Effect of Rotation Number on Heat Transfer Characteristics of a Row of Impinging Jets in Confined Channel

Abstract

Jet impingement has been applied for internal cooling in gas turbine blades. In this study, heat transfer characteristics of impinging jets from a row of circular orifices were investigated inside a flow channel with rotations. The Reynolds number (Re) based on the jet mean velocity was fixed at 6,700. Whereas, the rotation number (Ro) of a channel was varied from 0 to 0.0099. The jet-to-impingement distance ratio (L/Dj) and jet pitch ratio (P/Dj) were respective 2 and 4, Dj is a jet diameter of 5 mm. The thermochromic liquid crystals (TLCs) technique was used to measure the heat transfer coefficient distributions on an impingement surface. The results show that heat transfer enhancement on a jet impingement surface depended on the effects of crossflow and Coriolis force. The local Nusselt number at X/Dj?20 on the leading side (LS) was higher than on the trailing side (TS) while heat transfer on the LS at 20?X/Dj?40 gained the lowest, compared to on the TS. The average Nusselt number ratios ( ) on the TS at Ro = 0.0049 gave higher than on the LS of around 2.17%. On the other hand, the on the TS at Ro = 0.0099 was less than the LS of about 0.08%.