Aerodynamic Noise and Flow Visualization around Two-dimensional Airfoil

Fujisawa, Nobuyuki; Shibuya, Satoshi; Nashimoto, Atsushi; Takano, Tsuyoshi

doi:10.3154/tvsj.21.123

Cited by 9 publications

(15 citation statements)

References 10 publications

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“…Figure 6 shows distributions of the mean surface pressure coefficients of the NACA0018 airfoil at an angle of attack of 68, at which the discrete frequency noise is mostly produced by experiment. The distribution by LES is in good agreement with the experimental data of Fujisawa et al [24] both on the pressure and on the suction side. In order to understand the flow phenomenon near the TE of the airfoil, the instantaneous vorticity fields by LES around the airfoil are compared with the PIV measured ones in Fig.…”

Section: Unsteady Flow Simulation Of Naca0018supporting

confidence: 89%

Large eddy simulation of unsteady flows in turbomachinery

Lee

Kim

Runchal³

2004

Proceedings of the Institution of Mechanical Engineers, Part A:

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Unsteady computations of flows through a rotor of turbomachinery are very essential, and another challenge is to predict performances at off-design points, and to provide information on source fields as an input to the Ffowcs Williams -Hawkings (FW -H) equation for noise prediction. A deductive dynamic SGS modelling in large eddy simulation (LES) is proposed that does not impose averaging of the SGS model coefficients in homogeneous directions. This approach is tested and applied to the unsteady simulation of turbomachinery flow. The LES results from three typical cases of unsteady flows in turbomachinery, namely a NACA0018 airfoil, a compressor cascade and an axial fan, are reported. The flow characteristics on and around a symmetrical NACA0018 airfoil at moderate Reynolds number are simulated to establish the mechanism of discrete tone noise by unsteady flows near the trailing edge (TE) of the airfoil in a uniform flow. The flow past a compressor blade cascade is simulated to predict aerodynamic losses and self-noise by unsteady flows at off-design points. As a third example, the flowfields around rotating fan blades are simulated and used as an input to the FW -H equation to predict their farfield noise, which is in good agreement with experimental data.

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Section: Unsteady Flow Simulation Of Naca0018supporting

confidence: 89%

Large eddy simulation of unsteady flows in turbomachinery

Lee

Kim

Runchal³

2004

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Fujisawa et al. 21 has measured the noise field around the NACA0018 airfoil with zero angle of attack, which would supply abundant validating data for the numerical methodology of the study. The NACA0018 airfoil’s 3D model was presented in Figure 2(a), while the calculation domain was shown in Figure 2(b).…”

Section: Validation Of the Numerical Methodologymentioning

confidence: 99%

“…To further test the gird, the numerical results of the different grids would be compared with the experimental results. 21…”

Section: Validation Of the Numerical Methodologymentioning

confidence: 99%

A bionic noise reduction strategy on the trailing edge of NACA0018 based on the central composite design method

Liu

et al. 2021

International Journal of Aeroacoustics

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New innovative approaches to reduce noise are of great significance in engineering. Taking the typical NACA0018 airfoil as the study target, the serrated treatment of the trailing edge is carried out with the bionic noise reduction technology. To boost the design efficiency and clarify the distributing laws between the design parameters and the noise performances, a special investigation about optimizing the NACA0018 airfoil’s serrated trailing edge is implemented here. Firstly, a united parametric approach to represent various design schemes is proposed. Then, with the integration of the Computational Fluid Dynamics/Computational Acoustics analysis, Central Composite Design, and the Respond Surface Method, a bionic noise reduction strategy is established. The findings can be gotten as: taking into account the existence of the casing or wall near the span-end of the airfoil, the newly defined install location adjustment factor has an influence on the reduction noise, and the install location adjustment factor mainly affects the near-wall flow field of the serrated trailing edge; the optimal design scheme is obtained successfully, which can reduce the overall sound pressure level by about 2 dB in relative to the target; through the mechanism analysis of noise reduction, it can be found that the serrated trailing edge can suppress the development of the laminar separation bubbles, so the noise is reduced.

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“…The laser sheet of Ar-ion and the flush lamp of metal-halide are used for lighting. The oil-film method [9] is also performed to visualize the surface flow of airfoil.…”

Section: Flow Visualizationmentioning

confidence: 99%

An experimental study on aerodynamic sound generated from wake interaction of circular cylinder and airfoil with attack angle in tandem

Munekata¹,

Koshiishi²,

Yoshikawa³

et al. 2008

J. Therm. Sci.

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In our previous study, the effects of the interval between the cylinder and the airfoil on the aerodynamic sound were investigated and compared with the cases of single circular and single airfoil. In this study, the effects of the attack angle of the airfoil located downstream on the characteristics of aerodynamic sound and the wake structure are investigated at a given interval between the cylinder and the airfoil. It is found that the sound pressure level of DFN and the peak frequency decrease with increasing attack angle of airfoil because of the diffusive wake structure due to the increased back pressure of circular cylinder, which is caused by the blocking effect of airfoil. It is shown that the sound sources are corresponded to the attack points of shedding vortex form the upstream circular cylinder to the downstream airfoil. We conclude that the pressure fluctuation at the airfoil surface effects on the sound pressure level, from the flow visualizations and the exploration test of sound source.

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Aerodynamic Noise and Flow Visualization around Two-dimensional Airfoil

Cited by 9 publications

References 10 publications

Large eddy simulation of unsteady flows in turbomachinery

Large eddy simulation of unsteady flows in turbomachinery

A bionic noise reduction strategy on the trailing edge of NACA0018 based on the central composite design method

An experimental study on aerodynamic sound generated from wake interaction of circular cylinder and airfoil with attack angle in tandem

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