Investigation on Noise Control Technology of Ultra-High Expansion Ratio Turbine

Aerodynamic noise control is one of the key technologies in the development of stealth technology of torpedo. The noise producing mechanism in an ultra-high expansion ratio turbine with partial admission were discussed. Wide wakes originating from non-outlet region between elliptical nozzles, circumferential non-uniformity owing to partial admission design and complex shock system formed in narrow space between nozzles and rotors are three main sources of aerodynamic noise in this turbine. Thus, two kinds of aerodynamic noise control methods were put forward, namely adding axial gap between the nozzle and rotor, nozzle-down, bilateral repair and trailing edge blowing. Steady annulus simulation results showed that the aerodynamic noise was significantly reduced by more than 10 dB after optimization, which had little impact on the aerodynamic performance of the turbine.