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为了评估短周期涡轮性能试验测量精度以及非稳态效应对其的影响,本文结合适当的扩展不确定度模型对涡轮效率及进口折合质量流量的测量不确定度进行了计算及分析。研究结果表明:短周期涡轮试验台特有的非稳态效应对效率测量不确定度的影响小于1.12%;涡轮进口马赫数对测量不确定度影响最大,流量测量不确定度与涡轮进口马赫数平方近似呈反比例关系,效率测量不确定度亦随其减小而迅速增大。研究发现对于涡轮进口马赫数小于0.158的工况,效率测量不确定度将不符合HB 7081-1994要求。针对此类工况,出于提高流量及效率测量精度的目的,研究了利用差压传感器测量涡轮进口动压进而计算流量的方法,结果表明该方法的效率及流量测量不确定度比使用总、静压传感器测量流量这种方法可分别减小58%及73%以上,且其均不随马赫数减小而增大。进一步的分析表明,对于马赫数小于0.158的工况,应采用该方案进行流量测量。
In order to evaluate the measurement accuracy of the short-term turbine performance test and the influence of the non-steady-state effect on it, this paper calculates and analyzes the measurement uncertainty of the turbine efficiency and the imported equivalent mass flow with an appropriate extended uncertainty model. The results show that the instability of the short-term turbine test bed has an effect on the measurement uncertainty of less than 1.12%. The Mach number of the turbine inlet has the greatest influence on the measurement uncertainty. The uncertainty of the flow measurement is proportional to the square of the turbine inlet Mach number Approximately inversely proportional relationship, the efficiency measurement uncertainty also increases rapidly with decreasing. The study found that for turbine inlet Mach less than 0.158 operating conditions, the uncertainty of the measurement of efficiency will not meet the requirements of HB 7081-1994. In order to improve the measurement accuracy of flow rate and efficiency for such conditions, the method of measuring the dynamic pressure of the turbine inlet by differential pressure sensor and calculating the flow rate is studied. The results show that the efficiency of the method and the measurement uncertainty of flow rate are better than those of the total, This method of measuring the flow rate by the static pressure sensor can be reduced by 58% and 73% respectively, and none of them increases with decreasing Mach number. Further analysis shows that the program should be used to measure the flow rate when the Mach number is less than 0.158.