Prediction of Sound Generated by Complex Flows at Low Mach Numbers

Khalighi, Yaser; Mani, Ali; Ham, Frank; Moin, Parviz

doi:10.2514/1.42583

Cited by 71 publications

(53 citation statements)

References 28 publications

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“…The first one is the flow over a single circular cylinder at Re D = 10 000 and free-stream Mach number of 0.2. The acoustic prediction was shown to agree well with the sound computed by directly solving the compressible Navier-Stokes equations (Khalighi et al 2010). 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).…”

Section: Acoustic Calculationmentioning

confidence: 74%

“…To solve the Lighthill equation using a boundary-element method, the approach of Khalighi et al (2010) is followed. Equation (3.1) along with a hard-wall boundary condition on the solid surfaces are recast into a boundary-integral equation, where G(x| y, k) is the free-space Green's function, x and y denote the observer and acoustic source locations, respectively, n i (y) is the solid surface unit normal into the fluid, ∂Ω is the solid surface, Ω is the source domain, α is equal to 1/2 when x ∈ ∂Ω and 1 when x ∈ Ω, and d is the dimension of the problem.…”

Section: Acoustic Calculationmentioning

confidence: 99%

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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 Calculationmentioning

confidence: 74%

Section: Acoustic Calculationmentioning

confidence: 99%

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

et al. 2014

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“…As these methods of noise prediction are based on structured flow solvers for modeling noise sources and approximate Green's functions for propagation/scattering of sound sources, their predictive capability is limited to the flow-generated sound induced by fairly simple geometries. Recently, Khalighi et al (2010) developed a technique for predicting the sound generated by low-Mach number flows in the presence of arbitrarilycomplex geometries by using unstructured, incompressible LES solver of Ham et al (2007) in conjunction with a boundary element method.…”

Section: Introductionmentioning

confidence: 99%

Unstructured Large Eddy Simulation Technology for Prediction and Control of Jet Noise

Khalighi

Ham

Moin

et al. 2010

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Education; Electric Power; Manufacturing Materials An

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Development of concepts for reduction of jet noise has relied heavily on expensive experimental testing of various nozzle designs. For example, the design of nozzle serrations (chevron) and internal mixer/ejector nozzles have relied largely on laboratory and full-scale testing. Without a deeper understanding of the sources of high-speed jet noise it is very difficult to effectively design configurations that reduce the noise and maintain other performance metrics such as nozzle thrust. In addition, the high complexity of the flow limits the success of a parametric black-box optimization.

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“…However, lifting surfaces with thick profiles or spanwise variations in geometry such as trailing edge serrations are not well represented by such analytical Green's functions based on vanishingly thin planes. Accurately resolving the scattering from such lifting surfaces requires a technique such as the boundary element method [22]. Khalighi et al [22] developed a boundary integral equation from Lighthill's wave equation which was solved using the BEM.…”

mentioning

confidence: 99%

“…Accurately resolving the scattering from such lifting surfaces requires a technique such as the boundary element method [22]. Khalighi et al [22] developed a boundary integral equation from Lighthill's wave equation which was solved using the BEM.…”

mentioning

confidence: 99%