An experimental investigation is conducted to study the effect of crossflow on the local heat transfer distribution of a flat surface normally impinged by round air jet. The influence of jet-to-plate distances (z/d of 4, 6 and 12), the crossflow velocity to the jet velocity (M varying from 1/6 to 1/12) and the Reynolds number (Re varying from 6000 to 12,000) on the heat transfer distribution was studied. The local heat transfer characteristics are estimated using thermal images obtained by infrared thermal imaging technique. The center-line distribution of the Nusselt number along the length of the plate is provided and a correlation for the stagnation point Nusselt number varying with the experimental parameters was proposed. It is observed that the distance of the stagnation point from the geometric impingement point and its magnitude increase with the increase in M. This distance is seen to be higher for higher values of z/d.

An experimental investigation is performed to study the effect of jet to plate spacing and low Reynolds number on the local heat transfer distribution to normally impinging submerged circular air jet on a smooth and flat surface. A single jet from a straight circular nozzle of length-to-diameter ratio (l/d) of 83 is tested. Reynolds number based on nozzle exit condition is varied between 500 and 8,000 and jet-to-plate spacing between 0.5 and 8 nozzle diameters. The local heat transfer characteristics are obtained using thermal images from infrared thermal imaging technique. It was observed that at lower Reynolds numbers, the effect of jet to plate distances covered during the study on the stagnation point Nusselt numbers is minimal. At all jet to plate distances, the stagnation point Nusselt numbers decrease monotonically with the maximum occurring at a z/d of 0.5 as opposed to the stagnation point Nusselt numbers at high Reynolds numbers which occur around a z/d of 6.

The impingement cooling of the leading edge of a gas turbine airfoil is modeled by considering impingement of three rows of jets on a semicylindrical concave surface. Experimental investigations are conducted to study the influence of jet-to-jet distance (s/d = 2.83, 4, and 6) and jet-to-plate distance (z/d = 2, 4, 6, and 8) on the local heat transfer of a semicylindrical concave surface impinged by three rows of multiple jets for different Reynolds numbers (12,000, 15,000, and 18,000). The local heat transfer coefficient is estimated using thermal images obtained by infrared thermal imaging technique. The local distribution of Nusselt numbers and the overall average Nusselt numbers were computed and compared. It was observed that the local heat transfer coefficients at 0 = 0° decrease with increase in z/d, whereas the heat transfer coefficients at θ = 60 and 80° increase with an increase in z/d at all Reynolds numbers. The configuration with s/d = 2.83 and z/d = 4 is observed to have the maximum heat transfer distribution with minimum coefficient of variance compared to other configurations at all Reynolds numbers covered in this study.

An experimental investigation is performed to study the effect of jet-to-plate spacing and Reynolds number on the local heat transfer distribution to normally impinging submerged circular air jet on a smooth semi-cylindrical concave surface. A single jet from a straight circular nozzle of length-to-diameter ratio (l/d) of 83 is tested. Reynolds number based on nozzle exit condition is varied between 11000 and 28000 and jet-to-plate spacing between 0.5 to 8 nozzle diameters. Experiments were carried out for two relative curvatures (D/d) of 4.4 and 6 by changing the jet tube diameter. The local heat transfer characteristics are estimated using thermal images obtained by infrared thermal imaging technique. Effect of curvature on heat transfer distribution is studied and compare with the flat plate results. Curvature results in decrease of Nusselt number compared to flat plate values.