Abstract

LES and acoustic analogy are performed to investigate the effect of wavy leading edge on a linear low pressure turbine cascade aerodynamic performance and the turbulence cascade interaction noise. One straight leading edge cascade and two different wavy leading edge cascades are studied. In each case a rod with a diameter of 2.05mm is placed upstream of the cascade to produce wake which will then interact with the cascade leading edge. Results show that the wavy leading edge can reduce the turbulence cascade interaction noise peak by up to about 6∼8dB in narrow band and attenuate interaction broadband noise by about 3dB in the frequency range below 4000Hz. However, wavy leading edge can lead to a self noise increase in some frequency and increase cascade total pressure loss. Wavy leading edge can change the flow field near the leading edge while the further downstream flow field is altered only a little. The mechanism of noise reduction is also investigated. It is shown that wavy leading edge can reduce blade surface pressure fluctuation near the leading edge. In addition, the spatial-temporal correlation coefficient of pressure fluctuation near the blade leading edge is also decreased. These factors may work jointly and contribute to the final noise reduction.

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