Large Eddy Simulation of Unsteady Flow Around a Door Mirror Model and Prediction of Resulting Far-Field Sound

2005 ◽  
Author(s):  
Hong Wang ◽  
Chisachi Kato ◽  
Yoshinobu Yamade ◽  
Yang Guo
Keyword(s):  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Surface Pressure ◽  
Measured Data ◽  
Far Field ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Mesh Resolution ◽  
Field Sound

Unsteady flow and resulting far-field sound are numerically investigated for a door mirror model in this paper. The flow field is solved by Large Eddy Simulation (LES) with the dynamic Smagorinsky model while the surface pressure fluctuations obtained by LES are used to predict the far-field sound based on the acoustic analogy. For the prediction of the far-field sound, Curle’s equation is used under the assumption that the characteristic length of the door mirror model is much smaller than the wavelength of the sound. Comparisons between the predicted and measured data are presented in terms of the time-averaged and fluctuating surface pressure distributions as well as the far-field sound spectrum. Reasonably good agreements have been obtained between the predicted and the measured data. Investigation of the effects of the mesh resolution also shows that improved results can be obtained efficiently if the mesh resolution is increased along the stream-wise direction within the separation region and wake region.

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]).

Numerical Simulation of Unsteady Flow and Flow Induced Sound of Airfoil and Wing/Plate Junction by LES and FW-H Acoustic Analogy

2013 ◽  
Vol 444-445 ◽  
pp. 479-485
Author(s):  
Nan Zhang ◽  
Shi Jin Lv ◽  
Hua Xie ◽  
Sheng Li Zhang
Keyword(s):  
Numerical Simulation ◽  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuations ◽  
Water Channel ◽  
Wall Pressure ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Wall Pressure Fluctuations ◽  
Large Eddy

Numerical simulation of unsteady flow and flow-induced sound of an airfoil and a wing/plate junction are performed in the paper by large eddy simulation (LES) and FW-H acoustic analogy. The vortical flows around a NACA0015 airfoil at two angles of attack (0°and 8°) are simulated and analyzed by vortex identification. Simultaneously, the wall pressure fluctuations of the airfoil are computed. At two angles of attack, the flow induced sound of the airfoil is predicted. The computed power spectra agree well with experimental measurements. So the capability of large eddy simulation in predicting unsteady flow and flow induced sound is validated. Subsequently, the horse-shoe vortex around a wing/plate junction in water is computed. Furthermore, the calculations of wall pressure fluctuations and flow induced sound of the junction model at three velocities are accomplished. The predicted results are compared favorably with measured data in large circulation water channel. So the numerical approach for flow induced sound of wing/plate junction in water is validated. It shows that the numerical simulation method in the paper is credible.

An Overset Finite-Element Large-Eddy Simulation Method With Applications to Turbomachinery and Aeroacoustics

2003 ◽  
Vol 70 (1) ◽  
pp. 32-43 ◽  
Author(s):  
C. Kato ◽  
M. Kaiho ◽  
A. Manabe
Keyword(s):  
Finite Element ◽  
Fluid Flow ◽  
Flow Field ◽  
Moving Boundary ◽  
Far Field ◽  
Eddy Simulation ◽  
Unsteady Fluid Flow ◽  
Large Eddy ◽  
Unsteady Fluid ◽  
Field Sound

A numerical method for the prediction of an unsteady fluid flow in a complex geometry that involves moving boundary interfaces is presented in this paper. The method is also applicable to the prediction of the far-field sound that results from an unsteady fluid flow. The flow field is computed by large-eddy simulation (LES), while surface-pressure fluctuations obtained by the LES are used to predict the far-field sound. To deal with a moving boundary interface in the flow field, a form of the finite element method in which overset grids are applied from multiple dynamic frames of reference has been developed. The method is implemented as a parallel program by applying a domain-decomposition programming model. The validity of the proposed method is shown through two numerical examples: prediction of the internal flows of a hydraulic pump stage and prediction of the far-field sound that results from unsteady flow around an insulator mounted on a high-speed train.

scholarly journals Large-Eddy Simulation of Unsteady Flow in a Mixed-Flow Pump

2003 ◽  
Vol 9 (5) ◽  
pp. 345-351 ◽  
Author(s):  
Chisachi Kato ◽  
Hiroshi Mukai ◽  
Akira Manabe
Keyword(s):  
Large Eddy Simulation ◽  
Unsteady Flow ◽  
Mixed Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Flow Pump
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