Combustion Chamber Geometry Research Articles

Effect of combustion chamber geometries in biodiesel fueled CI engine: A comprehensive review

Depleting fossil fuels and raise in prices day by day has paid attention to alternative fuels. Emissions are the major concern in biofuels. Stringent future emissions norms can be met with implementation of key technologies. Performance of a biodiesel fueled CI engine can be improved by some modifications in the engine. One such is the combustion chamber geometry. This paper summarizes the results of different types of combustion chamber geometry with various biodiesel. The variations in performance parameters, emissions (UBHC, CO, NOx, smoke) and combustion parameters are also discussed in detail. The summary shows that suitability of alternative fuels can be improved by selecting the proper combustion chamber geometry.

CFD analysis of a swirl stabilized coal combustion burner

Anthropogenic Greenhouse Gases (GHG) emissions have increased since the pre-industrial era, driven by the economic and population growth. In the last decades, significant efforts have been made to develop cleaner and more efficient technologies able to control GHG emissions. In the field of combustion burners, this commitment strongly relies on the development of new and detailed numerical models, which allow a deep investigation of complex burner performance and a significant reduction of full-scale experimental costs. The knowledge previously acquired on the TEA-C coal burner CFD study is here expanded in the framework of the Be4GreenS project, targeting to the development of a new generation of burners. The new implemented model accounts for the detailed chemical and kinetic characterization of the pulverized coal together with the exact inner volume geometry of the experimental combustion chamber and the actual extension of the heat exchanging and refractory surfaces. In addition, the secondary and tertiary air registers are here numerically investigated. The outcome from the CFD analysis is validated against the experimental data. The NOx formation analysis is also provided.

Effect of combustion geometry on combustion, performance and emission characteristics of CI engine using simarouba oil methyl ester

Present study investigates the effect hemispherical (HCC), cylindrical (CCC), toroidal (TCC) and toroidal re-entrant (TrCC) type combustion chamber (CC) geometry on the characteristics of combustion, performance and exhaust emissions from the engine using Simarouba Oil Methyl Ester (SuOME) and to compare with base engine operated with diesel fuel. Simarouba oil biodiesel is prepared by 2 stage transesterification using methanol and KoH. 4-stroke naturally aspirated single-cylinder water-cooled direct-injection diesel engine with different optimized injection parameters of injection pressure to 240 bar, injection timing to 270bTDC, 6 hole injector of 0.2 mm diameter, and loading condition at rated speed of 1500 rpm were used for testing. Ignition delay (ID), combustion duration (CD), peak pressure (PP), brake thermal efficiency (BTE), exhaust gas temperature (EGT) and exhaust emissions (HC, CO, smoke opacity and NOx) were measured to estimate the behaviour of the diesel engine running on SuOME with different combustion geometry. Results were indicated that, use of SuOME reduces the engine performance with increased emissions compared to fossil diesel conventional fuel. However use of toroidal re-entrant CC gave the better combustion and performance with reduced emission except NOx comparing with other combustion chamber design.

Impact of changing combustion chamber geometry on emissions, and combustion characteristics of a single cylinder SI (spark ignition) engine fueled with ethanol/gasoline blends

The aim of this study was to investigate the range of opportunities and future prospects of presenting a blend of gasoline/ethanol fuel to run a gasoline engine. Biofuel’s advantages involve emission of low quantities of contaminants to the atmosphere and its renewable character in order to trim down dependency on gasoline as a fuel. Analyses have been carried out to show the influence of compression ratio on engine performance and tailpipe emissions by using unleaded gasoline and gasoline blends with (10 and 20%) pure ethanol SI (spark ignition) engine having a variable compression ratio with the air-cooled single-cylinder engine. Experiments were conducted on five different compression ratios (CRs) of 4:1, 5.5:1, 7:1 8.5:1, and 10:1 with a wide-open throttle. Two combinations of blended fuels were compared to the unleaded gasoline. The results showed that the BMEP (brake mean effective pressure), BTE (brake thermal efficiency), and BSFC (brake specific fuel consumption) obtained with the use of gasoline blends at all CRs were generally higher in comparison to those of pure gasoline. In general, gasoline blends provided a lower exhaust emission compared to gasoline’s emissions at all CRs. Furthermore, NOx emissions were affected much more than other exhaust emissions when changing the compression ratios compared to unleaded gasoline.

Combined effect of combustion chamber shapes and nozzle geometry on the performance and emission characteristics of C.I. engine operated on Pongamia

The performance of the engine improved by modifying the shapes of the combustion chamber and nozzle geometry. The present work investigated the combined effect of combustion chamber shapes and nozzle geometry on performance and emission characteristics of POME biodiesel fueled diesel engine. Engine tests have been carried out on a single cylinder −4 stroke direct injection diesel engine using various blends of POME with standard diesel and comparison is made between baseline shape (HCC shape with 3 holes nozzle geometry) and modified shapes (CCC, SCC and TCC with 5 holes nozzle geometry). For comparison, the 17.5 CR, speed 1500 rpm, 205 bar IOP and IT 23° BTDC of the engine were kept constant. The experimental results showed that BTE increases up to B40 blend of POME in baseline shape and up to B20 POME blend in modified CCC shape at full load condition. A drastic reduction in UBHC and NOx emissions were observed in modified SCC and TCC shapes as compared to base line shape. CO emissions were decreased in modified CCC and baseline shapes as compared to modified SCC and TCC shapes at full load condition. CO2 emission higher in all modified shapes in diesel engine.

A Comparative Analysis of In-Cylinder Flow, Heat Transfer and Turbulence Characteristics in Different Type Combustion Chamber

Recently some studies have been carried out on combustion chamber design for diesel and gasoline engines; however, they routinely used piston bowl model approach, which may neglect interactions with cylinder head design. Fluid motion within the cylinder of internal combustion engines has a significantly influence on the combustion process and engine efficiency. The aim of this study two different geometries of the combustion chamber of internal combustion engine were compared in terms of in cylinder flow and heat transfer during the intake process. For this, complete calculations of the intake stroke were performed under realistic operating conditions and heat transfer, velocity and turbulence flow fields obtained in each combustion chamber investigation detail. They were solved with finite volume method and ANSYS-Fluent 12.0 commercial code. The findings include using k-e turbulence model and dynamic mesh generation model for different crank angle. The result of studies show that flow structure and turbulence intensity are affected on combustion chamber geometries. Also, the pent-roof type combustion chamber configuration was found to generate turbulence intensity more efficiently than the conventional type combustion chamber.

Effects of lateral swirl combustion chamber geometries on the combustion and emission characteristics of DI diesel engines and a matching method for the combustion chamber geometry

Previous experimental results show that a lateral swirl combustion system (LSCS) significantly improves the fuel consumption and the soot emission in direct injection (DI) diesel engines. To further improve LSCS performance and effectiveness, this study undertook numerical simulation to analyze the effects of the LSCS chamber geometries on combustion and emission characteristics under the condition of 2500 r/min and full load, revealing the relevant influence mechanisms. Based on a sensitivity analysis on the indicated power, the chamber geometry optimization was accomplished. The performance improvement of the optimized LSCS was verified using a single-cylinder DI engine. However, due to the interplay between fuel spray jets and wall surfaces, the optimized results are different for various fuel supply systems. To apply the LSCS effectively in different fuel supply systems, a matching method for LSCS chamber geometry is proposed in this paper.The results show that the combustion performance of the LSCS is primarily affected by the geometries of the split-flow creation, in which θ (the deviation angle of flow-guide) plays a dominant role. When θ was in the range of 15–27°, the combustion chamber created favorable flow guidance for spray and promoted the fuel/air mixture formation. After the geometrical optimization of the LSCS, fuel consumption decreased by 2.8–4.1 g/(kW.h) and soot emission decreased by 69–75% under various engine speeds as compared with the double swirl combustion system (DSCS).

Numerical investigations on feasibility of Quasi “MR-Process” for 2-valve diesel engines

MR-Process consists two stage combustion mechanism in twin swirl flow conditions which is created by special design of 2 intake manifolds and combustion chamber (CC) geometry of a 4-valve engine. It is a question if it is possible to apply a Quasi MR-Process by modifying CC of a 2-valve engine which has only one intake manifold. Previously engine tests were successfully conducted on a 2-valve and modified CC (MR-2 CC) single cylinder test engine with one intake manifold using LPG and diesel fuels. Nevertheless because of there is no optical access inside the engine, it is not clear whether required twin swirl flow (to create Quasi MR-Process) occurs inside CCs of proposed 2-valve engines. In this study, our aim is to improve the clarification of the swirl motion and air-fuel mixture formation for said Quasi MR-Process CC application in 2-valve diesel engines. Two different CC geometries were investigated in terms of Quasi MR-Process generation potential by using KIVA3V-R2 code. CFD predictions of air flow motion, air-fuel mixture formation and diesel spray combustion were analyzed and compared with each other in a methodical manner. The results showed that 2 valve engine CC is not capable of creating optimal twin swirl. However, it is presented that generation of twin swirl can be improved by application of modified (MR-2 CC) piston head design.

CFD study and experimental investigation of piston geometry induced in-cylinder charge motion on LPG fuelled lean burn spark ignition engine

The performance and emission characteristics of LPG fuelled SI engine is determined by efficient combustion. This depends on the in-cylinder motion of intake homogenous charge generated by combustion chamber geometry. The inherent, unsteady, turbulent motion of the mixture helps in flame propagation which in turn enhances the combustion rate. Compression ratio, charge squish velocity and turbulent kinetic energy are responsible for stable combustion and laminar flame propagation. The in-cylinder charge motion is generally described by swirl, squish, tumble and turbulence which have a vital role on air-fuel mixing and combustion. The piston geometry helps in aiding in-cylinder motion for reducing fuel consumption and enhancing the combustion parameters. In particular, piston squish area in combustion chamber geometry has a major influence in charge motion inside the combustion chamber. The effect of piston squish area on charge motion was studied by CFD using STAR-CD with 25%, 30%, 35% and 40% squish areas to optimize piston crown geometry. Experiments were also conducted with above squish area pistons at a compression ratio of 10:1 to validate the CFD study. It was found that 30% piston squish area improved the performance, combustion characteristics and reduced the emission with LPG fuelled lean burn SI engine.

The effect of combustion chamber geometry on in-cylinder flow and combustion process in a stoichiometric operation natural gas engine with EGR

The performances of three representative chamber geometries, i.e. the nebula, cross and reentrant geometries, in a stoichiometric operation natural gas engine with exhaust gas recirculation (EGR) were investigated through experiments and simulations. The results indicate that the cross and reentrant chambers show quite similar performances in improving the combustion and thermal efficiency, followed by the nebula chamber. The asymmetrical turbulence distribution and hence asymmetrical flame propagation, which reduce the flame development in a certain direction, should be one of the main reasons for increasing the combustion duration with nebula chamber. The cross chamber has similar issues; and its grooves could further reduce the flame surface. Its higher combustion rate than that of the nebula chamber can be mainly attributed to the stronger squish effect which results in a stronger turbulence during initial combustion stage. The reentrant chamber has the highest turbulence intensity before top dead center (TDC) and hence a higher flame surface density. Furthermore, it shows a more symmetrical flame propagation, and also a larger flame surface development during the late period of combustion. However, the effect of its turbulence on flame propagation reduces obviously after TDC since the high intensity region rapidly separates from the flame surface.

Effect of piston profile on performance and emission characteristics of a GDI engine with split injection strategy – A CFD study

Gasoline direct injection (GDI) engines have gained popularity in the recent times because of lower fuel consumption and exhaust emissions. But in these engines, the mixture preparation plays an important role which affects combustion, performance and emission characteristics. The mixture preparation in turn depends mainly upon combustion chamber geometry. Therefore, in this study, an attempt has been made to understand the effect of piston profile on the performance and emission characteristics in a GDI engine. The analysis is carried out on a four-stroke wall guided GDI engine using computational fluid dynamics (CFD). The spray breakup model used is validated with the available experimental results from the literature to the extent possible. The analysis is carried out for four piston profiles viz., offset pentroof with offset bowl (OPOB), flat piston with offset bowl (FPOB), offset pentroof with offset scoop (OPOS) and inclined piston with offset bowl (IPOB) fitted in an engine equipped with a six-hole injector with the split injection ratio of 30:70. All the CFD simulations are carried out at the engine speed of 2000 rev/min., with the overall equivalence ratio of about 0.65±0.05. The performance and emission characteristics of the engine are compared while using the above piston profiles. It is found that, the OPOB piston is preferred compared to that of the other pistons because it has better in-cylinder flow, IMEP and lower HC emissions compared to that of other pistons.

The swirl ratio influence on combustion process and heat transfer in the opposed piston compression-ignition engine

In order to maximise engine heat efficiency an engines charge flow must be properly designed -especially its swirl and tumble ratio. A two-stroke compression-ignition opposed piston engine reacts to engine swirl differently compared to a standard automotive engine with axially symmetric combustion chamber. In order to facilitate direct fuel injection, high-pressure injectors must be positioned from the side of combustion chamber. Depending on the combustion chamber geometry the swirling gases impact greatly how the injection stream is formed. If the deformation is too high the high temperature combustion gases can hit the piston surface or get into gaps between the pistons. This greatly affects the heat lost to the pistons and raises their local temperature. More atomised injection stream is more prone to swirling gas flow due to its reduced droplet size and momentum. The paper presents simulation results and analyses for different intake process induced swirl ratios and different types of combustion chambers in an experimental aviation opposed piston engine.

Reducing emissions by optimising the fuel injector match with the combustion chamber geometry for a marine medium-speed diesel engine

The effects of seven matching parameters of a fuel injector and combustion chamber geometries on nitrogen oxide (NOx), soot and specific fuel oil consumption (SFOC) were investigated by means of a parametric study. The study was carried out on four different engine loads, i.e. L25 (25%), L50 (50%), L75 (75%) and L100 (100%) loads. The injection-related parameters were found to have more prominent influences as opposed to the combustion chamber geometries. Then, a multi-objective genetic algorithm (MOGA) method was proposed in order to identify a set of optimal designs for the L100 load. The emissions and performance of these optimal designs were also examined and compared on the other three engine loads. Finally, an optimal design which meets the IMO (International Maritime Organization) Tier II NOx emissions regulations (research shows it is impossible to meet Tier III NOx emissions regulations solely on the basis of the optimisation of the combustion progress) and which has the best fuel economy was singled out.

Influence of combustion chamber geometry and compression ratio on the main parameters of a diesel aircraft engine

This paper considers the problem of increasing the fuel efficiency of a diesel aircraft engine and decreasing the smokiness of its exhaust gases (EG) by means of the experimental determination of optimum compression ratio and combustion chamber dimensions. Necessity for matching of these parameters in a wide variation range of load and crankshaft speed was identified and proved.

Influence of combustion chamber bowel geometry on combustion, performance and emission characteristics of a diesel engine using grape seed oil methyl ester

In this paper, the combustion, performance and emission characteristics of a single cylinder diesel engine was investigated using two combustion chamber geometries such as toroidal combustion chamber and standard piston combustion chamber in a 5.2 kW single cylinder diesel engine. The experiments were carried out at an ambient temperature of 30 ± 2°C. The performance was observed at no load 20, 40, 60, and 80%, and full load operating conditions. The results showed that the GOME 25 operated with toroidal combustion chamber has improved combustion, performance, and emission characteristics when compared to standard piston combustion chamber. The GOME 25 has improved brake thermal efficiency by about 23, 13.6, 10.6, 9.9, and 10.9% when compared to standard piston combustion chamber operated with diesel at no load, 20, 40, 60, 80, and 100% loading conditions, respectively. The smoke density and CO were reduced by about 14.8% and 38%, respectively. The NOx emission operated with GOME 25 using toroidal combustion chamber was increased by about 36% when compared to standard piston combustion chamber with diesel. The heat release rate of GOME 25 with toroidal combustion chamber was observed to be better when compared to diesel with standard piston combustion chamber. The results confirmed that toroidal combustion chamber piston is a good option for the use of GOME 25 blend.

Combustion Simulation and Emission Prediction of Different Combustion Chamber Geometries Using Finite Element Method

In global scenario rapid advancements in engineering and technology reflects in core mechanical engineering and automotive sector viz automobile and aeronautical engineering. Various researchers are working on smart materials, nano materials and composites materials for aeromechanical applications through sustainable manufacturing. Now a day’s light weight high strength, functional materials are manufactured using micro and nano-machining through computer integrated manufacturing. Advancements of computer interfaced tool are quite common in day to day life in the field of design, simulation and analysis. In the area of computational study, the governing equations are used in FEM and FEA to determine the feasibility of CAE model. For optimizing the combustion chamber geometries, CAE provides the most suitable tool. This research paper encompasses the simulation technique in different combustion chamber geometries with three different cavities on the piston land. The appropriate boundary conditions were constrained in the corresponding numeric model and the combustion simulations were solved using 3D Navier-Stokes equation. The NS solver discretized the FE model into FVM, coupled with species transport equations. The engine combustion parameters peak cylinder pressure of 110 bar, maximum temperature of 1075 K, emission particulates 12.4 PPM NOx and 0.000335 % CO were predicted in the elliptical bowl type of piston using Finite Element Method.

Experimental Study on Performance, Combustion and Emissions of Diesel Engine with Re-entrant Combustion Chamber of Aluminum Alloy

Internal combustion engines have been in use for more than a century and have undergone tremendous changes in their design, materials used and operating characteristics. Diesel engine is the most efficient type of internal combustion engines. In past few decades research efforts have been focused largely on better engine design from the perspective of reducing pollutants emission without sacrificing performance and fuel economy. Gas motion inside the engine cylinder, which depends on combustion chamber geometry is highly influences the performance of any internal combustion engine. Hence an attempt is made to study the performance, combustion parameters and emission particulates of diesel engine using different designs of combustion chambers of Aluminum alloy, in order to enhance the air swirl. Experiments are conducted on four stroke single cylinder water cooled diesel Engine at constant speed of 1500 rpm at different loads with hemispherical, toroidal and re-entrant toroidal geometries of the combustion chambers. The effect of varied piston bowl geometry on performance & combustion parameters viz. brake thermal efficiency (BTE), Brake specific fuel consumption (BSFC), exhaust gas temperature (EGT), heat release rate (HRR) & cylinder pressure and emission particulates have been investigated and presented in this paper. Results suggest that re-entrant piston bowl geometry has significant impact on performance, combustion characteristics and emission particulates inside the cylinder with varied piston bowl geometry shows that the squish flow effects the turbulence near the TDC during compression stroke. However, there is slight increase in particulates of NOx particulates due to increase in combustion temperature with enhanced air swirl with varied piston bowl geometry.

Flow field analysis of turbojet combustion chamber

The paper presents some results regarding the identification of a turbojet engine’s optimal combustion chamber geometry, characterized by small dimensions, with enhanced possibilities for air and fuel mixture circulation in the primary combustion zone in order to obtain good residence time in the flame tube, higher turbulence and optimal radial temperature distribution. Also, it deals with the identification of some solutions of the differential equation for reduced temperature under imposed initial conditions. Some models of combustion numerical computations have been applied, as presented by the specialized documentation, to establish the combustion rate and flame speed for laminar combustion. The geometry of a combustion chamber, with twenty-four injectors and size comparable to a real combustion chamber, has been created in order to obtain the speed and temperature flow field within the flame tube. The major conclusion of the current research is that the distribution of holes within the liner does not need to be symmetric, which means that they have to be positioned in such as a manner as to ensure a higher degree of turbulence in the combustion primary zone and a helical shape of stream lines in the proximity of the walls of the flame tube.

발전용 커먼레일 디젤엔진에 적합한 최적화 연소실형상 설계를 위한 수치해석

발전용 커먼레일 디젤엔진에 적합한 최적화 연소실형상 설계를 위한 수치해석

Optimization of combustion chamber geometry and operating conditions for compression ignition engine fueled with pre-blended gasoline-diesel fuel

In this study, experiments and numerical simulations were used to improve the fuel efficiency of compression ignition engine using a gasoline-diesel blended fuel and an optimization technology. The blended fuel is directly injected into the cylinder with various blending ratios. Combustion and emission characteristics were investigated to explore the effects of gasoline ratio on fuel blend. The present study showed that the advantages of gasoline-diesel blended fuel, high thermal efficiency and low emission, were maximized using the numerical optimization method. The ignition delay and maximum pressure rise rate increased with the proportion of gasoline. As the gasoline fraction increased, the combustion duration and the indicated mean effective pressure decreased. The homogeneity of the fuel-air mixture was improved due to longer ignition delay. Soot emission was significantly reduced up to 90% compared to that of conventional diesel. The nitrogen oxides emissions of the blended fuel increased slightly when the start of injection was retarded toward top dead center. For the numerical study, KIVA-CHEMKIN multi-dimensional CFD code was used to model the combustion and emission characteristics of gasoline-diesel blended fuel. The micro genetic algorithm coupled with the KIVA-CHEMKIN code were used to optimize the combustion chamber shape and operating conditions to improve the combustion performance of the blended fuel engine. The optimized chamber geometry enhanced the fuel efficiency, for a level of nitrogen oxides similar to that of conventional diesel over a variety of operation ranges.