不同进汽压力下向心汽轮机特性数值仿真

Numerical Simulation of a Radial Steam Turbine with Various Inlet Pressures

针对进口压力波动影响背压式向心汽轮机的问题,选取某高转速向心透平,通过调整进口总压模拟工况变化,采取单通道定常数值计算的方式求得不同工况下的数值解并将其无量纲化;预测出向心透平在变工况时的效率特性、通流特性等特性变化规律,借助流场分布及损失模型,分析出不同工况下热损失的主要形式。结果表明,低压时转子进口攻角偏离较大,攻角损失可以比设计点工况多出近40%;而随着压力增大,攻角逐渐稳定在合适范围内,通道二次流损失和余速损失开始以较大比率增长,余速损失在高压工况下可超出设计点附近工况的5倍。

The performance characteristics of back-pressure radial inflow turbines(RIT)vary with the inlet pressures.It is required that for optimization purposes,the designers can not only simulate the overall performances,but also understand the reason behind.To solve this scientific problem,this paper with the help of a high-speed radial turbine,which was simulated with a single-passage model and steady state numerical methods.Under various inlet total pressures,the performance curves of efficiency and massflow were calculated.The loss mechanisms were then analyzed with the help of loss models and the calculated flow fields.It is found that the rotor inlet incidence deviates greatly at low pressure,and the incidence loss can be nearly 40%more than that at design point.With the increase of pressure,the incidence gradually stabilizes within the appropriate range,and the passage secondary flow loss and exit energy loss begin to increase in a larger ratio,and the exit energy loss can exceed the design point condition by about 5 times under high pressure conditions.