PERFORMANCE OF 24-INCH SUPERSONIC AXIAL-FLOW COMPRESSOR IN AIR III – COMPRESSOR PERFORMANCE WITH INLET GUIDE VANS

摘要

As a continuation of the research program on supersonic axial-flow compressors, the 24-inch-diameter rotor was run with a set of inlet guide vanes designed to improve the relative inlet Mach num¬ber distribution near the hub. The inlet guide vanes were con¬structed of sheet-metal plates formed to airfoil mean-line shapes with design turning of about 7° in a counter-wheel-rotation dir¬ection. The results obtained with this set of inlet guide vanes are compared with the data obtained without inlet guide vanes.nThe use of these inlet guide vanes resulted in a decrease in maximum pressure ratio and adiabatic efficiency and a slight increase in equivalent mass flow over most of the speed range of this investigation. The loss in total-pressure ratio and effi¬ciency resulted from reduced diffusion in the rotor-blade passages and increased shock losses encountered at the higher entrance Mach number, as well as increased mixing losses accompanying increased boundary-layer thickness, separation, and transfer, of mass flow toward the compressor hub. The unsteady flow field created at the compressor entrance by the wakes is also responsible for some of the losses in performance encountered in the use of inlet guide vanes. This inherent loss will be encountered whenever inlet guide vanes are used with the shock-in-rotor type supersonic compressor.