Prediction of thermal characteristics of turbulent spot using Large Eddy Simulation

8th TSME-International Conference on Mechanical Engineering

Pichitpreecha, Warakorn^1 ; Mingbunjerdsuk, Jirachai^1 ; Chaiworapuek, Weerachai^1

Department of Mechanical Engineering, Faculty of Engineering, Kasetsart University, 50 Ngamwongwan Road, Ladyao, Chatuchak, Bangkok

10900, Thailand^1

关键词: Accurate prediction;    Bypass transition;    Constant heat flux;    Convective coefficient;    Spreading angle;    Surface temperatures;    Thermal behaviors;    Thermal characteristics;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/297/1/012029/pdf
DOI  :  10.1088/1757-899X/297/1/012029

来源: IOP

【 摘 要 】

This research presents the prediction of thermal behavior of a turbulent spot on a flat plate having a constant heat flux of 1893 W/m2 using Large Eddy Simulation (LES) with 7.1 million grid points. In this study, the water is used as a working fluid. The mainstream flow on the heating plate having the width of 0.2 m x the length of 0.4 m, corresponding to the local Reynolds number between 42,200 and 98,400. A laminar boundary layer on the test plate was transformed into Bypass transition by injecting the water to initiate the turbulent spot in upward direction and perpendicular to the mainstream flow with the velocity of 26.31 m/s and the period of 0.01 seconds through a 1 mm diameter hole. The results are presented as the contours of Nusselt number and temperature of the spot in the top and elevation views, respectively. They show that the heated near wall water is accumulated by the spot and cause the increase of the temperature inside the spot body in the higher layer flow. The near wall water is replaced by the water from the upper layer and makes the decrease of the surface temperature underneath the spot. Consequently, this leads to the increase of the Nusselt number within the spot bound above the laminar state. The yielded convective coefficient, spot celerities, and half spreading angle from the LES agree well with experimental results reported by other researchers. Thus, this obtained information is a strong evidence to confirm that the LES can provide an accurate prediction of the characteristics of the artificially initiated turbulent spot.