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.

Local Internal Impingement Heat Transfer Near a 30 and 90 Deg Row of Film Cooling Holes: Part 1 — Effect of Flow Parameters

2006 ◽  
Author(s):  
Lei Xu ◽  
Haiping Chang ◽  
Jingyang Zhang
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Heat Transfer Characteristics ◽  
Flow Parameters ◽  
Section Area ◽  
Cooling Hole ◽  
Film Cooling Holes

Experimental investigations of local impingement heat transfer characteristics near a row of film cooling holes in a simulated internal midchord region of gas turbine blade have been carried out. The research of heat transfer characteristics is focused on three film cooling hole diameter area located upstream and downstream a row of film holes. There is a line of equally spaced film cooling holes whose angles are 30 or 90 degrees. When there is no impingement, the investigation about the effect of the film cooling bleed has been carried out under different cross flow Reynolds Numbers and film outflow-to-crossflow mass flux ratios based on each film cooling hole/channel section area. The results indicate that the local heat transfer near the film cooling holes is enhanced with the increase of the crossflow Reynolds Numbers and film outflow-to-crossflow mass flux ratios based on each film cooling hole/channel-section area. The local heat transfer characteristic downstream film cooling holes is better than that upstream film cooling holes. The average Nusselt number of one time diameter area downstream the row of film holes is generally 40% more than that upstream the row of film cooling holes. The place closer to the hole will have stronger heat transfer whether upstream film cooling holes or downstream film cooling holes. When there is impingement, the impinging air is provided by a single line of equally spaced jets. The spacing of the jet holes is twice that of the film cooling holes with staggered arrangements. The local heat transfer near the row of film cooling holes has been studied experimentally through changing flow parameters, such as impinging Reynolds Numbers and mass flux ratios of crossflow-to-jet based on each channel/jet hole section area etc. A great number of experimental data has been obtained. Based on this, the effects of the flow parameters 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 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.

Detailed Measurements of Local Heat Transfer Coefficient in the Entrance to Normal and Inclined Film Cooling Holes

1996 ◽  
Vol 118 (2) ◽  
pp. 285-290 ◽  
Author(s):  
D. R. H. Gillespie ◽  
A. R. Byerley ◽  
P. T. Ireland ◽  
Z. Wang ◽  
T. V. Jones ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Film Cooling ◽  
Large Scale ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Gas Temperature ◽  
Entry Length ◽  
Cooling Hole ◽  
Film Cooling Holes

The local heat transfer inside the entrance to large-scale models of film cooling holes has been measured using the transient heat transfer technique. The method employs temperature-sensitive liquid crystals to measure the surface temperature of large-scale perspex models. Full distributions of local Nusselt number were calculated based on the cooling passage centerline gas temperature ahead of the cooling hole. The circumferentially averaged Nusselt number was also calculated based on the local mixed bulk driving gas temperature to aid interpretation of the results, and to broaden the potential application of the data. Data are presented for a single film cooling hole inclined at 90 and 150 deg to the coolant duct wall. Both holes exhibited entry length heat transfer levels that were significantly lower than those predicted by entry length data in the presence of crossflow. The reasons for the comparative reduction are discussed in terms of the interpreted flow field.

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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