带支板轴对称弯曲管道的流动特性

以一种带支板的轴对称弯曲管道为研究对象,通过试验与仿真手段,获得了有无支板时的内部流场特性,并探讨了尾迹流特性以及出口马赫数的影响规律.研究结果表明:试验数据与仿真结果在趋势和数值上均吻合良好.气流在弯曲管道中先减速后加速,并在"一弯"中心体侧和"二弯"外罩侧附近形成局部低压区;支板对弯曲管道的内部流动结构影响显著,诱导了尾迹流和旋涡的形成,尾迹区附近不同径向位置处的总压分布规律呈现明显差异;此外,随出口马赫数的增大,弯曲管道壁面沿程静压和出口总压恢复系数均降低,而"一弯"和"二弯"处的逆压力梯度增大,故发生边界层分离的风险性增大. 

Flow field characteristics in an axisymmetric bend duct with struts

An axisymmetric bend duct was investigated numerically and experimentally to obtain the flow field characteristics in its internal passage with/without struts. The wake characteristics and influences of exit Mach numbers were also analyzed in detail. Results indicate that experiments agree well with simulations. The airflow accelerated at first and then decelerated in the bend duct. And two local low-pressure areas were generated respectively at both leeward sides of the two bends. Moreover, struts had a great effect on the flow structure in the bend duct, inducing wake and vortexes. At different radial positions near the wake, the total pressure distributions were quite different. In addition, with the increase of exit Mach number, the static pressure on the wall surface and the total pressure recovery of the outlet cross section decreased, but the adverse pressure gradients near the two bends increased. So this indicates a greater risk of boundary layer separation.