Effects of Casing Shape on the Performance of a Small-sized Centrifugal Compressor

  • Kim, D.W. (School of Mechanical Engineering, SungKyunKwan University) ;
  • Kim, H.S. (School of Mechanical Engineering, SungKyunKwan University) ;
  • Kim, Youn-J. (School of Mechanical Engineering, SungKyunKwan University)
  • 발행 : 2003.09.01


The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-sized centrifugal compressor are investigated. Especially, numerical analyses are conducted for the centrifugal compressor with both a circular casing and a volute one. The optimum design for each element (i.e., impeller, diffuser and casing) is important to develop an efficient and compact compressor using alternative refrigerant as working fluids. Typical rotating speed of the compressor is in the range of 40,000∼45,000 rpm. The impeller has backswept blades due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside an entire impeller, vaneless diffuser and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For computations of compressible turbulent flow fields, the continuity and time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained for various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. The static pressure around the casing and pressure difference between the inlet and outlet of the compressor are measured for the circular casing.



  1. Majidi, K., 1998, Numerical calculation of secondary flow in pump volute and circular casings using 3D viscous flow techniques, Proceedings of the 7th International Symposiumon Transport Phenomena and Dynamics of Rotating Machinery, Vol. C, pp. 1459-1469
  2. Lorett, J. A. and Gopalakrishnan, S., 1986, Interaction between impeller and volute of pumps at off-design conditions, ASME J. of Fluids Engineering, Vol. 108, No. 1, pp, 12-18
  3. Croba, D. and Kueny, J. L., 1996, Numerical calculation of 2D, unsteady flow in centrifugal pumps: Impeller and volute interaction, Int'l J. for Numerical in Fluids, Vol. 22, pp. 467-481
  4. Hillewaert, K. and Van den Braembussche, R. A., 1999, Numerical simulation of impeller-volute interaction in centrifugal compressor, J. of Turbomachinery, Vol. 121, pp. 603-608
  5. Ayder, E., Braembussche, R. A. and Brasz, J. J., 1993, Experimental and theoretical analysis of the flow in a centrifugal compressor volute, ASME J. of Turbomachinery, Vol. 15, pp. 582-589
  6. Van den Braembussche, R. A., Ayder, E.and Keiper, R, 1999, Improved model for the design and analysis of centrifugal compressor volutes, J. of Turbomachinery, Vol. 121, pp. 619-625
  7. Stepanoff, A. J., 1957, Centrifugal and Axial Flow Pumps, John Wiley & Sons, New York
  8. Reynolds, W. T., 1979, Thermodynamic Property in SI, Stanford University Press, Stanford
  9. Japikse, D. and Baines, N. C., Introduction to turbomachinery, J. Concepts ETI, Inc and Oxford University Press, New York