Embodiments of the disclosure relate to systems and methods for holding target turbomachine compressor pressure ratio constant while varying the shaft speed. In order to characterize a load compressor and validate the compressor design, the speed of the load compressor can be changed while controlling the compressor operating line and holding the inlet guide vanes at a constant angle. Discharge control valves can be dynamically adjusted to maintain the pressure ratio equal to the operating line over a range of speeds.