Analysis of a free surface film from a controlled liquid impinging jet over a rotating disk including conjugate effects, with and without evaporation Jeremy Rice, Amir Faghri * , Baki Cetegen Department of Mechanical Engineering, University of Connecticut, 261 Glenbrook Road U-237, Storrs, CT 06269-3139, United States Received 18 January 2005; received in revised form 30 July 2005 Available online 7 October 2005 Abstract A detailed analysis of the liquid film characteristics and the accompanying heat transfer of a free surface controlled liquidimpingingjetontoarotatingdiskarepresented.Thecomputationswererunonatwo-dimensionalaxi-symmetric Eulerian mesh while the free surface was calculated with the volume of fluid method. Flow rates between 3 and 15 lpm with rotational speeds between 50 and 200 rpm are analyzed. The effects of inlet temperature on the film thickness and heat transfer are characterized. The evaporative effects are captured when the fluid impinges on the disk at saturated conditions. The conjugate heating effect is modeled, and was found to effect the heat transfer results the most at both the inner and outer edges of the heated surface. The heat transfer was enhanced with both increasing flow rate and increasing rotational speeds. When evaporative effects were modeled, the evaporation was found to increase the heat transfer at the lower flow rates the most because of a fully developed thermal field that was achieved. The evaporative effects did not significantly enhance the heat transfer at the higher flow rates. Ó 2005 Elsevier Ltd. All rights reserved. 1. Introduction Impinging jets on rotating surfaces have received a lot of attention lately because of the high potential of heat transfer rates that can be achieved. There are two major classes of impinging jets useful for engineering applications; they are the submerged jet and the free jet. A submerged jet is one that flows into a stagnant fluid of similar properties, whereas a free jet is a liquid that flows from a nozzle into a gaseous region, and is virtually unaffected by gas, hence the term free. There are numerous applications of impinging jets, which in- clude material processing, turbine blade cooling and cooling of electronics. In the present study, a controlled liquid impinging jet is studied. A controlled liquid impinging jet flows onto a planar disk; near the center of the disk there is another smaller coaxial disk (collar), which controls the entrance free film thickness and en- trance radius of the free film. The present study is moti- vated because of the envisioned potential of rotating thin film fluids in an absorber unit for a spacecraft vapor-absorption heat pump system. This unit will work in a micro-gravity environment, where the disk can be rotated to apply an additional force to thin the fluid and enhance the heat transfer. 0017-9310/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijheatmasstransfer.2005.07.022 * Corresponding author. Tel.: +1 860 486 2221; fax: +1 860 486 0318. E-mail address: faghri@engr.uconn.edu (A. Faghri). International Journal of Heat and Mass Transfer 48 (2005) 5192–5204 www.elsevier.com/locate/ijhmt