An experimental and numerical investigation on a confined impinging air jet at high Reynolds numbers

An experimental and numerical study is carried out to investigate flow field of a confined jet issuing from the lower surface and impinging normally on the upper surface. The mean velocity, turbulence intensity and pressure distributions in the impingement region were obtained for Reynolds numbers ranging from 30,000 to 50,000 and a nozzle-to-plate spacing range of 0.2–6. The effects of Reynolds number and nozzle-to-plate spacing on the flow structure are examined. A subatmospheric region occurs on the impingement plate at nozzle-to-plate spacings up to 2 for Reynolds numbers studied and it moves radially outward from the stagnation point with increasing nozzle-to-plate spacing. It is concluded that there exists a linkage among the subatmospheric region, turbulence intensity and heat transfer coefficients. The numerical results obtained using the standard k– ε turbulence model are in agreement with the experimental results except for the nozzle-to-plate spacings less than one.