scholarly journals Sound Source Measurement of a Semi-Circular Cylinder in a Uniform Flow by Particle Image Velocimetry

2016 ◽  
Vol 04 (04) ◽  
pp. 162-170 ◽  
Author(s):  
Yasuyuki Oguma ◽  
Nobuyuki Fujisawa
Keyword(s):  
Particle Image Velocimetry ◽  
Circular Cylinder ◽  
Sound Source ◽  
Particle Image ◽  
Uniform Flow ◽  
Image Velocimetry

Energy Concentration by Bluff Bodies—A Particle Image Velocimetry Investigation

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Eshodarar Manickam Sureshkumar ◽  
Maziar Arjomandi ◽  
Bassam B. Dally ◽  
Benjamin S. Cazzolato ◽  
Mergen H. Ghayesh
Keyword(s):  
Particle Image Velocimetry ◽  
Circular Cylinder ◽  
Bluff Body ◽  
Particle Image ◽  
Transverse Velocity ◽  
Water Channel ◽  
Energy Concentration ◽  
Backward Facing Step ◽  
Flow Energy ◽  
Image Velocimetry

Particle image velocimetry (PIV) of four cylinders with different cross sections were performed in a recirculating water channel at Reynolds numbers of 5000 and 10,000. The cylinders were split into two distinct categories; semicircular and convex-edged triangular (c-triangular) prisms which have a smooth diverging fore-face and a flat, backward facing step aft-face, and a trapezoid which has a flat fore face and a backward-facing step aft-face. The resulting streamwise and transverse velocity vectors (u and v, respectively) were analyzed to provide a qualitative comparison of the bluff body wakes to the circular cylinder, which is the standard upstream stationary body in wake-induced vibration (WIV) energy technology. The Reynolds stresses, turbulent kinetic energy (TKE), mean spanwise vorticity, and the energy in the fluctuating component of the wake were compared. The main findings are: (i) a convex fore-face and a backward-facing step aft face are more effective at converting the flow energy to temporal wake energy (+20%) compared to a circular cylinder, (ii) a trapezoid type shape is less effective at converting flow energy to temporal wake energy (−40%) compared to a circular cylinder, (iii) increasing Reynolds number reduces the efficiency of conversion of upstream flow energy to downstream transverse temporal energy. Utilizing stationary upstream bodies such as the semicircle and the c-triangle can result in concentrating more energy in the fluctuating components for the downstream transversely vibrating bluff body in a WIV system, and hence can realize in more efficient WIV technology.

scholarly journals representative driven system to interrogate passive dynamics of an airfoil in the wake of a cylinder

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Morgan Louise Hooper ◽  
Beverley Jane McKeon
Keyword(s):  
Particle Image Velocimetry ◽  
Circular Cylinder ◽  
Flow Field ◽  
Particle Image ◽  
Flow Structures ◽  
Passive Motion ◽  
Sinusoidal Motion ◽  
Image Velocimetry ◽  
Driven System ◽  
Thrust Production

Passive motion of an airfoil in the wake of a circular cylinder is compared with driven motion of an airfoil in the same configuration, through simultaneous measurement of both the airfoil dynamics and the surrounding flow field. The passive mounting allows the airfoil to move in the transverse (heaving) direction in response to oncoming forcing, while introducing significant parasitic effects to the dynamics including friction. The driven motion of the airfoil reproduces important characteristics of the imperfect passive motion, validating idealized sinusoidal motion as a model for dynamics of the passive airfoil operating in a more realistic engineering context. Particle Image Velocimetry (PIV) of the driven case is then used to illuminate flow structures contributing to observed power and thrust production in both cases.

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.

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