Aerodynamic Noise Simulation of Propeller Fan by Large Eddy Simulation

In this paper, unsteady flow and aerodynamic noise are numerically investigated for a half-open type propeller fan used for outdoor air conditioner components. The flow field is calculated by Front Flow/Blue, which is based on Large Eddy Simulation (LES). The Standard Smagorinsky Model (SSM) and Dynamic Smagorinsky Model (DSM) were used as sub-grid scale models. Aerodynamic noise was calculated by Curle’s equation based on the pressure fluctuation on the blade surface computed by LES. The computed static pressure rise of the fan showed reasonable agreement with the measured equivalent. The time-averaged distributions of the three velocity components downstream of the blades were also compared with those measured by hotwire anemometry, which showed satisfactory agreement between the computed and measured velocity profiles. But the tip vortex passage which was detached from the blade surface predicted by LES was not stable as measured by the experiment. Finally, the predicted far-field sound spectrum agrees reasonably well with measurements in a frequency range of 100 to 1000 Hz although the sound pressure level was underpredicted in the lower frequency range.

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Wind Turbine Blade Tip Flow and Noise Prediction by Large-eddy Simulation

Journal of Solar Energy Engineering ◽

10.1115/1.1800551 ◽

2004 ◽

Vol 126 (4) ◽

pp. 1017-1024 ◽

Cited By ~ 14

Author(s):

Oliver Fleig ◽

Makoto Iida ◽

Chuichi Arakawa

Keyword(s):

Large Eddy Simulation ◽

Wind Turbine ◽

Turbine Blade ◽

Acoustic Emissions ◽

Wind Turbine Blade ◽

Tip Vortex ◽

Aerodynamic Noise ◽

Eddy Simulation ◽

Large Eddy ◽

Blade Tip

The purpose of this research is to investigate the physical mechanisms associated with broadband tip vortex noise caused by rotating wind turbines. The flow and acoustic field around a wind turbine blade is simulated using compressible large-eddy simulation and direct noise simulation, with emphasis on the blade tip region. The far field aerodynamic noise is modeled using acoustic analogy. Aerodynamic performance and acoustic emissions are predicted for the actual tip shape and an ogee type tip shape. For the ogee type tip shape the sound pressure level decreases by 5 dB for frequencies above 4 kHz.

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A hybrid dynamic Smagorinsky model for large eddy simulation

International Journal of Heat and Fluid Flow ◽

10.1016/j.ijheatfluidflow.2020.108698 ◽

2020 ◽

Vol 86 ◽

pp. 108698

Author(s):

Qingxiang Shui ◽

Cuie Duan ◽

Xinyi Wu ◽

Yunwei Zhang ◽

Xilian Luo ◽

...

Keyword(s):

Large Eddy Simulation ◽

Smagorinsky Model ◽

Eddy Simulation ◽

Large Eddy

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Comparative Study of Standard Smagorinsky Model and Dynamic Smagorinsky Model in Large Eddy Simulation of Turbulent Channel Flow

Journal of Scientific Research ◽

10.3329/jsr.v12i1.41924 ◽

2020 ◽

Vol 12 (1) ◽

pp. 39-53

Author(s):

M. S. I. Mallik ◽

M. A. Hoque ◽

M. A. Uddin

Keyword(s):

Large Eddy Simulation ◽

Comparative Study ◽

Channel Flow ◽

Flow Simulation ◽

Turbulent Channel Flow ◽

Smagorinsky Model ◽

Order Accuracy ◽

Eddy Simulation ◽

Large Eddy ◽

Contour Plots

This paper presents results of comparative study of large eddy simulation (LES) that is applied to a plane turbulent channel flow. The LES is performed by using a finite difference method of second order accuracy in space and a low-storage explicit Runge-Kutta method with third order accuracy in time. In the LES for subgrid-scale (SGS) modelling, Standard Smagorinsky Model (SSM) and Dynamic Smagorinsky Model (DSM) are used. Essential turbulence statistics from the two LES approaches are calculated and compared with those from direct numerical simulation (DNS) data. Comparing the results throughout the calculation domain, it has been found out that SSM performs better than DSM in the turbulent channel flow simulation. Flow structures in the computed flow field by the SSM and DSM are also discussed and compared through the contour plots and iso-surfaces.

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Tip vortex prediction for contra-rotating propeller using large eddy simulation

Ocean Engineering ◽

10.1016/j.oceaneng.2019.106410 ◽

2019 ◽

Vol 194 ◽

pp. 106410 ◽

Cited By ~ 2

Author(s):

Jian Hu ◽

Yingzhu Wang ◽

Weipeng Zhang ◽

Xin Chang ◽

Wang Zhao

Keyword(s):

Large Eddy Simulation ◽

Tip Vortex ◽

Eddy Simulation ◽

Large Eddy

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Performance of the Finite Element and Finite Volume Methods for Large Eddy Simulation in Homogeneous Isotropic Turbulence

Journal of Scientific Research ◽

10.3329/jsr.v2i2.2582 ◽

2010 ◽

Vol 2 (2) ◽

pp. 237-249 ◽

Cited By ~ 1

Author(s):

M. A. Uddin ◽

C. Kato ◽

N. Oshima ◽

M. Tanahashi ◽

T. Miyauchi

Keyword(s):

Finite Element ◽

Large Eddy Simulation ◽

Finite Volume ◽

Isotropic Turbulence ◽

Finite Volume Methods ◽

Homogeneous Isotropic Turbulence ◽

Smagorinsky Model ◽

Eddy Simulation ◽

Large Eddy ◽

Better Than

Large eddy simulation (LES) in homogeneous isotropic turbulence is performed by using the Finite element method (FEM) and Finite volume vethod (FVM) and the results are compared to show the performance of FEM and FVM numerical solvers. The validation tests are done by using the standard Smagorinsky model (SSM) and dynamic Smagorinsky model (DSM) for subgrid-scale modeling. LES is performed on a uniformly distributed 643 grids and the Reynolds number is low enough that the computational grid is capable of resolving all the turbulence scales. The LES results are compared with those from direct numerical simulation (DNS) which is calculated by a spectral method in order to assess its spectral accuracy. It is shown that the performance of FEM results is better than FVM results in this simulation. It is also shown that DSM performs better than SSM for both FEM and FVM simulations and it gives good agreement with DNS results in terms of both spatial spectra and decay of the turbulence statistics. Visualization of second invariant, Q, in LES data for both FEM and FVM reveals the existence of distinct, coherent, and tube-like vortical structures somewhat similar to those found in instantaneous flow field computed by the DNS. Keywords: Large eddy simulation; Validation; Smagorinsky model; Dynamic Smagorinsky model; Tube-like vortical structure; Homogeneous isotropic turbulence. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v2i2.2582 J. Sci. Res. 2 (2), 237-249 (2010)

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Enstrophy Cascade and Smagorinsky Model of 2D Turbulent Flows

Journal of Mechanics ◽

10.1017/s1727719100004482 ◽

2001 ◽

Vol 17 (3) ◽

pp. 121-129

Author(s):

Mei-Jiau Huang

Keyword(s):

Reynolds Number ◽

Large Eddy Simulation ◽

Turbulent Flows ◽

Smagorinsky Model ◽

Large Wave ◽

Eddy Simulation ◽

Large Eddy ◽

Wave Numbers ◽

Enstrophy Cascade ◽

Stretching Effect

ABSTRACTDirect numerical simulations of 2D turbulent flows, freely decaying as well as forced, are performed to examine the mechanism of the enstrophy cascade and serve as a template of developing LES models. The stretching effect on the 2D vorticity gradients is emphasized on the analogy of the stretching effect on 3D vorticity. The enstrophy cascade rate, the Reynolds stresses and the associated eddy viscosity for 2D turbulence are correspondingly derived and investigated. Proposed herein is that the enstrophy cascade rate to be modeled in a large-eddy simulation can be and should be calculated using the only available large-eddy information, especially when the Reynolds number is not very large or when the flow is not stationary.The simulation results suggest all Kolmogorov's, Kraichnan's, and Saffman's similarity spectra. The Kolmogorov's spectrum appears in front of forced wave numbers and creates a subrange of a zero enstrophy cascade rate and a constant energy cascade rate. The Saffman's spectrum is the dissipation spectrum at large wave numbers. Kraichnan's spectrum shows up at intermediate wave numbers when the Reynolds number is sufficiently high. When the Smagorinsky model is employed for a large eddy simulation, its inability of capturing the significant reverse cascade phenomenon as observed in the DNS data becomes a fatal defect. Nonetheless, if only the mean cascade rate is concerned, the required Smagorinsky constant is evaluated using the DNS data and compared with the theoretical prediction of the Kraichnan's spectrum.

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High-Pass Filtered Eddy-Viscosity Models for Large-Eddy Simulations of Compressible Wall-Bounded Flows

Journal of Fluids Engineering ◽

10.1115/1.1949652 ◽

2005 ◽

Vol 127 (4) ◽

pp. 666-673 ◽

Cited By ~ 13

Author(s):

Steffen Stolz

Keyword(s):

Boundary Layer ◽

Turbulent Boundary Layer ◽

Large Eddy Simulation ◽

Eddy Viscosity ◽

Correct Prediction ◽

Smagorinsky Model ◽

Eddy Simulation ◽

Viscosity Models ◽

Large Eddy ◽

High Pass

In this contribution we consider large-eddy simulation (LES) using the high-pass filtered (HPF) Smagorinsky model of a spatially developing supersonic turbulent boundary layer at a Mach number of 2.5 and momentum-thickness Reynolds numbers at inflow of ∼4500. The HPF eddy-viscosity models employ high-pass filtered quantities instead of the full velocity field for the computation of the subgrid-scale (SGS) model terms. This approach has been proposed independently by Vreman (Vreman, A. W., 2003, Phys. Fluids, 15, pp. L61–L64) and Stolz et al. (Stolz, S., Schlatter, P., Meyer, D., and Kleiser, L., 2003, in Direct and Large Eddy Simulation V, Kluwer, Dordrecht, pp. 81–88). Different from classical eddy-viscosity models, such as the Smagorinsky model (Smagorinsky, J., 1963, Mon. Weath. Rev, 93, pp. 99–164) or the structure-function model (Métais, O. and Lesieur, M., 1992, J. Fluid Mech., 239, pp. 157–194) which are among the most often employed SGS models for LES, the HPF eddy-viscosity models do need neither van Driest wall damping functions for a correct prediction of the viscous sublayer of wall-bounded turbulent flows nor a dynamic determination of the coefficient. Furthermore, the HPF eddy-viscosity models are formulated locally and three-dimensionally in space. For compressible flows the model is supplemented by a HPF eddy-diffusivity ansatz for the SGS heat flux in the energy equation. Turbulent inflow conditions are generated by a rescaling and recycling technique in which the mean and fluctuating part of the turbulent boundary layer at some distance downstream of inflow is rescaled and reintroduced at the inflow position (Stolz, S. and Adams, N. A., 2003, Phys. Fluids, 15, pp. 2389–2412).

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