Ph.D. Proposal Presentation by
Monday, August 8, 2005
(Dr. Fred Ahrens, Co-Chair, Dr. Tim Patterson, Co-Chair)
"A Numerical Study of Pulsating Jet Impingement Heat Transfer"
Surface heat transfer in an impingement drying hood could be enhanced by using a pulsating jet generated by a pulse combustor. This technology could be combined with conventional dryers in the papermaking process so that the total drying capacity can be increased or the size of the dryer system can be reduced. However, previously published experimental results of heat transfer enhancement were based on only one condition of flow pulsation. In addition, the impingement condition, which was with a stationary surface and without a confinement wall, was different from industrial impingement drying systems. Thus, further investigation of this enhancement technique is necessary. The ultimate goal of a project at IPST is to develop this technology to a commercial scale. A part of this project is the proposed research, which is a numerical study focusing on impingement heat transfer. The objectives are to study effects of pulsating jet characteristics and impingement geometry on surface heat transfer and to determine optimum conditions for maximum surface heat transfer in terms of an enhancement factor or thermal efficiency.
he main tool of the research is commercial CFD software, Fluent. A key factor is the appropriate turbulence model that can predict impingement heat transfer from pulsating jets accurately. The research plan consists of four main phases. The first phase is to preliminarily determine an appropriate turbulence model from available literature data. The second phase is to validate the turbulence model with experimental data from the IPST pulse combustor. The third phase is to predict the effects of parameters of pulsating jets and nozzle configuration on surface heat transfer. Results from this phase will serve as a guideline for pulse combustor design and a screening process for optimization variables. The last phase is to optimize surface heat transfer from multiple-jet impingement. The optimization approach will be the response surface method. Independent variables for the optimization will be the parameters of impingement geometry and flow pulsation