下击暴流移动增大效应及带协同流壁面射流模拟方法

目前对移动型下击暴流的研究主要基于冲击射流模型,但研究中通常考虑的平移速度较低且缩尺比较小.为此,通过风洞试验与数值模拟方法,研究移动冲击射流风场中平移速度对出流段平均风场的影响,得到了平移速度对下击暴流出流段最大风速增大效应的经验表达式.同时考虑到采用壁面射流方法能够得到较大尺度的下击暴流出流段风场,但并未考虑下击暴...

A study of translational incremental effect of downburst and wall jet method with co-flow

The current investigation on moving downburst flow is mainly based on impinging jet model. However, the translation velocity is usually low hence the scale is normally small. The influences of translational velocity on radial velocity of impinging jet wind field were studied experimentally and numerically. The empirical expression of the effect of translational velocity on the maximum wind speed in the downburst outflow was obtained. The current wall jet approach can generate large-scale wind field of downburst outflow, but it does not consider the downburst translation. Hence, the wall jet model was improved to simulate the translation of downburst by co flow. To this end, the influence of co flow on the characteristic length and velocity of the average wind profile of a wall jet was numerically investigated. The empirical expression of the effect of co flow on the maximum wind speed of wall jet was also obtained. The results show that with the increase of translational velocity, the maximum average velocity of the impinging jet outflow increases by more than 13.3%, and the maximum wind velocity is generated closer to the wall. Co-flow is introduced into the wall jet method, which can simulate the influence of translation effectively. Lastly, the relationship between translating velocity of impinging jet and co-flow velocity of plane wall jet can be determined for downburst outflow simulation. This provides a reference to effectively get the maximum mean velocity profile of downburst outflow at arbitrary translation velocity using wall jet method.