The Experimental Simulation Of Thunderstorm Downbursts

The thunderstorms downburst is a wind burst of strong thunderstorms in the formation of thunderstorm weather, which the quick release of instable energy in the atmosphere. Many inland areas of the building wind-resistant design of the extreme wind speeds are based on the wind speed in the thunderstorms downburst. Due to the complexity of formation mechanism of thunderstorm downburst wind, velocity of downburst is very large, and jet height, inclination angle and moving speed have a great impact on the wind field. So the wind field of thunderstorm downburst is not based on the specific design features. Therefore, it is quite necessary for the building wind-resistant design in the thunderstorm downburst through the test device to simulate thunderstorms downburst. Thunderstorm downburst simulation test can not be done in the existing wind tunnel. A few researchers abroad have designed simple wall jet devices to simulate thunderstorm downbursts; however, the devices with single functions can not simulate the complex flow field of thunderstorm characteristics of the impact of wind. Therefore a large proportion of thunderstorm downburst multi-function testing device is designed.In the design of test device for thunderstorm downburst, in view of the specificity of the thunderstorm downburst testing device and the commonality of low-speed wind tunnel, the low-speed wind tunnel design of test equipment is referenced to complete the whole body structure .And the plate is used to simulate the ground with the production of a regulatory function. By adjusting the plate, the device can also change the downburst parameters such as wind intensity, diameter, jet height, incident angle of downburst. The plate movement system is established to simulate the impact of the wind movement, and it provides a basis for the thunderstorm downburst wind-resistant design of building structures.In the thunderstorm downburst simulation in steady-state flow-field test, considering the downburst changes in wind intensity, diameter, jet height, incident angle of the case, the test measurements under steady-state conditions, the vertical wind speed distribution of jet exit, as well as along the Vertical distribution and horizontal distribution of horizontal wind speed, research horizontal distance, height and the impact of the wind parameters. While the overall model test device of CFD numerical simulation is established to comparing with the experimental data,In the unsteady flow-field test simulation of thunderstorm downburst, through the plate relative motion wind of simulation of movement, the real-time measurement of the speed treadmill is measured to ensure a uniform state of motion. The equivalent displacement wind speed is established to simplify data processing, and the different measuring point height, default speed, jet height, jet velocity, incident angle of wind speed are measured. The differences between forward movement and reverse movement under the same angle are also researched. Low-pass filtering FFT is used to extract the equivalent displacement of the peak wind speed, and velocity is compared to establish a corresponding empirical model.