Aerothermal Investigation of a Single Row Divergent Narrow Impingement Channel by Particle Image Velocimetry and Liquid Crystal Thermography

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Alexandros Terzis ◽  
Christoforos Skourides ◽  
Peter Ott ◽  
Jens von Wolfersdorf ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Particle Image Velocimetry ◽  
Liquid Crystal ◽  
Flow Field ◽  
Particle Image ◽  
Field Measurements ◽  
Single Row ◽  
Transient Techniques ◽  
Liquid Crystal Thermography ◽  
Image Velocimetry

Integrally cast turbine airfoils with wall-integrated cooling cavities are greatly applicable in modern turbines providing enhanced heat exchange capabilities compared to conventional cooling passages. In such arrangements, narrow impingement channels can be formed where the generated crossflow is an important design parameter for the achievement of the desired cooling efficiency. In this study, a regulation of the generated crossflow for a narrow impingement channel consisting of a single row of five inline jets is obtained by varying the width of the channel in the streamwise direction. A divergent impingement channel is therefore investigated and compared to a uniform channel of the same open area ratio. Flow field and wall heat transfer experiments are carried out at engine representative Reynolds numbers using particle image velocimetry (PIV) and liquid crystal thermography (LCT). The PIV measurements are taken at planes normal to the target wall along the centerline for each individual jet, providing quantitative flow visualization of jet and crossflow interactions. The heat transfer distributions on the target plate of the channels are evaluated with transient techniques and a multilayer of liquid crystals (LCs). Effects of channel divergence are investigated combining both the heat transfer and flow field measurements. The applicability of existing heat transfer correlations for uniform jet arrays to divergent geometries is also discussed.

Aerothermal Investigation of a Two-Pass Rotating Cooling Channel by Means of Particle Image Velocimetry and Liquid Crystal Thermography

2018 ◽  
Author(s):  
Dimitra Tsakmakidou ◽  
Ignacio Mayo ◽  
Tony Arts
Keyword(s):  
Heat Transfer ◽  
Particle Image Velocimetry ◽  
Liquid Crystal ◽  
Particle Image ◽  
Flow Stability ◽  
Secondary Flows ◽  
Mean Flow ◽  
Liquid Crystal Thermography ◽  
Dean Vortices ◽  
Image Velocimetry

Heat transfer and aerodynamic measurements are conducted by means of Liquid Crystal Thermography and Particle Image Velocimetry in a two-pass rotating ribbed channel. The channel presents a square cross section, a sharp U-bend connecting the inlet and outlet passes and square ribs placed on two opposite walls, normal to the mean flow. In the heat transfer experimental campaign, the Reynolds (Re) and rotation (Ro) numbers are respectively ranging between 15,000–55,000 and 0–0.26 to investigate their influence upstream and downstream of the bend region. The aerodynamic measurements are taken in the symmetry plane of the channel at Re = 15,000 and Ro = 0 and 0.26, to complement the heat transfer data in the same regions. The results show how the Coriolis forces affect the flow stability and the secondary flow pattern. In the first pass, the behavior with varying Reynolds and rotation numbers is very similar to the one observed in a similar single-pass channel in terms of flow stability, velocity distribution and heat transfer performance. The measurements indicate an increase of the turbulent kinetic energy and the heat transfer downstream of the bend due to the large separation bubble, the high streamline curvature and the Dean vortices. Both the heat transfer and velocity distributions suggest that the interaction of the Dean vortices and Coriolis-induced secondary flows downstream of the bend is also highly dependent on the rotational regime.

Endoscopic 2D particle image velocimetry (PIV) flow field measurements in IC engines

2002 ◽  
Vol 33 (6) ◽  
pp. 794-800 ◽  
Author(s):  
U. Dierksheide ◽  
P. Meyer ◽  
T. Hovestadt ◽  
W. Hentschel
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Field Measurements ◽  
Image Velocimetry ◽  
Ic Engines

Electroosmotic Flow Field Measurements With Particle Image Velocimetry

2000 ◽  
Author(s):  
Shankar Devasenathipathy ◽  
Joshua I. Molho ◽  
James C. Mikkelsen ◽  
Juan G. Santiago ◽  
Kohsei Takehara
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Electric Field ◽  
Particle Tracking ◽  
Electroosmotic Flow ◽  
Particle Image ◽  
Field Measurements ◽  
Local Electric Field ◽  
Seed Particles ◽  
Image Velocimetry

Abstract A micron-resolution particle image velocimetry (PIV) system has been developed to spatially and temporally resolve electroosmotic flow fields within microfluidic bioanalytical devices. A second diagnostic technique, particle tracking velocimetry (PTV) has been used to determine the distribution of electrophoretic mobilities of seed particles and thereby make the PIV measurements quantitative. This second particle tracking technique has been used to determine probability distribution functions of the seed particles. Results from simulations of electric fields yield local electric field strengths in the geometries of interest. The measured mean mobility of the seed particles (obtained from PTV measurements) is then multiplied by the local electric field vector to obtain the electrophoretic velocity. The variance on the particle mobility measurement influences the errors introduced in the electroosmotic flow measurements. After total particle velocities are measured within a microfluidic system of interest, the seed particle electrophoretic velocities are subtracted from the PIV total velocity data to obtain electroosmotic flow field velocities. Ensemble-averaged velocity field measurements for electroosmotic flow at the intersection of a cross-channel are presented.

Flow Field Measurements in Gain Zone of XeF(C-A) Gas Laser Based on Particle Image Velocimetry

2019 ◽  
Vol 46 (2) ◽  
pp. 0204007
Author(s):  
栾昆鹏 Luan Kunpeng ◽  
叶景峰 Ye Jingfeng ◽  
王晟 Wang Sheng ◽  
沈炎龙 Shen Yanlong ◽  
赵柳 Zhao Liu ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Field Measurements ◽  
Gas Laser ◽  
Image Velocimetry

scholarly journals Feasibility of Optical Flow Field Measurements of the Coolant in a Grinding Machine

2021 ◽  
Vol 11 (24) ◽  
pp. 11615
Author(s):  
Björn Espenhahn ◽  
Lukas Schumski ◽  
Christoph Vanselow ◽  
Dirk Stöbener ◽  
Daniel Meyer ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Fluid Flow ◽  
Flow Field ◽  
Optical Flow ◽  
Particle Image ◽  
Field Measurements ◽  
Optical Flow Field ◽  
Metalworking Fluid ◽  
Image Velocimetry ◽  
Grinding Machine

For industrial grinding processes, the workpiece cooling by metalworking fluids, which strongly influences the workpiece surface layer quality, is not yet fully understood. This leads to high efforts for the empirical determination of suitable cooling parameters, increasing the part manufacturing costs. To close the knowledge gap, a measurement method for the metalworking fluid flow field near the grinding wheel is desired. However, the varying curved surfaces of the liquid phase result in unpredictable light deflections and reflections, which impede optical flow measurements. In order to investigate the yet unknown optical measurement capabilities achievable under these conditions, shadowgraphy in combination with a pattern correlation technique and particle image velocimetry (PIV) are applied in a grinding machine. The results show that particle image velocimetry enables flow field measurements inside the laminar metalworking fluid jet, whereby the shadowgraph imaging velocimetry complements these measurements since it is in particular suitable for regions with spray-like flow regimes. As a conclusion, optical flow field measurements of the metalworking fluid flow in a running grinding machine are shown to be feasible.

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