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

Thantup Nontula; Natthaporn  Kaewchoothong; Wacharin Kaew-apichai; Chayut Nuntadusit

Authors

Thantup Nontula Department of Mechanical Engineering, Faculty of Engineering, Prince of Songkla University, Hatyai, Songkhla 90110, Thailand
Natthaporn Kaewchoothong Department of Mechanical Engineering, Faculty of Engineering, Prince of Songkla University, Hatyai, Songkhla 90110, Thailand
Wacharin Kaew-apichai Department of Computer Engineering, Faculty of Engineering, Prince of Songkla University, Hatyai, Songkhla 90110, Thailand
Chayut Nuntadusit Energy Technology Research Center (ETRC), Prince of Songkla University, Hatyai, Songkhla 90110, Thailand

Keywords:

Impinging jets, Rotation number, Heat transfer, Thermochromic liquid crystals

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/D_j) and jet pitch ratio (P/D_j) were respective 2 and 4, D_j 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/D_j?20 on the leading side (LS) was higher than on the trailing side (TS) while heat transfer on the LS at 20?X/D_j?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%.