TY - JOUR
T1 - On the effect of streamwise disturbance on the airfoil-turbulence interaction noise
AU - Zhong, Siyang
AU - Zhang, Xin
N1 - Funding Information:
The authors would like to thank Zhen Shen from HKUST for the discussions on anisotropic turbulence noise. This work is supported by the National Natural Science Foundation of China (Grant No. 11772282) and the Research Grants Council of Hong Kong (RGC Nos. 16203817 and 16204316).
Publisher Copyright:
© 2019 Acoustical Society of America.
PY - 2019/4/1
Y1 - 2019/4/1
N2 - Usually the prediction of airfoil-gust interaction noise is mainly based on the flat plate solution, and only the transverse velocity disturbance that is perpendicular to the flat plate surface is considered. However, the solution might underestimate the sound generation in non-uniform mean flows for finite thickness airfoils, in which the velocity disturbance in the streamwise direction could probably produce sound as well. The effect is studied in this work by using both numerical simulations and theoretical analysis. To highlight the effect of streamwise disturbance, the anisotropic turbulences with constant transverse velocity components while varying streamwise components are employed, which can be realised by adjusting the integral length scales in the Gaussian energy spectra. The simulation results explicitly show that more sound is produced by the streamwise components for airfoils at higher Mach numbers when the flow non-uniformities are more significant. An analytical model based on acoustic analogy to account for the sound generation by the coupling between the gust and non-uniform mean flows is proposed, which explains the observations in the numerical simulation well. Also, a correction to Amiet's flat plate solution using the proposed model yields better agreement with the numerical results, especially for anisotropic turbulences with larger integral length scale in the streamwise direction.
AB - Usually the prediction of airfoil-gust interaction noise is mainly based on the flat plate solution, and only the transverse velocity disturbance that is perpendicular to the flat plate surface is considered. However, the solution might underestimate the sound generation in non-uniform mean flows for finite thickness airfoils, in which the velocity disturbance in the streamwise direction could probably produce sound as well. The effect is studied in this work by using both numerical simulations and theoretical analysis. To highlight the effect of streamwise disturbance, the anisotropic turbulences with constant transverse velocity components while varying streamwise components are employed, which can be realised by adjusting the integral length scales in the Gaussian energy spectra. The simulation results explicitly show that more sound is produced by the streamwise components for airfoils at higher Mach numbers when the flow non-uniformities are more significant. An analytical model based on acoustic analogy to account for the sound generation by the coupling between the gust and non-uniform mean flows is proposed, which explains the observations in the numerical simulation well. Also, a correction to Amiet's flat plate solution using the proposed model yields better agreement with the numerical results, especially for anisotropic turbulences with larger integral length scale in the streamwise direction.
UR - http://www.scopus.com/inward/record.url?scp=85065327841&partnerID=8YFLogxK
U2 - 10.1121/1.5098783
DO - 10.1121/1.5098783
M3 - Journal article
C2 - 31046306
AN - SCOPUS:85065327841
SN - 0001-4966
VL - 145
SP - 2530
EP - 2539
JO - Journal of the Acoustical Society of America
JF - Journal of the Acoustical Society of America
IS - 4
ER -