Jet impingement heat transfer of a lobed nozzle: Measurements using temperature-sensitive paint and particle image velocimetry

2018 ◽  
Vol 71 ◽  
pp. 111-126 ◽  
Author(s):  
Chuangxin He ◽  
Yingzheng Liu
Keyword(s):  
Heat Transfer ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Jet Impingement ◽  
Temperature Sensitive ◽  
Impingement Heat Transfer ◽  
Image Velocimetry ◽  
Temperature Sensitive Paint ◽  
Lobed Nozzle

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.

scholarly journals Visualization of flow characteristics between the ribbed plates via particle image velocimetry

2019 ◽  
pp. 300-300
Author(s):  
Ilker Goktepeli ◽  
Ulas Atmaca ◽  
Sercan Yagmur
Keyword(s):  
Heat Transfer ◽  
Particle Image Velocimetry ◽  
Flow Separation ◽  
Particle Image ◽  
Reference Model ◽  
Water Channel ◽  
Flow Characteristics ◽  
Advanced Technology ◽  
Particle Image Velocimetry System ◽  
Image Velocimetry

Heat transfer is considerably influenced by flow stagnation, separation and reattachment regions due to the ribbed plates. Placing the ribs such as fins, turbulators that trigger the flow separation, enhances the heat transfer inside the channel by increasing the turbulence intensity. The flow separation is caused by disturbing the thermal and hydrodynamic development lengths. Moreover, these ribs also make an impact that increases the heat transfer by enlarging the heat transfer area. However, the ribs lead to the increment of the required pumping power in the meantime due to the increasing pressure loss in such systems. This aforementioned method is used for the heat exchangers, the solar collectors, the cooling of electronic devices. The investigation of the flow characteristics is very crucial to understand the heat transfer mechanism in the ducts for this reason. In the present paper, the flow characteristics between the plates have been experimentally researched. Particle Image Velocimetry system in the open water channel of Selcuk University Advanced Technology Research and Application Center has been used. The smooth plates have been taken as the reference model and used for the comparison with the plates having the rectangular cross-sectional ribs. The ribs with various heights of 0.1 ? h' = h/H ? 0.3 have been symmetrically placed on the internal surfaces of the plates via several spacing values of 0.5 ? S' = S/H ? 1 for varying Reynolds numbers as 10000 ? Re ? 20000. As a result, the flow characteristics have been given in terms of the contour graphics for velocity vector field, velocity components and vorticity.

The Influence of Boundary Condition on Solidification of Binary Solution in Rectangular Cavity

1999 ◽  
Author(s):  
N. Pradeep ◽  
H. J. Kang ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
Binary Solution ◽  
Solidification Process ◽  
Heat Transfer Process ◽  
Bottom Surface ◽  
Piv Technique ◽  
Image Velocimetry

Abstract The solidification of a binary mixture of ammonium chloride and water flow cooling in rectangular cavities was investigated experimentally under different boundary conditions. Two cavities measuring 63.5 × 180 × 165 mm and 76 × 120 × 96 mm were employed in this study. For the first cavity, its three surfaces (i.e., two side surfaces and one bottom surface) were cooled. For the second cavity, however, only two side surfaces were cooled (i.e., the bottom surface was adiabatic). The influence of the change of boundary was studied. All investigations were carried out in the surface temperature range from −15 to −30°C under a constant refrigerant temperature of −22°C. The effect of cooling boundary condition had a great effect on the heat transfer process during the solidification process. The advanced Particle Image Velocimetry (PIV) technique was used to catch the velocity profiles during the solidification process.

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.

Particle Image Velocimetry and Heat Transfer Measurements of a Disk at High Rotational Speeds

2002 ◽  
Author(s):  
N. Saniei ◽  
A. B. Olcay ◽  
X. Yan
Keyword(s):  
Heat Transfer ◽  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Local Heat Transfer ◽  
Rotating Disk ◽  
Disk Drive ◽  
Local Heat ◽  
Image Velocimetry ◽  
Back Calculation

Flow field and local heat transfer measurements were conducted on a rotating disk in an open environment for a variety of rotational speeds ranging from 1500 to 5500 rpm. Two-dimensional particle image velocimetry (PIV) measurements were conducted on the flow field above the surface of the rotating disk. Experiments were made on a rotating disk twice as large as a computer hard disk drive and therefore, the flow conditions may be comparable with a computer disk rotating with a speed up to 20,000 rpm. Velocity field, local heat transfer, and temperature distribution are presented as the result of this investigation. Transient liquid crystal technique was employed for heat transfer measurements, while a back calculation scheme was used to obtain the temperature distributions. Heat transfer measurements were made for r/R > 0.4 which excludes the central hub holding the disk assembly. Results reveals that heat transfer increases with a smaller slope near the corner of the hub, while it increases sharply near the outside edge of the disk.

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