Streamwise curvature effects on turbulent wall jet heat transfer.

摘要

An experimental study of the heat transfer from a heated circular cylindrical aluminum wall to a bounded air jet blowing over it is presented. The jet was initially at ambient temperature and was considered to be incompressible since the maximum jet velocity was 150 ft./sec. Velocity and temperature profiles were measured at various stations for two temperatures, three Reynolds numbers and three cylinder radii. Heat transfer data were obtained from the Colburn analogy between heat transfer and skin friction (combined with Preston's method of measuring skin friction). Heat flow sensors were also used to measure heat transfer but the results were unsatisfactory and were disregarded.;The numerical values of the empirical constants C1 , C2 and C3 did not change appreciably for the three cylinders investigated.;The Nusselt numbers for the curved wall jets were lower than those for the plane wall jet and exhibited a stronger dependency on downstream distance.;A correlation was made between the Nusselt number, the Reynolds number and the downstream distance as follows: Nut=C 1Ret C2x/t -C3