Local heat transfer due to several configurations of circular air jets impinging on a flat plate with and without semi-confinement

A technique based on infrared thermography is used to determine the convective heat transfer on a flat plate on which either a single circular air jet or a row of jets impinged. The flat plate is heated using the thin-foil technique, which enables one to impose different convective heat fluxes. For each flux, a temperature distribution is recorded using a thermographic camera. After that, local heat transfers and local adiabatic temperatures are determined by means of a linear regression method. Parameters that are made to vary include jet injection temperature, the Reynolds number, spacing between adjacent jet, and the distance between the flat plate and jets orifices. In each case, two configurations are investigated: one with and the other without semi-confinement. Results show the independence of heat transfer coefficients and effectiveness from the jet injection temperature within the range studied. The influence of confinement on heat transfer coefficient is weak, but it has a great impact on effectiveness.