Numerical Study on the Effect of Thermocouple Mounting Coating on Temperature Measurement of Nozzle Guide Vane

热电偶涂层对导向叶片温度测量影响的数值研究

¹ School of Power and Energy, Northwestern Polytechnical University, Xi'an 710072, China
² Faculty of Aviation Engine, Shenyang Aerospace University, Shenyang 110136, China
³ China Gas Turbine Establishment, Jiangyou 621703, China

Received: 21 January 2019

Abstract

To analyze the measurement error of thermocouple covered by mounting coating, which is mainly used in air-engine nozzle guide vane temperature test, a mathematical model of the temperature measurement structure was established referring to Mark Ⅱ nozzle guide vane. Based on the heat-flow coupling theory and conjugate heat transfer analysis, the Navier-Stokes equations and heat transfer problem were solved by using SST γ-θ turbulence model. The effects of coating position, coating thickness and coating edge fillet on the temperature of test positions were investigated, respectively. From this study, we find that the temperature predicted by SST γ-θ turbulence model well caters for the test data. The maximum error between calculation and test result is less than 10%. When the leading edge coating is near to the transition point of the suction side, the temperature error will increase. Comparing with that on the middle surface of the pressure side and the leading surface of the suction side, the thermocouple coating has slight effect on the temperature measurement accuracy of the middle surface and the trailing surface of the suction side. If the coating thickness is less than the total temperature boundary layer thickness, the measurement accuracy is almost unaffected. To apply a fillet to the leading edge of thermocouple coating is an effective method to improve the measurement accuracy.

摘要

为分析涂层测温结构对航空发动机涡轮导向叶片表面温度测量精度的影响，建立了测温结构的数学模型。以热流耦合理论为基础，采用SST-γ-θ湍流模型求解动量和能量方程，研究了涂层位置、涂层厚度和前缘形状对叶片待测区域温度的影响。研究表明：考虑转捩的SST-γ-θ具有较好的数值计算精度，其温度计算结果与试验误差不超过10%；当涂层前缘位于转捩点附近时，涂层对测量精度的影响较大；与叶盆中部和叶背前缘相比，涂层对叶背中部和叶背尾缘的测温精度影响较小；当涂层厚度小于总温边界层厚度时，测量精度几乎不受影响；将涂层前缘加工成圆角可以有效减小涂层对叶盆面测温精度的影响。