Effect of Entrainment on the Heat Transfer to a Heated Circular Air Jet Impinging on a Flat Surface

An experimental investigation is described that characterizes the convective heat transfer of a heated circular air jet impinging on a flat surface. The radial distributions of the recovery factor, the effectiveness, and the local heat transfer coefficient are presented. The recovery factor and the effectiveness depend on the spacing from jet exit to the impingement plate, but do not depend on jet Reynolds number. The effectiveness does not depend on the temperature difference between the jet and the ambient. A correlation is obtained for the effectiveness. The heat transfer coefficient is independent of the temperature difference between the jet and the ambient if it is defined with the difference between the heated wall temperature and the adiabatic wall temperature.