scholarly journals Experimental study of the application of micro-PIV on the flow characteristics detection of micro-gap rotational flow field

AIP Advances ◽  
2015 ◽  
Vol 5 (4) ◽  
pp. 041311 ◽  
Author(s):  
Fei Tang ◽  
Chunze Wang ◽  
Yupeng Shi ◽  
Xiaohao Wang
Author(s):  
Hui Hu ◽  
Ahmet Ozbay ◽  
Wei Tian ◽  
Zifeng Yang

An experimental study was conducted to investigate the interferences of wind turbines sited over hilly terrains in order to elucidate underlying physics to explore/optimize design paradigms of wind turbines sited over complex terrains for higher power yield and better durability. The experiments were conducted in a large wind tunnel with of wind turbine models sited over a flat terrain (baseline case) and a 2D-ridge with non-homogenous atmospheric boundary layer winds. In addition to measuring dynamic wind loads (both forces and moments) and the power outputs of the wind turbine models, a high-resolution digital Particle Image Velocimetry (PIV) system was used to conduct detailed flow field measurements to quantify the flow characteristics of the surface winds and wake interferences among multiple wind turbines over flat (baseline case) and complex terrains. The detailed flow field measurements were correlated with the wind load measurements and power outputs of the wind turbine models to elucidate the underlying physics associated with turbine power generation and fatigue loads acting on the wind turbines.


2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Shicong Li ◽  
Xiaoyu Wang ◽  
Jing He ◽  
Mei Lin ◽  
Hanbing Ke

An experimental study is carried out to investigate the flow characteristics of the trailing edge of the horizontal vanes mounted at the branch entrance of a T-junction duct by means of particle image velocimetry (PIV). The measured region starts at the trailing edge of the vanes and ends at about 1.26D (hydraulic diameter) length at downstream of the branch duct. The velocity field is obtained across a number of vertical height planes (z/D = ±0.2, 0, and −0.4) under different flow conditions (cross velocity: uc = 30–50 m/s; velocity ratio: R = 0.08–0.18). The instantaneous flow results show that Kelvin-like vortices with counter-clockwise direction appear at the heights of z/D = ±0.2 and 0, and that a separation bubble is formed at the upper wall of the branch duct at the same heights, respectively. As for near wall z/D = −0.4, one large vortex is observed at the downstream channel, but the separation bubble vanishes as the branching Reynolds number is increased to 3.6 × 104. The time-average flow field is slightly different from that of instantaneous flow field. In addition, the vorticity distribution indicates that two significant vortex sheet layers with negative and positive values are found at the high velocity ratio or high cross velocity, and the normalized vorticity strength increases with increasing velocity ratio and decreases with increasing cross velocity except at z/D = −0.4.


2021 ◽  
Vol 108 ◽  
pp. 106377
Author(s):  
Mohammed Faheem ◽  
Aqib Khan ◽  
Rakesh Kumar ◽  
Sher Afghan Khan ◽  
Waqar Asrar ◽  
...  

2019 ◽  
Vol 125 ◽  
pp. 92-101 ◽  
Author(s):  
Shuaiwei Gu ◽  
Yuxing Li ◽  
Lin Teng ◽  
Cailin Wang ◽  
Qihui Hu ◽  
...  

1996 ◽  
Vol 61 (6) ◽  
pp. 856-867 ◽  
Author(s):  
Oldřich Brůha ◽  
Ivan Fořt ◽  
Pavel Smolka ◽  
Milan Jahoda

The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.


2017 ◽  
Vol 100 ◽  
pp. 283-291 ◽  
Author(s):  
Mingjun Wang ◽  
Di Liu ◽  
Yan Xiang ◽  
Shijie Cui ◽  
G.H. Su ◽  
...  

2011 ◽  
Vol 54 (9) ◽  
pp. 2475-2482 ◽  
Author(s):  
WanXi Zhang ◽  
LiJun Yang ◽  
XiaoZe Du ◽  
YongPing Yang

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 927
Author(s):  
Yi Zhang ◽  
Longxi Han ◽  
Lina Chen ◽  
Chenfang Wang ◽  
Bo Chen ◽  
...  

Flumes have been widely used in water conservancy science and environmental science research. It is of great significance to obtain the hydrodynamic characteristics and flow field uniformity in the flume. In this study, a new type of annular flume was taken as an example. The 3D flow field was simulated by using a commercial computational fluid dynamics (CFD) code, and was also measured by acoustic doppler velocimeter (ADV) to verify the simulation results. The average relative error range was between 8.37% and 9.95%, the simulated results basically reflected the actual situation of the flow field. On this basis, the structural characteristics of flow field were analyzed. A new calculation method of flow velocity uniformity was presented according to the flow characteristics of natural open channels. The velocity uniformity in the straight channel was calculated and analyzed based on this method, and the influence of speed on the velocity uniformity was further discussed. The length of uniform section was negatively correlated with the rotational speed (average velocity), which was between 39 cm and 101 cm in the straight, and the uniformity coefficient was less than 10%. Finally, the water flow characteristics in the straight channel without wheel were compared with the natural open channel flow. The longitudinal velocity was well fitted with the Prandtl logarithmic distribution formula (R2 > 0.977), and the application feasibility of the flume was analyzed. This study can provide technical support for the development and application of annular flume.


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