Sound Generated by Boundary-Layer Flow over Small Steps: Effect of Step Non-Compactness

Jin, Hao; Eltaweel, Ahmed; Wang, Meng

doi:10.2514/6.2012-2051

Cited by 5 publications

(1 citation statement)

References 9 publications

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“…In the second case, the sound of flow over a rod-airfoil configuration was computed, and the results showed excellent agreement with the experimental measurements of Jacob et al (2005). Additionally, the same method was used recently to compute the sound from small steps and gaps in turbulent boundary layers (Hao, Eltaweel & Wang 2013a;Hao et al 2013b). The results were consistent with those obtained using an approximate tailored Green's function for acoustically compact step and gap sizes.…”

Section: Acoustic Calculationsupporting

confidence: 69%

Numerical investigation of tandem-cylinder noise reduction using plasma-based flow control

et al. 2014

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The noise of flow over tandem cylinders at Re D = 22 000 and its reduction using single dielectric barrier discharge (SDBD) plasma actuators are simulated numerically both to confirm and extend experimental results. The numerical approach is based on large-eddy simulation (LES) for the turbulent flow field, a semi-empirical plasma actuation model, and Lighthill's theory for acoustic calculation. Excellent agreement between LES and experimental results is obtained for both the baseline flow and flow with plasma control in terms of wake velocity profiles, turbulence intensity, and frequency spectra of pressure fluctuations on the downstream cylinder. The validated flow-field results allow an accurate acoustic analysis based on Lighthill's equation, which is solved using a boundary-element method. The effectiveness of plasma actuators for reducing noise is clearly demonstrated. In the baseline flow, the acoustic field is dominated by the interaction between the downstream cylinder and the upstream wake. Through suppression of vortex shedding from the upstream cylinder, the interaction noise is reduced drastically by the plasma flow control, and the vortex-shedding noise from the downstream cylinder becomes equally important. At a free-stream Mach number of 0.2, the peak sound pressure level is reduced by approximately 16 dB. This suggests the viability of plasma actuation for active aeroacoustic control of airframe noise.

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Section: Acoustic Calculationsupporting

confidence: 69%