Determination of heat transfer into a wedge model in a hypersonic flow using temperature-sensitive paint

Experiments are conducted to determine the heat transfer to a jet impinging at different oblique angles to a plane surface. The main portion of the test plate contains a composite sheet of temperature-sensitive liquid crystal, which is sandwiched between a thin metallic-foil heater and a specially designed liquid bath. The results indicate a displacement of the peak heat transfer from the geometric center of the jet origin, the displacement being a function primarily of impingement angle. Contours of constant heat transfer coefficient are obtained and correlated with an empirical equation that permits determination of average Nusselt numbers over areas of interest.

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Heat Transfer Characteristics of Jet Array Impingement at Low Streamwise Spacing

Volume 3A: Heat Transfer ◽

10.1115/gt2013-94469 ◽

2013 ◽

Author(s):

Roberto Claretti ◽

Jahed Hossain ◽

S. B. Verma ◽

J. S. Kapat ◽

James P. Downs ◽

...

Keyword(s):

Heat Transfer ◽

Nusselt Number ◽

Reynolds Numbers ◽

Temperature Sensitive ◽

Wall Heat Transfer ◽

Impingement Cooling ◽

Target Wall ◽

Temperature Sensitive Paint ◽

Set Up ◽

Streamwise Distance

The present work studies the effect of low streamwise jet-to-jet spacing and uneven spanwise jet-to-jet spacing on target wall heat transfer coefficient in impingement cooling systems. Temperature sensitive paint alongside constant flux heaters were used to gather heat transfer data on the target wall. Two different geometries have been tested with varying jet-to-jet spanwise distance. The streamwise jet spacing was set to 3 jet diameters, the spanwise jet spacing was set to 3, 8 and 13 jet diameters while the jet-to-target spacing was set to 3 jet diameters. The tests were run at three average jet Reynolds numbers of 10,000, 13,000 and 16,000. Results show little effect of crossflow on the target wall heat transfer. Nusselt number profiles are compared to the Florschuetz prediction, the area averaged Nusselt number matches closely; however, the Florschuetz correlation shows a decreasing trend in Nusselt number as a function of streamwise distance while the data shows a Nusselt number profile that remains relatively constant as a function of streamwise distance, x. To better understand the flow physics behind this trend, a CFD run was set up using the ν2-f turbulence model for all cases. Computational and experimental results display a strong similarity of their heat transfer trends. The crossflow is seen to not be able to reattach behind each jet due to their proximity to one another.

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Heat Transfer Determined by the Temperature Sensitive Paint Method

Transactions on Aerospace Research ◽

10.2478/tar-2018-0029 ◽

2018 ◽

Vol 2018 (4) ◽

pp. 45-57

Author(s):

Łukasz Jeziorek ◽

Krzysztof Szafran ◽

Paweł Skalski

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Surface Temperature ◽

Transfer Coefficient ◽

Thermal Power ◽

Test Method ◽

Temperature Sensitive ◽

Complex Objects ◽

Temperature Sensitive Paint ◽

The Heat Transfer Coefficient

Abstract The paper presents practical aspects of determining the amount of heat flow by measuring the distribution of surface temperature using the Temperature Sensitive Paint (TSP) method. The quantity measured directly with TSP is the intensity of the excited radiation, which is then converted to surface temperature. The article briefly presents three different methods for determining the heat transfer coefficient. Each of these methods is based on a separate set of assumptions and significantly influences the construction of the measuring station. The advantages of each of the presented methods are their individual properties, allowing to improve accuracy, reduce the cost of testing or the possibility of using them in tests of highly complex objects. For each method a mathematical model used to calculate the heat transfer coefficient is presented. For the steady state heat transfer test method that uses a heater of constant and known thermal power, examples of the results of our own research are presented, together with a comparison of the results with available data and a discussion of the accuracy of the results obtained.

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