). Commercially available gasoline spark-ignition engines and heavy-fuel spark-ignition engines were also considered in the trade study. The series hybrid configuration allowed the engine to be mechanically decoupled from propeller, so that the engine could be operated at the load/speed condition for peak fuel-conversion efficiency. An energy-dense rechargeable battery pack was used to store energy and allow the UAS to operate with the engine shut off, which provided an engine-off operating mode. The ISA allowed re-starting the engine in flight without the need for a separate starter motor. Simulation-based design tools were developed, and trade studies were performed for the various system components. The series hybrid UAS outfitted with the custom diesel engine demonstrated endurance improvements, due to additional benefits netted from the improved engine efficiency. Development of the hybrid propulsion system is ongoing, with current efforts focused on reducing system mass, packaging, and gearing up for a future hardware demonstration.
Merical, Kyle, Beechner, Troy, Yelvington, Paul
The Radial Turbine for Small Turbocharger Applications: Evolution and Analytical Methods for Twin-Entry Turbine Turbochargers2014-01-16474/1/2014
In 1917, French Prof. Rateau built and operated the first turbocharger. He used an axial turbine because of existing experience from the steam turbine to drive a centrifugal compressor. From then on the axial turbine was improved regarding temperature capability and performance and is still the first choice for larger turbochargers today. From the beginning, multi-entry turbines, as discussed in the patent of Büchi in 1925, were applied to make use of the pulse effect and, thus, to improve the engine performance at low speed and during transient operation. Between 1936 and 1945, the radial turbine for gaseous substances was proposed and finally implemented for smaller units, mainly because of lower complexity and cost. From the beginning, variable nozzle turbines were designed and built but without entering mass production. Up until 1963, multi entry turbine housings for radial turbines, like the axial turbine variants, were solely segment controlled. The twin entry turbine patent for radial turbines was filed by Garrett in August 1963 and the turbochargers went into production the same year at Caterpillar. Today there is an increasing share of 4 cylinder gasoline engines that make use of the twin entry turbine feature. This paper proposes a gas stand analysis process to measure the behavior of these turbines under unequal flow conditions in an extended pressure ratio operating range. A special turbocharger test rig for low turbocharger speed was set up in addition to a friction test rig to extend the turbine map for part load and transient optimization and simulation. Friction measurements as function of speed and thrust load were performed to separate mechanical from aerodynamic performance. A method to describe and analyze twin flow turbines is presented. In addition, backflow in the turbine was measured. These methods should help to improve the turbocharger behavior and to achieve refined turbocharger-engine interaction.
Schorn, Norbert A.
Visualization of the Rotary Engine Oil Transport Mechanisms2014-01-16654/1/2014
The rotary engine provides high power density compared to piston engine, but one of its downside is higher oil consumption. In order to better understand oil transport, a laser induced fluorescence technique is used to visualize oil motion on the side of the rotor during engine operation. Oil transport from both metered oil and internal oil is observed. Starting from inside, oil accumulates in the rotor land during inward motion of the rotor created by its eccentric motion. Oil seals are then scraping the oil outward due to seal-housing clearance asymmetry between inward and outward motion. Cut-off seal does not provide an additional barrier to internal oil consumption. Internal oil then mixes with metered oil brought to the side of the rotor by gas leakage. Oil is finally pushed outward by centrifugal force, passes the side seals, and is thrown off in the combustion chamber.
Picard, Mathieu, Hidaka, Hiroyuki, Tian, Tian, Nishino, Takayuki, Arai, Eiji, Ohkubo, Masaki
Oil Transport Cycle Model for Rotary Engine Oil Seals2014-01-16644/1/2014
The rotary engine provides high power density compared to piston engine, but one of its downside is higher oil consumption. A model of the oil seals is developed to calculate internal oil consumption (oil leakage from the crankcase through the oil seals) as a function of engine geometry and operating conditions. The deformation of the oil seals trying to conform to housing distortion is calculated to balance spring force, O-ring and groove friction, and asperity contact and hydrodynamic pressure at the interface. A control volume approach is used to track the oil over a cycle on the seals, the rotor and the housing as the seals are moving following the eccentric rotation of the rotor. The dominant cause of internal oil consumption is the non-conformability of the oil seals to the housing distortion generating net outward scraping, particularly next to the intake and exhaust port where the housing distortion valleys are deep and narrow. Simulation with housing transverse waviness shows that increasing spring force can lead to an unexpected increase in internal oil consumption. Roughness and O-ring friction can also increase significantly internal consumption for small housing distortion. Calculated internal oil consumption is on the same order of magnitude as measurement.
Picard, Mathieu, Baelden, Camille, Tian, Tian, Nishino, Takayuki, Arai, Eiji, Hidaka, Hiroyuki
Into the DEAP14AERD03_013/5/2014
The Distributed Electrical Aerospace Propulsion project looks toward a future optimized integrated propulsion system that will allow cleaner, quieter, and more efficient performance to be incorporated into a radically innovative airframe that will feature enclosed electrically powered fans. Tucked away in the static aircraft park at last year's Paris Air Show, totally dwarfed by a massive Airbus A380, was a small two-seat demonstrator aircraft, the E-Fan. Looking at first glance like many light-weight modern composite aircraft, the E-Fan is actually a much more significant creation for it represents the first fully electric general aviation training aircraft. The prime driving force for such technology demonstrators is the need to continue to reduce carbon dioxide emissions. While today's air transport sector is responsible for “a mere” 2% of man-made CO2 emissions worldwide, the political pressure globally for continued improvements in environmental standards will just keep on growing. Conventional aero engines and airframes, with more geared turbofans, advanced turbofans, and possibly open rotor fans, will most likely see an evolutionary development path continue in the short term, but to achieve a further 70% cut in CO2, a 90% cut in NOx, and 75% reduction in external noise, compared to standards in 2000, more radical innovation will be needed.
Gardner, Richard
Single Cylinder 25kW Range Extender as Alternative to a Rotary Engine Maintaining High Compactness and NVH Performance2013-32-913210/15/2013
Due to the restricted capacity of today's battery systems and therefore limited operating range of electric vehicles (EV), several solutions for recharging the energy storage during driving already have been published and still are the subject of extensive development programs. One example is the Range Extender (RE), which is a combination of an internal combustion engine (ICE) with a generator unit, which serves the purpose of a power back-up in case of a battery with low state of charge (SOC), without any direct connection to the drivetrain. For this kind of RE-application, different boundary conditions are very important. Especially in EVs topics like packaging space and NVH behavior play a main role. To fulfill these important characteristics, AVL has developed a Wankel-RE unit in which the generator is driven directly from the eccentric shaft of the rotary-piston ICE. With such an arrangement and the correct balancing of the power unit directly on the rotor of the generator, a very small packaging size in combination with smooth and silent running can be achieved and fulfills the most important characteristics for an electric vehicle. Besides these outstanding attributes, and although RE rotary engine concepts have proven to have acceptable fuel efficiency even under stringent emission challenges, the main drawback of rotary engines can be seen in non-availability of large scale manufacturing devices for specific rotary engine components. Therefore, the industry would prefer and is demanding solutions based on conventional piston engines. Following this request, AVL has developed an alternative concept which shows the potential of substituting the Wankel engine by a common single-cylinder piston engine within the same tight packaging boundaries. By means of a tailor made balancing system, the mass forces and torsional vibration have been brought to a level which is competitive to the excellent NVH behavior of the Wankel engine. This paper shows the development of this concept, the resulting design and packaging in combination with simulation results confirming the NVH behavior of the single cylinder RE.
Hubmann, Christian, Beste, Frank, Friedl, Hubert, Schoffmann, Wolfgang
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