Experimental Investigation of Flow Field Around An Asymmetric Beveled Trailing Edge and Aerodynamic Sound

This work details an experimental investigation on the effects of the variation of flap gap and overlap sizes on the flow field in the wake of a wing-section equipped with a trailing edge Fowler flap. The airfoil was based on the NACA 0014-1.10 40/1.051 profile, and the flap was deployed with 40 deg deflection angle. Two-dimensional (2D) particle image velocimetry (PIV) measurements of the flow field in the vicinity of the main wing trailing edge and the flap region were performed for the optimal flap gap and overlap, as well as for flap gap and overlap increases of 2% and 4% chord beyond optimal, at angles of attack of 0 deg, 10 deg, and 12 deg. For all the configurations investigated, the flow over the flap was found to be fully stalled. At zero angle of attack, increasing the flap gap size was found to have minor effects on the flow field but increased flap overlap resulted in misalignment between the main wing boundary layer (BL) flow and the slot flow that forced the flow in the trailing edge region of the main wing to separate. When the angle of attack was increased to near stall conditions (at angle of attack of 12 deg), increasing the flap gap was found to energize and improve the flow in the trailing edge region of the main wing, whereas increased flap overlap further promoted flow separation on the main wing suction surface possibly steering the wing into stall.

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Numerical and Experimental Investigation of Beveled Trailing EDGE Flow Fields

Journal of Hydrodynamics ◽

10.1016/s1001-6058(08)60057-8 ◽

2008 ◽

Vol 20 (3) ◽

pp. 273-279 ◽

Cited By ~ 17

Author(s):

M. M. Mosallem

Keyword(s):

Experimental Investigation ◽

Flow Fields ◽

Trailing Edge ◽

Beveled Trailing Edge ◽

Edge Flow

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Experimental investigation of a blunt trailing edge flow field with application to sound generation

Experiments in Fluids ◽

10.1007/s00348-006-0200-3 ◽

2006 ◽

Vol 41 (5) ◽

pp. 777-788 ◽

Cited By ~ 23

Author(s):

Daniel W. Shannon ◽

Scott C. Morris

Keyword(s):

Experimental Investigation ◽

Flow Field ◽

Sound Generation ◽

Trailing Edge ◽

Blunt Trailing Edge ◽

Edge Flow

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Numerical and experimental investigation of a beveled trailing edge flow and noise field

21st AIAA/CEAS Aeroacoustics Conference ◽

10.2514/6.2015-2366 ◽

2015 ◽

Cited By ~ 3

Author(s):

Wouter C. van der Velden ◽

Stefan Pröbsting ◽

Arjen de Jong ◽

Alexander van Zuijlen ◽

Yaoyi Guan ◽

...

Keyword(s):

Experimental Investigation ◽

Trailing Edge ◽

Noise Field ◽

Beveled Trailing Edge ◽

Edge Flow

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Numerical and Experimental Investigation of Flow-Acoustic Resonance of Side-by-Side Cylinders in a Duct

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2013-97020 ◽

2013 ◽

Author(s):

Atef Mohany ◽

David Arthurs ◽

Michael Bolduc ◽

Marwan Hassan ◽

Samir Ziada

Keyword(s):

Experimental Investigation ◽

Flow Field ◽

Cross Flow ◽

Sound Field ◽

Acoustic Resonance ◽

Acoustic Power ◽

Bluff Bodies ◽

Aerodynamic Sound ◽

Spacing Ratio ◽

Piping Systems

The phenomenon of flow-excited acoustic resonance is a design concern in many engineering applications, especially when wakes of bluff bodies are encountered in ducts, piping systems, heat exchangers, and other confined systems. In this article, the case of self-excited acoustic resonance of two side-by-side cylinders in a duct with cross-flow is investigated both numerically and experimentally. A single spacing ratio between the cylinders, T/D = 2.5, is investigated, where D is the diameter of the cylinders and T is the center-to-center distance between them. The numerical investigation is performed using a finite-volume method at a Reynolds number of 30,000 to simulate the unsteady flow field, which is then coupled with a finite element simulation of the resonant sound field. The experimental investigation is performed using phase-locked Particle Image Velocimetry (PIV) during the occurrence of flow-excited acoustic resonance. The results of both methods reveal that the flow-excited acoustic resonance produces a strong oscillatory flow pattern in the cylinder wakes with strong in-phase vortex shedding being synchronized by the excited acoustic resonance. The distribution and strength of the aeroacoustic sources and sinks within the flow field have been computed by means of Howe’s theory of aerodynamic sound for both the experimental and numerical cases, with the results of the two methods comparing favorably, showing similar trends in the oscillating flow fields, and very similar trends in the distribution of net acoustic power.

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Numerical study on the airfoil self-noise of three owl-based wings with the trailing-edge serrations

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410020988229 ◽

2021 ◽

pp. 095441002098822

Author(s):

Dian Li ◽

Xiaomin Liu ◽

Lei Wang ◽

Fujia Hu ◽

Guang Xi

Keyword(s):

Flow Field ◽

Noise Reduction ◽

Numerical Study ◽

Barn Owl ◽

Aerodynamic Noise ◽

Frequency Noise ◽

Trailing Edge ◽

Reduction Mechanisms ◽

Trailing Edge Serrations ◽

Bionic Airfoil

Previous publications have summarized that three special morphological structures of owl wing could reduce aerodynamic noise under low Reynolds number flows effectively. However, the coupling noise-reduction mechanism of bionic airfoil with trailing-edge serrations is poorly understood. Furthermore, while the bionic airfoil extracted from natural owl wing shows remarkable noise-reduction characteristics, the shape of the owl-based airfoils reconstructed by different researchers has some differences, which leads to diversity in the potential noise-reduction mechanisms. In this article, three kinds of owl-based airfoils with trailing-edge serrations are investigated to reveal the potential noise-reduction mechanisms, and a clean airfoil based on barn owl is utilized as a reference to make a comparison. The instantaneous flow field and sound field around the three-dimensional serrated airfoils are simulated by using incompressible large eddy simulation coupled with the FW-H equation. The results of unsteady flow field show that the flow field of Owl B exhibits stronger and wider-scale turbulent velocity fluctuation than that of other airfoils, which may be the potential reason for the greater noise generation of Owl B. The scale and magnitude of alternating mean convective velocity distribution dominates the noise-reduction effect of trailing-edge serrations. The noise-reduction characteristic of Owl C outperforms that of Barn owl, which suggests that the trailing-edge serrations can suppress vortex shedding noise of flow field effectively. The trailing-edge serrations mainly suppress the low-frequency noise of the airfoil. The trailing-edge serration can suppress turbulent noise by weakening pressure fluctuation.

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