小容积流量工况下汽轮机级内流场的数值分析

Numerical Analysis of Steam Turbine Flow Field with Small Flow Rate

采用FLUENT软件对某300MW汽轮机高压缸内小容积流量工况下的多级流动进行数值分析。结果表明:小容积流量工况下,负攻角也引起高压缸叶片流道内产生分离流动,并且上级流场对下级流场的影响很大。前一级的分离流动使下一级动静叶流道内的分离区域增多,分离涡的强度变大,甚至影响了叶片压力面中间部分的流场,导致流体在动叶前缘近壁区域的主流流向和速度有很大程度的改变。因此,进行小容积流量下多级流动的模拟是非常必要的。

Making use of FLUENT software,the multistage flow at a small flow rate within high pressure cylinder of a 300MW steam turbine was analyzed.The results show that at a small flow rate,the negative attack angle can result in separation flow and the upstream flow field affects downstream flow field much;the separated flow at upstream stage can increase separation zones within next runner bladders and intensifies separation vortex there,including the middle flow field within blade section,all these can change both flow direction and velocity at leading edge in the wall region.Simulating multistage flow fields at a small flow rate becomes necessary.