Browse Topic: Exhaust valves

Items (81)

A CFD Investigation Comparing the Performance of an Alternative Valvetrain Design Against a Traditional Poppet Valvetrain

2022-01-076003/29/2022

The poppet valve is by far the most widely used cylinder head design in internal combustion engines; however, poppet valves themselves create significant flow restrictions during both the intake and exhaust strokes, thus causing a reduction in overall engine efficiency. By removing the restrictive poppet valve from the flow path of air into and out of the cylinder head and allowing air to flow unobstructed, any given ICE engine can achieve higher specific output and greater volumetric efficiency. A new alternative valvetrain design, the flow through barrel valve (FTBV) cylinder head, utilizes straight-cut flow passages that reduce such restrictions. The FTBV, designed by Vaztec, LLC., is a rotary valve system that is designed to be belt driven by the crankshaft, thereby replacing the camshaft and poppet valve system altogether. This paper will primarily explore the differences in flow characteristics between the FTBV and conventional poppet valve cylinder heads using both CFD and flow

Robinson, Austin Clay, Garrett, Norman, Vaseleniuck, Darrick, Uddin, Mesbah

Improvement of Transient Response on a Downsized 4 Cylinder Engine for Automobile Application

2021-28-028010/01/2021

The automobile industry is one among the fastest in terms of adapting the technological advancements and evolving based on changing customer requirements. Researchers are focusing on making the automobiles better by means of making the vehicles more efficient, powerful and less polluting. In this study, venues of improving low end torque via improvement in volumetric efficiency as well as proper selection of turbochargers. An in-depth analysis of gas dynamics with respect to valve timing is studied along with the AVL boost simulation. It was found that volumetric efficiency starts to improve when there is a reduction in exhaust – exhaust valve overlap. There is an improvement found in the fresh air ratio (lambda) as the residual gas content is reduced. After the selection of valve timing, turbocharger optimization is done with comparison between two turbine sizes. Along with turbocharger comparison, technology comparison is also done namely between normal electronic VGT (Variable

Jain, Praveer Kirtimohan, Chendil, Chellapandi, Asthana, Shivam, Sanjay, Nehal, Meda, Venkata Saikumar, R, Sivasubramamanian, Daithankar, Parag, Ramadandi, Padmavathi, RS, Ranganathan, A, Guru Sankar

Investigations into the Effects of Spark Plug Location on Knock Initiation by using Multiple Pressure Transducers

2021-01-115909/21/2021

Despite a long history of development, modern spark-ignition engines are still restricted in obtaining higher thermal efficiency and better performance by knock. Knocking combustion is an unnatural combustion phenomenon caused by the autoignition of unburned air-fuel mixture ahead of the propagating flame front. This work describes investigations into the significance of spark plug location (with respect to inlet and exhaust valve position) on the knock formation mechanism. To facilitate the investigation, four spark plugs were installed in a specialized liner at four equispaced distinct locations to propagate flames from those locations, which provoked a distinct flame travel from each and thus individual autoignition profiles. Six pressure transducers were arranged to precisely record the pressure oscillations, knock intensities, and combustion characteristics. Four of the six transducers were mounted on the circumference of the liner (each next to one of the spark plugs), one was

Uddeen, Kalim, Shi, Hao, Tang, Qinglong, Turner, James

The Study on the Characteristics of Different Intake Port Structures in Scavenging and Combustion Processes on a Two-Stroke Poppet Valve Diesel Engine

2020-01-048604/14/2020

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

Eaton goes internal with its next-generation EGR solution

18AUTP08_0501/01/2018

Eaton's Internal Exhaust Gas Recirculation (iEGR) solution production-debuts in the 2020MY as a next-generation technology providing near-instantaneous heating of the selective catalytic reduction system to reduce diesel exhaust emissions. “The iEGR technology is controlled by an electro-mechanical actuator, so operation can occur in cold conditions,” Nicola Andrisani, Eaton's Engineering Manager of the Valvetrain Advanced Engineering Vehicle Group based in Torino, Italy, said in an Automotive Engineering interview.

Numerical Analysis of Scavenging Process in a Large Marine Two-Stroke Diesel Engine

2017-01-220110/08/2017

For uniflow scavenged two-stroke marine diesel engines, the main function of scavenging process is to replace the burned gas with fresh charge. The end state of scavenging process is integral to the subsequent compression and combustion, thereby affecting the engine’s fuel economy, power output and emissions. In this paper, a complete working cycle of a large marine diesel engine was simulated by using the 3D-CFD software CONVERGE. The model was validated by mesh sensitivity test and experiment data. Based on this calibrated model, the influences of swirl ratio and exhaust valve closing (EVC) timing on the scavenging process were investigated. The parameters evaluating the performance of scavenging process were introduced. The results show that, by adjusting the swirl orientation angle(SOA) from SOA=10° to SOA=30°, different swirl ratios are generated and have obvious differences in flow characteristics and scavenging performance. Advancing or delaying the EVC has limited effects on

Cao, Zhongye, Wang, Tianyou, Sun, Kai, Cui, Lei, Gui, Yong

Scavenge Ports Ooptimization of a 2-Stroke Opposed Piston Diesel Engine

2017-24-016709/04/2017

This work reports a CFD study on a 2-stroke (2-S) opposed piston high speed direct injection (HSDI) Diesel engine. The engine main features (bore, stroke, port timings, et cetera) are defined in a previous stage of the project, while the current analysis is focused on the assembly made up of scavenge ports, manifold and cylinder. The first step of the study consists in the construction of a parametric mesh on a simplified geometry. Two geometric parameters and three different operating conditions are considered. A CFD-3D simulation by using a customized version of the KIVA-4 code is performed on a set of 243 different cases, sweeping all the most interesting combinations of geometric parameters and operating conditions. The post-processing of this huge amount of data allow us to define the most effective geometric configuration, named baseline. In the second step of the study, the baseline is further optimized, keeping into account some fundamental design constraints, such as the

Mattarelli, Enrico, Rinaldini, Carlo, Savioli, Tommaso, Cantore, Giuseppe, Warey, Alok, Potter, Michael, Gopalakrishnan, Venkatesh, Balestrino, Sandro

Investigation of the Gas Exchange (Scavenging) on a Single-Scroll Turbocharged Four Cylinder GDI Engine

2016-01-102404/05/2016

For scavenging the combustion chamber during the gas exchange, a temporary positive pressure gradient between the intake and the exhaust is required. On a single-scroll turbocharged four cylinder engine, the positive pressure gradient is not realized by the spatial separation of the exhaust manifold (twin-scroll), but by the use of suitable short exhaust valve opening times. In order to avoid any influence of the following firing cylinder onto the ongoing scavenging process, the valve opening time has to be shorter than 180 °CA. Such a short valve opening time has both, a strong influence on the gas exchange at the low-end torque and at the maximum engine power. This paper analyzes a phenomenon, which occurs due to short exhaust valve opening durations and late valve timings: A repeated compression of the burned cylinder charge after the bottom dead center, referred to as “recompression” in this paper. By means of a new energetic analysis (available technical work capacity) the

Wolany, Adalbert, Glahn, Claus, Berner, Hans-Juergen, Bargende, Michael

Design of 65 degree V4 Moto GP Engines with Pneumatic Poppet Valves or Rotary Valves

2015-26-017601/14/2015

Moto GP engines have since the year 2012 4 cylinders in V or inline layout for a total capacity of up to 1,000cc. With pneumatic valve spring but wet sump, and with the maximum bore limited to 81mm, the maximum speed these engines may have is about 18,000 rpm, with power outputs 250-260 HP. The paper presents the design of a 65 degree V4 Moto GP engine further optimizing the pneumatic poppet valve design, as well as a novel rotary valve design. The rotary valve permits up to extremely sharp opening or closing and very large gas exchange areas. The two engines are then modeled by using a 1D engine & gas dynamics simulation software package to assess the potentials of the solution. The improved design produces much larger power densities than the version of the engines with traditional poppet valves revving at higher speeds.

Boretti, Alberto, Scalzo, Joseph

Simulation Study of Divided Exhaust Period for a Regulated Two-stage Downsized SI Engine

2014-01-255010/13/2014

The Divided Exhaust Period (DEP) concept is an approach which has been proved to significantly reduce the averaged back pressure of turbocharged engines whilst still improving its combustion phasing. The standard layout of the DEP system comprises of two separately-functioned exhaust valves with one valve feeding the blow-down pulse to the turbine whilst the other valve targeting the scavenging behaviour by bypassing the turbine. Via combining the characteristics of both turbocharged engines and naturally aspirated engines, this method can provide large BSFC improvement. The DEP concept has only been applied to single-stage turbocharged engines so far. However, it in its basic form is in no way restricted to a single-stage system. This paper, for the first time, will apply DEP concept to a regulated two-stage (R2S) downsized SI engine. By controlling the timing of the exhaust valves separately to feed the exhaust mass flow to the high-pressure turbine or the low-pressure turbine or the

Hu, Bo, Brace, Chris, Akehurst, Sam, Copeland, Colin, Turner, J.W.G.

Particle Image Velocimetry Measurements of Swirl and Scavenging in a Large Marine Two-Stroke Diesel Engine

2014-01-117304/01/2014

In-cylinder flow velocity measurements using particle image velocimetry (PIV) have been performed for the first time in a full-size marine Diesel engine. The engine was a four cylinder two-stroke engine with a bore diameter of 0.5 meter and a stroke of 2.2 meter. For such engines uniflow scavenging is used, with fresh air entering through angled ports at the bottom of the cylinder to generate a swirling flow and burnt gases exiting through a centrally located exhaust valve at the top. For efficient design of this process and for validation of CFD models it is essential to obtain an experimental characterization of the flow inside a fully operational engine. Optical access was obtained through a custom designed engine cover, fitted with a number of optical ports into which sapphire windows were mounted. Both the laser and camera used for PIV were mounted directly onto the engine in order to minimize effects of vibrations on optical alignment. Laser sheet generation and relay imaging

Hult, Johan, Matlok, Simon, Mayer, Stefan

Muffler Sound Development Using Analysis of Acoustic Source of Engine Exhaust System

2014-01-002604/01/2014

In order to achieve the proper automobile interior sound, the tailpipe noise of the exhaust system must be considered as a main contributor. This paper describes a study of the achievement of dynamic sound quality through exhaust system design. Firstly, we determined the vehicle's interior sound quality and established a target sound using a subjective assessment of 10 benchmark vehicles. The exhaust noise target is determined by means of transfer path analysis focusing on the noise source and how it's impacted by the muffler design. The exhaust system is commonly modeled as a combination of source strength and impedance. We obtained the source character by the wave decomposition method using two microphones and six loads ultimately leading to an optimized design of the inner muffler structure. Based on this study, we achieved dynamic interior sound and improved exhaust system performance.

Han, HakSon, Park, ChulMin, Heo, JeongHoi, Kang, Sang Kyu

Exhaust System Sounds

2006-01-137204/03/2006

More and more automobile manufacturers are requiring a typical sound pattern for a car or a platform, even the unique „brand sound” for a whole brand, on the top of their specification. By this image factor sound design becomes increasingly important for the exhaust system development. The whole sound pattern, especially the tailpipe noise of the exhaust system, plays an important role at the subjective impression of the car [1, 2]. There are two sound classifications: the limousines with an harmonic, quiet and discrete sound whereas for sports cars a more rough and powerful sound is requested. Compared with the gasoline engine the diesel engine has, based on inner power driven processes, a minor sound spectrum because its harmonics and main orders are hardly audible and mostly attenuated by a turbo charger. For turbo charged engines special concepts have been worked out in order to achieve a sporty sound. Especially resonances of the connecting pipes and the muffler chambers are used

Fuhrmann, Bernd, Garcia, Patrick, Wiemeler, Dirk

Ion Current During the Exhaust Process Under the Idling Condition in a Spark Ignition Engine

2005-01-387210/24/2005

Recently, in order to warm up the catalyst temperature rapidly, the retard ignition management has been developed. However, the excess retard of ignition causes the combustion instability and misfire. In this case, the ion sensor has been used for detecting the combustion quality for the late burned cycle under the idling condition. Several researchers have focused on the potential of ion-current measurement for the retard ignition management. However, the interpretation of ion-current during the exhaust process under the idling condition is not clear. In this study the source of ion-current for the late burned cycle during the exhaust process is focused. In order to measure the flame propagation process in the cylinder and the exhaust pipe, the single-cylinder test engine was used instead of production engine. Several ion probes were mounted on the cylinder head gasket, the piston head and the exhaust pipe for detecting the flame front. There are significant signals in the spark ion

Yoshiyama, Sadami, Tomita, Eiji, Kitawaki, Shunsuke, Kamada, Keizo

Finite-Element Analysis of Al-SiCp Composite Poppet Valve Guides

2005-26-31010/23/2005

Aluminum matrix composites are finding increased application in automotive, aircraft and aerospace industries and hold the greatest promise for the future growth. In the present work an attempt has been made to access the opportunity for Al-SiCp composites as an alternative material for the poppet valve guides. The finite element analysis of the Al-SiCp composite poppet valve guide was done using Ansys software. The temperature, principal stress and principal strain distribution over the entire surface of the poppet valve guide were obtained. The stresses were found to be well below the allowable stress for the Al-SiCp composites.

Purohit, Rajesh, Sagar, Rakesh

Passive Exhaust System With Cylinder Deactivation

2005-01-235105/16/2005

Cylinder deactivation is an efficient way to significantly improve fuel economy without compromising the horsepower and torque. For an exhaust system to manage both V4 and V8 modes, a unique development approach for exhaust system design needs to be incorporated. Simulation tools and correlation testing can be used to achieve great sound quality without the use of an active valve design classically (believed to be required) implemented. A quasi-Computer Aided Engineering (CAE) 1-Dimensional code drove the design of the passive (without a valve) system. The 1-Dimensional code analyzes pressure waves, mass flow and energy losses in ducts and junctions. To achieve the objective for cylinder deactivation, this tool also allows significant changes with relatively fast results for trends to be evaluated. The goal for this cylinder deactivation system was to have a smooth transition between the two modes and achieve the commercial performance with low backpressure. The challenge of this

Bemman, Ya-Juan, Frei, Tom, Jones, Chris, Keck, Mathias

Exhaust System Design for a Four Cylinder Engine

2002-01-331612/02/2002

The 2002 Lawrence Technological University Formula SAE team set out to develop a tuned exhaust system for a restricted Honda CBR 600 F4i engine. The exhaust system was targeted for maximizing low rpm torque while maintaining a broad flat torque curve without a significant loss of high rpm horsepower. In order to do this, considerable attention had to be given to the exhaust primary tracts, collector and silencer designs. To test theory, two equal length, fully adjustable headers were manufactured and tested on an engine dynamometer. Experimentally, the optimal exhaust design to meet our vehicles needs was determined.

Jawad, Badih, Biggs, Christopher, Klein, Bradley

Investigation of Post Oxidation and Its Dependency on Engine Combustion and Exhaust Manifold Design

2002-01-074403/04/2002

In response to ever more stringent emission limits (EURO IV, SULEV), engine developers are increasingly turning their attention to engine start-up and warm-up phases. Since in this phase the catalytic converter has not yet reached its operating temperature, problems occur especially with regard to hydrocarbon emissions (HC) which are emitted untreated. Secondary air injection represents one option for heating up the catalytic converter more quickly. The engine is operated during the heating up cycle with retarded ignition angles and a rich mixture. Ambient air (secondary air) is injected close to the exhaust valve seat. During the spontaneously occurring post oxidation phase, the reactive exhaust components ignite and heat up the catalytic converter while simultaneously reducing HC. The various processes which affect the post oxidation, are not well known up to now. In order to achieve concrete improvements, detailed knowledge of its influences are necessary. This paper will give an

Koehlen, Christoph, Holder, Eberhard, Vent, Guido

EMISSION AND CONSUMPTION REDUCTION FOR SMALL TWO-STROKE GASOLINE ENGINES

2001-01-182712/01/2001

Automotive pollutant emissions have been drastically restricted during the last ten years. These emission standards are now concerning small two-stroke engine. A Lot of technologies are offered to automotive engine manufacturers, such as direct injection or catalyst converter, but needs for low production price do not allow small two-stroke engine designers to use such evolutions. So, despite its high weight and complex mechanic, today's trend is towards four-stroke cycle. In order to meet future emission standard, different concepts have been implemented on a small two-stroke engine. An optimum combination between boost pressure and port timing has been found, using CFD, connected with results from hydraulic simulation, in correlation with tests on engine. The intake required conditions are reached through an external device, which is giving the right in-cylinder scavenging flow. Significant gains have been observed, concerning pollutant emissions as well as fuel consumption. These

DRECQ, D., BENTEYN, P.E., du GARDIN, A., CONTE, T.

Automotive Engineering International 2000-01-01

AUTOJAN0001/01/2000

Car of 2100 A.D. AEI gave readers a chance to speak out on what they thought people in 2100 would be driving. We have chosen the best submissions. Also, the AEI editors have included their best guess as to what cars will be in 2100. We realize that this is a guess but the real answer will not be known for 100 years. V8 power for BMW's M5 The new 294-kW (400-hp) S62 engine developed by BMW's M GmbH features Double VANOS variable intake and exhaust valve timing, electronic drive-by-wire, and oil circulation boosted as a function of lateral cornering force. Northstar revised for 2000 Improvements to the powerplant include a roller-follower valvetrain, improved combustion chamber, center-feed intake manifold, coil-on-plug cassette ignition system, and a Siemens powertrain controller. Aston Martin's first V12 Available in both the DB7 Vantage Coupe and Volante, the flexible all-alloy engine delivers 85% of its peak torque at just 1500 rpm. GM develops a global four The all-aluminum engine

A Study of Rotary Valve for a Single Cylinder Engine

1999-01-332209/28/1999

The authors have experimentally produced a new type of Rotary Valve (ca11ed R.V.) which has a unique gas sealing mechanism. In this study, first, the mechanical loss in the valve train was measured comparing to that of the poppet valve drive train, and it was found that the mechanical loss of rotary valve train is much lower level. Secondary, three dimensional numerical calculation of the flow field from the intake-port to in-cylinder during the intake stroke was carried out. As a result, it was found that the flow field is very complicated due to the interaction between the moving piston and valve and that the profiles of “valve notch” and intake port affect the flow field and then, the modification of profile with a round edge form of the “notch” enables higher mass flow rate.

Moriyoshi, Yasuo, Sekizuka, Susumu, Muroki, Takumi

Provision for Emission Reduction of Sports Utility Motorcycle

1999-01-325909/28/1999

The purpose of this study was to find compatible specifications both of emission reduction and high power output with good throttle response for a sports utility motorcycle. In the emission reduction challenge, we examined equipping the exhaust system with a catalytic converter to achieve sufficient emission reduction. The catalytic converter, however, caused a temperature rise in the exhaust system, which caused a pressure propagation change. Additional muffler design optimization effectively maintained high performance and acceleration. The exhaust valve device was also optimized for emission reduction and high power output over a wide engine speed range. The optimized control of the exhaust valve was beneficial to preventing short-circuit of fresh mixture gas and early activation of the catalyst. Such comprehensive specifications could satisfy the performance and driveability characteristics required for sports utility motorcycles.

Mishina, Fusayuki, Ohira, Tetsuya

Computational Fluid Dynamics in Solid Particles Effect Estimation in Hydraulic Poppet Valves

1999-01-283509/13/1999

This paper deals with the analysis of the interaction between solid contamination and internal geometry in hydraulic conical and spherical poppet valves, performed through a non-dimensional, axis-symmetric CFD analysis of their internal flow. The information coming from the flow field solution is used to identify regions having higher probability to be impacted by particles dragged by the fluid, and to estimate the erosion potential of solid particles having different size. The value of the kinetic energy of particles approaching the walls of the geometric domain is used to estimate the amount of material potentially eroded by impacting particles, and to provide a potential correlation between ISO 4406 and NAS 1638 solid contamination level classification. The long-term target is a numerical estimation of service life in hydraulic components.

Borghi, M., Milani, M., Paoluzzi, R.

Flow Analysis and Catalytic Characteristics for the Various Catalyst Cell Shapes

1999-01-154105/03/1999

The shape of unit cell of catalytic converter has great influence on the conversion efficiency and pressure drop characteristics. Therefore, the properties of design parameters of catalyst monolith were analyzed and the parameters of various cell shapes of catalyst were compared. Also, the numerical study of a three dimensional compressible flow in a Close-coupled Catalyst Converter (CCC) system was performed to investigate the flow characteristics and the flow distribution of exhaust gases. Unsteady flow analysis shows that severe interferences of each pulsating exhaust gas flow as well as geometric factors (junction, mixing pipe, cell shape etc.) influence greatly on the flow uniformity and flow characteristic in substrate. The results can be applied for the catalytic converter design.

Park, Simsoo, Kim, Ho Young, Cho, Young Jin, Lee, Sun Youp, Yoon, Kum Jung

Efficient CFD Simulations for In-Cylinder Flows Using Hybrid Grids

1999-01-118403/01/1999

An edge-based, three dimensional, characteristic-based upwind Roe/TVD unstructured flow solver with chemical kinetics and turbulence modeling for simulation of in-cylinder flowfields, CRUNCH, has been extended to improve computational efficiency and utilize multiple element types. Solution efficiency is achieved using an implicit GMRES time integration procedure which is capable of advancing the solution with very large CFL numbers. The grid motion is accomplished using an automated scheme wherein layers of cells are introduced and subsequently removed as valves increase/decrease lift and as the piston moves through its stroke. A multi-zone mesh framework allows various portions of the domain to slide past each other in a noncontiguous manner. Detailed simulations have been performed for the Ford Motor Company 4.6 liter, twin valve engine. Swirl, tumble, and cross-tumble histories compare well with prior simulations performed at Ford Motor Company. Extension of the current method to a

Sinha, N., Cavallo, P. A., Hosangadi, A., Lee, R. A., Affes, H., Chu, D.

Digital Valve Technology Applied to the Control of an Hydraulic Valve Actuator

1999-01-082503/01/1999

The use of electrohydraulic actuators in engine control applications has the potential to improve engine performance and fuel economy. Digital latching valves open and shut extremely quickly. Furthermore, by using residual magnetism, the valves remain latched in the open or closed position and only use energy when transitioning between positions. In this paper, the control issues involved with using latching valves for closed loop position control of a piston-cylinder actuator are examined. The valve design, system models and alternative controller designs are presented. The first control design is based on minimizing a cost function measure of errors and control energy usage, which quantifies a trade-off between tracking accuracy, resolution and control energy usage. The second design, which is called inner sample modulation of the valve, is based on calculating the appropriate control action as some fraction of the sampling time. Experimental data showing trajectory tracking and

Misovec, Kathleen M., Johnson, Bruce G., Mansouri, Gary, Sturman, Oded E., Massey, Steven

Cavitation Behaviour of Hydraulic Orifices and Valves

98203809/14/1998

Cavitation is a common and usually undesirable phenomenon in hydraulic systems. Understanding the basics of cavitation phenomenon as well as detecting existing cavitation are important in order to prevent cavitation in hydraulic systems. In this paper past studies of orifice cavitation are discussed and also new studies of orifice and valve cavitation with hydraulic oils are presented. Cavitation behaviour of different kinds of orifices and a poppet valve have been studied. Studies were done with different cavitation numbers. Rough design guidelines for reducing and preventing cavitation in orifices and valves are presented.

Koivula, T. S., Ellman, A. U.

Diesel Engine Smoke Measurements in the Rapid Acceleration Test

98041102/23/1998

Smoke is the most obvious part of the exhaust emitted from Diesel engines. The methods for smoke testing currently used in Taiwan are the rapid acceleration test under no load and the constant speed test under full load. The smoke concentration is measured with the light reflection method. According to the test procedure, the smoke meter sampling time in the rapid acceleration test is 1∼2 seconds. The current range in sampling time may cause discrepancies in test results. In these tests, free acceleration of engine is achieved by actuating the pedal rapidly. However, the speed of engine acceleration has not been defined clearly in the test procedure. The objective of this research is to study the effect of the operating conditions upon the results of smoke tests. Experiments were carried out in this study. The results of measurements showed that the opacity of the engine exhaust increased rapidly after a delay of about 0.3 seconds and then fell. The entire period of smoke variation was

Liou, Chew-Cherng, Szu, Chun-Te, Lu, Jau-Huai, Lee, Haw-Ran

The Effects of Cylinder Head Deformation and Asymmetry on Exhaust Valve Thermo-Mechanical Stresses

98103402/23/1998

A geometrically accurate, three-dimensional finite element model of a Diesel engine exhaust valve and cylinder head assembly has been developed to analyze the effect of cylinder head interactions on exhaust valve stresses. Results indicate that a multi-lobed stress pattern occurs around the exhaust valve head due to cylinder head deformation, stiffness variations, and thermal asymmetry. Consequently, peak valve bending and hoop stresses from the three-dimensional model are 48% and 40% higher, respectively, than for the two-dimensional, axisymmetric model. These results indicate the degree of model complexity required for more accurate analyses of exhaust valve operating stresses.

Meyer, Terrence R., White, Robert A.

New Fe-base Exhaust Valve Material for Higher Heat Resistance

98070402/01/1998

Nishizawa, Yoshitaka, Umino, Shin-ichi, Hamada, Akihiro, Kenmoku, Takeji

The Characteristics of Scavenging Flow in a Poppet-Valve Type 2-Stroke Diesel Engine by Using RSSV System

96036802/01/1996

Optimization study is performed for the scavenging process as the first step for the development of a poppet-valve type automotive two-stroke diesel engine. The scavenging flow pattern is varied by the RSSV (rotatable shrouded scavenging valve) system, which was designed for application of a shroud valve to an actual engine. The scavenging flow is analyzed by flow visualization and numerical calculations under a steady condition. Water is used as the working fluid, instead of air for effective visualization of the flow pattern in the flow visualization study. More details in the scavenging characteristics are observed by a dye experiment, in which the dye path indicates the flow streamline in the cylinder. In the numerical study, three-dimensional flows are calculated by a modified version of KIVA-2 code, with a special technique to consider the valve and shroud shapes. The results show that a large shroud angle generates a center vortex in the cylinder by a strong reverse tumble flow

Huh, Kang Y., Jeong, Hee T., Kang, Kern Y., Lee, Jin W., Jeong, Young I.

Hot Vibration Durability of Ceramic Preconverters

95241410/01/1995

The advent of thermally durable catalyst technologies has created the opportunity to move catalytic converters closer to the engine, providing a potential solution for cold start emissions. Close-coupled positioning exposes the converter to higher exhaust gas temperatures than experienced in underbody applications, permitting earlier catalyst light-off. The proximity of the converter to the engine will result in increased exposure to the vibrational energy created by combustion processes as well as intake and exhaust valve dynamics. This study investigated the thermo-mechanical challenges of mounting a ceramic substrate under severe conditions. In some instances ceramic substrates have been overlooked for application in the more demanding close-coupled environment. It will be shown that ceramic substrates mounted with standard intumescent mats survive under the most severe hot vibration testing conditions in the industry. Hot vibration testing is a very expensive activity. Therefore

Locker, R. J., Schad, M. J., Sawyer, C. B.

Computer Aided Assessment of Catalyst Ageing Cycles

95093402/01/1995

In view of recent and future US and european regulations the design optimization of 3-way catalytic converters (3WCC) should also account for catalyst durability. The purpose of this paper is to extend the authors' approach for 3WCC modeling and evaluation in the direction of covering some aspects of ageing behavior. After a brief examination of the commonly accepted ageing mechanisms, a new methodology for the assessment of catalyst durability is formulated. This methodology takes into account the effect of thermal loading, high-temperature oxidation and poisoning of the catalyst. Based on the approach presented, along with the 3WCC and other related models and computer codes already in-use by the authors, a comparative assesment of engine bench ageing cycles may be computationally supported. Correlation of vehicle ageing cycles with engine bench cycles may also be accomplished as illustrated by a case study. As a second step, a methodology for tailoring fast engine bench ageing

Pattas, K. N., Stamatelos, A. M., Koltsakis, G. C., Konstantinidis, P. A., Volpi, E., Leveroni, E.

Collector/Catalyst/Muffler Package: Racing Car Exhaust Noise Reduction

95106002/01/1995

Significant reduction in the exhaust noise levels of racing cars has been achieved through the use of a special header-collector design. This design combines the primary header tubes, the collector, and the muffler into a compact package. The accommodation of exhaust systems on race cars -- especially those with mid or rear engine designs -- upsets the weight bias of the vehicle by moving the mass of the exhaust behind the rear axle, thus increasing the polar moment. The ducting of the exhaust to the rear also exposes vital components to extreme heat generated by the exhaust system. The CCM occupies fractionally more space than the header alone, allowing great flexibility in the design of the rest of the exhaust system. Testing has demonstrated that this design not only attenuates noise, but it provides increased horsepower and torque as well.

Borla, Alexander, Guzek, Joseph

Study on Oxidation Processes of Unburnt HC in Exhaust System of Spark Ignition Engines

93198511/01/1993

This study focuses on the time history of the concentration of unburnt HC in an exhaust system of spark ignition engine. A mathematical model which can estimate gas temperature, and degree of oxidation in an exhaust system for given engine specifications and operating conditions is developed. This model is confirmed by experiment in which instantaneous HC concentrations are measured by using a fast sampling valve, and measurement of HC emissions in an exhaust pipe of a methane fueled engine.

Tanaka, Junya, Korematsu, Koji

Closed Loop Electro-Hydraulic Control for Combine Header Floatation and Height

93240809/01/1993

Proportional raise and lower poppet valves used in conjunction with a microcontroller can provide closed loop control of hydraulic cylinder pressure or position. Closed loop control of headers on agricultural harvesters enables more sophisticated functionality than present techniques. Floatation (regulating the header's applied ground force) and stubble height (regulating the header's height) are two strategies which can increase crop yield. These allow for more precise tracking of ground contour variations with the header contacting or following above the ground. Machine productivity is increased by consistent and repeatable operation, reduction of operator interaction and automation of header raise and repositioning at the start of each row.

Chmielewski, Thomas A., Torbett, Mark K., Bohman, Carl E.

Engine Poppet Valve Information Report

J775_199308 (Historical)08/01/1993

This specification supplies engineers and designers with: 1) poppet valve nomenclature; 2) poppet valve alloy designations; 3) chemical compositions of poppet valve alloys; 4) a guide to alloy metallurgy and heat treatments; 5) general information on properties of valve alloys; 6) a guide to the applications of alloys; 7) a description of valve design and construction, and their relation to valve alloy selection; and 8) valve gear design considerations that affect valves.

Elev Temp Prop of Ferrous Metals Committee

A Numerical Method for the Prediction of Exhaust Noise in Internal Combustion Engine Exhaust Systems

93134805/01/1993

A numerical method is presented for the prediction of exhaust noise in internal combustion engine exhaust systems. The prediction is based on a linear model for the exhaust system which is dependent on a nonlinear model for the engine. A fired engine is modeled by a combustion process, and the energy balance in the gas content of each cylinder. A set of nonlinear differential equations are obtained to model the engine, and a set of linear differential equations are obtained to model the exhaust system. The mathematical model for the engine is coupled with the exhaust system by appropriate boundary and initial conditions at area discontinuities. The governing equations for the system are solved by an explicit solution procedure for in-cylinder thermodynamical processes, and acoustical field quantities in the exhaust system.

Ghafouri, M M., Ricci, G.

Automobile Exhaust-System Steady-State Heat Transfer

93108504/01/1993

Temperatures were measured in the exhaust manifolds, takedown pipes, and post-converter components (tailpipe section) of several passenger cars under equilibrium conditions on a chassis dynamometer. Cast and fabricated exhaust manifolds of several designs were instrumented, as were single-wall and double-wall takedown pipes. Steady-state heat fluxes in exhaust components correlated with interior Reynolds numbers regardless of the engine operating condition. Nusselt numbers on component interior and exterior wall surfaces also correlated with Reynolds number. The interior Nusselt number was greater than that calculated for ideal flow with fully developed boundary layers. The ratio of measured to ideal-flow Nusselt numbers was relatively constant for a given component. These parameters are required for analytical modeling of the heat transfer performance of exhaust components, e.g., for the study of underhood and underbody heat loads. They also find application in the modeling of

Wendland, Daniel W.

Advanced Design of Automotive Exhaust Silencer Systems

92208809/01/1992

This paper presents some of the innovative exhaust noise reduction techniques an exhaust system development engineer can employ, when his customer, the car manufacturer, increases the engine swept volume and engine power without allowing any change in the layout of the exhaust system, which may already be on the borderline from the acoustic point of view. The solution to this problem could be an “electronic” muffler. Here there are two possibilities: 1. A semiactive muffler, which will change the internal geometry of the muffler system or muffler in accordance with changes of engine conditions during driving. 2. An active system, which adds antinoise or modulates the pulsating exhaust gas flow in order to smooth the gas pressure pulsation and to get in this way a sound attenuation. The possibilities and limits of both solutions are shown by different measurement results.

Hutchins, S. M., Krause, P., Weltens, H.

Effect of Port Sizes and Timings on the Scavenging Characteristics of a Uniflow Scavenged Engine

92078202/01/1992

Multidimensional prediction of the scavenging characteristics of a homogeneous charge uniflow scavenged two-stroke cycle engine has been carried out. An engine geometry having the same dimensions as the General Motors EMD 710 engine has been analyzed. A multidimensional computer program, CARE, has been developed for this purpose. The fluid flow problem is subdivided into its global and local parts and the two parts are solved simultaneously. Flow is assumed to be axisymmetric. Turbulence is modelled by a zero-equation eddy viscosity model. Combustion is treated as a stoichiometric heat release phenomenon. The simulation is repeated over many cycles of the crank to achieve a periodicity in the results obtained. This computer program is used to study the effects of port/valve sizes and timings on the scavenging characteristics of the engine, given that the pressures at the inlet and exhaust ports are held constant. The results are preseted in the form of flow field plots and efficiency

Ravi, M.R., Marathe, A.G.

Correlation of Exhaust Valve Temperatures with Engine Reynolds Number in a 1.9 L Engine

92006302/01/1992

Exhaust valve temperatures are important in the selection of valve materials, and have strong effects on borderline spark angle and pre-ignition borderline limit. In order to support analytical modeling of exhaust valve temperatures and to correlate exhaust valve temperatures as a function of engine Reynolds number, exhaust valve temperatures were mapped as a function of spark angle and engine coolant temperatures at 2000 rpm. In addition temperatures were measured at wide open throttle at 2000, 3000, and 4000 rpm. The exhaust valve temperature was expressed as a dimensionless temperature using the exhaust gas temperature and the engine coolant temperature, then the dimensionless temperature was correlated as a function of spark angle and engine Reynolds number. The results indicate that once the temperature is known at a given speed and load condition for any one cylinder, the temperature at other speed and load conditions can be reasonably estimated.

Swank, L. R., Caverly, J. C., Galietti, C. A.

Real-Time Measurements of Soot Particles at the Exhaust Valve of a Diesel Engine

91266711/01/1991

Diesel particles are formed and also reduced during diffusion-controlled spray combustion in the chamber of a Diesel engine. In earlier investigations it was found that the particles directly sampled near the exhaust valve were irregularly shaped, having a median diameter of 50 to 100 nm. The engine combustion process is cyclic and nonuniform and is imbedded in a highly nonstationary flow. The soot particles formed during the combustion process were emitted during the opening period of the exhaust valve together with the burned gas. This results in strong time-dependent fluctuations of the particle mass density in the exhaust pipe. It is the aim of this study to measure the dynamic particle behaviour during the exhaust gas flow. Laser light scattered by the diesel particles was measured very close to the exhaust valve. The light flux signals obtained under several fixed angles showed a periodic structure and were interpreted in terms of size parameters by applying the Mie theory.

Klingen, Hermann-Josef, Roth, Paul

Development of Automatic Exhaust Valve Control Device of 2 Stroke Engines

91122611/01/1991

Recently, motocross racetrack configurations have been changing from speed-oriented layouts to rider's talented performance-oriented layouts. This has created a demand for engines that can provide both power at high speeds and torque at low speeds as well as having quick response at all speeds. The most efficient way to achieve all round power range in the 2-stroke-racing engine was to increase the area of exhaust port and to vary the exhaust chamber volume at the same rate as the increased engine revolution. The authors developed an automatic exhaust control valve device called “KIPS”. In this paper we will describe how KIPS was developed, its output characteristics, and operation. Figure I shows a 1992 model KX250 motocross racing bike equipped with the newest KIPS device (3-Way KIPS).

Fujikawa, Tetsuzo, Ohtsu, Makoto

Development of a Prototype Active Muffler for the Detroit Diesel 6V-92 TA Industrial Engine

91104505/01/1991

This paper describes the successful development of an active muffler system for the Detroit Diesel 6V-92TA industrial diesel engine used in a generator set application. The active muffler analyzes the structure of the exhaust sound and generates ‘anti-noise’ through loudspeakers. The ‘anti-noise’ is equal in magnitude and 180 degrees out of phase with the exhaust sound. The exhaust sound and ‘anti-noise’ cancel each other at the exhaust outlet. Adaptive filter techniques are used to update the ‘anti-noise’ signal in response to changes in engine operating conditions. This technique is effective at frequencies less than 500 Hz, where a significant portion of the exhaust sound is concentrated. Combined with a low flow restriction passive silencer to attenuate primarily high frequency sound, exhaust noise is reduced well below levels emitted by conventional passive mufflers. The final prototype active muffler system included a three driver loudspeaker active element and low flow

Arnold, Everett, Frazer, Warner

Development of Nickel-Base Superalloy for Exhaust Valves

02/01/1991

These days, nickel-base superalloy has been applied to reduce the valve weight of motorcycles. Inconel 751 is excellent in performance but expensive in cost. Therefore, we verified the constituents of nickel-base superalloys corresponding to the requirements of valves and we succeeded in developing a new superalloy and applying it to motorcycle exhaust valves. The characteristics are summarized as follows: 1. The basic composition is Fe-46Ni-18Cr-4Ti-1Al-0.3C-0.004B. It is a precipitation-hardened nickel alloy characterized by precipitation of Ni3 (Al,Ti) and, crystallization and dispersion of fine TiC. 2. It has the following distinctive features. (1) Superior to Inconel 751 in wear and heat resistance. (2) Superior to 20-11P steel in resistance to lead oxide corrosion. (3) Applicable to both unleaded and low-lead gasoline. 3. The exhaust valves using this new superalloy are lighter in weight by 18% and lower in cost by 13% as compared to the conventional type using 20-11P hard-faced

Hagiwara, Yoshitoshi, Ishida, Masao, Oka, Tomoo, Watanabe, Rikizo, Koji, Sato

Comparison of Performance Characteristics of Loop and Cross Scavenged Two-Stroke Engines

90166609/01/1990

This paper describes an experimental comparison of loop and cross scavenged single-cylinder research engines. The cross scavenged engines have employed the QUB type deflector piston. The initial results show that the QUB cross scavenged engine exhibited inferior performance characteristics. Utilizing the QUB single cycle test rig, a study of the QUB cross scavenging system has shown that the bore-to-stroke ratio significantly influences the scavenging behaviour; reduction of the bore-to-stroke ratio from over-square values gave improved characteristics. On the basis of this finding, a new cross scavenged cylinder barrel was designed. In a subsequent series of dynamometer tests, improvements in power, fuel economy and emission characteristics were recorded for the new cylinder. These improved results approximate closely to those recorded for the loop scavenged engine and are considerably superior to those of the original cross scavenged cylinder.

Kee, Robert J., Blair, Gordon P., Douglas, Roy

A Computer Simulation Approach to Exhaust System Noise Attenuation

90039202/01/1990

A computer simulation program has been developed to aid the engineer in the exhaust system noise attenuation process. This program allows for the manipulation of key component positions and configurations and predicts the resulting sound pressure level throughout the operating frequency range. This process can eliminate some of the “trial and error” approach to exhaust tuning, thus significantly reducing total development time.

Ewing, William H., Nemoto, Hiroshi

Exhaust Temperature Response of Trap Oxidizer Systems

90032302/01/1990

Exhaust temperature response is very important in the design of exhaust aftertreatment systems. Analysis of this response is made in this paper by means of heat transfer calculations at the exhaust system, leading to a model that predicts exhaust system and exhaust temperature response. Thus, the effect of differences in design of exhaust system components may be studied for optimization purposes. The model is readily extended to predict heating response of ceramic honeycomb filters. An approximate method for quick computation of exhaust system response based on the response of individual components, is also presented to facilitate the computations.

Pattas, K. N., Stamatelos, A. M., Constantinidis, J. C.

Characteristics of Dual Mode Mufflers

89061202/01/1989

Automobile exhaust system engineers have conflicting goals which must be achieved to meet customer demands for improved vehicle performance and quietness. They must reduce exhaust system pressure loss which improves volumetric efficiency of the engine and increases power output. At the same time they must reduce the discharge noise from the exhaust system to achieve desired noise levels for the vehicle. This study presents an analysis of the basic characteristics of discharge gas noise of internal combustion engines and presents solutions which reduces exhaust system pressure loss and reduces discharge noise level. The solution involves a technique utilizing a flow control valve to control discharge gas flow and control the propagation of sound waves toward the exhaust piping system. The effect is to muffle the subharmonic element in the low speed range of the engine. This element is resonant and becomes amplified in the piping system increasing noise level. The valve also reduces jet

Suyama, Eizo, Inaba, Motohiro, Mashino, Ryuo

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