Design and Test of an Ultralow Solidity Flow-Controlled Compressor Stator

A full annulus fluidic flow-controlled compressor stator ring was designed and tested in the third stage of a four-stage low-speed research compressor. The solidity of the flow-controlled stator was near unity and significantly below design practice with a commensurately high diffusion factor. The design intent was to reduce the vane count by 30% and load the stator to the point of stall at the design point, then employ flow control to restore attached boundary layers and regain design-point stage matching. The flow control applied, which maintained attached flow, was 1% of the compressor mass flow and was introduced via discrete steady jets on the suction side of the stator. The design method used steady Computational Fluid Dynamics (CFD) with the flow control jets simulated to drive stator exit angles, velocities, and blockage to match the baseline machine. The experiment verified the pretest predictions and demonstrated degraded compressor performance without flow control and restoration of the pumping characteristics of the baseline high solidity compressor when flow control was applied. An assessment of the engine cycle impact of the flow-controlled compressor shows a 2.1 point stage efficiency reduction for the increased loading. Extrapolation of the data and analysis to a high-speed compressor shows a more modest 0.5 point stage efficiency trade.