Spray Simulations to Support the Development of a Monte Carlo-Based Spray Cooling Model

Abstract

Spray cooling is a crucial method for meeting today's thermal management challenges in many areas including space applications, high speed computers, microelectronic components and other high energy density devices. The extreme complexity of the flow created by the impact of millions of droplets per second creates a need for a heat transfer model which incorporates enough physical detail to yield accurate predictions while being sufficiently simplified to use in routine design computations. The spray cooling group at West Virginia University (WVU) is pursuing a coordinated program of computational simulations and laboratory experiments to develop a Monte Carlo-based spray cooling model that will satisfy this requirement. This paper reports our initial simulations of sprays. A companion paper focuses on progress in the laboratory. The results reported here include simulations of sprays generated by a pressure swirl nozzle and a full cone nozzle and their impact on surfaces. The goals of these simulations are to demonstrate that they can accurately reproduce the characteristics of sprays seen in previous numerical simulations and laboratory experiments and also to develop the capability to perform the simulations that will be needed in the development of the Monte Carlo spray cooling model. The computations have been performed using the commercial ANSYS FLUENT CFD software. The fully three dimensional and axisymmetric simulations use the Finite Volume Method (FVM) computational technique to solve the Navier-Stokes and continuity equations for the air and the Discrete Phase Model (DPM) to calculate the trajectories of discrete droplets. Sprays are injected using the pressure-swirl atomizer and full cone nozzle models which are sub-models of DPM in FLUENT. Inertial, gravity, viscous, and surface tension forces are accounted for but heat transfer has not yet been included.