scholarly journals Analysis of Influence of Different Parameters on Numerical Simulation of NACA0012 Incompressible External Flow Field under High Reynolds Numbers

2022 ◽  
Vol 12 (1) ◽  
pp. 416
Author(s):  
Lu Yang ◽  
Guangming Zhang
Keyword(s):  
Reynolds Numbers ◽  
External Flow ◽  
Far Field ◽  
Trailing Edge ◽  
Modeling Methods ◽  
Blunt Trailing Edge ◽  
Data Points ◽  
Accuracy Difference ◽  
High Reynolds ◽  
Simulation Parameters

Currently, influence analysis of simulation parameters, especially the trailing edge shape and the corresponding modeling method on the force coefficients of NACA0012 under a high Reynolds number, is relatively sparse. In this paper, two trailing edge shapes are designed by three modeling methods and combined with three far-field distances to establish eighteen two-dimensional external flow fields. The same number of structured grids are generated by a unified grid strategy and the SST k-omega and the Spalart–Allmaras models are adopted to solve the NS equations to realize the numerical simulations. Unlike under low Reynolds numbers, the analysis results show that although the accuracy difference between the sharp trailing edge and the blunt trailing edge decreases as the attack angle range increases, the former is preferred in all studied ranges. As to the corresponding modeling methods, the NACA4 and the definition formula are preferred, the choice of which depends on the studied range. In particular, a greater number of data points adopted into the definition formula is not necessarily better. Considering the error ratios comprehensively, the simulation configurations of sharp trailing edge + 20 m far-field distance + SA/SST/SST/SST/SST/SA turbulence model obtains optimal simulation effects.

Airfoil Trailing Edge Noise Reduction Using a Boundary-Layer Bump

2019 ◽  
Vol 105 (5) ◽  
pp. 814-826 ◽  
Author(s):  
Yuejun Shi ◽  
Seongkyu Lee
Keyword(s):  
Boundary Layer ◽  
Noise Reduction ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Numerical Approach ◽  
Trailing Edge ◽  
Velocity Deficit ◽  
Trailing Edge Noise ◽  
Field Noise ◽  
High Reynolds

This paper presents a new idea of reducing airfoil trailing edge noise using a small bump in the turbulent boundary layer. First, we develop and validate a new computational approach to predict airfoil trailing edge noise using steady RANS CFD, an empirical wall pressure spectrum model, and Howe's diff raction theory. This numerical approach enables fast and accurate predictions of trailing edge noise, which is used to study the noise reduction from the bump for various airfoil geometries and flow conditions at high Reynolds numbers. Three types of bumps, the suction-side bump, pressure-side bump, and both-side bumps, are studied. The results show that all types of bumps are able to reduce far-field noise up to 10 dB compared to clean airfoils, but their impacts are diff erent in terms of the eff ective frequency range. Also, bumps with four diff erent heights are compared with each other to investigate the eff ect of the height of bumps on noise reduction. It is demonstrated that a bump causes velocity deficit within the boundary layer near the wall. This velocity deficit results in reduced turbulence kinetic energy near the wall, which is responsible for trailing edge noise reduction. Overall, this paper demonstrates the potential of a boundary-layer bump in trailing edge noise reduction and sheds light on the physical mechanism of noise reduction with boundary-layer bumps.

The Effect of Base Bleed on the Flow behind a Two-Dimensional Model with a Blunt Trailing Edge

1967 ◽  
Vol 18 (3) ◽  
pp. 207-224 ◽  
Author(s):  
P. W. Bearman
Keyword(s):  
Vortex Formation ◽  
Reynolds Numbers ◽  
Base Pressure ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Trailing Edge ◽  
Model Base ◽  
Blunt Trailing Edge ◽  
Two Dimensional Model ◽  
Base Bleed

SummaryThe effects of base bleed on the flow about a two-dimensional model with a blunt trailing edge were examined at Reynolds numbers, based on model base height, between 1·3×104 and 4·1×104. The ratio of boundary layer thickness at the trailing edge to half the model base height was approximately 0·4. Measurements were made of base pressure, vortex shedding frequency and the distance to vortex formation. With a sufficiently large bleed quantity the regular vortex street pattern disappeared and the base drag of the section was reduced to about a third of its value without bleed. The base pressure was found to vary linearly with the inverse of the vortex formation distance. Results of a previous splitter plate investigation were found to agree closely with those of the present experiments.

scholarly journals Flow visualization over a thick blunt trailing-edge airfoil with base cavity at low Reynolds numbers using PIV technique

2016 ◽  
Vol 20 (4) ◽  
pp. 695-710 ◽  
Author(s):  
Gholamhossein Taherian ◽  
Mahdi Nili-Ahmadabadi ◽  
Mohammad Hassan Karimi ◽  
Mohammad Reza Tavakoli
Keyword(s):  
Flow Visualization ◽  
Reynolds Numbers ◽  
Trailing Edge ◽  
Low Reynolds Numbers ◽  
Blunt Trailing Edge ◽  
Piv Technique ◽  
Base Cavity ◽  
Low Reynolds

Experimental Investigation of the Vortex Shedding in the Wake of Oblique and Blunt Trailing Edge Hydrofoils Using PIV-POD Method

2010 ◽  
Author(s):  
Amirreza Zobeiri ◽  
Philippe Ausoni ◽  
Franc¸ois Avellan ◽  
Mohamed Farhat
Keyword(s):  
Experimental Investigation ◽  
Phase Shift ◽  
Vortex Shedding ◽  
High Speed ◽  
Flow Induced Vibration ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Vortex Induced Vibrations ◽  
Image Velocimetry ◽  
High Reynolds

This paper presents an experimental investigation of the vortex shedding in the wake of blunt and oblique trailing edge hydrofoils at high Reynolds number, Re = 5 105 − 2.9 106. The velocity field in the wake is surveyed with the help of Particle-Image-Velocimetry, PIV, using Proper-Orthogonal-Decomposition, POD. Besides, flow induced vibration measurements and high-speed visualization are performed. The high-speed visualization clearly shows that the oblique trailing edge leads to a spatial phase shift of the upper and lower vortices at their generation stage, resulting their partial cancellation. For the oblique trailing edge geometry and in comparison with the blunt one, the vortex-induced vibrations are significantly reduced. Moreover, PIV data reveals a lower vorticity for the oblique trailing edge. The phase shift between upper and lower vortices, introduced by the oblique truncation of the trailing edge, is found to vanish in the far wake, where alternate shedding is recovered as observed with the blunt trailing edge. The phase shift generated by the oblique trailing edge and the resulting partial cancellation of the vortices is believed to be the main reason of the vibration reduction.

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