Effect of Leading-Edge Serrations on Trailing-Edge-Bluntness Vortex-Shedding Noise Radiation

2019 ◽  
Author(s):  
Seyed Mohammad Hasheminejad ◽  
Tze Pei Chong ◽  
Phillip Joseph ◽  
Giovanni Lacagnina
Keyword(s):  
Vortex Shedding ◽  
Leading Edge ◽  
Trailing Edge ◽  
Noise Radiation ◽  
Vortex Shedding Noise

Wake Frequency Analysis of a Plunging Airfoil with Trailing-Edge Strips

2012 ◽  
Vol 225 ◽  
pp. 3-7
Author(s):  
Fariba Ajalli ◽  
Mahmoud Mani ◽  
Mozhgan Gharakhanlou
Keyword(s):  
Vortex Shedding ◽  
Power Spectra ◽  
Leading Edge ◽  
Hot Wire ◽  
Initial Angle ◽  
Trailing Edge ◽  
Wake Structure ◽  
Velocity Defect ◽  
Edge Vortex ◽  
Dominant Frequencies

Experimental measurements were conducted on a plunging Eppler 361 strip flapped airfoil to study wake structure in the wake. The heights of strip flap were 2.6% and 3.3% chord. The velocity in the wake was measured by hot-wire anemometry. It was found that the trailing-edge strip had different effects on the plunging wake profile during the oscillation cycle. At initial angle of 0 degree, the trailing-edge strip causes more velocity defect in the oscillation phases of 180º and 270º. At high initial angle 12 degrees, a significant decrease in value of velocity is found at 180º because of the leading edge vortex shedding. The power spectra of dominant frequencies were significantly increased by fitting the strip flap on the plunging airfoil.

Sound generation by a supersonic aerofoil cutting through a steady jet flow

1990 ◽  
Vol 216 ◽  
pp. 193-212 ◽  
Author(s):  
Y. P. Guo
Keyword(s):  
Vortex Shedding ◽  
Sound Field ◽  
Leading Edge ◽  
Jet Flow ◽  
Generation Process ◽  
Sound Waves ◽  
Leading Order ◽  
Sound Generation ◽  
Trailing Edge ◽  
Kutta Condition

This paper examines the sound generation process when a supersonic aerofoil cuts through a steady jet flow. It is shown that the principal sound is generated by the leading edge of the aerofoil when it interacts with the streaming jet. To the leading order in terms of the jet velocity, no trailing-edge sound is generated. This is not the result of the cancellation of a trailing-edge sound by that from vortex shedding through the imposition of the Kutta condition. Instead, the null acoustic radiation from the trailing edge is entirely because, to the leading order, there is no interaction between the trailing edge and the jet. The effect of the trailing edge is to diffract sound waves generated by the leading edge. It is shown that the diffracted field (as well as the incident field) is regular at the trailing edge and the issue of satisfying the Kutta condition does not arise during the diffraction process. Thus, there is no extra vortex shedding from the trailing edge owing to its interaction with the flow, apart from those resulting from the discontinuity across the aerofoil, generated by the flow-leading edge interaction. This is in sharp contrast to the case of subsonic aerofoils where the removal of the singularity in the diffracted field at the trailing edge through the imposition of the Kutta condition results in vortex shedding from the sharp edge and energy exchange between the sound field and the vortical wake.

Vortex Shedding and Noise Radiation from a Slat Trailing Edge

AIAA Journal ◽  
2010 ◽  
Vol 48 (2) ◽  
pp. 502-509 ◽  
Author(s):  
Sanehiro Makiya ◽  
Ayumu Inasawa ◽  
Masahito Asai
Keyword(s):  
Vortex Shedding ◽  
Trailing Edge ◽  
Noise Radiation

Interaction and acoustics of separated flows from a D-shaped bluff body

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guangyuan Huang ◽  
Ka Him Seid ◽  
Zhigang Yang ◽  
Randolph Chi Kin Leung
Keyword(s):  
Vortex Shedding ◽  
Bluff Body ◽  
Leading Edge ◽  
Separated Flows ◽  
Pressure Waves ◽  
Bluff Bodies ◽  
Trailing Edge ◽  
Content Type ◽  
Trailing Edges ◽  
Edge Vortex

Purpose For flow around elongated bluff bodies, flow separations would occur over both leading and trailing edges. Interactions between these two separations can be established through acoustic perturbation. In this paper, the flow and the acoustic fields of a D-shaped bluff body (length-to-height ratio L/H = 3.64) are investigated at height-based Reynolds number Re = 23,000 by experimental and numerical methods. The purpose of this paper is to study the acoustic feedback in the interaction of these two separated flows. Design/methodology/approach The flow field is measured by particle image velocimetry, hotwire velocimetry and surface oil flow visualization. The acoustic field is modeled in two dimensions by direct aeroacoustic simulation, which solves the compressible Navier–Stokes equations. The simulation is validated against the experimental results. Findings Separations occur at both the leading and the trailing edges. The leading-edge separation point and the reattaching flow oscillate in accordance with the trailing-edge vortex shedding. Significant pressure waves are generated at the trailing edge by the vortex shedding rather than the leading-edge vortices. Pressure-based cross-correlation analysis is conducted to clarify the effect of the pressure waves on the leading-edge flow structures. Practical implications The understanding of interactions of separated flows over elongated bluff bodies helps to predict aerodynamic drag, structural vibration and noise in engineering applications, such as the aerodynamics of buildings, bridges and road vehicles. Originality/value This paper clarifies the influence of acoustic perturbations in the interaction of separated flows over a D-shaped bluff body. The contribution of the leading- and the trailing-edge vortex in generating acoustic perturbations is investigated as well.

Particle image velocimetry and visualization of natural and forced flow around rectangular cylinders

2003 ◽  
Vol 478 ◽  
pp. 299-323 ◽  
Author(s):  
RICHARD MILLS ◽  
JOHN SHERIDAN ◽  
KERRY HOURIGAN
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Visualization ◽  
Vortex Shedding ◽  
Particle Image ◽  
Leading Edge ◽  
Trailing Edge ◽  
Image Velocimetry ◽  
Edge Vortex ◽  
Rectangular Cylinders ◽  
Leading Edge Vortices

Particle image velocimetry (PIV) measurements and flow visualization in a water tunnel show that vortex shedding at the leading and trailing edges of rectangular cylinders can be simultaneously phase-locked to transverse velocity perturbations when the applied perturbation Stp is close to an impinging leading-edge vortex/trailing-edge vortex shedding (ILEV/TEVS) frequency. The transverse perturbations, analogous to β-mode duct acoustic resonances, are generated through harmonic oscillations of the sidewalls. When this occurs, the leading-edge vortices are found always to pass the trailing edge at the same phase in the perturbation cycle regardless of the chord-to-thickness (c/t) ratio. Applying perturbations at an Stp not equal to the natural global frequency also results in phase-locked vortex shedding from the leading edge, and a near wake with a frequency equal to the perturbation frequency. This is consistent with previous experimental findings. However, vortex shedding at the trailing edge is either weaker or non-existent. PIV results and flow visualization showed trailing-edge vortex growth was weaker because leading-edge vortices arrive at the trailing edge at a phase in the perturbation cycle where they interfere with trailing-edge shedding. The frequencies at which trailing-edge vortices form for different c/t ratios correspond to the natural ILEV/TEVS frequencies. As in the case of natural shedding, peaks in base suction occur when the leading-edge vortices pass the trailing edge at the phase in the perturbation cycle (and thus in the leading-edge shedding cycle) that allows strong trailing-edge shedding. This is the reason for the similarity in the Stvs.c/t relationship for three seemingly different sets of experiments.

Numerical Simulation of Noise Radiated from a Blunt Trailing Edge

2014 ◽  
Vol 629 ◽  
pp. 3-8
Author(s):  
Siti Nur Aishah Mohd Haris ◽  
Mohamed Sukri Mat Ali ◽  
Sheikh Ahmad Zaki Shaikh Salim ◽  
Sallehuddin Muhamad ◽  
Muhammad Iyas Mahzan
Keyword(s):  
Numerical Simulation ◽  
Vortex Shedding ◽  
Vortex Generator ◽  
Acoustic Analogy ◽  
Trailing Edge ◽  
Noise Radiation ◽  
Blunt Trailing Edge ◽  
Tone Level

The Lighthill acoustic analogy is applied to estimate the noise radiation from flow over a blunt trailing edge. The blunt trailing edge is an effective vortex generator. Periodic vortex shedding near the trailing edge induces fluctuating lift that radiates a strong Aeolian tone. The frequency of the Aeolian tone is similar to that of the vortex shedding. A 50.1 dB of Aeolian tone level is radiated from this blunt trailing edge.

Vortex shedding noise from a beveled trailing edge

2016 ◽  
Vol 15 (8) ◽  
pp. 712-733 ◽  
Author(s):  
Stefan Pröbsting ◽  
Martina Zamponi ◽  
Stefano Ronconi ◽  
Yaoyi Guan ◽  
Scott C Morris ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Trailing Edge ◽  
Vortex Shedding Noise ◽  
Beveled Trailing Edge

Some modeling issues on trailing-edge vortex shedding

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 787-793
Author(s):  
Wei Ning ◽  
Li He
Keyword(s):  
Vortex Shedding ◽  
Trailing Edge ◽  
Edge Vortex
Sign in / Sign up

Export Citation Format

Share Document