Flow Periodicity Improvement in a High Speed Compressor Cascade with a Large Turning-Angle

Abstract

An experimental program was carried out to improve the flow uniformity/periodicity in a high speed compressor cascade. This program was motivated by recent compressor cascade testing conducted in the Virginia Tech high speed cascade wind tunnel, which was intended to experimentally evaluate the performances of optimized compressor stator blades. The tunnel facility was modified by adding tailboards and guide vanes as well as employing bottom wall suction. Their effects on flow periodicity were investigated through cascade testing on a modern compressor stator cascade with a large turning-angle of about 55°. The tests were conducted for different inlet Mach numbers at the same incidence angle. Experimental results show either the tailboards (always used with the guide vanes) or bottom wall suction can improve flow periodicity effectively, and when used in conjunction, they can help to further improve flow periodicity. Based on the improved tunnel facility condition, a typical series of cascade tests (loss and flow angle) on the modern compressor stator blades was performed. Experimental results show that the flow periodicity is excellent for low inlet Mach number around 0.6 and fairly good for high inlet Mach number about 0.9. This program has allowed the Virginia Tech high speed cascade wind tunnel to be used for cascade testing on modern-featured compressor blades, i.e., high speed and high turning.