Impingement Cooling Experiments With Flat Plate and Pin Plate Target Surfaces

1999 ◽  
Author(s):  
Rainer Hoecker ◽  
Bruce V. Johnson ◽  
Josef Hausladen ◽  
Matthias Rothbrust ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Copper Plate ◽  
Orifice Plate ◽  
Plate Model ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Target Plate ◽  
Average Heat ◽  
Heat Transfer Coefficients

Heat transfer experiments were conducted with three (3) different target plate configurations: a baseline copper flat smooth plate, a copper plate model with copper pins and a copper plate model with Teflon pins, to determine average heat transfer coefficients on the flat and pin surfaces for application with different plate materials. For each target plate surface configuration, the heat transfer experiments were conducted with selected impingement orifice plate configurations and with selected spacing between the orifice plate and the heat transfer target plate. The heat transfer results for the baseline copper smooth flat plate were in good agreement with a well-recognized correlation for the flow regions used in the correlation. An analytical procedure, similar to that used by Metzger et al. for pin-fins in coolant channels, was developed to separate the average heat transfer coefficients on the flat and pin surfaces. The results with the copper pins showed modest increases of approximately 35 percent in heat transfer at lower Reynolds numbers, decreasing with increased Reynolds number. Application of the experimental results to an analysis for high-pressure engine conditions with modest thermal conductivity materials showed that the overall heat transfer coefficient can decrease with pin surfaces for some conditions, compared to flat plates.

Heat Transfer Characteristics of Impinging Two-Dimensional Air Jets

1966 ◽  
Vol 88 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Robert Gardon ◽  
J. Cahit Akfirat
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients ◽  
Transfer Characteristics ◽  
Air Jets

Local as well as average heat transfer coefficients between an isothermal flat plate and impinging two-dimensional jets were measured for both single jets and arrays of jets. For a large and technologically important range of variables the results have been correlated in relatively simple terms, and their application to design is briefly considered.

Angular Dependency on Film Boiling Heat Transfer From Relatively Long Inclined Flat Plates

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Chan Soo Kim ◽  
Kune Y. Suh
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Boiling Heat Transfer ◽  
Flow Direction ◽  
Film Boiling ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Heat Transfer Coefficients ◽  
Inclination Angles ◽  
Angular Dependency

The effect of inclination angle of the downward facing flat plate on the interfacial wavy motion is investigated utilizing the water quenching test apparatus downward ebullient laminar transition apparatus flat surface (DELTA-FS) in a quasi-steady state. Film boiling heat transfer coefficients are obtained on the relatively long surface in the flow direction. Interfacial velocities at the various inclination angles and wall superheat conditions are determined through the analysis of the visualized continuous snapshots with 1000 fps. Visualization of the vapor film reveals that the interfacial wavelength increases and the interfacial velocity decreases as the flat plate moves from the vertical to downward facing locations. A new semi-empirical correlation is developed from the measured heat transfer coefficients and interfacial velocities. The correlation shows good agreement with the previous water test results on vertical plates. In the case of the previous other fluid experimental results on the vertical plates, the correlation overpredicts the film boiling heat transfer coefficients at the experimental condition.

Film Boiling on Downward Facing Flat Plates With Varying Inclination Angles

2005 ◽  
Author(s):  
Chan S. Kim ◽  
Mong J. Yu ◽  
Kune Y. Suh ◽  
Joy L. Rempe ◽  
F. Bill Cheung ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Flat Surface ◽  
Flow Direction ◽  
Film Boiling ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Heat Transfer Coefficients ◽  
Inclination Angles ◽  
Water Test

The effect of inclination angle of the downward facing flat plate on the interfacial wavy motion is investigated utilizing the water test apparatus DELTA FS (Downward Ebullient Laminar Transition Apparatus Flat Surface) in a quasi-steady state. Film boiling heat transfer coefficients are obtained on the relatively long surface in the flow direction. The measured heat transfer coefficients are compared with those predicted by the laminar film boiling and interfacial wavy film boiling correlations at the same experimental condition. Visualization of the vapor film revealed that the interfacial wavelength decreases as the flat plate moves from the vertical to downward facing locations.

Experimental Study of Multiple Air Jets Impinging a Moving Flat Plate

2020 ◽  
Author(s):  
Flavia Barbosa ◽  
Senhorinha Teixeira ◽  
Carlos Costa ◽  
Filipe Marques ◽  
José Carlos Teixeira
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Jet Impingement ◽  
Plate Motion ◽  
Test Facility ◽  
Flat Plates ◽  
Target Plate ◽  
Wall Jets ◽  
Air Jets ◽  
Flow Interactions

Abstract The motion of the target plate is important in some industrial applications which apply multiple jet impingement, such as reflow soldering, drying and food processing. Multiple jet impingement is widely used due to its ability to generate high heat transfer rates over large and complex areas. This convective process is characterized by several flow interactions essentially due to adjacent jets mixing prior the impingement, wall jets collision after the impingement, as well as crossflow interactions induced by the motion of the wall jets that flow through the exits of the domain. These interactions lead to strong flow recirculation, pressure gradients and boundary layer development. However, the complexity of the flow interactions is increased with the surface motion in confined space, due to the generation of strong shear regions. These interactions can induce problems and product defects due to complicated thermal behavior and non-uniform heating or cooling, being important to fully understand the process in order to reduce time and costs. This work addresses the experimental analysis of multiple air jets impinging on a moving flat plate. The experiments are conducted on a purpose-built test facility which has been commissioned, using a 2D-PIV system. Through this technique, the flow structure and velocity profiles will be analyzed in detail. The effects of the impinging plate motion on the resulting global and local velocity profile is compared with a static flat plate. The multiple jet configuration consists on air flowing through 14 circular nozzles, at a Reynolds number of 690 and 1,380. The experiments are conducted for a nozzle-to-plate distance of 8 and a jet-to-jet spacing of 2. The target plate motion remains constant throughout the experiments and equal to 0.03 m/s. The results are compared for both stationary and moving flat plates cases and express the increased complexity of the flow due to strong interaction between jets and the target surface, which affects the heat transfer performance. The results obtained experimentally are important to clearly define this complex flow and these data can be used in future works for numerical model validation.

Heat Transfer and Pressure Distribution in Open Cavity Flow

1967 ◽  
Vol 89 (1) ◽  
pp. 103-108 ◽  
Author(s):  
A. F. Emery ◽  
J. A. Sadunas ◽  
M. Loll
Keyword(s):  
Heat Transfer ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Cavity Flow ◽  
Rectangular Cavity ◽  
Open Cavity ◽  
Transfer Coefficients ◽  
Transient Techniques ◽  
Heat Transfer Coefficients ◽  
Mach 3

The heat transfer and pressure distribution in a rectangular cavity in a Mach 3 flow were investigated for a rectangular and an inverted-wedge recompression step. Noticeable differences between the results for the two steps were found in the recovery factors, but no real differences were detected in the heat-transfer coefficients or the velocity profiles. Heat-transfer coefficients in the cavity were determined by transient techniques and were found to range from 50 to 110 percent of the flat-plate value just prior to the expansion step.

An Experimental Investigation of the Rib Surface-Averaged Heat Transfer Coefficient in a Rib-Roughened Square Passage

1997 ◽  
Vol 119 (2) ◽  
pp. 381-389 ◽  
Author(s):  
M. E. Taslim ◽  
C. M. Wadsworth
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Performance ◽  
Blockage Ratio ◽  
Transfer Coefficients ◽  
Height Ratio ◽  
Average Heat ◽  
Heat Transfer Coefficients ◽  
The Heat Transfer Coefficient

Turbine blade cooling, a common practice in modern aircraft engines, is accomplished, among other methods, by passing the cooling air through an often serpentine passage in the core of the blade. Furthermore, to enhance the heat transfer coefficient, these passages are roughened with rib-shaped turbulence promoters (turbulators). Considerable data are available on the heat transfer coefficient on the passage surface between the ribs. However, the heat transfer coefficients on the surface of the ribs themselves have not been investigated to the same extent. In small aircraft engines with small cooling passages and relatively large ribs, the rib surfaces comprise a large portion of the passage heat transfer area. Therefore, an accurate account of the heat transfer coefficient on the rib surfaces is critical in the overall design of the blade cooling system. The objective of this experimental investigation was to conduct a series of 13 tests to measure the rib surface-averaged heat transfer coefficient, hrib, in a square duct roughened with staggered 90 deg ribs. To investigate the effects that blockage ratio, e/Dh and pitch-to-height ratio, S/e, have on hrib and passage friction factor, three rib geometries corresponding to blockage ratios of 0.133, 0.167, and 0.25 were tested for pitch-to-height ratios of 5, 7, 8.5, and 10. Comparisons were made between the rib average heat transfer coefficient and that on the wall surface between two ribs, hfloor, reported previously. Heat transfer coefficients of the upstream-most rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared. It is concluded that: 1 The rib average heat transfer coefficient is much higher than that for the area between the ribs; 2 similar to the heat transfer coefficient on the surface between the ribs, the average rib heat transfer coefficient increases with the blockage ratio; 3 a pitch-to-height ratios of 8.5 consistently produced the highest rib average heat transfer coefficients amongst all tested; 4 under otherwise identical conditions, ribs in upstream-most position produced lower heat transfer coefficients than the midchannel positions, 5 the upstream-most rib average heat transfer coefficients decreased with the blockage ratio; and 6 thermal performance decreased with increased blockage ratio. While a pitch-to-height ratio of 8.5 and 10 had the highest thermal performance for the smallest rib geometry, thermal performance of high blockage ribs did not change significantly with the pitch-to-height ratio.

Effect of Rib Configuration and Lateral Ejection on a High Aspect Ratio Trailing Edge Channel

2013 ◽  
Author(s):  
Rui Kan ◽  
Li Yang ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Local Heat Transfer ◽  
Large Aspect Ratio ◽  
Thermochromic Liquid Crystal ◽  
Transfer Coefficients ◽  
Trailing Edge ◽  
Average Heat ◽  
Edge Channel ◽  
Heat Transfer Coefficients

Thermal issues of gas turbine blade trailing edge are complex and challenging, due to limited space for effective cooling. The trailing edge cavities are usually large aspect ratio ducts with lateral ejection. The objective of this study is to investigate the effects of different rib configurations and lateral ejection on heat transfer characteristics inside a trailing edge channel. The investigations were conducted on a large aspect ratio wedge-shaped channel with square ribs of e/Dh = 0.05, under Reynolds number 15,000. Twelve different configurations were tested: 1)three rib types, including a symmetry V-shaped rib configuration and two non-symmetry V-shaped rib configurations, of which the rib angles are 60 degrees, 2) two rib pitches, P/e = 10 and P/e = 5, 3) two flow directions, with an open tip outlet or with lateral ejection. Spatially resolved heat transfer distributions were obtained using the transient thermochromic liquid crystal experimental method. The configurations were also investigated numerically for the detailed flow field and for the validation of CFD codes. Results show that with lateral ejection, the heat transfer coefficients decrease from inlet to outlet. The heat transfer near the ejection holes is enhanced while heat transfer coefficients near the wall opposite to the exit holes decrease. The curvature of the streamlines creates a large separation area near the end of the channel and thus results in low local heat transfer coefficients. The P/e = 10 configurations have higher average heat transfer compared with P/e = 5 configurations. Average heat transfer coefficient is the highest with the center of the V-shaped rib placed at the middle of the channel, and is the lowest when the V-shaped rib center is located near the narrow part of the channel.

Sign in / Sign up

Export Citation Format

Share Document