离心透平变工况性能分析

Off-Design Performance Analysis of Centrifugal Turbine

针对离心式透平,以一维气动分析方法为基础,引入径比,建立了离心透平级组的变工况分析方法。以280 kW三级离心透平为例,得到径比对反动度与焓降的关系的影响规律,以及流量随着级前后热力参数的变化关系。与数值模拟结果对比表明:反动度估算公式能定性分析级的反动度变化规律;临界状态下,离心透平流量与级前压力成正比,与级前温度的平方根成反比,与背压无关;非临界状态下,流量不仅与级前后热力参数有关,而且与级的反动度有关。增加反动度修正后,能使得流量随热力参数变化的估算结果与数值模拟结果更接近.

In this paper,the diameter ratio concept was introduced,the off-design performance analysis method for centrifugal turbine was established based on one dimensional aerodynamic analysis.In the case of 150 kW level centrifugal turbine and combining with CFD technology,the thermodynamic parameters curves of the centrifugal turbine in ofF-design conditions was carried out,and then the effect of diameter ratio on various thermodynamic parameters was obtained,the results show:The reaction estimation formula can be used to qualitatively analyze the variation of reaction degree.Under critical conditions,the mass flow rate of centrifugal turbine is proportional to the inlet pressure and inversely proportional to the square of inlet temperature,but it is independent of back pressure.Under subcritical conditions,the mass flow rate of centrifugal turbine is related to the pressure and temperature as well as reaction degree.The calculated mass flow rate with reaction degree modification is closer to the numerical simulation results.