PARAMETRIC STUDY ON REPRODUCTIVITY OF TORNADO-LIKE VORTEX IN WARD-TYPE CHAMBER BY USING OPENFOAM

抄録

Tornadoes are a common weather hazard to consider as they may damage nuclear power plant facilities. In such situations, damage to the power plant facilities due to windborne debris should be evaluated. Tornado-like vortex (TLV) generators have been built to determine the effect of wind load under various conditions. However, installing wind-borne debris inside these facilities was difficult to protect them from damage. Therefore, a numerically efficient model that could evaluate the wind load of an actual tornado is highly demanded. This study will focus on the VorTECH facility at Texas Tech University as a typical Ward-type TLV chamber and present a numerically efficient and reproducible TLV model based on its experimental information. A series of axisymmetric 2D RANS simulations targeting the VorTECH experiment was conducted. Based on results, the following results were derived. Firstly, the mesh resolution at the wall of the confluence region was found to be important for the development of the boundary layer. The blended mesh did not affect the convergence and the resulting velocity distribution. As for the domain effect, the existence of the confluence region, the wall boundary condition, and the existence of the porous model all affected the flow structure. It was concluded that the development of the boundary layer, the acceleration of the tangential flow inside the confluence region, the roughness of the touchdown region, and the flow resistance at the rectifier should be carefully discussed to develop a reproducible TLV model.