On the use of Particle Image Velocimetry to predict trailing edge noise

2013 ◽  
Author(s):  
Marthijn Tuinstra ◽  
Stefan Pröbsting ◽  
Fulvio Scarano
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Trailing Edge ◽  
Trailing Edge Noise ◽  
Image Velocimetry

Particle Image Velocimetry Measurements of Wake Flows of Various Bridge Sections

2006 ◽  
Author(s):  
Emanuela Palombi ◽  
Gregory A. Kopp ◽  
Roi Gurka
Keyword(s):  
Particle Image Velocimetry ◽  
Vortex Shedding ◽  
Particle Image ◽  
Uniform Flow ◽  
Pressure Measurements ◽  
Trailing Edge ◽  
Wake Flows ◽  
Edge Geometry ◽  
Image Velocimetry ◽  
The Mean

Using Particle Image Velocimetry (PIV) we investigate the influence of leading and trailing edge geometry on the wake flows of various elongated cylinders in smooth uniform flow. The results present a comparison between the mean wake flows, as well as the vortex shedding activity found to occur in each case. Pressure measurements were recorded on the surface of the cylinders to examine the corresponding fluctuating and mean forces exhibited by each model tested. Significant variations in the wake topology and aerodynamic behaviour of the four cylinder geometries tested were observed.

Analysis of Passive Wake Mixing Techniques Using Time Resolved Digital Particle Image Velocimetry

2008 ◽  
Author(s):  
Christopher Weiland ◽  
Christopher Michie ◽  
Pavlos Vlachos
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Control ◽  
Particle Image ◽  
Digital Particle Image Velocimetry ◽  
Control Technique ◽  
Trailing Edge ◽  
Time Resolved ◽  
Mixing Properties ◽  
Passive Flow Control ◽  
Image Velocimetry

Wake mixing is a common flow control technique that can be used in a multitude of applications to disrupt undesired flow structures. A Time Resolved Digital Particle Image Velocimetry (TRDPIV) experiment was performed to analyze the wake mixing properties of flow control approaches in the wake of a flat plate. Triangular winglet-type vortex generators, two lobed trailing edge geometries, and trailing edge blowing are examined and quantitative comparisons of their passive wake mixing properties are compared. The TRDPIV fields were analyzed using the Proper Orthogonal Decomposition as a metric for deducing wake coherency. Results indicate that the airfoil geometry plays a significant role in decreasing wake coherency. Additionally, the eigenmodes of the lobed geometries revealed the greatest differences in the dynamics of the flow between the low and high Reynolds number flows. This suggests these geometries are sensitive to the character of the boundary layer incident on the passive flow control devices.

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.

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