Heat transfer and flow characteristics of impinging jet on a concave surface at small nozzle to surface distances

Highlights: • Investigations of the flow and heat transfer at small jet distances were performed. • The SST k-ω model fairly captures the shape of the velocity and Nu profiles. • The $\overline{\mathrm{Nu}}$ is related to ${(H/D)}^{-0.54}$ and ${(H/D)}^{-0.14}$ for H/D • Experiments reveal that the jets with H/D $\overline{\mathrm{Nu}}$. Experimental and numerical investigations were carried out to analyze the flow and heat transfer characteristics of an impinging jet on a concave surface at small jet-to-surface distances. Constant heat flux of 2000 W/m² is applied on the concave surface using a silicon rubber heater mat. In the steady-state condition, the temperature distribution of the concave surface is measured with an infrared camera. In the experimental study, a jet with 24 mm diameter and cylindrical surface with the curvature radius of 12 cm (C_r = 0.1) has been considered. The study of flow and heat transfer characteristics have been performed for different jet Reynolds numbers (10,000–35,000) and various nozzle diameters (18–30 mm). The distributions of velocity and Nusselt number for small jet-to-surface distances (H/D $\overline{\mathrm{Nu}}$ is related to ${(H/D)}^{-0.54}$ and ${(H/D)}^{-0.14}$ for small (H/D 1.0) jet-to-surface distances respectively.