Local heat transfer coefficients from a flat plate to a pair of circular air impinging jets are investigated experimentally, A pair of well-controlled, fully developed circular air impinging jets at room temperature are used in the experiments. The experimental method in this investigation is the transient liquid-crystal technique. During the experiments, the surface liquid-crystal color distribution of the test plate is recorded using a video imaging acquisition system, and the color information is translated into a surface temperature distribution through a digital color image processing unit. Local heat transfer coefficients art obtained using a surface transient heat conduction analysis. The flow Reynolds number of the jet is kept at 23,000. The jet-to-plate distance and the jet-to-jet spacing are varied in the experiment. Detailed radial heat transfer distributions at different radial directions are obtained and analyzed for L/D = 2, 4, 6, 8, and 10. The effect of jet spacing distance (S/D =1.75, 3.5,5.25, 7.0) is analyzed by comparing to data obtained from a single jet with similar flow configurations.
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