Numerical study of heat transfer from an isothermally heated flat surface due to turbulent twin oblique confined slot-jet impingement

Abstract

The heat transfer from an isothermally heated flat surface due to two-dimensional turbulent twin oblique confined slot-jet impingement is studied numerically using the ANSYS FLUENT commercial code. Initially the flow and thermal fields for a normal confined slot-jet impingement are investigated using the RNG k–ε model and the SST k–ω model, and their performance is evaluated against experimental data. The local Nusselt number distribution predicted by the SST k–ω model agrees notably better with the existing experimental data. Subsequently, the SST k–ω model is employed to study the twin oblique impinging jet heat transfer problem. Systematic parametric study is conducted by varying the jet exit Reynolds number (Re = 23,000 and 50,000), the jet-to-jet separation distance (L = 0, 2, and 4), the jet exit to the target plate distance (H = 2.6, 4, and 6), and the inclination angle of the jet to the impingement surface (45° ≤ φ ≤ 90°). Results indicate that, as the impingement angle is reduced from 90° (normal impingement), the peak Nusselt number at the impingement surface is gradually reduced and its location slightly shifts away from the jet axis with a corresponding slight decrease of the average Nusselt number for any combination of Re, L, and H. The average Nusselt number is a strong direct function of the Reynolds number and the impingement angle whereas it is a weak inverse function of the jet to target plate separation distance.