An analytical and experimental study was done to determine the effect of entrainment on the heat transfer to a single, plane, turbulent impinging jet. Solutions to the momentum and energy equations were obtained with similarity and series analyses. The analytical model is compared with measured heat transfer rates to single air jets impinging normally on an isothermal heated surface. To determine the effect of entrainment, the temperature of the environment surrounding the jet was varied between the initial temperature of the jet and the plate temperature. Results obtained for jet arrays show that entrainment of air in the recirculation region between the jets can significantly affect the heat transfer rates. Comparison of the analytical model to the measured heat transfer rates for jet arrays shows that the single jet model can be successfully applied to jet arrays when the effect of entrainment is considered. / Master of Science