Experimental and numerical analysis of controlled impinging liquid jet

An experimental and numerical study of the heat transfer from a heated horizontal disk to a thin film of liquid is described. The liquid was delivered to the disk by a collar arrangement such that the film thickness and radial velocity were known at the outer radius of the collar. This method of delivery is termed as a controlled impinging liquid jet.;The mean thickness of a thin liquid film of deionized water with a free surface on a rotating horizontal disk has been measured with a nonintrusive capacitance technique. The measurements were taken when the rotational speed ranged from 0 to 300 rpm and the flow rate varied from 7.0 to 15.0 lpm. When the disk was stationary, a circular hydraulic jump was present on the disk. Upstream from the jump, the film thickness was determined by the inertial and frictional forces on the fluid, and the radial spreading of the film. The surface tension coupled with the curvature at the edge of the disk affected the film thickness downstream from the jump. For the rotating disk, the film thickness was dependent upon the inertial and frictional forces near the center of the disk and the centrifugal forces near the edge of the disk.;Flow visualization tests were performed and heat transfer data were collected along the radius of the disk for different volumetric flow rates and inlet temperatures in the supercritical (upstream from the hydraulic jump) and subcritical regions (downstream from the jump). The heat transfer coefficient was found to increase with flow rate when both supercritical and subcritical regions were present on the heated surface. A numerical simulation of this free surface problem was performed, which included the effects of conjugate heat transfer within the heated disk and the liquid. The numerical predictions agree with the experimental results and show that conjugate heat transfer has a significant effect on the local wall temperature and heat transfer coefficient.