scholarly journals Jet Impingement Heat Transfer Characteristics with Variable Extended Jet Holes under Strong Crossflow Conditions

Aerospace ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 44
Author(s):  
Xing Yang ◽  
Hang Wu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Thermochromic Liquid Crystal ◽  
Pumping Power ◽  
Heat Transfer Characteristics ◽  
Target Plate ◽  
Transfer Characteristics

In this paper, detailed flow patterns and heat transfer characteristics of a jet impingement system with extended jet holes are experimentally and numerically studied. The jet holes in the jet plate present an inline array of 16 × 5 rows in the streamwise (i.e., the crossflow direction) and spanwise directions, where the streamwise and spanwise distances between adjacent holes, which are normalized by the jet hole diameter (xn/d and yn/d), are 8 and 5, respectively. The jets impinge onto a smooth target plate with a normalized distance (zn/d) of 3.5 apart from the jet plate. The jet holes are extended by inserting stainless tubes throughout the jet holes and the extended lengths are varied in a range of 1.0d–2.5d, depending on the jet position in the streamwise direction. The experimental data is obtained by using the transient thermochromic liquid crystal (TLC) technique for wide operating jet Reynolds numbers of (1.0 × 104)–(3.0 × 104). The numerical simulations are well-validated using the experimental data and provide further insight into the flow physics within the jet impingement system. Comparisons with a traditional baseline jet impingement scheme show that the extended jet holes generate much higher local heat transfer levels and provide more uniform heat transfer distributions over the target plate, resulting in the highest improvement of approximately 36% in the Nusselt number. Although the extended jet hole configuration requires a higher pumping power to drive the flow through the impingement system, the gain of heat transfer prevails over the penalty of flow losses. At the same pumping power consumption, the extended jet hole design also has more than 10% higher heat transfer than the baseline scheme.

Heat Transfer of Confined Circular Jet Impingement

2001 ◽  
Vol 17 (1) ◽  
pp. 29-38
Author(s):  
Shou-Shing Hsieh ◽  
Jung-Tai Huang ◽  
Huang-Hsiu Tsai
Keyword(s):  
Heat Transfer ◽  
Average Nusselt Number ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Plate Spacing ◽  
Single Jet

ABSTRACTExperiments for heat transfer characteristics of confined circular single jet impingement were conducted. The effect of jet Reynolds number, jet hole-to-plate spacing and heat flux levels on heat transfer characteristics of the heated target surface was examined and presented. The local heat transfer coefficient along the surface is measured and correlations of the stagnation point, local and average Nusselt number are developed and discussed. Finally, comparisons of the present data with existing results were also made.

Local Internal Impingement Heat Transfer Near a 90 Deg Row of Film Cooling Holes: Part 2 — Effect of Jet Row Position

2006 ◽  
Author(s):  
Lei Xu ◽  
Haiping Chang ◽  
Guoqiang Chang
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Flux Ratio ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Target Plate ◽  
Transfer Characteristics ◽  
Cooling Hole ◽  
Film Cooling Holes

Investigation of local heat transfer characteristics near a row of film cooling holes in the inner side of a simulated turbine blade midchord region with impingement has been carried out experimentally. The research about heat transfer characteristics is focused on three diameter of film cooling hole area located upstream and downstream a row of film cooling holes, which angle is at a 90 degrees. The internal impingement air is provided by a single line of equally spaced jets. The film cooling air extracts through a line of holes on the impinging target plate. The projection of the jets on the target plate is always on the center line between two film holes. The spacing of the jet holes is twice that of the film cooling holes. The effect of the streamwise arrangement of the impingement nozzles relative to the position of the film cooling holes and impinging distance on the heat transfer characteristics have been mainly investigated. The experiment is conducted under the flow condition of Reynolds number 10000∼30000, crossflow-to-jet mass flux ratio based on each channel/jet hole section area 0.1 and film outflow-to-crossflow mass flux ratio based on film cooling hole/channel section 12∼20. In the range of experimental parameter, the experimental results indicate that there is optimal ratio of the impinging distance to film hole diameter, on which the heat transfer characteristics is best. Similarly for the area upstream film cooling hole, there is the optimal ratio of distance of the impingement nozzles relative to the position of the film cooling holes to film hole diameter. As impinging holes are away from film cooling holes in the streamwise direction of crossflow, the effect of impingement on local heat transfer near film cooling holes is weakened, but film cooling extraction effect stand out. The place closer to the hole will have stronger heat transfer whether upstream the film cooling holes or downstream the holes. Based on this, the effects of position of the jets relative to the film cooling holes on the heat transfer characteristics have been obtained qualitatively and quantitatively. It can be the important reference for accurately designing gas turbine blade.

scholarly journals Local Heat Transfer Characteristics of Multi Jet Impingement on High Temperature Plate Surfaces

2018 ◽  
Vol 58 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Bingxing Wang ◽  
Dong Lin ◽  
Bo Zhang ◽  
Lei Xiong ◽  
Zhaodong Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Heat Transfer Characteristics of an Impinging Jet in Crossflow

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Lei Wang ◽  
Bengt Sundén ◽  
Andreas Borg ◽  
Hans Abrahamsson
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Velocity Ratio ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Impinging Jet ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Jet In Crossflow

The heat transfer characteristics of an impinging jet into a crossflow have been investigated by the liquid crystal thermography technique. The jet nozzle is circular and is inclined at 10 deg with respect to the target wall. In a turbulent flow regime, the effects of the jet Reynolds number, the velocity ratio, and the crossflow Reynolds number on the heat transfer are examined. The results show that the heat transfer patterns are strongly affected by the jet Reynolds number and the velocity ratio. For a given jet Reynolds number, it is found that the crossflow diminishes the peak Nusselt number in the jet impingement region. However, in the wall jet region, the results suggest that the local heat transfer is nearly independent of the crossflow Reynolds number.

Local Heat Transfer Characteristics in Simulated Electronic Modules

2003 ◽  
Vol 125 (3) ◽  
pp. 362-368 ◽  
Author(s):  
Seong-Yeon Yoo ◽  
Jong-Hark Park ◽  
Min-Ho Chung
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Dimensional Array ◽  
Transfer Characteristics

When heat is released by forced convection from electronic modules in a narrow printed circuit board channel, complex flow phenomena—such as stagnation and acceleration on the front surface, separation and reattachment on the top surface, wake or cavity flow near the rear surface—affect the heat transfer characteristics. The purpose of this study is to investigate how these flow conditions influence the local heat transfer from electronic modules. Experiments are performed on a three-dimensional array of hexahedral elements as well as on a two-dimensional array of rectangular elements. Naphthalene sublimation technique is employed to measure three-dimensional local mass transfer, and the mass transfer data are converted to their counterparts of the heat transfer process using the analogy equation between heat and mass transfer. Module location and streamwise module spacing are varied, and the effect of vortex generators on heat transfer enhancement is also examined. Dramatic change of local heat transfer coefficients is found on each surface of the module, and three-dimensional modules have a little higher heat transfer value than two-dimensional modules because of bypass flow. Longitudinal vortices formed by vortex generator enhance the mixing of fluids and thereby heat transfer, and the rectangular wing type vortex generator is found to be more effective than the delta wing type vortex generator.

Numerical Research on Heat Transfer Characteristics Analysis of Two Particles in Supercritical Water

2021 ◽  
Author(s):  
Xiaoyu Li ◽  
Zhenqun Wu ◽  
Huibo Wang ◽  
Hui Jin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Phase Flow ◽  
Heat Transfer Characteristics ◽  
Particle Cluster ◽  
Two Phase ◽  
Transfer Characteristics

Abstract In the supercritical water (SCW)-particle two-phase flow of fluidized bed, the particles that make up the particle cluster interact with each other through fluid, and it will affect the flow and heat transfer. However, due to the complex properties of SCW, the research on particle cluster is lacking, especially in terms of heat transfer. This research takes two particles as an example to study the heat transfer characteristics between SCW and another particle when one particle exists. This research uses the distance and angle between the two particles as the influencing factors to study the average heat transfer rate and local heat transfer rate. In this research, it is found that the effect is obvious when L/D = 1.1. When L = 1.1D, the temperature field and the flow field will partially overlap. The overlap of the temperature field will weaken the heat transfer between SCW and the particle. The overlap of the flow field has an enhanced effect on the heat transfer between SCW and the particle. The heat transfer between SCW and particles is simultaneously affected by these two effects, especially local heat transfer rate. In addition, this research also found that as the SCW temperature decreases, the thermal conductivity and specific heat of SCW increases, which enhances the heat transfer between SCW and the particles. This research is of great significance for studying the heat transfer characteristics of SCW-particle two-phase flow in fluidized bed.

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