NACA Research Memorandums

The use of inlet guide vanes with the 24-inch supersonic compressor resulted in a decrease in maximum pressure ratio and adiabatic efficiency, and a slight increase in equivalent mass flow. The loss in total pressure and efficiency resulted from reduced diffusion in the rotor-blade passages, increased shock losses at the higher entrance Mach number, and increased mixing separation, and transfer of mass flow toward the rotor hub. The unsteady flow field created at the compressor entrance by the guide-vane wakes is also responsible for some of the losses. This inherent loss will be encountered whenever inlet guide vanes are used with the shock-in-rotor type of supersonic compressor