Four-quadrant total to static characteristics of an axial flow compressor

Abstract

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.An axial flow compressor operating under near-design conditions exhibits rotation, °ow and pressure difference between inlet and outlet and rotation in the expected directions. However, during abnormal operating conditions, some of these properties may reverse in direction. In this paper, the experimentally determined four-quadrant compressor maps for pressure-rise, torque and efficiency for a three-stage, low speed axial flow compressor are presented. Six possible modes of operation were identified and investigated; two compressor-like modes in the first and third quadrants, and two turbine-like modes and two highly dissipative modes in the second and fourth quadrants. This paper presents total to static pressure and torque coefficient characteristics for operation in all six quadrants, including reverse rotation modes, as well as efficiency characteristics where appropriate. Results are compared with those of previous researchers for reverse flow, positive rotation operation. The zero-rotation total to static pressure characteristic has been experimentally determined, and found to take the form of an S-shaped curve passing through the second and fourth quadrants, separating the turbine and dissipative modes in both the second and fourth quadrants.