scholarly journals Wind-tunnel study of the wake behind a vertical axis wind turbine in a boundary layer flow using stereoscopic particle image velocimetry

2015 ◽  
Vol 625 ◽  
pp. 012012 ◽  
Author(s):  
V Rolin ◽  
F Porté-Agel
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Wind Tunnel ◽  
Particle Image ◽  
Vertical Axis ◽  
Stereoscopic Particle Image Velocimetry ◽  
Vertical Axis Wind Turbine ◽  
Image Velocimetry ◽  
Layer Flow ◽  
Wind Tunnel Study

Experimental Study of Free Stream Turbulent Effects on Dynamic Stall of Pitching Airfoil by Using Particle Image Velocimetry

2012 ◽  
Vol 225 ◽  
pp. 103-108 ◽  
Author(s):  
Tzong Shyng Leu ◽  
J.M. Yu ◽  
C.C. Hu ◽  
J.J. Miau ◽  
S.Y. Liang ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Turbulence Intensity ◽  
Particle Image ◽  
Free Stream ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Vertical Axis Wind Turbine ◽  
Free Stream Turbulence ◽  
Pitching Airfoil ◽  
Image Velocimetry

The unsteady flow fields above NACA 0015 airfoil pitching with/without upstream turbulence generator are investigated in a water tunnel by mean of particle image velocimetry (PIV). The turbulence was generated by a square bar mesh situated at the inlet of the test section. The airfoil pitching waveform is performed under the condition calculated from the angle of attack histogram of a vertical axis wind turbine (VAWT). By using PIV, the instantaneous vortex structures above the pitching airfoil can be revealed. It allows us to study the free stream turbulence effects on dynamic stall over an airfoil at pitching waveform the same as VAWT. It is found that the free stream turbulence intensity has significant impacts on the dynamic stall process. The dynamic stall process is delayed to higher incidence angles on increasing the turbulence intensity.

scholarly journals Experimental Investigation of Vortex Structures in Wake of Hyperboloid-Shaped Model by Means of 2D Particle Image Velocimetry Measurement

2018 ◽  
Vol 180 ◽  
pp. 02004
Author(s):  
V. Barraclough ◽  
J. Novotný ◽  
P. Šafařík
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Wind Tunnel ◽  
Atmospheric Boundary Layer ◽  
Bluff Body ◽  
Particle Image ◽  
Reynolds Numbers ◽  
High Rate ◽  
Incoming Flow ◽  
Image Velocimetry

This paper deals with flow around a bluff body of hyperboloid shape. It consists of results gathered in the course of research by means of Particle Image Velocimetry (PIV). The experiments were carried out by means of low-frequency 2D PIV in a range of Reynolds numbers from 40000 to 50000. A hyperboloid-shaped model was measured in a wind tunnel with a modelled atmospheric boundary layer (and additionally, in a low-speed wind tunnel with low turbulence). The model was tested in a subcritical range of Reynolds numbers and various planes in a wake of the model were captured with the intention of getting an estimation of 3D flow structures. The tunnel with the modelled atmospheric boundary layer has a high rate of turbulence, so the influence of the turbulence of incoming flow on the wake could be outlined. The ratio of the height of the model to a thickness of the modelled boundary layer in the tunnel was 1/3, meaning the turbulence in the boundary layer strongly influenced the flow around the model; it suppresses the wake which leads to a lot shorter area of recirculation than low turbulence incoming flow would cause.

Investigation of the Boundary Layer Flow Under Engine-Like Conditions Using Particle Image Velocimetry

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Daming Liu ◽  
Tianyou Wang ◽  
Ming Jia ◽  
Wei Li ◽  
Zhen Lu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Image Velocimetry ◽  
Turbulent Boundary Layer ◽  
Reynolds Stress ◽  
Boundary Layer Flow ◽  
Particle Image ◽  
Viscous Sublayer ◽  
Wall Jet ◽  
Image Velocimetry ◽  
Layer Flow

The turbulent boundary layer flow in internal combustion (IC) engines has a significant effect on the in-cylinder flow and the wall heat transfer. A detailed analysis of the in-cylinder near-wall flow was carried out on an optical steady flow test bench by using high-resolution particle image velocimetry (PIV) in order to characterize the in-cylinder boundary layer flow in this study. The difference between the in-cylinder boundary layer and the canonical turbulent boundary layer was analyzed. The experimental results show that small-scale vortices with a length scale of about 1–2 mm in the instantaneous flow fields appeared in the wall jet region due to the entrainment of the free jet in the outer region of the wall jet. The viscous sublayer thickness decreased from 0.5 mm to 0.3 mm as the valve lift increased from 2.32 mm to 7.975 mm and the pressure drop from 0.5 kPa to 1 kPa. The dimensionless velocity profile is in good agreement with the law of the wall in the viscous sublayer. However, no obvious logarithmic law distribution region was observed in the logarithmic layer. The distribution of the Reynolds stress and the turbulent kinetic energy is similar to that of the canonical turbulent boundary layer. But the Reynolds stress had a much larger magnitude because the turbulent velocity measured in this boundary layer included not only the turbulence generated by wall shear but also the large-scale turbulent vortices caused by the wall jet.

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