Local and area average Nusselt number correlation for a circular impinging jet over a flat plate

Jet impingement technique is extensively used for cooling in various industrial applications. The present study deals with identifying the area affected by jet cooling and investigating the local and area average Nusselt number. Investigation of heat transfer is carried out on a 0.6 × 0.3 m2 flat plate impinged by a jet of air from a nozzle of 11.5 mm diameter. The area average and local heat transfer characteristics are studied over the target surface for Reynolds number 10,000–45,000, jet to plate spacing 3–20 d. The wall temperature distribution has been measured through non-intrusive infrared thermography technique. The work identifies the region of maximum heat transfer and its zone-wise distribution over the entire plate. The study investigates the impact of shape of imping area i.e., circular and square sections on heat transfer characteristics. A comparison is made between two sections having the same radial span and same area ratios. The experimental data are compared with the available local and average Nu correlations. Correlations are developed for local and area average Nu. The new correlations validate the local and area average Nu reasonably well from stagnation to maximum radial span, for the wide range of Reynolds number and jet plate spacing with less than ± 11% deviation.