Effect of surface-to-jet temperature difference on impingement cooling of rotating bodies

The effect of the surface-to-jet temperature difference on the convective heat transfer from rotating bodies cooled by jet impingement is investigated. The rotating bodies are circular disks, and impingement is provided by a single circular jet of oil impinging at the axis of rotation of the disk. The temperature difference between the disk surface and the oil jet is large enough to cause significant property variations in the oil flowing over the surface of the disk.

The investigation is made over a range of jet flow rates, jet temperatures, and disk rotational speeds for various jet and disk diameters. A correlation of the data is presented that gives Nusselt number as a function of jet Reynolds number. Re., rotational Reynolds nijmber. Re , and jet Prandtl number, Pr. The ranges of these parameters are: jet Reynolds number, 220 < Re. < 1,300, rotational Reynolds number, 25,000 < Re < 400,000, and jet Prandtl number, 87 < Pr < 400. A comparison is made between the convective heat transfer behavior of this variable property situation with that of the constant property situation where the surface-to-jet temperature difference is small.