Performance of Axial Compressors with Asymmetric Inlet Flows

An experimental and analytical investigation was undertaken to determine the influence of asymmetric inlet flows on the performance of axial turbomachinery. Overall performance measurements and circumferential surveys of total pressures, velocities and flow angles were obtained in an axial compressor with inlet disturbances covering approximately 25% of the inlet annulus area. Three configurations were tested to find the principal effects in a single rotor, a complete stage and a multi-stage machine. A two-dimensional linearized theory was developed which includes the effect of losses and leaving angle deviations in the blade rows. The analysis may also be applied to propagating stall so that this theory allows a unified treatment of the two phenomena. Introducing the inlet disturbances did not alter the two-dimensional character of the flow in the compressor. Considerable attenuation of the disturbances occurred through a single rotor and the disturbances were almost completely attenuated downstream of a three stage configuration. The mutual interference of the blade rows with small axial spacing was responsible for significant stator losses. The overall performance deteriorated primarily due to losses occurring in the blade rows. In the three configurations tested the inception of propagating stall, as based on the mean flow rate, was essentially unchanged. The theory qualitatively described the flow behavior and a simple application of the theory would give an estimate of the blade forces.