scholarly journals Heat transfer in a channel with inclined target surface cooled by single array of centered impinging jets

2013 ◽  
Vol 17 (4) ◽  
pp. 1195-1206
Author(s):  
Mubarak Al ◽  
S.M. Shaahid ◽  
Luai Al-Hadhramic
Keyword(s):  
Heat Transfer ◽  
Target Surface ◽  
Reynolds Numbers ◽  
Impinging Jets ◽  
Heat Transfer Characteristics ◽  
Target Plate ◽  
Maximum Heat ◽  
Transfer Characteristics ◽  
Aspect Ratios ◽  
Feed Channel

An experimental investigation has been carried out to study the heat transfer characteristics in a channel with heated target plate inclined at an angle cooled by single array of equally spaced centered impinging jets for three different jet Reynolds numbers (Re=9300, 14400 and 18800). Air ejected from an array of orifices impinges on the heated target surface The target plate forms the leading edge of a gas turbine blade cooled by jet impingement technique. The work includes the effect of jet Reynolds numbers and feed channel aspect ratios (H/d = 5, 7, 9 where H=2.5, 3.5, 4.5 cm and d=0.5 cm) on the heat transfer characteristics for a given orifice jet plate configuration with equally spaced centered holes with outflow exiting in both directions (with inclined heated target surface). In general, It has been observed that, H/d=9 gives the maximum heat transfer over the entire length of the target surface as compared to all feed channel aspect ratios. H/d=9 gives 3% more heat transfer from the target surface as compared to H/d=5 (for Re=14400). Also, it has been observed that the magnitude of the averaged local Nusselt number increases with an increase in the jet Reynolds number for all the feed channel aspect ratios studied.

Heat Transfer in a Channel With Inclined Target Surface Cooled by Single Array of Impinging Jets

2007 ◽  
Author(s):  
Luai M. Al-Hadhrami ◽  
S. M. Shaahid ◽  
Ali A. Al-Mubarak
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Target Surface ◽  
Impinging Jets ◽  
Heat Transfer Characteristics ◽  
Target Plate ◽  
Transfer Characteristics ◽  
Aspect Ratios ◽  
Channel Aspect Ratio ◽  
Feed Channel

An experimental investigation has been carried out to study the heat transfer characteristics in a channel with heated target plate inclined at an angle cooled by single array of centered impinging jets. The target plate forms the leading edge of a gas turbine blade. The work includes the effect of various exit outflow orientations and crossflow and feed channel aspect ratios on the heat transfer characteristics for a given orifice-jet plate configuration. Three feed channel aspect ratios (H/d = 5, 7, 9) and have been examined. In general, it has been observed that Nu is high for higher aspect ratios. This increase can be attributed to increase in strength of impinging jets due to increase in feed channel aspect ratio. Additionally, for a given jet-orifice plate with centered holes and for a given Re = 18800, the heat transfer is almost the same through out the target surface for the outflow passing out in both the directions.

Effect of Orifice Jet Configuration on Heat Transfer in a Channel With Inclined Target Surface Cooled by Single Array of Impinging Jets With Outflow in Both Directions

2008 ◽  
Author(s):  
Ali A. Al-Mubarak ◽  
S. M. Shaahid ◽  
Luai M. Al-Hadhrami
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Target Surface ◽  
Impinging Jets ◽  
Percentage Increase ◽  
Heat Transfer Characteristics ◽  
Target Plate ◽  
Aspect Ratios ◽  
Transfer Behavior ◽  
Feed Channel

An experimental work has been carried out to investigate the effect of orifice-jet plate configuration on heat transfer behavior in a channel with inclined heated target plate cooled by single array of equally spaced impinging jets. Air ejected from an array of orifices is impinges on the heated target surface. The target plate forms the leading edge of a gas turbine blade. The study includes the effect of various orifice-jet plate configurations, feed channel aspect ratios H/d = 5, 7, and 9, and Reynolds number Re = 9300, 14400, and 18880 on the heat transfer characteristics for a given outflow orientation (outflow passing out in both the directions). Three orifice-jet plate configurations (centered, staggered, and tangential holes) have been examined. It has been noticed that Nusselt number (Nu) is high for higher aspect ratios. For a given plate-1 with single array of equally spaced centered jets and for Re = 18800 (outflow passing out in both directions), the local Nu for H/d = 9 has been found to be greater than Nu of H/d = 7 by 5%. The percentage increase in average Nu has been found to be about 11% with centered holes as compared staggered orifice-jet plate. The percentage increase in average Nu has been found to be about 11% with staggered jet-plate as compared to tangential orifice-jet plate configuration.

Two Dimensional Simulation of Flow and Heat Transfer Characteristics of Turbulent Jets

2010 ◽  
Author(s):  
Tarek Abdel-Salam
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbulent Jets ◽  
Reynolds Numbers ◽  
Impinging Jets ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Dimensional Simulation

In this study, flow and heat transfer characteristics of two-dimensional impinging jets are investigated numerically. Flow geometries under consideration are single and multiple impinging jets issued from a plane wall. Both confined and unconfined configurations are simulated. Effects of Reynolds number and the distance between the jets are investigated. Results are obtained with a finite volume CFD code. Structured grids are used in all cases of the present study. Turbulence is treated with a two equation k-ε model. Different jet velocities have been examined corresponding to Reynolds numbers of 5,000 to 20,000. Results show that the Reynolds number has significant effect on the heat transfer rate and has no effect on the location of the maximum Nusselt number.

Effect of Feed Channel Width on Heat Transfer in a Rectangular Duct With an Array of Off-Set Jets

2006 ◽  
Author(s):  
Luai M. Al-Hadhrami
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Target Surface ◽  
Reynolds Numbers ◽  
Impinging Jets ◽  
The Other ◽  
Channel Width ◽  
Rectangular Duct ◽  
Feed Channel ◽  
Plate Distance

Experimental investigation was carried out to study the heat transfer characteristics in a rectangular duct cooled by an array of impinging jets. Air ejected from an array of orifices is aimed at the heated target surface and exits from the radial outlets. The effect of feed channel widths (5 ≤ H / d ≤ 9), jet to target plate distance (4 ≤ S/d ≤ 8), outflow orientation and jet Reynolds numbers (9300 ≤ Rej ≤ 18800) with a single array of equally spaced off-set orifice jets of diameter d = 0.5 cm on heat transfer was studied. Results indicated that the outflow orientation causing crossflow effect significantly affects the Nusselt number distributions on the target surface. Relatively higher Nusselt number values were obtained for the outflow orientation where the flow exits in both the directions. The feed channel width H/d = 7 gave relatively higher values of heat transfer compared to the other two feed channel widths. The jet-to-plate distance S/d = 4 resulted in higher heat transfer compared to the other jet-to-plate distances.

scholarly journals Heat Transfer Characteristics of Swirling Impinging Jets

2009 ◽  
Author(s):  
Karl J. Brown ◽  
Darina B. Murray ◽  
Tim Persoons ◽  
Tadhg S. O’Donovan
Keyword(s):  
Heat Transfer ◽  
Swirling Flow ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
High Heat ◽  
Impinging Jets ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
Transfer Characteristics ◽  
High Reynolds

Impinging jets are used in a wide number of industrial cooling applications due to their high heat and mass transfer abilities. The current research is concerned with the effect of swirl on the heat transfer characteristics of jet impingement cooling. Two inserts were designed order to generate swirling flow. These two designs, “Swirl Insert A” and “Swirl Insert B”, were tested at various Reynolds numbers, between 8000 and 16000 inclusive, and at H/D = 0.5 and 1. The jet was directed downwards onto a 25μm thick stainless steel foil which was ohmically heated. Images were recorded using a thermal imaging camera focused on the underside of the foil. These images were then analysed using Matlab and the Nusselt number profile was obtained. It was found that, while both swirl inserts establish an improvement in the heat transfer by comparison to that of a jet with no swirl, the “Swirl Insert B” design performed better that the “Swirl Insert A” design for high Reynolds number at H/D = 0.5 and consistently for H/D = 1. It was also discovered that, while both the “No Insert” and “Swirl Insert B” results did not change dramatically with an alteration in H/D, “Swirl Insert A” decreased by ∼10%.

scholarly journals Investigations of Flow and Heat Transfer Characteristics in a Channel Impingement Cooling Configuration with a Single Row of Water Jets

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4327
Author(s):  
Min-Seob Shin ◽  
Santhosh Senguttuvan ◽  
Sung-Min Kim
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Channel Height ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Impingement Cooling ◽  
Average Heat ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

The present study experimentally and numerically investigates the effect of channel height on the flow and heat transfer characteristics of a channel impingement cooling configuration for various jet Reynolds numbers in the range of 2000–8600. A single array consisting of eleven jets with 0.8 mm diameter injects water into the channel with 2 mm width at four different channel heights (3, 4, 5, and 6 mm). The average heat transfer coefficients at the target surface are measured by maintaining a temperature difference between the jet exit and the target surface in the range of 15–17 °C for each channel height. The experimental results show the average heat transfer coefficient at the target surface increases with the jet Reynolds number and decreases with the channel height. An average Nusselt number correlation is developed based on 85 experimentally measured data points with a mean absolute error of less than 4.31%. The numerical simulation accurately predicts the overall heat transfer rate within 10% error. The numerical results are analyzed to investigate the flow structure and its effect on the local heat transfer characteristics. The present study advances the primary understanding of the flow and heat transfer characteristics of the channel impingement cooling configuration with liquid jets.

Effect of Jet-to-Jet Distance and Pipe Position on Flow and Heat Transfer Features of Active Clearance Control Systems

2021 ◽  
Author(s):  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini ◽  
Riccardo Da Soghe ◽  
Lorenzo Mazzei ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Target Surface ◽  
Reynolds Numbers ◽  
Metal Plate ◽  
Target Distance ◽  
Target Plate ◽  
Ir Camera ◽  
Supply Pipe ◽  
Heating Up ◽  
Clearance Control

Abstract The goal of the present work is to investigate the effect of supply pipe position on the heat transfer features of various active clearance control (ACC) geometries, characterized by different jet-to-jet distances. All geometries present 0.8 mm circular impingement holes arranged in a single row. The jets generated by such holes cool a flat target surface, which is replicated by a metal plate in the experimental setup. Measurements are performed using the steady-state technique, obtained by heating up the target plate thanks to an electrically heated Inconel foil applied on the side of the target opposite to the jets. Temperature is also measured on this side by means of an IR camera. Heat transfer is then evaluated thanks to a custom designed finite difference procedure, capable of solving the inverse conduction problem on the target plate. The effect of pipe positioning is studied in terms of pipe-to-target distance (from 3 to 11 jet diameters) and pipe orientation (i.e. rotation around its axis, from 0° to 40° with respect to target normal direction), while the investigated jet Reynolds numbers range from 6000 to 10000. The obtained results reveal that heat transfer is maximized for a given pipe-to-target distance, dependent on both jet-to-jet distance and target surface extension. Pipe rotation also affects the cooling features in a non-monotonic way, suggesting the existence of different flow regimes related to jet inclination.

Sign in / Sign up

Export Citation Format

Share Document