Sliding grid simulation of cascade noise
Summary
Turbofan engines are commonly used on modern commercial aircrafts
and have become a significant source of noise pollution. The tonal noise
generated by turbofan engines has been extensively studied, and noise
reduction approaches such as acoustic liners have been developed. The
dominant source of broadband noise is due to the turbulent fan-wake
interacting with the leading edges of the outlet guide vanes (OGV)
The rotational motion of the fan blades was considered, by applying a
high-order hybrid sliding interface between the turbulence injection
region and the OGVs.
The effect of the advance ratio and turbulence properties of the fanwakes, such as the wake width and turbulent integral length scale, on
the sound power level, were investigated. The sound power level
obtained are compared to analytical predictions.
The wake rotation speed has no significant effect on the noise generated
by the cascade, due to the similar levels of averaged turbulence intensity
across each case. This will remain true, as long as the separation
between adjacent wakes is a constant.
The changes in the wake width have a significant
influence on the upstream and downstream sound power levels. Wider wakes tend
to increase the PWL at low frequencies and decrease the levels at high frequencies.
Similar effects were observed for the downstream PWL spectra.
Reference
1. W. Ying, R. Fattah, S. Zhong*, X. Zhang*, and Gea-Aguilera F., “A numerical investigation of the rotor blockage effect on cascade noise using a sliding mesh method”, Journal of Sound and Vibration, 502, pp.116030, 2021 2. W. Ying, R. Fattah, S. Zhong*, J. Guo, X. Zhang, “An efficient and high-order sliding mesh method for computational aeroacoustics”, Journal of Supercomputing, 1-29, 2022