涡轮叶栅通道内颗粒物沉积过程的数值模拟

为了更加准确获得颗粒物在涡轮中的沉积分布,以某涡轮叶片为模型,选用最接近航空发动机内部颗粒组成的Jim Bridger Power Station(JBPS)颗粒为污染物,同时,利用C++编写合适的User Defined Function(UDF)经过调试来分析颗粒沉积后叶片边界的复杂变形和边界网格依赖于时间变化的重构生成,在考虑每个时间步长颗粒沉积在叶片上从而改变叶片几何特性和换热特性的情况下,来深入研究颗粒物沉积在叶片的整个过程,最终得出了沉积的分布情况,并且通过数值研究结果与实验结果的对比,验证了网格重构与融合程序的合理性、准确性。根据叶片变形情况预测腐蚀的发生情况。随后,改变主流温度、颗粒直径来研究颗粒沉积特性。结果表明:颗粒主要沉积在叶片压力面中部,但会使得叶片前缘和压力面中部均产生明显变形;叶片前缘由于颗粒沉积使得粗糙度增加形成锯齿形,最先遭受腐蚀;颗粒直径影响颗粒沉积的分布与沉积生长速度;只影响沉积速度,并不改变沉积分布。

Numerical simulation of particle deposition process inside turbine cascade

A numerical simulation is conducted to obtain more accurate distribution of particle deposition on turbine blade with Jim Bridger Power Station (JBPS).C++ is used to code suitable User Defined Function (UDF),which reconstructs grids to accomdate complex boundary deformation in every time step.In such a way that deposition can change geometry features and heat transfer characteristics,and the whole deposition process on blade can be analyzed and the exact deposition distrbution can be obtained.A fair comparison of numerical results with existing experimental results shows the rationality and accuracy of grid reconstruction code.On the basis of deposition distribution and geometry deformation of turbine blade,the erosion area on the blade is predicted.Thereafter,the effect of mainstream temperature and particle diameter is analyzed.The research results show that the main deposition occurs on the central area of blade pressure side,whereas there is obvious deformation in leading edge and central area.The obvious deformation reveals that roughness is increased and erosion is more severe on leading edge.The diameter of particle has important influence on particle deposition and deposition rate,whereas temperature of mainstream only has influence on deposition rate.