NUMERICAL STUDY OF TURBULENT FORCED CONVECTION FLOW OVER SUDDEN EXPANSION WITH TRIANGULAR OBSTACLE
Mohamed Abed Alabas Siba† & Kadhum Audaa Jehhef‡*
†University of Technology, Training and Workshops Center
†Department of Power Machines, Institute of Technology, Middle Technical University, Baghdad, Iraq
‡Department of Power Machines, Institute of Technology, Middle Technical University, Baghdad, Iraq
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The objective of the present numerical study is to investigate the influence of using triangular obstacle on the flow separation, with subsequent reattachment that occurs by sudden expansion. In this study, a numerical analysis is presented on turbulent forced convection flow over the 2D horizontal sudden expansion in order to investigate the performance of using a triangular obstacle with different height ratio. The duct top wall is subjected to heat flux that varied from 400 to 2000 W/m2, and the Reynolds number (Re) varied from 9800 to 19000 but the bottom is equipped with triangular obstacle with different height ratio is maintained at (h/di = 0.5, 07, 1.1 and 1.5) and different distance ratio is maintained at (s/di = 1, 2.5 and 3.5). The finite volume method is used to solve the continuity, momentum, and energy equations. The results show an increase in the thermal and hydrodynamic performance by about 35% and 77% respectively, due to the effect of using different height and distance ratios of the triangular obstacle on recirculation cell region size. Generally, the results show that the length of the recirculation reattachment zone is increased with increasing the following parameters of heat flux, ratios of obstacle height and obstacle distance, but it decreases with increasing the (Re). The results show that with increasing the expansion ratio from 2.5 to 3.5, the reattachment length decreased by 10.3 % and the maximum temperature decreased by 1.8 %. Finally, the highest enhancement of Nusselt number (Nu) is about 31.9 % that detected at the obstacle height ratio of (h/di=1.5).