Доступ предоставлен для: Guest

ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-472-4

ISBN Online: 978-1-56700-471-7

3rd Thermal and Fluids Engineering Conference (TFEC)
March, 4–7, 2018, Fort Lauderdale, FL, USA

NUMERICAL INVESTIGATION OF IMPINGING HEAT TRANSFER AND FLUID FLOW DUE TO A TURBULENT ANNULAR JET

Get access (open in a dialog) pages 491-502
DOI: 10.1615/TFEC2018.cmd.020958

Аннотация

This paper presents numerical investigation of heat transfer and fluid flow of turbulent annular jet impinging on a flat heated surface maintained at constant temperature condition. Annular impinging jet causes fluctuations in the flow and has one noteworthy characteristics of forming a reverse stagnation flow. The parametric numerical study for turbulent annular jet impingement is conducted for various blockage ratios and jet exit -to-target plate separation distances at a constant Reynolds number. The numerical computation is performed using the ANSYS Fluent commercial code and the numerical model is validated against other published experimental data on similar flow and geometric configuration. The performance of different turbulence model is evaluated based on the comparison against experimental Nusselt number distribution on the flat surface and the Realizable k-ε model was chosen over other turbulence model in this study. There are two different distinguished critical jet-to-target plate distance or a specific blockage ratio that generates three different flow patterns. When the separation distance is large, the impinging annular jet flow patterns defined as flow pattern-1, which is comparable to the flow patterns of conventional impinging round jet. For intermediate separation distance, a doughnut shaped recirculation region develops just downstream of the annular nozzle exit, which is defined as the flow pattern-2. For small separation distance, the flow diverges more to the outer side of the annular slot and a reverse stagnation flow develops, which influences the heat transfer rate on impingement plate. This is designated as flow pattern-3. The separation distances at which the transition from one flow pattern to the other occurs are designated as Hc1 and Hc2. These critical distances are determined for each blockage ratio considered. The heat transfer processes are analyzed and the average Nusselt number as a function of the blockage ratio are calculated and presented.