Browse Topic: Two stroke engines

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Basic Investigation of Thermodynamic Effects on a Hydrogen Two-Stroke Engine2024-32-003904/18/2025
The spark ignited two-stroke engine, as a cost-efficient power unit with low maintenance demand, is used millionfold for the propulsion of hand-held application, motorcycles, scooters, boats and others. The outstanding power to weight ratio is the key advantage for two-stroke engines. However, poor exhaust emissions, caused by high scavenge losses, especially on port controlled two-stroke engines, and a low efficiency are disadvantages of this combustion process. Under the aspect of increasing environment- and health awareness, the two-stroke technology driven with fossil resources, shows no future advantage. The anthropogenic climate change force for sustainable development of combustion engines whereby reduction of fuel consumption or usage of alternative fuels is an important factor. Best way of a decarbonization to fulfil future climate goals is the utilization of non-carbon fuels. In this field of fuels, hydrogen, with its high energy content and close inexhaustible availability
Yasuda, Terutaka, Oswald, Roland, Kirchberger, Roland
Enhancements in Hydrogen Low Pressure Injection on Small Two-Stroke Engines2024-32-004704/18/2025
The use of small 2-stroke crankcase scavenged engines running on hydrogen is very attractive for low power rates, when low cost and compact dimensions are the fundamental design constraints. However, achieving optimal performance with hydrogen fuel presents challenges, including uneven air-fuel mixtures, fuel losses, and crankcase backfiring. This research focuses on a small 50cc 2-stroke loop-scavenged engine equipped with a patented Low-Pressure Direct Injection (LPDI) system, modified for hydrogen use. Experimental results demonstrate performance comparable to the gasoline counterpart, but further optimizations are needed. Consequently, CFD-3D simulations are employed to analyses the injection process and guide engine development. The numerical analysis focuses on a fixed operating condition: 6000 rpm, Wide Open Throttle (WOT), with a slightly lean mixture and injection pressure fixed at 5 bar. A numerical model of the entire engine is set up with the primary objective of improving
Caprioli, Stefano, Schoegl, Oliver, Oswald, Roland, Kirchberger, Roland, Mattarelli, Enrico, Rinaldini, Carlo Alberto
test download manager cache issue 12/27/2023 at 9 amSAE-PP-0908512/27/2023
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Mutagaana, Festo
Regression 11/1/23SAE-PP-0892211/01/2023
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Mutagaana, Festo
Effects of Port Angle on Scavenging of an Opposed Piston 2-Stroke Engine 2022-01-070703/29/2022
Opposed-Piston 2-Stroke (OP2S) engines have the potential to achieve higher thermal efficiency than a typical diesel engine. However, the uniflow scavenging process is difficult to control over a wide range of speeds and loads. Scavenging performance is highly sensitive to pressure dynamics, port timings, and port design. This study proposes an analysis of the effects of port angles on the scavenging performance of an opposed-piston 2-stroke engine via simulation. A CFD model of a three-cylinder opposed-piston 2-stroke was developed and validated to experimental data collected by Achates Power Inc. One of the three cylinders was then isolated in a new model and simulated using cycle-averaged and cylinder-averaged initial/boundary conditions. This isolated cylinder model was used to efficiently sweep port angles from 12.5 deg to 30 deg at different pressure ratios. Results indicate that scavenging performance is correlated with the bulk swirl ratio generated by these port angles
O'Donnell, Patrick Christopher, Gandolfo, John, Gainey, Brian, Vorwerk, Erik, Prucka, Robert, Filipi, Zoran, Lawler, Benjamin, Hessel, Randy, Kokjohn, Sage, Huo, Ming, Salvi, Ashwin
Numerical Investigation of the Effect of Engine Speed and Delivery Ratio on the High-Speed Knock in a Small Two-Stroke SI Engine2022-32-008001/09/2022
Knocking occurs within the high-speed range of small two-stroke engines used in handheld work equipment. High-speed knock may be affected by the engine speed and delivery ratio. However, evaluation of these factors independently using experimental methods is difficult. Therefore, in this study, these factors were independently evaluated using numerical calculations. The purpose of this study was to clarify the mechanism by which the intensity of high-speed knocking that occurs in small two-stroke engines becomes stronger. The results suggest that temperature inhomogeneity due to insufficient mixing of fresh air and previously burned gas may induce high-speed knocking in the operating range at high engine speeds.
Eto, Kuniyoshi, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Yamada, Toshio
Study of Pre-chamber Jet Combustion Behavior using a Small Two-stroke Optically Accessible Engine2022-32-007601/09/2022
A small 2-stroke engine can be an effective power source for an electric generator mounted on a series hybrid electric vehicle. In recent years, a technology referred to as pre-chamber jet combustion has attracted attention as a means of enhancing thermal efficiency by improving mixture ignitability. In this study, experiments were conducted to investigate differences in combustion behavior between the application of spark-ignited (SI) combustion and pre-chamber jet combustion to a small, two-stroke engine. The experimental equipment used was a two-stroke, single-cylinder, optically accessible engine with a displacement of 63.3 cm3. Differences between conventional SI combustion and pre-chamber jet combustion were examined by means of in-cylinder pressure analysis, in-cylinder combustion visualization and image processing software. The diameter of the connecting orifice of the pre-chamber was varied between two types. The results revealed that the combustion time and indicated mean
DEUSHI, Takato, NAKA, Takuma, TSUJIGUCHI, Tatsuya, IIJIMA, Akira, YAMAGUCHI, Shiro, KUROIWA, Minoru, ETO, Kuniyoshi
Increased Reliability and Usability through the Introduction of a User Interface Module for Hand-Held Small Engines2022-32-004801/09/2022
Mobile hand-held or back-carried small engines must be weight-optimized due to their operability. At the same time there is enormous cost pressure within this market segment. Therefore, not all comfort and additional functions to increase user-friendliness can be adopted from the stationary applications. These include, for example, electric starting devices or additional sensors and actuators that take over advanced control processes to prevent or detect and report user or system errors. In the mobile small engine segment, this situation leads to the problem that the systems have many requirements for the user. These include, for example: physical ability to operate a pull starter know-how about the functioning of a combustion engine (2-stroke and 4-stroke) know-how for detecting failures and remedial actions If the knowledge about the behavior of engines is not given, or failures are overlooked, this automatically leads to a form of physical strain on the user due to the many
Öztürk, Bahattin, Stoffregen, Thorsten
E-Fuel applications in Non Road Mobile Machinery2022-32-007401/09/2022
Professional users in particular will continue to rely on internal combustion engine drives in the future due to high power requirements and high daily energy consumption. Especially if they have to work in rural areas without the possibility of recharging batteries, such as in forestry or maintenance of road verges or railway lines. For these applications, it must be possible to run sustainable fuels for defossilization and drastically reduced CO2 emissions. This paper provides insights into a possible future fuel market and describes its evolution towards a more sustainable future from the perspective of a handheld equipment manufacturer. As developments in the fuel market are currently difficult to predict, manufacturers of hand-held power tools with combustion engines need to be prepared for changes in the composition of fuels that might become available on the market. This paper presents the engine performance results of both a 2-stroke engine and a 4-stroke engine, each with
von Gaertringen, Christoph Hiller, Schwerin, René, Schweiger, Stefan, Kölmel, Armin, Lochmann, Holger, Schmidt, Stephan, Zinner, Christian, Kirchberger, Roland, Gschanes, Dominik
Impact of Zero CO 2 Fuels on Engine Behaviour of Two-Stroke Engines in Hand-Held Powertools2022-32-006101/09/2022
One possible path to reduce the CO2 emissions of hand-held power tools are fuels with different amount of renewable content. Within this paper test bench measurements on a small two-stroke engine were carried out. We are trying to reduce CO2 emissions by using fuels which absorbed CO2 from the air during its lifetime or production, so called Zero CO2 fuels The focus was set on the investigation of combustion behaviour, performance and emissions of Zero CO2 fuels in comparison to commonly available fuels. For our measurements we chose a 46 cc serial engine, which was slightly modified for scientific research. This paper shows findings on effects of renewable fuels on engine characteristics. Additionally, the chemical properties of each fuel were investigated in order to form a comprehensive picture, together with the performed dyno measurements.
Gschanes, Dominik, Schmidt, Stephan, Kirchberger, Roland
Experimental Assessment of the Heat Losses Due to the Adoption of a Passive Prechamber in a Jet Ignition 4-Stroke Engine2022-32-006001/09/2022
The passive prechamber concept, known as jet ignition (JI), represents an effective way to promote mixture ignitability, reduce combustion duration and extend knock limits in spark ignition engines. These aspects allow the adoption of a higher compression ratio and the operation in lean conditions, thus increasing thermal efficiency. Despite the potential benefits, the literature typically shows that in port fuel injection (PFI) engines at full load a shorter combustion duration does not necessarily translate in a growth of IMEP. Despite this issue has been frequently observed, the causes have not been fully explained. In previous works some of the authors supposed that the gain in indicated efficiency could be counterbalanced by the lower adiabatic efficiency, as a result of the higher heat exchange coefficient and the additional heat transfer from the prechamber surface. This paper thus aims at explaining the thermal losses of a single-cylinder four-stroke PFI engine, both in
Romani, Luca, Bosi, Lorenzo, Ciampolini, Marco, Raspanti, Sandro, Balduzzi, Francesco, Ferrara, Giovanni, Trassi, Paolo, Fiaschi, Jacopo, Carpentiero, Davide, Fabbri, Alessandro
On the Potential of Transfer Port Injection Strategies for a Two-Stroke Engine2022-32-005701/09/2022
The main drawback of an in-cylinder Low Pressure Direct Injection (LPDI) in a two-stroke engine is the difficulty of achieving a satisfactory vaporization level in low load conditions. The liquid droplets are characterized by large diameters and, when the temperature level and the velocity of the scavenging flow field are low, the time needed for the droplet vaporization and the homogenization with fresh air becomes too long to guarantee a suitable mixture formation. A transfer port injection allows a higher flexibility, due to the possibility of performing a mixed injection either directly in the cylinder or indirectly in the crank case, depending on the load request or engine speed. Also, an even lower injection pressure can be adopted with respect to an in-cylinder LPDI injection, which is relevant in case of lightweight and low power applications. On the other hand, the time available for the direct in-cylinder injection is limited to the scavenge phase. In the present work, a
Balduzzi, Francesco, Romani, Luca, Ferrara, Giovanni, Trassi, Paolo, Fiaschi, Jacopo
Development of a Rotary Valve Engine for Handheld Equipment2022-32-002801/09/2022
A multi-position 4-stroke piston engine utilizing a novel rotary valve system was developed for handheld outdoor power equipment applications such as chainsaws, brush cutters, and string trimmers. The purpose of the project was to create a low-emission 4-stroke engine with 2-stroke performance levels including high RPM limits and power output. This was accomplished using a rotary valve system in lieu of the typical poppet valves of traditional 4-stroke engines. The prototype was then incorporated into a functional product for overall performance evaluation. Three prototype 45cc rotary valve engines were developed and tested in both real-world usage and on laboratory engine dynamometers to measure power output and emissions levels. The rotary valve system provided the ability to achieve high RPM limits without the risk of valve float, delivered improved volumetric efficiency, and exhibited lower vibration and noise levels with improved power density over traditional 4-stroke valvetrains
Garrett, Norman H., Uddin, Mesbah, Bergman, Mikael, Purvis, Garrett, Vaseleniuck, Darrick, Cordier, Dan
Describing the Auto-Ignition Quality in Small, Air Cooled, Two Stroke Engines2022-32-006301/09/2022
Auto-ignition quality is one of the most important properties in gasoline. Auto-ignition quality is today described by the Motor Octane Number (MON) and the Research Octane Number (RON). For modern, light duty, gasoline engines it has been quite well established that RON is the most accurate number. However, no study has been performed on hand held forest and garden products, such as chainsaws. Is the auto-ignition quality best described in the same way for these engines as for light duty engines? In this paper, a matrix of six different fuels with different combinations of MON and RON values were tested on a Husqvarna 550 XP Mark II, a modern air cooled, sequential stratified scavenging 2-stroke chainsaw engine. Ignition timing sweeps were performed and knock limited spark advance (KLSA) were calculated. Then the data has been analyzed with a multi-variate analysis of KLSA against both MON and RON to try to determine how MON and RON should be combined to best describe the anti-knock
Risberg, Per, Elm, Thomas, Bergman, Mikael, Hellquist, Fredrik, Karvo, Anna, Tripathi, Rupali
Effects of Ignition Timing and Fuel Chemical Composition on Autoignition Behavior and Knocking Characteristics under Lean Conditions2022-32-007001/09/2022
This study focused on autoignition behavior and knocking characteristics. Using an optically accessible engine, autoignition behavior was observed over the entire bore area, and the relationship between autoignition behavior and knocking characteristics was clarified on the basis of visualized combustion images and frequency analysis of the in-cylinder pressure waveform. In addition, chemical kinetic simulations were used to investigate the effects of different fuel chemical compositions on combustion and autoignition characteristics under equivalent octane ratings. The results showed that the rate of autoignition development has a significant effect on knocking intensity. In addition, the ρ1,0 mode is the dominant vibration mode caused by knocking, regardless of the location of autoignition. It can be inferred that strong knocking is caused by multiple vibration modes. Furthermore, chemical kinetic simulation results and experimental data show that different fuel chemical compositions
Shirane, Kaede, Kimura, Toshiki, Nakamura, Sota, Furusyo, Karin, Iijima, Akira
Impacts of methanol blended fuels on emissions and operating performance of two-wheelers2022-32-002101/09/2022
Aiming to investigate the influence of methanol blends on the combustion process of a PFI four-stroke boxer engine, four mixtures of pure methanol and oxygen-free gasoline (M0) are prepared. The fuels tested are labelled by M15, M25, M35 and M50, where the number represents the percentual in volume of methanol within the mixture. In order to establish a base for comparisons, standard gas-station gasoline (S95) is also tested. Backwards compatibility is evaluated through test-bed measurements, when the engine operates without any modifications in the ECU. Over the whole operational area of the engine map, M15 and M25 can be used in the motorcycle application. Raw emissions of THC, CO2, CO and NOx decrease with the increase of methanol for almost all the conditions tested. It is observed that knock resistance is higher for higher methanol contents. At WOT, power is increased with the methanol proportion, being M50 and M35 more powerful than standard gasoline. Indicated efficiency also
Pellizzaro Batalha, Guilherme, Schmidt, Stephan, Kirchberger, Roland
Power and Torque Determination for UAS Engines Having Maximum Power Ratings at or Below 22.4 kWARP6971 (Current)04/07/2021
This recommended practice is applicable to reciprocating engines powering unmanned aerial vehicles (UAV) having rated power values less than 22.4 kW, and which are not to be used for human transport.
E-39 Unmanned Aircraft Propulsion Committee
Power and Torque Determination for UAS Engines Having Maximum Power Ratings at or Below 22.4 kWARP6971-TEST-REC (Historical)04/07/2021
This recommended practice is applicable to reciprocating engines powering unmanned aerial vehicles (UAV) having rated power values less than 22.4 kW, and which are not to be used for human transport.
E-39 Unmanned Aircraft Propulsion Committee
7.0.101 - A New Image De-hazing Method for Safety Critical ADAS ApplicationsSAE-PP-0027702/04/2021
Driver safety and Advanced Driver Assistance Systems (ADAS) is gaining lot of importance these days. In some countries, there are strict regulations in place which mandate the use of certain ADAS features in automobiles. However, as the need for these safety critical systems increases, the challenges associated also increase. These challenges can arise due to technology, human factors or due to nature. In countries like India, where one can expect different weather conditions with changing geography, the associated challenges are mainly due to the natural factors like haze, fog, rain and smoke. This poses a challenging problem in terms of visibility for the drivers as well as in vision based ADAS; thereby, leading to many fatal road accidents. In this paper, a novel pre-processing technique, which addresses the interesting problem of enhancing the perceptual visibility of an image that is degraded by atmospheric haze, is proposed. The solution to this problem is presented by combining
Lname, Fname
6.0.116 - Development of 6 Years Old Child Virtual Model by Automatic ScalingSAE-PP-0027102/04/2021
Traffic accidents cause one of the highest numbers of severe injuries in the whole population. The numbers of deaths or seriously injured citizens prove that traffic accidents and their consequences are still a serious problem to be solved. A lot of effort is devoted to both passive and active safety systems development. The transportation standards usually define safety requirements by regulations (e.g. ECE-R94, 96/79/EC and ECE-R95, 96/27/EC in Europe) with specific dummies for children to be used. The dummies include hardware sensors for monitoring accelerations, loads and other signals and each dummy is developed for a specific scenario, but there are limitations of these dummies, such as only a specific age or calibration just for a specific test. Taking into account that the consequence of a traffic accident is highly influenced by the stature of the body, virtual human body models, including those for children, start to play a significant role because they can be scaled or even
Mutagaana, Festo
6.0.101 - Piston Sealing System Structure Design for Automobile's Lightweight Auto-TransmissionSAE-PP-0025702/04/2021
Current automobile's auto-transmission has problems of defects and cost reduction because of welding process and very complicated assembly process due to individualized transmission piston and sealing components. Also, size and heavy weight of transmission piston components are the source of low mileage because they are made of aluminum, steel material. In this study, therefore, we perform structure design for piston sealing system which integrates piston and sealing material for automobile's lightweight auto-transmission. Also performed stress analysis through finite element analysis to secure required suitable strength when internal pressure is applied after assemble.
Mutagaana, Festo
Near-TDC flow field analysis in a high-tumble production SI engine using endoscopic high-speed Particle Image Velocimetry (eHS-PIV)SAE-PP-0025102/03/2021
The latest generation spark-ignition (SI) engines implement high tumble flow design to achieve unprecedented high brake thermal efficiency of over 40%, which will continue to play an important role in both conventional and electrified future vehicles. To maximise the potential of high-tumble SI engines, there is a clear need for in-cylinder flow and flame analysis conducted timely in a realistic environment. For the first time, this study meets this need by performing innovative endoscopic imaging of flow fields and flame inside the cylinder of a selected production engine using a particle image velocimetry (PIV) laser and high-speed camera system operated at 35 kHz. Through this timeresolved, two-dimensional measurement of the realistic in-cylinder phenomenon, many new findings have been achieved. Regarding the tumble vortex, its centre is seen more shifted to the exhaust valve side, which is related to an asymmetric, “surging” flow structure formed during the upward motion of the
Anthony, Lindsay
2.0.101 - Experimental Study of cooling of Continuously Variable Transmission (CVT) in ScooterSAE-PP-0021002/01/2021
The continuously variable transmission (CVT), which was conceptualized more than 500 years ago, is just now beginning to replace traditional transmissions in some automobiles. It is mostly used in scooter transmission. Engine power is transmitted to wheel through belt drive between two pulleys. The diameter of belt contact with pulley can change continuously and hence provide infinite gear ratios between driver and driven shafts. This technology leads to a smoother ride of vehicle. Heat is generated inside CVT due to friction between drive belt and clutch pulley. Amount of heat generated is even more due to clutch slippage during acceleration and deceleration. This will affect the service life of CVT components such as front movable drive (FMD), clutch pulley, clutch outer, and belt. In scooters generally, air cooling is preferred over liquid cooling. Cooling is achieved by incorporating centrifugal fan inside CVT housing. For better durability/service life, the degree of heat
Mutagaana, Festo
Improvement of Working Parameters in an Opposed Piston CI Two-Stroke Engine by Modelling Research2020-01-206209/15/2020
Two-stroke opposed piston engines (2sOPEs) have great potential for industrial applications due to their simple design, technology and high efficiency, particularly with a turbocharging system. The paper presents possibilities for altering 2sOPE working parameters by changing geometrical parameters and boosting parameters. Obtaining higher engine efficiency is realised by altering the crank phase shift of the exhaust piston in relation to the transfer piston. It has been assumed that only the piston of the exhaust cylinder changes its position relative to the piston in the cylinder with transfer ports. Modifying the scavenging process by changing pistons’ position through connecting with two crankshafts enables asymmetrical scavenging timing. Closing the exhaust ports before the compression process and extending the time allotted to empty exhaust gases from the cylinder provides greater engine work, and a high boost ratio increases engine power. This type of engine was recently
Mitianiec, Wladyslaw
Research of the Gas Fuel Supply Process on the Compression Stroke in Ship’s Low-Speed Gas-Diesel Engines2020-01-210709/15/2020
In connection with the tightening of environmental standards, the leading manufacturers of marine low-speed engines are carrying out intensive work on their conversion to gas fuels. Due to the design features in this class of engines, only internal mixture formation is possible. For the organization of which two different approaches are possible. To date, only two are currently implemented. MAN started production of engines with gas fuel supply to the working cylinder under high pressure at the end of the compression stroke, and WinGD under low pressure at the beginning of the compression stroke. The analysis, performed by the authors, showed, that increasing the pressure before the gas supplying mechanisms to 3.5...6.0 MPa can reduce the residence time of the gas-air mixture in the working cylinder and reduce the likelihood of detonation combustion. The supply of gas fuel to the working cylinder with a changing back pressure significantly affects on the flow characteristics of the gas
Belousov, Evgen, Marchenko, Andrii, Gritsuk, Igor V., Savchuk, Volodymyr, Bulgakov, Nickolay, Mitienkova, Vira, Ahieiev, Maksym, Samarin, Oleksandr, Vrublevskyi, Roman, Volodarets, Mykyta, Kalashnikov, Yevhen, Pronin, Sergii
Review of Additive Manufacturing for Internal Combustion Engine Components03-13-05-003909/09/2020
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
Gray, Jamee, Depcik, Christopher
The IC future points to more downsizing, lean mixtures20AUTP09_0909/01/2020
Three engineers from the front lines of advanced internal-combustion (IC) engine development affirmed that despite the industry's promotion of a battery-electric future for light-vehicle propulsion, committed R&D continues for IC. They said work is focused on incremental enhancement to IC efficiency and reduction in greenhouse-gas emissions, including oxides of nitrogen (NOx). The engineers participated in a recent webinar as part of the WCX Digital Summit, a series of video presentations, speeches and webinars replacing the in-person programming planned for SAE's April WCX 2020 conference that was cancelled because of the COVID-19 outbreak.
Visnic, Bill
Measurement of Fuel Distribution in a Small PFI Spark-Ignition Engine Using Tracer PLIF2020-01-078604/14/2020
The distribution of fuel-air mixture inside the engine cylinder strongly influences the combustion process. Planar laser-induced fluorescence (PLIF) is commonly used for fuel distribution measurement, however, it is mostly reported on moderate- to large-sized engines. In the present work, PLIF is applied to measure the fuel distribution inside the cylinder of a small, four-stroke, port-fuel-injection (PFI), spark-ignition engine with displacement volume of 110 cm3. Iso-octane was used as the base fuel, and 3-pentanone (15% by volume) was added as a fluorescent tracer in the base fuel. The effect of equivalence ratio, considering ϕ = 1.2, 1.0, and 0.8, on in-cylinder fuel distribution was studied with low throttle opening of 25% at 1200 rpm. PLIF images were recorded at different crank angle degrees during both intake and compression strokes over a swirl measurement plane located at the TDC position. It was found that the fuel stratification was present from intake to even late
Garg, Shubham, Mittal, Mayank, Sahu, Srikrishna, Lakshminarasimhan, V
Initial Investigations into the Benefits and Challenges of Eliminating Port Overlap in Wankel Rotary Engines2020-01-028004/14/2020
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
Turner, James, Turner, Matthew, Vorraro, Giovanni, Thomas, Toby
Optical Characterization of the Combustion Process inside a Large-Bore Dual-Fuel Two-Stroke Marine Engine by Using Multiple High-Speed Cameras2020-01-078804/14/2020
Dual-fuel engines for marine propulsion are gaining in importance due to operational and environmental benefits. Here the combustion in a dual-fuel marine engine operating on diesel and natural gas, is studied using a multiple high-speed camera arrangement. By recording the natural flame emission from three different directions the flame position inside the engine cylinder can be spatially mapped and tracked in time. Through space carving a rough estimate of the three-dimensional (3D) flame contour can be obtained. From this contour, properties like flame length and height, as well as ignition locations can be extracted. The multi-camera imaging is applied to a dual-fuel marine two-stroke engine, with a bore diameter of 0.5 m and a stroke of 2.2 m. Both liquid and gaseous fuels are directly injected at high pressure, using separate injection systems. Optical access is obtained using borescope inserts, resulting in a minimum disturbance to the cylinder geometry. In this type of engine
Hult, Johan, Matamis, Alexios, Baudoin, Eric, Mayer, Stefan, Richter, Mattias
The Use of Piezoelectric Washers for Feedback Combustion Control2020-01-114604/14/2020
The use of piezoelectric cylinder pressure sensors is very popular during engine testing, but cylinder pressure information is becoming mandatory also in several on-board applications, where Low Temperature Combustion (LTC) approaches require a feedback control of combustion, due to poor combustion stability and the risk of knock or misfire. Several manufacturers showed the capability to develop solutions for cylinder pressure sensing in on-board automotive and aeronautical applications, and some of them have been patented. The most straight-forward approach seems the application of a piezo-electric washer as a replacement of the original part equipping the spark plug; the injector could also be used to transfer the cylinder pressure information to the piezoelectric quartz, in diesel or Gasoline Direct Injections (GDI) engines. The paper describes the features of signals acquired using piezoelectric washers, discussing possible applications, highlighting the factors which impact the
Corti, Enrico, Abbondanza, Marco, Ponti, Fabrizio, Raggini, Lorenzo
Pre-design Investigation of Resonant Frequency Effects on Gas Exchange Efficiencies of a One-kW Natural-Gas Linear Engine Alternator2020-01-048804/14/2020
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
Zamani Meymian, Nima, Darzi, Mahdi, Johnson, Derek, Famouri, Parviz
Downsized-Boosted Gasoline Engine with Exhaust Compound and Dilute Advanced Combustion2020-01-079504/14/2020
This article presents experimental results obtained with a disruptive engine platform, designed to maximize the engine efficiency through a synergetic implementation of downsizing, high compression-ratio, and importantly exhaust-heat energy recovery in conjunction with advanced lean/dilute low-temperature type combustion. The engine architecture is a supercharged high-power output, 1.1-liter engine with two-firing cylinders and a high compression ratio of 13.5: 1. The integrated exhaust heat recovery system is an additional, larger displacement, non-fueled cylinder into which the exhaust gas from the two firing cylinders is alternately transferred to be further expanded. The main goal of this work is to implement in this engine, advanced lean/dilute low-temperature combustion for low-NOx and high efficiency operation, and to address the transition between the different operating modes. Those include well-mixed charge compression-ignition at low-load, and a mixed-mode combustion at
Dernotte, Jeremie, Najt, Paul M., Durrett, Russell P.
Numerical Simulation and Optimization for Combustion of an Opposed Piston Two-Stroke Engine for Unmanned Aerial Vehicle (UAV)2020-01-078204/14/2020
An opposed piston two-stroke engine is more suitable for use in an unmanned aerial vehicle because of its small size, excellent self-balancing, stable operation, and low noise. Consequently, in this study, based on experimental data for a prototype opposed piston two-stroke engine, numerical simulation models were established using GT-POWER for 1D simulation and AVL-FIRE for 3D CFD simulation. The mesh grid and solver parameters for the numerical model of the CFD simulation were determined to guarantee the accuracy of the numerical simulation, before studying and optimizing the ventilation efficiency of the engine with different dip angles. Furthermore, the fuel spray and combustion were analyzed and optimized in details.
Zhou, Lei, Li, Hao, Chen, Zeyu, Zhao, Zhenfeng, Zhang, Fujun
The Study on the Characteristics of Different Intake Port Structures in Scavenging and Combustion Processes on a Two-Stroke Poppet Valve Diesel Engine2020-01-048604/14/2020
Two-stroke engines have to face the problems of insufficient charge for short intake time and the loss of intake air caused by long valve overlap. In order to promote the power of a two-stroke poppet valve diesel engine, measures are taken to help optimize intake port structure. In this work, the scavenging and combustion processes of three common types of intake ports including horizontal intake port (HIP), combined swirl intake port (CSIP) and reversed tumble intake port (RTIP) were studied and their characteristics are summarized based on three-dimensional simulation. Results show that the RTIP has better performance in scavenging process for larger intake air trapped in the cylinder. Its scavenging efficiency reaches 84.7%, which is 1.7% higher than the HIP and the trapping ratio of the RTIP reaches 72.3% due to less short-circuiting loss, 11.2% higher than the HIP. The RTIP also behaves better in mixture formation and combustion performance with higher air utilization and superior
Dong, Mengmeng, Pei, Yiqiang, Qin, Jing, Wang, Chenxi, Zhang, Yan, Liu, Wei, Zhang, Shuyong
Waste Heat Recovery System Thermal ManagementJ3173_202002 (Current)02/24/2020
Waste heat recovery (WHR) systems are used in vehicles and machines powered by internal combustion (IC) engines to capture unused/waste heat and utilize it thereby reducing fuel consumption and emissions by improving efficiency. This information report is a survey of the waste heat recovery methods that include the use of heat exchangers.
Cooling Systems Standards Committee
Intermittent Injection for a Two-Stroke Direct Injection Engine2019-32-052401/24/2020
Cycle-to-cycle variation is one of the main factors for high fuel consumption and emissions of a two-stroke engine during the low-load and low-speed running. The increase of residual gas ratio due to the lower delivered amount of fresh scavenging air leads to a lower flame front speed and, therefore, to a slow combustion or even misfiring. The consequence is a very high level of unburnt hydrocarbons, since a large amount of fuel does not take part in the combustion process. The use of a direct injection system allows a more flexible management of the injection of fuel over subsequent engine cycles. Under a low-load condition, the low request in terms of brake mean effective pressure (BMEP) can be achieved by performing a load control based on an intermittent injection, thus reducing the need for intake throttling and avoiding the loss of fresh fuel resulting from cycles without combustion. In more detail, the supply of fuel to the combustion chamber can be skipped for one or more
Balduzzi, Francesco, Romani, Luca, Bosi, Lorenzo, Ferrara, Giovanni
Calcium in Oil Effects on Pre-ignition of Two-stroke Engine2019-32-057901/24/2020
Investigations of the influence of calcium on pre-ignition in a two-stroke engine have shown that the lower the calcium concentration, the lower the frequency of pre-ignition. Pre-ignition problems can occur in small, air-cooled, two-stroke engines such as a chainsaw. In contrast, in a supercharged automobile engine, it has been reported that calcium, which is a detergent component in engine oil, causes low-speed pre-ignition. The oil for two-stroke engines also contains calcium and is mixed with the fuel and lubricated before being supplied to the combustion chamber. This makes, two-stroke engines more likely to be affected by oil components. Based on this, we investigated the influence of calcium on pre-ignition of a two-stroke engine. First, we investigated driving conditions in which pre-ignition is likely to occur, such as warming up the engine. Under this condition, oil with calcium concentrations ranging from 0 ppm to 1,500 ppm were tested at a mixing ratio of 2%. The results
Eto, Kuniyoshi, Kihara, Masaki
Effect of Two-point Ignition on Knocking in Spark-assisted HCCI Combustion using an Optically Accessible Engine2019-32-056201/24/2020
This study investigated the effect of the ignition positions in a two-point ignition system on homogeneous charge compression ignition (HCCI) combustion. Focus was put on controlling the ignition timing, and changes in combustion behavior due to the ignition positions were observed on the basis of in-cylinder combustion visualization and pressure analysis. Experimental results showed that misfire occurred under a condition where the temperature rise time was short and combustion became unstable. In contrast, combustion was stable under a condition where the rise time was sufficiently long and autoignition developed along the cylinder wall. As a result, knocking intensity was reduced by stable combustion.
Yoshida, Kojiro, Furusho, Takuma, Abe, Yosuke, Iimura, Masaya, Imai, Takafumi, Hoshi, Kazutoshi, Iijima, Akira
Replacement of a 50cc Two-stroke Engine with an Electric Powertrain2019-32-062301/24/2020
As global regulations look to create a dramatic reduction in CO2 emission and other forms of pollution, companies with products that rely on engine technology must be ready to take on the electrification challenge. Applications that remain using two-stroke engine technology continue to exist due to their very high power density requirements. However, their history of higher pollution compared to four-stroke engines makes them a target to be regulated out of existence. Such high power two-stroke applications include high performance off-road motorcycles. In this type of product, electrification can solve not only pollution challenges but market challenges, such as ridership and public perception. By addressing the core problems presented by the two-stroke engine and turning challenges into opportunity, a strong attraction is created to convert a two-stroke engine motorcycle to an electric vehicle. With Automotive electric vehicle technology paving the way, the basis for cost effective
Beeker, Jesse
Identifying the limitations of the Hot Tube test as a predictor of lubricant performance in small engine applications2019-32-051001/24/2020
The Hot Tube Test is a bench test commonly used by OEMs, Oil Marketers and Lubricant Additive manufacturers within the Small Engines industry. The test uses a glass tube heated in an aluminum block to gauge the degree of lacquer formation when a lubricant is subjected to high temperatures. This test was first published by engineers at Komatsu Ltd. (hence KHT) in 1984 to predict lubricant effects on diesel engine scuffing in response to a field issue where bulldozers were suffering from piston scuffing failures [1]. Nearly 35 years after its development the KHT is still widely used to screen lubricant performance in motorcycle, power tool and recreational marine applications as a predictor of high-temperature piston cleanliness - a far cry from the original intended performance predictor of the test. In this paper we set out to highlight the shortcomings of the KHT as well as to identify areas where it may still be a useful screening tool as it pertains to motorcycle applications.
Hanthorn, Jason, Schmiesing, Jessica
Development of a Novel Hybrid-Piston for Application in High Performance Two-Stroke Engines2019-32-050801/24/2020
The current development trends for high performance two-stroke engines have been identified in raising combustion pressures and therefore higher cylinder temperatures [1] [2]. Thus, the requirements on piston assembly are increased in such a way that pistons based on aluminium-silicon alloys – as most commonly used in high performance two-stroke engines - reach their application limit. A suitable solution has been shown by research work such as that conducted by Mahle König, by using a piston consisting of different materials. With this approach, the higher stressed piston crown consists of steel, while the lower stressed piston skirt is made out from aluminium. Previous basic examinations showed the high potential of the hybrid piston concept in terms of pressure and temperature increase, while also showing the need for a temperature-stable and pressure-tight joint between crown and skirt. This paper will focus on the development of two novel hybrid-piston concepts, where the piston
Bechter, Christian, Jahn, Axel, Zimmermann, Frieder, Stamm, Uwe, Herb, Thomas
Study on Robust Fuel Performance with Differing Fuel Types in a 2-Stroke CAI Combustion Engine2019-32-057301/24/2020
This study sought to achieve robust combustion with the differing fuel types and levels of fuel quality that are present in various areas of the world. The tests used the 2-stroke controlled auto ignition (CAI) engine from our earlier report [1], which was proven to have potential as an efficient, clean engine for diesel fuel. This study verified whether efficient, clean CAI combustion of gasoline fuel could be achieved with the same basic structure and engine system. Diesel and gasoline have very different volatility, viscosity and ignition characteristics, all of which significantly affect combustion in an engine. It is particularly necessary in CAI combustion to adjust the ignition timing according to the fuel used, as the difference in auto-ignition temperature from gasoline and diesel affects the CAI ignition timing. This issue was addressed by conducting experiments with a test engine to determine how the ignition timing is affected by the equivalent ratio, compression ratio and
Kurata, Mashu, Okubo, Masami, Yamada, Yoshikazu, Kitano, Sho
Sensor Fusion Concept for Improved Rotational Speed Measurement in Small Engines2019-32-051901/24/2020
Future developments for small engines, e.g. engines for handheld working tools, like chain saws require the integration of ECU-systems for engine control. For small engines often only a rotational speed senor is available. The application of additional engine sensors is in many cases unwanted, e.g. due to cost aspects and additional wiring. The lack of sensor data requires tailored control strategies and signal processing techniques to infer information about the engine from the sensor data. E.g. for rotational speed sensors the Δω method has been proposed, where the load is estimated from the temporal variation of the rotational speed. This approach requires a rotational speed sensor with sufficient angular resolution. In this paper we present a simulation study for a sensor fusion concept to improve the temporal resolution of engine speed measurements for low cost engines by means of an additional vibration sensor. The rotational sensor of the engine is assumed to have insufficient
Neumayer, Markus, Bretterklieber, Thomas, Suppan, Thomas
Chemical kinetic mechanisms for HCCI combustion of wet ethanol with exhaust gas recirculation2019-36-029301/13/2020
This work compares the accuracy of in-cylinder pressure and apparent heat release rate (AHRR) diagrams to the experimental data and the use of different chemical kinetics models applied to the GT-Power® software. The engine computational model is based on a naturally aspirated diesel engine with three cylinders, one of them modified to operate with hydrous ethanol with port fuel injection and HCCI combustion achieved with hot exhaust gas recirculation (EGR) of the Diesel cylinders. Operating points chosen to perform the comparison to experimental tests were 1800 rpm, 300 kPa of indicated mean effective pressure and fuels with 10% and 20% of water-in-ethanol by volume. The kinetic mechanisms for ethanol oxidation evaluated were the detailed NUI Galway and a Skeletal model based on it. With either model, cylinder pressure diagrams were not very different from the experimental values. The detailed mechanism was, on average, 9 times slower to process each case than the Skeletal mechanism
Herzer, Filipe A., Fagundez, Jean L. S., Martins, Mario E. S., Salau, Nina P. G.
Feasibility Study of the Fuel Magnetizer in Flex-Fuel Cars2019-36-023801/13/2020
The topic of energy efficiency is currently a subject widely debated in industrial sectors because of its high relevance due to the finite life time of fossil fuels and the need for reduction in consumption and consequently the emissions of gases and the environmental impact. The objective of this work was to evaluate the performance of fuel magnetizers, a product marketed that, according to suppliers, guarantees an improvement in combustion efficiency, representing a saving of 10% to 22% of fuel. For the analysis of the efficiency of the magnetizer, consumption tests were carried out on engine test bench with and without the use of the product in idling speed, 2000 rpm and 2700 rpm. The conclusions obtained showed that the use of magnetizers did not achieve a satisfactory result in the efficiency of internal combustion engines, a possible factor responsible is the high content of ethanol in Brazilian gasoline.
Amorim, Pablo A., De N. Mattos, Luiz F., Almeida, Everton L. P., Pellacani, Gustavo C., Marques, Luiz A. M. M.
OH, soot and temperature distributions of wall-impinging diesel fuel spray under different wall temperatures2019-01-218412/19/2019
OH, soot and temperature distributions of wall-impinging diesel fuel spray were investigated in a high-temperature high-pressure constant volume combustion vessel. The ambient temperature (Ta) was set as 773 K, and the wall temperature (Tw) was set as 523 K, 673 K, 773 K, respectively. Three different injection pressures (Pi) of 60 MPa, 100 MPa, 160 MPa, and the ambient pressures (Pa) of 4 MPa were applied. The OH spatial distributions of wall-impinging spray were measured by the method of OH chemiluminescence imaging. Two-color pyrometry was applied to evaluate the spatial distributions of KL factor and flame temperature of wall-impinging spray. The results reveal that, OH chemiluminescence is observed in the region near the impingement point firstly. The regions of high OH chemiluminescence intensity and high KL factor appear in the location near the wall surface along the whole combustion process. As the wall temperature increases, the appearance time of the OH moves up, the
Feng, Lei, Wang, Yu, Chen, Beiling, Geng, Chao, Yi, Wentao, Cui, Yanqing, Liu, Haifeng, Zheng, Zunqing, Wang, Hu, Yao, Mingfa
Investigation on Knock Resistance with Turbulent Jet Ignition at Different Engine Load in an Optical Engine2019-01-215112/19/2019
This research was focused on the effect of pre-chamber ignition and compared the knock limit of normal spark ignition in the main chamber and pre-chamber jet ignition combustion in a spark ignition gasoline engine. Experiments were conducted in a single-cylinder engine with optical access. Engine was operated with stoichiometric air/fuel mixtures at 1200 rev/min and different inlet pressures of 1, 1.2, and 1.4 bar. No auxiliary fuel was injected into the pre-chamber when jet-ignition mode was used. The results show that significant knock limit extension can be realized with use of a pre-chamber ignition unit. The main differences in engine performance, heat release and combustion, knock resistance and flame propagation were compared between the pre-chamber ignition and conventional spark ignition in the main chamber by in-cylinder pressure measurements and high-speed flame chemiluminescence imaging. Pre-chamber ignition is capable of extending the knock limit over conventional spark
Bureshaid, Khalifa, Shimura, Ray, Zhao, Hua, Feng, Dengquan, Bunce, Mike
A Study of Injection Directions on Improvement of Engine Performance and NOx Emission in A Low-speed Marine Engine2019-01-232212/19/2019
A computational fluid dynamics (CFD) simulation model for a two-stroke low-speed marine engine has been established in CONVERGE software, to study the impact of different injection directions on fuel consumption and emissions of the engine. The goal of this research was to investigate injection angles in horizontal and vertical directions respectively. According to the simulation results, “trade-off” relationship was found in both directions between fuel consumption and NOx emission. Based on these results, 8° and -16° were considered as optimal injection angles in horizontal and vertical directions. With the optimized injection angles, lower NOx emission can be achieved with a little penalty on fuel consumption.
Sun, Qian, Ji, Wenxia, Huang, Zhen, Zhu*, Lei
Effects of Engine Operating Condition and Fuel Property on Pre-Ignition Phenomenon in a Highly Boosted Premixed Natural Gas Engine2019-01-215412/19/2019
The stochastic pre-ignition phenomenon plays a vital role to limit the further increasing BMEP for natural gas engines. In this study, the pre-ignition propensities were examined in a highly boosted premixed natural gas engine by various engine loads and air/fuel ratios, as well as different methane number (MN) altered by hydrogen addition. A proper pre-ignition evaluation method was proposed referring to intake temperature. Moreover, the limits of in-cylinder temperature and pressure for the onset of pre-ignition were estimated. The results show that both higher IMEP and richer mixture conditions readily lead to pre-ignition. The significant increases of pre-ignition frequency and heavy-knocking pre-ignition cycle present with lowering MN.
Chen, Run, Kuboyama, Tatsuya, Moriyoshi, Yasuo, Yasueda, Shinji, Doyen, Valerie, Martin, Jean-Baptiste
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