Concept of self-excited unsteady flow control on a compressor blade and its preliminary proof by numerical simulation

Abstract

This paper presents a new concept of self-excited unsteady flow control technique on a compressor blade using a passive fluidic oscillator. This concept, as an unsteady flow control method, has the advantages that no additional air source or power supply needs to be introduced and no complex actuators or movable parts are included. Numerical simulations show that the passive fluidic oscillator will reduce the total pressure loss coefficient of the compressor cascade by 4.2% to 2.8% when the inlet Mach number of the compressor blade ranges from 0.28 to 0.39. The time domain and frequency spectrum analysis prove the unsteadiness of the jet produced by the passive fluidic oscillator. Within the Mach number scope, the reduced jet velocity equals approximately 0.68 to 0.7 and the reduced jet frequency equals nearly 1.1 to 1.2. This finding agrees with the order-of-magnitude study result that the jet parameters are compatible with the compressor (the reduced jet velocity and frequency are in the order of magnitude of 1) at the design point, and it conforms to the self-adaptivity of the passive fluidic oscillator in a certain degree (the reduced jet velocity and frequency are nearly invariant) at off-design points (providing small changes in angles of attack), which most passive flow control methods do not share.