Numerical investigation of a novel jet hole design for staggered array jet impingement cooling on a semicircular concave surface

Abstract

Staggered array jet impingement cooling (JIC) on a semi-circular concave surface has investigated numerically. The main objective of this work is to examine elongated jet holes on heat transfer and flow characteristics of the staggered array JIC and to elucidate its applicability on cooling of a turbine blade. Jet holes were elongated to the target surface by the nozzles. Numerical computations were performed with different jet Reynolds numbers (5000≤Re≤25000), normalized confinement plate-to-target plate distances (1.0≤H/d≤8.0) and jet nozzle-to-target plate gap (0.5≤G/d≤6.0). Average Nusselt (Nu) number, local Nu number distributions on the surface, flow characteristics and Thermal Performance Factor (TPF) were comprehensively investigated. Numerical results were compared with the normal staggered array JIC. Results showed that local Nu number and average Nu number increases with decreasing G/d. The highest enhancement of heat transfer using elongated jet hole is obtained as 20.16% by decreasing G/d to 0.5 at H/d = 8.0. However, highest TPF is estimated as 1.11 at H/d = 8.0 by G/d = 2.0 for Re = 25,000. Decreasing of G/d provides more uniform heat transfer on the surface of interest in comparison with normal staggered array JIC. Consequently, elongating jet hole is a feasible heat transfer enhancement design for the staggered array JIC on a semicircular concave surface.