Effect Of Piston Bowl Geometry Research Articles

Effect of piston bowl geometry and spray angle on engine performance and emissions in HCCI engine using multi‐stage injection strategy

AbstractThe homogeneous charge compression ignition (HCCI) and combustion chamber geometry play significant roles in improving the potential of compression ignition engines and their environmental sustainability. However, a major hindrance to the progress of HCCI technology has been the notable decline in brake thermal efficiency and emit high levels of hydrocarbon (HC) and carbon monoxide (CO) which is mainly due to the low temperatures during combustion and low post oxidation of these components. Combustion chambers like hemispherical combustion chamber (TCC) and toroidal combustion chamber (TCC) are known to provide better combustion characteristics due to their increased surface‐to‐volume ratio. Moreover, injection timing and spray position have shown a significant effect on the controlling onset of combustion and emission in HCCI engine. Therefore, the primary objective of this numerical study is to enhance the engine characteristics in HCCI mode using an HCC and TCC piston bowl geometry coupled with multistage injection and compare the results with flat piston bowl geometry. The results show that the toroidal shape piston geometry provides 3%–5% higher brake thermal efficiency compared to the conventional piston geometry. Additionally, the energy balance analysis revealed that the combination of modified piston geometry and multi stage injection improved the combustion process by reducing the energy losses due to incomplete combustion and heat transfer to the engine walls. These findings suggest that the proposed injection strategy combined with modified piston geometry has the potential to enhance the performance of HCCI engines and reduce their environmental impact.

An experimental investigation of new chamber geometry on the combustion characteristics, performance and emissions in a light-duty diesel engine

Piston bowl geometry directly affects many parameters such as combustion, flow, turbulence, and mixture formation in-cylinder. This causes a change in engine performance, combustion characteristics and exhaust emissions. In the present study, the effects of piston bowl geometry on mixture formation, combustion characteristics, and emission characteristics of a direct injection compression ignition engine have been experimentally tested. Novel bowl geometries namely New Combustion Chamber (NCC) were developed and made comparison Standard Combustion Chamber (SCC). Air-cooled, four-stroke, single-cylinder and direct injection compression ignition engine was used in the experiments. The diesel engine was operated under full load and different speed conditions (1800, 1900, 2000, 2100 and 2200 rpm). Within the scope of the study, brake specific fuel consumption, engine torque, exhaust emissions (CO2, CO, O2, HC, NO and soot) and combustion characteristics (Instantaneous heat release rate, in-cylinder pressure change, rate of pressure rise and mass fraction burned) were examined. The results showed that the eight pockets and sub-base radius in the NCC geometry significantly improved the specified parameters. The NCC geometry according to the SCC, the specific fuel consumption decreased by approximately 6.89% and engine torque increase 6.32% in the achieved maximum torque at 2000 rpm. Exhaust emissions are generally reduced thanks to the NCC bowl geometry. However, NO emissions increased due to increased temperatures, improved combustion and mixture formation at all speeds. When the combustion analyzes were examined, it was seen that the new type of bowl improved the combustion. The reason was that the increase of the bowl in the surface area, and the increased turbulence with it provided easier evaporation of the fuel droplets and better mixture formation with the air. The spread of combustion over a large area causes an increase in the flame surface area and more controlled combustion was achieved.

Experimental study on the effect of piston bowl geometry on the combustion performance and pollutant emissions of methane-diesel common rail dual-fuel engine

In dual-fuel operations, high methane substitution negatively affects combustion performance and creates high hydrocarbon (HC) and carbon monoxide (CO) pollutant emissions. Piston bowl geometry is proven an effective method for improving combustion performance and emissions. In the available study, combustion chamber geometry is experimentally indicated to succeed in dramatically reducing HC and CO pollutant emissions uncompromising nitrogen monoxide (NO) and smoke pollutant emissions.In this study, the effect of piston bowl geometry on the combustion performance and pollutant emissions of a single-cylinder methane-diesel common rail dual-fuel engine was studied experimentally. High-performance piston bowl geometries (Toroidal and Toroidal re-entrant) of conventional diesel operations were used versus original combustion chamber (OCC) geometry in diesel and dual fuel operation for enhancing combustion performance and reducing pollutant emissions. The experiments were conducted at constant 1850 r/min and five different engine loads. The methane energy fraction was set to 50% of the total energy fraction in dual fuel operations. Experimental results showed that the Toroidal re-entrant combustion chamber (TRCC) geometry reduced the long ignition delay period that was due to the methane addition and ensured more stable combustion at all torque conditions. In dual fuel operation, the TRCC geometry improved smoke, HC, and CO pollutant emissions by an average of 18%, 10%, and 3% for all loads, respectively, compared to the OCC geometry. However, NO pollutant emissions were an average of 2.5% higher than OCC geometry for the TRCC geometry. In sum, use of the TRCC geometry is an effective way for providing more complete combustion and reducing emissions under dual fuel operations at all torque conditions between 3 and 9 Nm.

Effect of piston geometry on combustion characteristics of CI engine used Sal seed oil

The effect of piston bowl geometry on reducing soot emissions, improving combustion, and in-cylinder flow movements in a direct injection diesel engine was investigated. Standard combustion chamber (SCC) and newly modified combustion chamber (MCC) geometries were compared at the same compression ratio (17.5:1). Experimental analysis of diesel engines is expensive and time consuming, and therefore the Computational Fluid Dynamics program was used to analyze the combustion, flow and emission process. AVL Fire ESE Diesel software was used in the numerical study. The numerical work was compared with the experimental results, and it was validated. In addition, 10% biodiesel mixture (10% Sal seed oil methyl ester + 90% diesel fuel) and diesel fuel were used in the analysis. These fuels and two different bowl geometries were investigated at 2000 rpm and full load conditions. Thus, the effect of the used biodiesel fuel and the developed bowl geometry were investigated. Sal seed oil methyl ester was used as biodiesel fuel. The results show that higher turbulence velocity distribution, better mixture fraction values and lower soot formation distribution are obtained by directing the MCC type fuel according to SCC type. When the pressure, temperature and heat release in the combustion chamber are examined, the highest values were obtained with B10 blended fuel used at the SCC type combustion chamber. The maximum heat release rates are 8.72, 9.38, 8.21, and 9.30 J/° for SCCD100, SCCB10, MCCD100 and MCCB10 fuels, respectively.

Effects of Piston Bowl Geometry on Combustion and Emissions of a Four-Stroke Heavy-Duty Diesel Marine Engine

Piston bowl geometry plays an important role in the fuel/air mixing quality which has a direct influence on the performance and emission characteristics of the engine. This work studied the effects of piston bowl geometry on the combustion and emissions of a four-stroke direct injection (DI) heavy-duty diesel marine engine. Three types of piston bowls with various parameters were numerically investigated, targeting to improve engine performance, fuel oil consumption, and emission characteristics. The results pointed out that the ω-type and re-entrant piston bowls enhanced cylinder power by 1.26% and 2.67% while reducing the indicated specific fuel oil consumption (ISFOC) of the engine by 1.06% and 1.60%, respectively, compared to the U-type bowl. Especially, the ω-type and re-entrant piston bowls reduced NO (nitric oxide) emission by up to 25.61% and 46.09%, respectively, owing to lower peak temperatures in comparison to the U-type piston bowl. The results also pointed out that changing the piston bowl type has negligible effects on the engine-out soot and CO2 emission characteristics of the engine. Based on this study, it is highly recommended to utilize the re-entrant piston bowl for four-stroke DI diesel engines to improve both engine performance and fuel oil consumption while reducing NO emission simultaneously.

Investigating the role of fuel injection pressure and piston bowl geometries to enhance performance and emission characteristics of hydrogen-enriched diesel/1-pentanol fueled in CRDI diesel engine.

This paper deals with the effects of piston bowl geometry (hemispherical bowl, troded bowl, and re-entrant bowl) and fuel injection pressure (200bar, 220bar, and 240bar) with hydrogen-diesel/1-pentanol (B20 (80% diesel and 20% pentanol) + 12 lpm of hydrogen) on the emission, combustion, and performance characteristics of a common rail direct injection diesel engine. Re-entrant bowl outperforms hemispherical and troded bowl in terms of brake thermal efficiency (5.67%) and hydrocarbon (8% reduction) with an increase in the fuel injection pressure (240bar) at part and full load. However, with the increase in the fuel injection pressure in the re-entrant bowl, a slight reduction in nitrogen oxide emissions (2%) is observed. With an increase in injection pressure in the case of re-entrant bowls, NHRR (net heat release rate), peak pressure (in-cylinder), and ROPR (rate of pressure rises) all rise significantly by 3.4%, 4.2%, and 2.3%. It is found that changing the piston shape and fuel injection pressure simultaneously is a potential alternative for improving engine performance and lowering emissions.

Effect of Piston Bowl Geometry on Performances of a High Speed Diesel Engine

As one of the primary performances of the diesel engine, the special power can be promoted by increasing the speed or the indicated mean effective pressure. However, the diesel engine will not have enough time for fuel-air mixing and combustion under higher speed, so the excellent matching of injection-bowl is the main way to improve mixing and accelerate combustion. In order to achieve the rapid combustion of a high-speed diesel engine, the effects of piston bowl geometry, diameter-depth ratio, and nozzle arrangement on combustion and performance are calculated by using CFD numerical simulation. The results show that the mixing quality can be improved, the combustion duration can be shortened, and higher combustion efficiency and higher power can be obtained by using a double-layer diverging combustion chamber with a shallow basin structure in the upper and lower layers. With the increase of the diameter-depth ratio of the two-layer diverging combustion chamber, the maximum explosion pressure, the peak heat release rate and the turbulent kinetic energy increase, and the power rise is continuously improved. A new double-layer diverging combustion system matched with a double-layer stagger nozzle based on double-layer diverging combustion chamber the is proposed, the mixing in the cylinder is uniform, the combustion is accelerated and close to complete combustion, and the special power is 61.39kW/L.

CFD Analysis of piston bowls geometry for CI direct injection engine using finite element analysis

Both NOx and soot emissions are major concerns in compression ignition (CI) engine with diesel fuel and the enhancement of variety of fuel and air can increase the performance of combustion engine. There are several methods to enhance the variety of air-fuel within the cylinder. Altering the geometry of piston bowl is one of the methods to improve the air-fuel mixture. This article proposes the effect of piston bowl geometry on the direct injection diesel engine performance and emissions, where various profiles of piston bowl referred as hemispherical combustion chamber (HCC), toroidal combustion chamber (TCC) and shallow depth combustion chamber (SCC) are designed using computer aided design and drafting (CADD) tool and ANSYS workbench is adopted for analysis. In addition, Karanja oil mixed with base fluid diesel at different volume fractions like0.2%, 0.3% and 0.4% and are calculated for their combination properties. Further, theoretical calculations are considered to determine the properties of Nano fluids which are later used as inputs for the analysis. Finally, CFD analysis is employed on different geometries at different fluid volume fractions and thermal analysis is done for piston bowl geometries with different composite materials like carbon fiber and armide fiber.

Optimization of hydrogen‐enriched diesel/n‐Amyl alcohol‐fueled engine to meet emission standards through varying nozzle opening pressure and static injection timing

AbstractImportant injection parameters such as fuel injection timing (FIT) and fuel injection pressure (FIP) on different piston bowl geometries substantially impact the performance, emissions, and combustion characteristics of a common rail direct injection engine. The aim of this study deals with the effects of piston bowl geometry (hemispherical bowl [HSB], troded bowl [TRB], and re‐entrant bowl [REB]), FIP (200, 220, and 240 bar), and variable FIT (20, 24, and 28°bTDC) with hydrogen‐diesel/1‐pentanol (B20) (80% diesel and 20% pentanol) with a constant flow rate of hydrogen at 12 Lpm. Furthermore, to decrease emission standards and energy consumption, biodiesel and hydrogen are the ideal substitutes for conventional fuels. REB outperforms HSB and TRB in terms of brake thermal efficiency (5.67%) and hydrocarbon (8% reduction), increasing the FIP at full load (240 bar). However, with the increase in the FIP in the REB, a slight reduction in nitrogen oxide (NOx) emissions (2%) is observed. With an increase in FIP in the case of REB, net heat release rate, peak pressure (in‐cylinder), and rate of pressure rise all rise significantly by 3.4%, 4.2%, and 2.3%. NOx emissions are marginally enhanced with higher FIP and advanced FIT. It is found that changing the piston shape and FIP simultaneously is a potential alternative for improving engine performance and lowering emissions.

Exploring the Effects of Piston Bowl Geometry and Injector Included Angle on Dual-Fuel and Single-Fuel RCCI

Abstract Reactivity control compression ignition (RCCI) is a low-temperature combustion technique that has been proposed to meet the current demand for high thermal efficiency and low engine-out emissions. However, its requirement of two separate fuel systems (i.e., a low-reactivity fuel system and a high-reactivity fuel system) has been one of its major challenges in the last decade. This leads to the single-fuel RCCI concept, where the secondary fuel (reformates of diesel) is generated from the primary fuel (diesel) through catalytic partial oxidation reformation. Following the in-depth analysis of the reformate fuel (reformates of diesel) and its benefit as the low-reactivity fuel with diesel, the effects of the start of injection (SOI) timing of diesel and the energy-based blend ratio were also studied in detail. In this study, the effects of piston profile and the injector included angles were experimentally examined using both conventional fuel pairs (gasoline—diesel and natural gas—diesel) and reformate RCCI. A validated computational fluid dynamics (CFD) model was also used for a better understanding of the experimental trends. Comparing a reentrant bowl piston with a shallow bowl piston at a constant compression ratio and SOI, the latter showed better thermal efficiency, regardless of the fuel combination, due to its 10% lower surface area for the heat transfer. Comparing the 150-degree included angle and 60-degree included angle on the shallow bowl piston, the latter showed better combustion efficiency, regardless of the fuel combination, due to its earlier combustion phasing (at constant SOI timing). The effect was particularly prominent on reformate RCCI because of its incredibly high diluent concentration, which retards the combustion further for the 150-deg injector. Later, using convergecfd, seven different injector included angles were studied at a constant SOI. With the change in injector included angle, the region of the cylinder targeted by the fuel spray varies significantly, and it was found to have a significant impact on the combustion efficiency and the engine-out emissions. As the injector included angle changed from 60-deg to 150-deg, the combustion efficiency increased by 15% and the CO, NOx, and HC emissions decreased by 96%, 70%, and 86%, respectively.

A Numerical Study to Control the Combustion Performance of a Syngas-Fueled HCCI Engine at Medium and High Loads Using Different Piston Bowl Geometry and Exhaust Gas Recirculation

Abstract This study aims to analyze the effect of piston bowl geometry on the combustion and emission performance of the syngas-fueled homogenous charge compression ignition (HCCI) engine, which operates under lean air–fuel mixture conditions for power plant usage. Three different piston bowl geometries were used with a reduction of piston bowl depth and squish area ratio of the baseline piston bowl with the same compression ratio of 17.1. Additionally, exhaust gas recirculation (EGR) is used to control the maximum pressure rise rate (MPRR) of syngas-fueled HCCI engines. To simulate the combustion process at medium load (5 bar indicated mean effective pressure (IMEP)) and high loads of (8 and 10 bar IMEP), ansys forte cfd package was used, and the calculated results were compared with Aceves et al.’s Multi-zone HCCI model, using the same chemical kinetics set (Gri-Mech 3.0). All calculations were accomplished at maximum brake torque (MBT) conditions, by sweeping the air–fuel mixture temperature at the inlet valve close (TIVC). This study reveals that the TIVC of the air–fuel mixture and the heat loss rate through the wall are the main factors that influence combustion phasing by changing the piston bowl geometry. It also finds that although pistons B and C give high thermal efficiency, they cannot be used for the combustion process, due to the very high MPRR and NOx emissions. Even though the baseline piston shows high MPRR (23 bar/degree), it is reduced, and reveals an acceptable range of 10–12 bar/degree, using 30% EGR.

Effect of piston bowl geometry and compression ratio on in-cylinder combustion and engine performance in a gasoline direct-injection compression ignition engine under different injection conditions

Low temperature combustion (LTC) of high-octane number fuels in compression ignition engines offers an opportunity to simultaneously achieve high engine thermal efficiency and low emissions of NOx and particulate matter without using expensive after-treatment technologies. LTC engines are known to be sensitive to the operation conditions and combustor geometry. It is important to understand the fundamental flow and combustion physics in order to develop the technology further for commercial application. A joint numerical and experimental investigation was conducted in a heavy-duty compression ignition engine using a primary reference fuel with an octane number of 81 to investigate the effects of injection timing, piston geometry, and compression ratio (CR) on the fuel/air mixing and combustion covering different regimes of LTC engines, homogeneous charge compression ignition (HCCI), partially premixed combustion (PPC), and the transition regime from HCCI to PPC. The results show that with the same combustion timing, a higher CR leads to a lower NOx, but a higher emission of UHC and CO. The piston geometry shows a significant impact on the combustion and emission process in the transition regime while it has minor influence in the HCCI and PPC regimes. It is found that high engine efficiency and low emissions of NOx, CO and UHC can be achieved in the earlier PPC regime and later transition regime. The fundamental reason behind this is the stratification of the mixture in composition, temperature and reactivity, which is dictated by the interaction between the spray and the cylinder/piston walls.

Investigating the effect of piston bowl geometry on the partially premixed dual fuel combustion engine at low load condition

One of the most important emerged technologies to improve the emission characteristics of internal combustion engines is the dual-fuel combustion engines being fueled with an abundant clean environmentally friendly fuel such as natural gas as the main fuel while having conventional compression ignition engine design. In this research, a three-dimensional CFD model of fluid flow coupled with the chemical kinetics mechanism is developed and the numerical results of a partially premixed combustion of natural gas and diesel fuel are presented in different piston bowl shapes. The results of the numerical analyses for different combustion chamber designs in the natural gas-diesel dual fuel engine reveal that the bathtub shape geometry, comparing with other piston-bowl geometries, results in a combustion being more efficient and yielding better performance.

Numerical Investigation on the Effect of Piston Bowl Geometry on Combustion Characteristics of a Heavy-Duty Diesel Engine

Today, due to increased efficiency of heavy-duty diesel engines in the global industry, discussion of the performance of these motors, including higher efficiency and lower emissions, is very important. Several methods exist to meet these demands by the diesel engine. Piston bowl geometry deformation strategy is a reliable method for achieving pollutants of lower nitrogen oxides (Nox) and soot and higher yield. This paper has used Converge software to model the CFD for the performance of a Caterpillar 3401 engine with three different piston bowl geometries and various depths and chamfers for one of the geometries. The compression, inlet temperature, and pressure ratio are assumed to be constant. The results of efficiency and pollution of the engine are presented at all stages for analysis, comparisons, and conclusions. The results show that the cylindrical piston bowl geometry has a proper performance in terms of efficiency and the pollutions produced.

Effect of piston bowl geometry on diesel engine performance operated with dairy scum biodiesel

ABSTRACT A sincere effort towards conversion and utilisation of any locally available bio-waste as alternative fuels for the internal combustion engine is most required nowadays. However, diesel engine parameters are more attuned with diesel fuel operation. In this regard, optimisation of piston bowl geometry is highly distinct to improve the substandard performance of the biodiesel operated diesel engine. In the present study, existing diesel engine hemispherical piston bowl geometry (HPBG) is modified into toroidal piston bowl geometry (TPBG) to evaluate the diesel engine performance operated with 20% dairy scum biodiesel (B20). The TPBG-ME operation has shown 6.50% of increased brake thermal efficiency, 17.24% of increased heat release rate, 1.97% of increased cylinder pressure, 3.92% of increased pressure rise rate 8.75% of reduced brake-specific fuel consumption, 15% of lowered HC emission, 8.33% of reduced ignition delay and 11.36% of decreased combustion duration when compared with the standard engine with piston HPBG run with B20 fuel blend (DSOME-B20-SE). Abbreviations: BSFC: Brake-specific fuel consumption (kg/KW h); bTDC: Before top dead centre (°CA); BTE: Brake thermal efficiency (%); CC: Combustion chamber; CHRR: Cumulative heat release rate (J/°CA); CO: Carbon monoxide (%); CO2: Carbon dioxide (%); CR: Compression ratio; deg.: Degrees; Diesel-SE: Diesel operated standard engine; DSOME: Dairy scum oil methyl ester; DSOME-B20: 20% dairy scum biodiesel + 80% Diesel (B20); DSOME-B20-SE: 20% dairy biodiesel operated standard engine (B20-SE); EGR: Exhaust gas recirculation; HC: Hydrocarbons; HPBG: Hemispherical piston bowl geometry; HPBG-ME: Modified engine with HPBG piston; HRR: Heat release rate; HS: High speed; IDP: Ignition delay period; IOP: Injector opening pressure; IT: Injection timing; KOH: Potassium hydroxide; kW: Kilo watt; ME: Modified engine; NH: Nozzle hole; NOx: Oxides of nitrogen; SE: Standard engine; TKE: Turbulent kinetic energy; TPBG: Toroidal piston bowl geometry; TPBG-ME: Modified engine with TPBG piston; TRCC: Toroidal combustion chamber; ULSD: Ultra low sulphur diesel

Comparative study of standard engine and modified engine with different piston bowl geometries operated with B20 fuel blend

Abstract The diesel engine parameters are more compatible with diesel fuel operation. However optimization of engine parameters for dairy scum biodiesel operation in diesel engine is highly pronounced as dairy scum biodiesel has higher viscosity and lesser heating value when compared to petroleum diesel. In the present study, nozzle hole (NH) geometry and engine parameters namely injector opening pressure (IOP), injection timing (IT), compression ratio (CR) are modified to appraise (optimize) the diesel engine performance. At the end optimized engine parameters (IOP: 230 bar, IT: 26 deg.bTDC, CR: 18, NH: 5 holes) are carried further to investigate the effect of piston bowl geometry on diesel engine performance operated with B20 (20% biodiesel+ 80% diesel) fuel blend. The experimental study revealed that the modified engine with Re-entrant Toroidal Piston Bowl Geometry (RTPBG) showed improved performance, combustion and emission characteristics when compared with standard engine (B20-SE) and modified engine (ME) with different piston bowl geometries, namely Hemispherical Piston Bowl Geometry (HPBG), Straight Sided Piston Bowl Geometry (SSPBG) and Toroidal Piston Bowl Geometry (TPBG). This improvement could be attributed to improved fuel atomization, smaller size droplets, increased cylinder temperature, swirl and squish, turbulent kinetic energy of the charge during combustion.

Design of piston bowl geometry for better combustion in direct-injection compression ignition engine

The current computational fluid dynamics (CFD) study presents the effect of piston bowl geometry on the performance and emissions of a direct-injection diesel engine. Different piston bowl profiles, namely, hemispherical combustion chamber (HCC), shallow depth combustion chamber (SCC) and toroidal combustion chamber (TCC), have been created with a baseline compression ratio of 17.5. CONVERGETM CFD code coupled with the SAGE combustion model was used for numerical analysis. It is observed that the TCC piston bowl geometry renders better air–fuel mixture inside the cylinder, which leads to a homogeneous charge. Further, numerical experiments are carried out to analyze suitable TCC piston bowl geometry by varying the depth of the bowl. Out of all the cases, the case with 1.26 mm decrease in depth of bowl from the baseline (TCC) design gives better emissions and performance characteristics.

Combined effects of piston bowl geometry and spray pattern on mixing, combustion and emissions of a diesel engine: A numerical approach

In the present work the combine effects of spray angle and the piston bowl geometry on mixing, combustion and emission characteristics of a direct injection diesel engine have been analyzed numerically. The piston bowl geometry is one of the most important factor that affect the air fuel mixing and combustion and emissions in a direct injection diesel engine. Four spray angles 150°, 155°, 160° and 165° and three different piston bowl geometries namely Toroidal Re-entrant Combustion Chamber (TRCC), Toroidal Combustion Chamber (TCC) and the baseline Hemispherical Combustion Chamber (HCC) have been considered for the same compression ratio of 17.5 and with same chamber volume for all three cases. To simulate the in-cylinder flow and combustion computational fluid dynamics (CFD) modeling based AVL FIRE code was performed and experimental results of the baseline hemispherical bowl were used to validate the numerical model. Simulation results show that spray angle significantly affects the mixing and combustion process for all three bowl geometries and the engine having TRCC type of combustion chamber gives better performance.

Effect of piston bowl geometry and different injection pressure on the performance, emission and combustion characteristics of diesel engine using biodiesel blend

The shape of the piston cavity, variable injection pressure and variable compression ratio are main input parameters to give better atomization of fuels and high swirling induction that improves the Diesel engine performance, combustion, and emissions characteristics. In this study, the engine test was carried out to improve the combustion, performance, and emissions with the use of two different pistons namely hemispherical shaped piston (standard engine), and toroidal cavity piston with varied injection pressures in a single-cylinder direct injection Diesel engine using 25% of corn oil methyl ester-diesel blend (COME25). Initially, the piston bowl was modified to toroidal combustion chamber with tangential cut on circumference of the piston crown in a standard piston of hemispherical type combustion chamber. The engine speed, compression ratio, and injection timing were kept constant and the results of toroidal combustion chamber compared with base engine piston of hemispherical combustion chamber using diesel and COME25 fuel. The results showed that the toroidal combustion chamber has improved performance, combustion and emissions with the exception of NOx emissions.

EFFECTS OF PISTON BOWL GEOMETRY ON COMBUSTION AND EMISSION CHARACTERISTICS ON DIESEL ENGINE: A CFD CASE STUDY

The present paper investigates effect of piston bowl geometry on combustion and emissions. One of the important parameters which affect the combustion in diesel engine is piston geometry. In this study four different piston geometries (HEMISPHERICAL, OMEGA, SINGLE CURVED, DOUBLE CURVED) have been selected for comparative study. Numerical investigation has been carried out using commercially available code AVL FIRE which is a finite volume based code .Automatic mesh generation feature of code is utilized for modelling. For validation of numerical model, simulation results of baseline shape have been validated with experimentally available results. Simulation has been carried out for various piston geometries while keeping parameters such as speed, compression ratio and mass of fuel injected constant. The study has been carried out at full as well as half load .A comparative study for in-cylinder pressure, rate of heat rejection, velocity and temperature field, turbulence kinetic energy has been performed .Emission and performance parameters like SOOT, NO ,efficiency and BSFC have been studied . The results indicated that omega shaped piston works best for the current set-up. As compared to baseline shape of hemisphere, it gives 12% higher NO but 19% less SOOT. Also, the efficiency and BSFC are better for omega shaped piston. KeywordsOMG, SC, DC, HEMI, piston bowl, combustion, emission, CFD, AVL, simulation ---------------------------------------------------------------------***---------------------------------------------------------------------