Fundamentals of four-quadrant axial flow compressor maps

Abstract The current paper describes the experimental determination of a complete four-quadrant map for a three stage low-speed axial flow compressor. Non-dimensional pressure rise and torque coefficients and efficiency characteristics were determined. Six possible modes of operation were identified in the four quadrants. The characteristic for a compressor with a rotational speed of zero rpm, in terms of pressure rise coefficient and flow coefficient, is S-shaped and forms the dividing line between two alternate modes of operation which exist in the second and fourth quadrants. First quadrant operation is only possible during positive rotation, and third quadrant operation during negative rotation, as the zero-speed S-curve passes through the origin and so does not pass through these quadrants. Consequently, only one mode of operation is possible in each of these two quadrants. A system of notation for describing the various modes of operation has also been developed. Second quadrant operation for positive compressor rotation, and fourth quadrant operation with negative rotation are highly dissipative conditions of operation. First and third quadrant operation are compressor-like modes. Second quadrant negative rotation and fourth quadrant positive rotation operation are turbine-like modes.