ISSN 2319-8885Vol.03,Issue.25 September-2014, Pages:5069-5075 www.semargroup.org, www.ijsetr.com Flow Analysis of Centrifugal Compressor Impeller for a Turbocharger AUNG AUNG1, WIN PA PA MYO2, ZAW MOE HTET3 Dept of Mechanical Engineering, Mandalay Technological University, Mandalay, Myanmar. Abstract: This paper presents the flow analysis of centrifugal compressor impeller for a turbocharger. The impeller is designed by assuming 575kW power supplied by the turbine (allowing for bearing friction) at 19500 rpm and 20 twisted blades. In so doing, the diameters of the hub (dh1=73.98mm), the shroud at inlet (ds1=199.62mm), the blade tip (d2=391.2mm), the blade angles at hub (βbh1 =59.31 degree), at shroud inlet (β bs1=31.98 degree), at impeller outlet (βb2=72.75 degree) are calculated. The geometry of this impeller and fluid domain around one blade can be achieved by using CFturbo 9.1 with these design data. The flow analysis of the compressor can be reached by importing fluid domain in the CFX from ANSYS 12.0 to show the comparison of pressure and temperature distribution across the impeller by theoretical and ANSYS simulation results. Keywords: Turbocharger; Turbine; Compressor; CFturbo; ANSYS. I. INTRODUCTION A turbocharger consists of a turbine and a compressor connected by a shaft. The turbine section is mounted to the exhaust line from the engine. The compressor is connected to the turbine by a shaft and its outlet is routed to the engine air intake. Exhaust gas from the engine enters the turbine and expands, performing work on the turbine. The turbine spins the shaft connected to the compressor. The compressor draws in ambient air and compresses it. Turbocharger systems are measured by the amount of pressure the compressor can output above ambient. This pressure is commonly called boost pressure or boost. Therefore, the compressor is also the main part of the turbocharger to arise pressure for diesel engine. A centrifugal compressor consists of three major sections with regard to the path through which the fluid passes. These are the inlet to the impeller (also known as the eye of the impeller or inducer section), the impeller section and the diffuser section. The inlet section may consist of suction elbow and guide vanes. The guide vanes give the fluid some degree of prewhirl or pre-rotation before entering the impeller section. In the absence of guide vanes, the fluid flows axially into the impeller section. A compressor stage is made up of the impeller and diffuser sections. What goes on inside the centrifugal compressor is very much influenced by the conditions of the fluid flow at the inlet of the compressor. Thus obtaining optimal flow of the working fluid through the compressor stage requires proper design of the compressor inlet and appropriate determination of the flow conditions at the inlet. The design of compressor has developed with the power supplied by the turbine(allowing for bearing friction), P,575 kW, air mass flow , m, 4 kg/s, rotational speed, N, 19500 rpm, and the number of impeller blade, Z, 20. In this paper, the impeller of compressor is designed with CFturbo9.1 software and 3-D simulation study of the impeller can be achieved by helping of CFD software ANSYS CFX. II. DESIGN OF IMPELLER WITH CFTURBO9.1 Compressor design is complex and time consuming. Therefore modern high-quality software tools are required to enable the engineer to create and analyze several geometry variations and find quickly an optimal solution. Here, the application of CFturbo9.1 is now used to design the impeller. To get this geometry, five parameters should be given: Fluid properties as ideal gas or as real gas with compressibility factor. Best point: mass flow, speed, specific work. Inlet condition: pressure and temperature. The main dimensions of hub and suction diameters as well as outlet width and diameter. The size of the tip, direction of rotation and blade numbers as well as spliter blade. The design data can be transformed into a parametric CADmodal and other neutral format such as STEP or IGES. The design procedure is shown in figs.1, 2 and 3. II. FLOW ANALYSIS OF THE IMPELLER The geometry of the fluid domain [Fig.5] imports to ANSYS CFX workbench. After creating the model, meshing is also done in CFX itself. This meshing domain is repeated twelve times at Turbo mode in CFX because the impeller has 12 blades. The whole domain of the impeller is meshed Copyright @ 2014 SEMAR GROUPS TECHNICAL SOCIETY. All rights reserved. IssueNo. Fig.3.1. for lower mass flow.4. Initial data input in the CFturbo9. the mass flow boundary conditions are set.2.AUNG AUNG. September-2014. The geometry of impeller. require little user time or effort. Fig. Unstructured grid method gives the the fully 3D. At the outlet static pressure boundary conditions for higher mass flow are set.1. International Journal of Scientific Engineering and Technology Research Volume. Fig. Main dimensions input the CFturbo9. viscous. Meridional contour. The geometry of fluid domain. ZAW MOE HTET by using the unstructured type of grid is as shown in Fig. compressible.5.4. The speed of impeller [rev/min] is also set. turbulent analysis of the advantage that they are much automated and. Pages: 5069-5075 . The details of meshing of Triangles in 2D and tetrahedral in 3D typically utilize in completed domain are shown in table1. WIN PA PA MYO. The total pressure and total temperature always set at the inlet boundary conditions. fluid (air) flow.1 software.25. therefore.03. TABLE I: Results of Impeller Fig. Fig. ANSYS CFX solves unstructured grids. The blade. of Domain Fig.8. Isometric 3D View of the Blade.Flow Analysis of Centrifugal Compressor Impeller for a Turbocharger III. Fig. IssueNo. BOUNDARY CONDITIONS At the inlet.0. At the outlet boundary conditions static pressure is set. The mesh of fluid domain. Hub and Shroud. hub and shroud are defined as adiabatic walls with appropriate rotational velocity and no-slip. The Geometry ANSYS12.8 provides the summary of the boundary conditions used in the impeller. Fig.9.7. by Importing Fig. Pages: 5069-5075 .6. with measured total temperature.7].03. total pressure and flow direction profiles.25. The following data in table (3) input the CFX and the boundary conditions are also set [table (4) and table (5)]. TABLE II: Meshing Details of Fluid Domain Fig. Hub and Shroud.10. The turbulence level is defined to be median intensity of about 5% because there is no idea of the turbulence levels in this simulation. by using the unstructured type of grid in table (2) of the domain can be achieved. The geometry [Fig. the boundary is defined as subsonic inlet. Fig. International Journal of Scientific Engineering and Technology Research Volume.6] and mesh [fig. September-2014. Meridional View of the Blade. Boundary conditions used in the impeller simulation. International Journal of Scientific Engineering and Technology Research Volume. Total Pressure Distribution across the Blade to Fig. ZAW MOE HTET Fig. Impeller.03. Fig.25. Static pressure Distribution across the Impeller.15. Pages: 5069-5075 .13.AUNG AUNG. IssueNo. Total pressure Distribution across the Impeller. Fig. Static Pressure Distribution across the Blade to Blade. Total Temperature Distribution across the Impeller. WIN PA PA MYO. September-2014. Fig. Fig.12.14. Static Temperature Distribution across the Blade.16.11. 19. Fig.18.Chart of Streamwise Location and Total Pressure Blade. Mach Number Distribution across the Blade to Fig.20. International Journal of Scientific Engineering and Technology Research Volume.03. Absolute Velocity Distribution across the Blade to Blade.17.22. Fig. Chart of Streamwise Location and Pressure on Inlet to Outlet.21. Fig.Flow Analysis of Centrifugal Compressor Impeller for a Turbocharger Fig. September-2014. Fig. IssueNo. Temperature Distribution across the Blade to Blade. Total Temperature Distribution across the Blade to Blade.25. on Inlet to Outlet. Pages: 5069-5075 . ZAW MOE HTET Fig. Pages: 5069-5075 . Chart of Streamwise Location and Total Temperature on Inlet to Outlet. Hub and Shroud Fig. IssueNo. TABLE III: Domain Physics for CFX TABLE IV: Boundary Conditions of Impeller Inlet & Outlet Fig.25.26. TABLE IV: Boundary Conditions of Impeller Blade.25. September-2014.24.23. International Journal of Scientific Engineering and Technology Research Volume. Fig. Chart of Streamwise Location and Temperature on Inlet to Outlet.03. Chart of Streamwise Location and Absolute Velocity on Inlet to Outlet. Chart of Streamwise Location and Mach Number on Inlet to Outlet. WIN PA PA MYO.AUNG AUNG. Head of mechanical engineering department.6. “An Advantageous Turbomachinery Design Method. And. A.541 K over 0. John Wiley and Sons. New York. Ph. co-supervisor of thesis.0. and U gradual increase in the total temperature (428. for her TABLE VI: Comparison of Theoretical and ANSYS valuable guidance. describe the static and total From this point. The temperature which the design of impeller depends. The From this point. Seventh Edition. then. Chapman and Hall.. Mandalay Technological University. CONCLUSIONS AND RECOMMENDATIONS pressure is nearly constant by 88. [6] Khin Maung Aye. [8] Victor L . The job of a diesel engine constant over 0. UK and C. And. Turbocharging the Internal Combustion Engine.2 of the streamwise location. In the first chart. From this point. Eng.Flow Analysis of Centrifugal Compressor Impeller for a Turbocharger 0. the absolute velocity is nearly constant by 130.4 and 0. IssueNo. the compressor with the engine exhaust gas power.28300 (2007). N.D. [7] Church. Kreuzfeld and R. Austin H. the impeller. then. Pages: 5069-5075 . UK: Fluid Mechanics and Thermodynamics of Turbomachinery .41 m/s over 0. the fluid flow domain of the impeller is analysed.853 K of the temperature on 1. Results at Inlet VII.2.. the comparison of theoretical and ANSYS simulation transferring data from ANSYS to MATLAB.2 on The modal for the impeller of centrifugal compressor has streamwise location. L. From this point.4 and paper. S. Mach Number number (about 0. London: Longman. Dixon. Yamaguchi : The Experimental Study of Matching Between Centrifugal Compressor Impellers and Vaneless Diffuser for Turbochargers Proceedings of ASME TURBO EXPO 2007 GT2007.2 on the streamwise location.15 to 20. B.4 of streamwise location.1 software. THE RESULTS OF FLUID FLOW From fig. The pressure is constant 103 kPa between 0. there is a Dr. thesis supervisor of the author. the static V. 2000.948881 on the end of streamwise location. In this location. Streeter.8) over 0. maintains at 298 K between 0.: Centrifugal Pumps and Blowers. 1972. show the static pressure. there is a dramatic incline in the Mach pressures. impeller is designed by the power from the turbine. The author is also end of streamwise location.21 to 26] are achieved by Here. Win Pa Pa Myo.11 to 14. In this charts. and Janota. Müller. From fig. [5] Watson. (362. Ltd. U: Fluid Machinery for Mechanical Engineers.2 on the streamwise location. the temperature is gradually inclined to 298 vanned diffuser and volute are recommended to design on K beyond 0. In the fourth. The analysis incline in the 103 kPa of pressure over 0.2.877 increasing power output. Ph.D. (1989).454 K) on the Zaw Moe Htet. then. Inc. Department of Engineering. it is gradually and absolute velocity distribution across the blade to blade.25. On the fifth. From this turbocharger is to supply compressed air to the engine for point. P. University of Liverpool.6. Ei Ei Htwe. The 0..468 m/s) at the outlet. there is a dramatic rise in the 362. University Lecturer in Turbomachinery.189 kPa over 0. At the second.03. September-2014. total pressure. there is a gradual incline in the velocity IV. Honorary Senior Fellow. On the sixth. the total pressure is gradually increased to 359. This static temperature is slightly constant at 284.6. And. then. [2] H. ACKNOWLEDGMENT streamwise location. Turbine drives the centrifugal kPa on the end of the streamwise location. University of Cambridge. TABLE VII: Comparison of Theoretical and ANSYS August-September 2011. the static and total temperatures. thankful to Dr. [3] G. there is a gradual been developed by using CFturbo9.385583 over 0. results are shown in Tables (6) and (7). (1982). Results at Outlet [4] Cumpsty. Hall. Compressor Aerodynamics. increased to 0. the velocity is dramatically increased to 280 m/s over International Journal of Scientific Engineering and Technology Research Volume. On the third.4 of streamwise has been carried out with the help of ANSYS12. M. And. December. the total temperature is The author likes to acknowledge the supports provided by constant at 293 K over 0.” Compressor Tech Two. The chart figures [Figs. N. the Mach number static temperature and total temperature distributions across maintains at 0.0 VI. From this point. University of Michigan: FLUID MECHANICS. REFERENCES [1] S.6. the streamwise locations are divided into 5 parts on the inlet to outlet meridional views. Tamaki and S. Professor Emeritus of Hydraulics. there is a dramatic rise in the 200 kPa of the next suggestion is to be analysed the fluid flow of the whole pressure at outlet. total pressure (100 kPa) is centrifugal compressor. A.