进气室作用下压缩空气储能轴流涡轮弯导叶流动特性

在压缩空气储能轴流涡轮中,紧凑型进气室常会形成三维不均匀流动结构并降低流场均匀性。为使下游导叶能够在上述流场不良影响下进一步减少流动损失,该文引入J型弯曲导叶,并采用三维计算流体动力学方法,对比研究进气室非均匀流场影响下,该结构内部流场结构、损失分布特点以及对轴流涡轮性能的提升效果。结果表明:J型弯曲导叶能够降低机匣和轮毂附近相邻叶片之间的压力梯度,减小端壁二次旋涡强度,并在全周范围内使10%、50%和90%叶高处的熵产值分别下降25.92%、42.10%、9.72%。在紧凑型进气室影响下,J型弯曲导叶仍使轴流涡轮的等熵效率和质量流量分别提高0.41%和1.59%。结果可为同类压缩空气储能轴流涡轮的优化设计提供参考。

基于导叶端弯的小展弦比燃气涡轮优化设计

以某型火箭发动机用亚声速小展弦比燃气涡轮为研究对象,为进一步改善涡轮内部流场,提高了涡轮效率,通过调整导叶子午端壁型线曲率、采用导叶端弯的设计方法对涡轮进行了优化设计,其作用在于减小叶片通道二次流损失,并将导叶出口压力分布进行调整,从而减小叶顶泄漏损失。基于六面体网格,采用CFX流场分析软件对优化前后结构进行了数值计算,结果表明:优化后单通道无叶顶间隙模型涡轮效率提高1.4%;采用正弯设计后,轮毂和叶顶处绝对和相对气流角显著增大,叶片中部气流角有所减小,整体分布更加均匀,消除了原型结构动叶轮毂区的流动分离;优化后全通道模型围带间隙前后压差明显降低,泄漏量从7%降低至4.75%,涡轮效率提高5.9%。

Flow-induced Noise and Vibration Analysis of a Piping Elbow with/without a Guide Vane

The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×10^5 to 6.81×10^5, and the position of guide vane is determined by publications. The turbulent flow in the piping elbow is simulated with large eddy simulation （LES）. Following this, a hybrid method of combining LES and Lighthill＇s acoustic analogy theory is used to simulate the hydrodynamic noise and sound sources are solved as volume sources in code Actran. In addition, the flow-induced vibration of the piping elbow is investigated based on a fluid-structure interaction （FSI） code. The LES results indicate that the range of vortex zone in the elbow without the guide vane is larger than the case with the guide vane, and the guide vane is effective in reducing flow-induced noise and vibration in the 90° piping elbow at different Reynolds numbers.