Computation of exhaust mixing noise using large-eddy simulation turbulence modeling and Lighthill's acoustic analogy

2004 ◽  
Vol 115 (4) ◽  
pp. 1383-1383
Author(s):  
David Brian Schein
Keyword(s):  
Large Eddy Simulation ◽  
Turbulence Modeling ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Mixing Noise

Wake-Airfoil Interaction as Broadband Noise Source: A Large-Eddy Simulation Study

2005 ◽  
Vol 4 (1-2) ◽  
pp. 93-115 ◽  
Author(s):  
Jérôme Boudet ◽  
Nathalie Grosjean ◽  
Marc C. Jacob
Keyword(s):  
Large Eddy Simulation ◽  
Particle Image ◽  
Broadband Noise ◽  
Far Field ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Naca0012 Airfoil ◽  
Image Velocimetry ◽  
Large Eddy ◽  
Proper Orthogonal

A large-eddy simulation is carried out on a rod-airfoil configuration and compared to an accompanying experiment as well as to a RANS computation. A NACA0012 airfoil (chord c = 0.1 m) is located one chord downstream of a circular rod (diameter d = c/10, Red = 48 000). The computed interaction of the resulting sub-critical vortex street with the airfoil is assessed using averaged quantities, aerodynamic spectra and proper orthogonal decomposition (POD) of the instantaneous flow fields. Snapshots of the flow field are compared to particle image velocimetry (PIV) data. The acoustic far field is predicted using the Ffowcs Williams & Hawkings acoustic analogy, and compared to the experimental far field spectra. The large-eddy simulation is shown to accurately represent the deterministic pattern of the vortex shedding that is described by POD modes 1 & 2 and the resulting tonal noise also compares favourably to measurements. Furthermore higher order POD modes that are found in the PIV data are well predicted by the computation. The broadband content of the aerodynamic and the acoustic fields is consequently well predicted over a large range of frequencies ([0 kHz; 10 kHz]).

Prediction of Profile Losses by Means of Large-Eddy Simulation Including Turbulence Modeling Assessment

2017 ◽  
Author(s):  
Karsten Hasselmann ◽  
Stefan aus der Wiesche
Keyword(s):  
Large Eddy Simulation ◽  
Turbulence Modeling ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Unsteady Separation ◽  
Power Spectral ◽  
Large Eddy ◽  
Experimental Values

In this contribution, a Large-Eddy Simulation (LES) analysis was carried out, to get detailed information about the unsteady flow behavior and loss generation in a turbine cascade at moderate Reynolds numbers. A comprehensive comparison study with experimental data was conducted to validate the LES results. Compared to Reynolds averaged Navier-Stokes (RANS) results, the LES shows a much better agreement with the measured values of the profile loss coefficient, downstream velocity profile, and blade pressure distribution. The unsteady separation and reattachment process was covered well by the LES approach. The power spectral density (PSD) profiles at several positions of the downstream wake were compared and analyzed. Although the results of the LES show mainly a good agreement with the experimental values, there are still some deviations at high frequency. In summery the present case study indicates the high potential of LES especially in case of moderate Reynolds numbers with flow separation.

Computation of aerodynamic noise of centrifugal fan using large eddy simulation approach, acoustic analogy, and vortex sound theory

2007 ◽  
Vol 221 (11) ◽  
pp. 1321-1332 ◽  
Author(s):  
Q Liu ◽  
D Qi ◽  
H Tang
Keyword(s):  
Large Eddy Simulation ◽  
Broadband Noise ◽  
Scale Model ◽  
Aerodynamic Noise ◽  
Centrifugal Fan ◽  
Acoustic Analogy ◽  
Vortex Sound ◽  
Eddy Simulation ◽  
Sound Theory ◽  
Large Eddy

Large eddy simulation is applied to solve the unsteady three-dimensional viscous flow in the whole impeller-volute configuration of a centrifugal fan. The results of the simulation are used to predict the impeller-volute interaction and to obtain the unsteady pressure, velocity, and vorticity fluctuations in the impeller and volute casing. The simulation at the design point is carried out with the wall-adapting local eddy-viscosity subgrid-scale model and a sliding mesh technique is applied to consider the impeller-volute interaction. The results show that a strongly unsteady flow field occurs in the impeller and volute casing of the fan, and the flow is characterized with obvious pressure and vorticity fluctuations, especially at the tongue and at the blade wake region. The large pressure fluctuation at the tongue and the large fluctuation of the blade wake vorticity appear as the blade wake is passing the tongue. Acoustic analogy and vortex sound theory are used to compute the radiated dipole and quadrupole sound fields, which are in good agreement with the experiment. The sound results show that the vortex sound theory is convenient for the broadband noise computation, and the dipole sound is much higher than the quadrupole sound. The dipoles, distributed over the volute tongue surface, are the dominant sound source of the fan.

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