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

An axial ∞ow compressor operating under neardesign conditions exhibits rotation, ∞ow and pressure difierence 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 e‐ciency for a three-stage, low speed axial ∞ow compressor are presented. Six possible modes of operation were identifled and investigated; two compressorlike modes in the flrst 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 coe‐cient characteristics for operation in all six quadrants, including reverse rotation modes, as well as e‐ciency characteristics where appropriate. Results are compared with those of previous researchers for reverse ∞ow, 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.