Numerical Study on Heat Transfer from a Square Pipe Nozzle Impinging Jet with Square Air-Augmented Duct

A numerical study has been performed to investigate impingement flow and heat transfer characteristics issued from a square pipe nozzle with a square air-augmented duct. Investigations were done for various nozzle-to-plate spacing, air duct lengths and diameters. The problem under investigation has been modelled three-dimensionally and under steady-state conditions. Investigations were done for a Re number value of 20000, H/d = 4–8, L/d = 1.5–4 and D/d = 1.5–6. The flow was modelled as incompressible and turbulent. A validation study has been performed by using experimental data from the literature and a fair agreement has been obtained. It was observed that, the variation in dimensionless duct diameter (D/d) has a low effect on heat transfer. The heat transfer increases with the decrease in dimensionless duct length (L/d) for H/d = 6, whereas for H/d = 8 it was seen that L/d has low effect on heat transfer. In addition, it was observed that the highest average Nu (Nuavg) could be obtained for L/d = 1.5. A correlation was proposed for Nuavg.