International Journal of Engineering & Science Research

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International Journal of Engineering & Science Research CFD ANALYSIS AND EXPERIMENTAL VERIFICATION OF EFFECT OF MANIFOLD GEOMETRY ON VOLUMETRIC EFFICIENCY AND BACK PRESSURE FOR MULTI- CYLINDER SI

1 International Journal of Engineering & Science Research CFD ANALYSIS AND EXPERIMENTAL VERIFICATION OF EFFECT OF MANIFOLD GEOMETRY ON VOLUMETRIC EFFICIENCY AND BACK PRESSURE FOR MULTI- CYLINDER SI ENGINE ABSTRACT KS Umesh* 1, VK Pravin 2, K Rajagopal 3 1 Dept. of Mech. Engg, Thadomal Shahani Engineering College, Mumbai, Maharastra, India 2 Dept. of Mech. Engg, P.D.A. College of Engg., Gulbarga, Karnataka, India. 3 Former Vice Chancellor, JNT University, Hyderabad (AP), India. In internal combustion engines, volumetric efficiency is one of the prime factors in determining how much power output an engine can generate as compared to its capacity. The purpose of this research work is to investigate using CFD whether design of exhaust manifold has any impact on volumetric efficiency of the multi-cylinder SI engine and if any verify those results obtained through CFD analysis via actual experiments. The scope of the research is further stretched to investigate whether exhaust geometry has any impact on mechanical efficiency of the multi-cylinder SI engine. Flow of the exhaust gases through exhaust manifold is simulated using ANSYS FLUENT V12.0 using pressure and velocity parameters as boundary condition. The analysis has been carried out on two designs an existing one and a modified one and results are subsequently compared. It was observed that the volumetric efficiency improved drastically upon modification in exhaust geometry. Physical models of the same these two systems were subsequently manufactured and exhaustive experiments were carried out on them. The results obtained through CFD analysis were experimentally confirmed. Keywords: Manifold, Volumetric Efficiency, Multi-cylinder Engine, ANSYS FLUENT, Existing model. 1. INTRODUCTION In any multi-cylinder IC engine, an exhaust manifold (also known as a header) collects the exhaust gases from multiple cylinders into one pipe. It is attached downstream of the engine and is major part in multi cylinder engines where there are multiple exhaust streams that have to be collected into a single pipe. When an engine starts its exhaust stroke, the piston moves up the cylinder bore, increasing the pressure. When the exhaust valve opens, the high pressure exhaust gas enters into the exhaust manifold or header, creating an exhaust pulse comprising three main parts: The high pressure head is created by the large pressure difference between the exhaust in the combustion chamber and the atmospheric pressure outside of the exhaust system. As the exhaust gases equalize between the combustion chamber and the atmosphere, the difference in pressure decreases and the exhaust velocity decreases. This forms the medium pressure body component of the exhaust pulse. The remaining exhaust gas forms the low pressure tail component. This tail component may initially match ambient atmospheric pressure, but the momentum of the high and medium pressure components reduces the pressure in the combustion chamber to a lower than atmospheric level. This relatively low pressure (known as back pressure) helps to extract all the combustion products from the cylinder. Thus back pressure is one of the most critical parameter for exhaust system. Also lower back pressure helps to induct the intake charge during the overlap period when both intake and exhaust valves are partially open. The effect is known as scavenging. Scavenging efficiency is function of Length of the exhaust manifold, cross sectional area, shaping of the exhaust ports and pipe works influences the degree of scavenging effect and the engine speed range over which scavenging occurs. The magnitude of the exhaust scavenging effect is a direct function of the velocity of the high and medium pressure components of the exhaust pulse. Headers are designed to increase the exhaust velocity as much as possible. One technique is tuned length primary tubes. This technique attempts to time the occurrence of each exhaust pulse, to occur one after the other in succession while still in the exhaust system. The lower *Corresponding Author 342

pressure tail of an exhaust pulse then serves to create a greater pressure difference between the high pressure head of the next exhaust pulse, thus increasing the velocity of that exhaust pulse.

Detailed information of flow property distributions and heat transfer were obtained by him to improve the fundamental understandings of manifold operation.

Seenikannan et al analysed a Y section exhaust manifold system experimentally to improve engine performance.

Yasar Deger et al did CFD-FE-Analysis for the Manifold of a Diesel Engine aiming to determine specific temperature and pressure distributions.

2 pressure tail of an exhaust pulse then serves to create a greater pressure difference between the high pressure head of the next exhaust pulse, thus increasing the velocity of that exhaust pulse. ive work has taken place already in this field. Scheeringa et al studied analysis of Liquid cooled exhaust manifold using CFD. Detailed information of flow property distributions and heat transfer were obtained by him to improve the fundamental understandings of manifold operation. A number of computations were performed by him to investigate the parametric effects of operating conditions and geometry on the performance of manifolds. Seenikannan et al analysed a Y section exhaust manifold system experimentally to improve engine performance. His paper investigates the effect of using various models of exhaust manifold on CI engine performance and exhaust emission. Yasar Deger et al did CFD-FE-Analysis for the Manifold of a Diesel Engine aiming to determine specific temperature and pressure distributions. The fluid flow and the heat transfer through the exhaust manifold were computed correspondingly by CFD analyses including the conjugate heat transfer. 2. DISCUSSION Model Description Two different Models considered for this research work are shown in the figure 1 & 2 respectively. Fig 1: Existing Model Fig 2: Modified Model Both existing model and modified model has header length of 335mm. ID and OD of headers is mm & 60.3 mm respectively. In existing model the bend radius is 48 mm and exhaust is on one side as shown in the figure. Modified model has bend radius of 100 mm and exhaust is at the centre of header. ID & OD of the bend & exhaust is 35.08mm and 42.2mm respectively for both models. 3. METHODOLOGY Both the models considered for this work were prepared using SOLIDWORKS. These models were imported into ANSYS CFX V12.0. The fluid body was subsequently generated from existing models using design Modular in ANSYS and subsequently meshed as shown in figures. Fig 3: Fluid Body (Existing Model) Fig 4: Existing Manifold (After Meshing) Copyright 2013 Published by IJESR. All rights reserved 343

Fig 5: Fluid Body (Modified Model) Fig 6: Modified Manifold (After Meshing) A steady state single species simulation will be carried out under isothermal conditions for

The reference pressure will be set at 1 atm and all pressure inputs and outputs will be obtained as gauge values with respect to this. 4.

The material properties under these conditions are Table 1: Material Fluid Properties Boundary Conditions Material Air + Gasoline Density (kg/m3) 1.

0250 The engine speed was maintained at 1500 RPM and results were obtained at different load Conditions viz. 2kg, 4kg, 6k, 8kg and 12 kg.

3 Fig 5: Fluid Body (Modified Model) Fig 6: Modified Manifold (After Meshing) A steady state single species simulation will be carried out under isothermal conditions for exhaust gas. Turbulence will be modeled by k-ε RNG turbulence model appropriate to account for high velocities and strong streamline curvature in the flow domain. The reference pressure will be set at 1 atm and all pressure inputs and outputs will be obtained as gauge values with respect to this. 4. MATERIAL FLUID PROPERTIES gas will be considered as an incompressible fluid operating at C. The material properties under these conditions are Table 1: Material Fluid Properties Boundary Conditions Material Air + Gasoline Density (kg/m3) Viscosity (Pa-s) x 10 5 Specific heat (J/kg-K) Thermal conductivity (W/m-K) The engine speed was maintained at 1500 RPM and results were obtained at different load Conditions viz. 2kg, 4kg, 6k, 8kg and 12 kg. The atmospheric gauge pressure was set at 0. And pressure distribution was obtained. 5. EXPERIMENTAL SET-UP Two models considered for the work were manufactured. The material used for pipe was SA106 (Grade B). Flange Material was IS 2062 (Grade B). Elbows were manufactured using SA 234 WPB. Fig 7: Existing model (left) and Modified Model (Right) Copyright 2013 Published by IJESR. All rights reserved 344

4 The test was conducted on 4 stroke 4 cylinder Engine of Maruti-Suzuki make. Experimental set up consisted of: (1) The engine & dynamometer fitted together on common channel frame (2) Fuel Consumption measuring unit & temperature measuring units (3) gas Calorimeter (4) Orifice Meter The experimental set up is shown in the figure. Fig 8: Experimental set up (a) s were measured at (b) Gas inlet to the calorimeter (c) gas outlet to calorimeter (d) Water inlet to calorimeter (e) Water outlet from Calorimeter (f) Water outlet from Engine Also pressure and temperatures were measured in header at points where bends are attached and in the exhaust. Engine Specifications Copyright 2013 Published by IJESR. All rights reserved 345

Table 2: Engine Specification 6. RESULTS Engine 4 Stroke 4 Cylinder SI engine Make Maruti-Suzuki Wagon-R Calorific Value of Fuel (Gasoline) 45208 KJ/Kg-K Specific Gravity of Fuel 0.

65 CFD analysis was carried out on both the models at 6 different loads. 2kg, 4kg, 6kg, 8kg, 10kg and 12 kg. The resulting pressure contour for 4 kg loading is shown in the figure for both the models.

5 Table 2: Engine Specification 6. RESULTS Engine 4 Stroke 4 Cylinder SI engine Make Maruti-Suzuki Wagon-R Calorific Value of Fuel (Gasoline) KJ/Kg-K Specific Gravity of Fuel 0.7 gm/cc Bore and Stroke mm X mm Swept Volume 1100 cc Compression Ratio 7.2 :1 Dynamometer Constant 2000 Diameter of Orifice 29 mm Coefficient of Discharge of orifice 0.65 CFD analysis was carried out on both the models at 6 different loads. 2kg, 4kg, 6kg, 8kg, 10kg and 12 kg. The resulting pressure contour for 4 kg loading is shown in the figure for both the models. The experiments were conducted with same loading conditions on same two models and results obtained after the calculation are enlisted in following table Fig 9: contours for existing and Modified Models The experiments were conducted with same loading conditions on same two models and results obtained after the calculations are enlisted in following tables. Qs and Qa specify swept volume and air intake respectively. Thus their ratio gives volumetric efficiency. Also morse test was conducted on engines to evaluate their Indicated power (I.P.). Brake power (B.P.) was experimentally determined using dynamometer. Thus Mechanical efficiency was also evaluated as ratio of B.P. to I.P. The pressures P1, P2, P3, P4, P5 and temperatures T1, T2, T3, T4, T5 were measured at exhaust manifold and points where 4 inlet bends are attached to header. was calculated using ideal gas equation. These are instantaneous velocities of exhaust gas at above mentioned points. Table 3: Results of experiments conducted on existing Model Unit 2 KG 4 KG 6 KG 8 KG 10 KG 12 KG Column1 B.P. (kw) KW Heat Equivalent Kj/min Fuel Consumption cc/min gm/min Heat Supplied Kj/min Heat Carried By water Kj/min Copyright 2013 Published by IJESR. All rights reserved 346

6 MgCpg Kj/Kg C Heat Carried by Kj/min Unaccounted Heat Loss Kj/min Qs *10-3 m Qa *10-3 m Volumetric Efficiency Air : Fuel Ratio B.S.F.C. Kg-Hr/ KW p1 mm of water p2 mm of water p3 mm of water p4 mm of water p5 mm of water t1 Celsius t2 Celsius t3 Celsius t4 Celsius t5 Celsius v1 m/s v2 m/s v3 m/s v4 m/s v5 m/s ma + mf (Kg/s) *10-3 kg/s Morse test(all Cylinder) Kg Morse test (1 st cylinder) Kg Morse test(2 nd cylinder) Kg Morse test (3 rd cylinder) Kg Morse test (4 th cylinder) Kg I.P. (1st) Kw I.P. (2nd) Kw I.P. (3rd) I.P. (4th) Kw IP Kw Mechanical Efficiency Percentage Frictional Power Kw Table 4: Results of experiments conducted on modified Model Column1 Unit 2 KG 4 KG 6 KG 8 KG 10 KG 12 KG B.P. (kw) KW Heat Equivalent Kj/min Fuel Consumption cc/min Copyright 2013 Published by IJESR. All rights reserved 347

7 gm/min Heat Supplied Kj/min Heat Carried By Water Kj/min MgCpg Kj/Kg C Heat Carried by Kj/min Unaccounted Heat Loss Kj/min Qs *10-3 m Qa *10-3 m Volumetric Efficiency Air : Fuel Ratio B.S.F.C. Kg-Hr/ KW p1 mm of water p2 mm of water p3 mm of water p4 mm of water p5 mm of water t1 Celsius t2 Celsius t3 Celsius t4 Celsius t5 Celsius v1 m/s v2 m/s v3 m/s v4 m/s v5 m/s ma + mf (Kg/s) *10-3 kg/s Morse test(all Cylinder) Kg Morse test (1 st cylinder) Kg Morse test(2 nd cylinder) Kg Morse test (3 rd cylinder) Kg Morse test (4 th cylinder) Kg I.P. (1st) Kw I.P. (2nd) Kw I.P. (3rd) I.P. (4th) Kw IP Kw Mechanical Efficiency Percentage Frictional Power Kw Aim of the work was to verify all the results obtained through CFD analysis by experimentation. Thus the results obtained through CFD analysis and experiments have been compared in following two tables for both the models at all load conditions. Copyright 2013 Published by IJESR. All rights reserved 348

8 Table 5: Comparison between theoretical results (Using CFD) and Experimental results For existing Model 2 Kg from ( Experimental) Kg from ( Experimental) Kg from ( Experimental) Kg from ( Experimental) Load: 10 Kg from Kg from ( Experimental) Copyright 2013 Published by IJESR. All rights reserved 349

9 Table 6: Comparison between theoretical results (Using CFD) and Experimental results For Modified Model Model Column1 Column2 Column3 Column4 Column5 Column6 Column7 2 Kg from ( Experimental) Kg from (Theoretical al) ( Experimental) (Experimental ) (theoretical al) (Experimental ) Temperatur e Kg from ( Experimental) Kg from ( Experimental) Kg Copyright 2013 Published by IJESR. All rights reserved 350

10 from ( Experimental) Kg from ( Experimental) OBSERVATION From table 5 and 6 it can be easily concluded that experimental results matches with the results of CFD analysis. Also pressure, velocity and temperature distribution in header is more uniform for modified design as compared to existing design. For making conclusions most important observations are enlisted below. Table 7: Results obtained for existing Model Load(kg) Volumetric Efficiency Mechanical Efficiency BSFC (Kg-hr/kW) Table 8: Results obtained for modified Model Load(kg) Volumetric Efficiency Mechanical Efficiency BSFC (Kg-hr/kW) Copyright 2013 Published by IJESR. All rights reserved 351

11 Volumetric Efficiency (Modified Model) Volumetric Efficiency (Existing Model) Volumetric Efficiency VS Load Fig 10: Comparison between Volumetric Efficiency of two Models Mechanical Efficiency (Modified Model) Mechanical Efficiency(Existing Model) Fig 11: Comparison between Mechanical Efficiency of two models 8. CONCLUSION From CFD analysis it was found that manifold geometry has a significant impact on the volumetric efficiency of the engine. It was concluded that the modified design gives better volumetric efficiency. The results of CFD analysis were subsequently proved by experimental analysis. Also more uniform pressure distribution and velocity distribution obtained in modified model eases out the design procedure for the exhaust manifold. Also even though there was slight variation in mechanical efficiency and brake specific fuel consumption (b.s.f.c.) the variation was found to be very small and thus no conclusion can be drawn regarding effect of manifold geometry on mechanical efficiency and b.s.f.c. Thus we conclude that Volumetric efficiency and thus power output of the engine can be improved significantly by deployment of suggested modified design. REFERENCES [1] Muthaiah PLS, Kumar MS, Sendilvelan S. CFD Analysis of catalytic converter to reduce particulate matter and achieve limited back pressure in diesel engine. Global journal of researches in engineering A: Classification (FOR) ,091399, 2010; 10(5). [2] Kamble PR, Ingle SS. Copper Plate Catalytic Converter: An Emission Control Technique, SAE Number Copyright 2013 Published by IJESR. All rights reserved 352

12 [3] Beardsley MB et al. Thermal Barrier Coatings for Low Emission, High Efficiency Diesel Engine Applications, SAE Technical Paper 1999; 1: [4] JacobE, Lammermann R, Pappenherimer A, Rothe D. Gas After treatment System for Euro 4: Heavy Duty Engines MTZ 6/2005. [5] Jacobs T, Chatterjee S, Conway R, Walker A, Kramer J, Mueller-Haas K. Development of a Partial Filter Technology for Hdd Retrofit, Sae Technical Paper [6] Lahousse C, Kern B, Hadrane H, Faillon L. Backpressure Characteristics of Modern Three-way Catalysts, Benefit on Engine Performance, SAE Paper No ,2006 SAE World Congress, Detroit, Michigan, April 36, [7] Muramatsu G, Abe A, Furuyama M. Catalytic Reduction of Nox in Diesel, SAE , [8] Heywood JB, Internal Combustion Engine Fundamentals (Tata McGrah Hill). [9] Labhsetwar NK, Watanabe A, Mitsuhashi T. Possibilities of the application of catalyst technologies for the control of particulate emission for diesel vehicles, SAE Transaction [10] Biniwale R, Labhsetwar NK, Kumar R, Hasan MZ. A non-noble metal based catalytic converter for two strokes, two-wheeler applications, SAE. [11] Pravin VK, Umesh KS, Rajagopal K, Veena PH. Simulative Analysis of Flow through the Manifold for Improved Volumetric Efficiency of a Multi-Cylinder Petrol Engine 2012; 4(2): Copyright 2013 Published by IJESR. All rights reserved 353

Thermal Analysis on 4 1 Tubular Type IC-Engine Exhaust Manifold through Anysis

International Journal of Advanced Mechanical Engineering. ISSN 2250-3234 Volume 4, Number 7 (2014), pp. 755-762 Research India Publications http://www.ripublication.com Thermal Analysis on 4 1 Tubular