Experimental and Numerical Investigation of Turbulent Natural Convection Flow in a Vertical Channel With a Heated Obstacle

摘要

In the present study, experiments were carried out for natural turbulent convection induced by a heated square bar in a two-dimensional (2D) open vertical channel for different Rayleigh numbers and bar positions. For this purpose, particle image velocimetry (PIV) system has been employed to investigate the velocity field in the vertical center channel plane. The present work is also concerned with computational fluid dynamics (CFD) simulation by employing large Eddy simulation (LES) turbulence model, used in fire dynamic simulation (FDS) code. Calculations were performed for different chimney aspect ratios A~* (height L_b over width d) and modified Rayleigh numbers ranging between 4 × 10~7 and 10~8. Experimental and numerical results included mean velocity profiles; flow structure and Nusselt number were presented and discussed. To validate CFD code, velocity profiles along channel elevation were compared with our experimental measurements, and a good agreement was observed. Therefore, FDS code is a useful tool to simulate natural turbulent convection dynamic field, and consequently the thermal field in such situation. CFD code has been used to study the best heated bar location (corresponding to the best cooling effect) in the channel as well as the best airflow rate. This best location and its explanation are discussed in this paper.