Experimental study on flow characteristics of downburst-like wind over the 3D hill using the wall jet and the impinging jet models

Engineering structures often suffer significant damage in the horizontal outflow region of downburst. The wall jet model, which simplifies the simulation device by only modeling the horizontal outflow region of downburst, has been widely employed to study downburst flow characteristics. However, research on downburst wind fields over hilly terrain using the wall jet model is limited, and the relationship between the downburst wind fields generated by wall jet and impinging jet remains unclear. This study investigates the flow characteristics of downburst-like wind over a 3D ideal hill model using wind tunnel tests with the wall jet and impinging jet models. The effects of hill height, slope, shape, and radial position on the speed-up ratio are examined using the wall jet flow. The results indicate that slope and radial position significantly affect the speed-up ratio, while hill height have a slight impact and shape have a minimal impact. Additionally, this study investigates the wind field characteristics over flat terrain using the impinging jet, and investigated the connection between the impinging jet model and the wall jet. Based on this connection, a comparison of the downburst-like flow characteristics over the same 3D ideal hill using the wall jet and impinging jet models is conducted, which further validates the reliability of the wall jet model for studying downburst flow characteristics over hilly terrain.