Heat transfer investigation of an array of jets impinging on a target plate with detached ribs

Abstract

This combined experimental and numerical study focuses on impingement jet cooling in combination with detached rib turbulators on a flat target for turbomachinery applications. The investigated impingement array consists of an impingement plate with 9 × 9 jet holes with diameter D and a target plate with detached ribs installed beneath the jet hole. The effects of different separation distances (H/D=3-5), jet Reynolds numbers (15,000-35,000) and rib clearances (0.3D and 0.08D) are investigated. The heat transfer is investigated experimentally by the transient liquid crystal (TLC) method. A computational fluid dynamics (CFD) model is carried out within the software package ANSYS CFX. This model uses a steady-state three-dimensional Reynolds-Averaged Navier-Stokes (RANS) approach with the Shear Stress Transport (SST) turbulence model. Numerical simulations allow detailed insight into the fluid mechanics of the complex flow field and complement experimental measurements. Detached ribs in the impingement channel have a strong influence on the flow field and can increase the global Nusselt number by up to 4% if the ribs have adiabatic boundary conditions. The usage of the detached rib reduces the relative discharge coefficient by up to 11% compared to a smooth target.