基于总温探针的高精度总焓测量方法优化研究

Optimization of high-precision total enthalpy measurement method based on the total temperature probe

  • 摘要: 为提高中低焓来流的总焓测量精准度,以铱铑铱热电偶为测温元件研制了一种总温探针。基于流热耦合计算模型对该探针各部件尺寸参数进行了优化设计,使得总温探针的复温率不低于0.9;计算和试验结果表明铱铑铱热电偶结点温度会随着热电偶后端面温度和屏蔽罩温度的升高而缓慢升高,导致不同测量时间段下得到的总温值不同,因此必须规定测量时间段并进行溯源校准。为此,借助一种新设计的加热器弧室总温探针,将应用于电弧风洞超声速流场的总温探针向亚声速流场总温校准装置进行了溯源校准。在电弧风洞中开展了总焓测量验证试验,采用基于精度极限和偏差极限的不确定度评估方法,计算了总焓测量结果的不确定度。结果表明:所研制的总温探针具有较高的总焓测量精准度,就本文试验结果而言,其重复性精度约为3%,不确定度约为6.4%。

     

    Abstract: A kind of total temperature probe with Iridium Rhodium Iridium thermocouple is developed for improving the total enthalpy measurement accuracy. The size parameters of each component are optimized based on the fluid-thermal coupling model of the probe. The reheating rate of the probe is not less than 0.9 after optimization. The calculation and test results show that the temperature of the thermocouple node rises slowly as the temperature of the thermocouple tail and the shielding case rises. This fact results in the temperature of thermocouple node changing according to the measurement time period. So the measurement time period of the total temperature value should be regulated and the total temperature value must be calibrated. Therefore, a comparison calibration method is proposed, in which the total temperature probe used in the supersonic flow field can be traced to the standard calibration device in the subsonic flow field by an arc chamber total probe developed. Finally, the total enthalpy measurement test based on the total temperature probe is carried out in the arc heated wind tunnel. And the uncertainty of the total enthalpy measurement is calculated according to the uncertainty evaluation method based on the precision limit and deviation limit. The test results show that the total temperature probe has a high total enthalpy measurement accuracy. The repeatability precision is about 3% and the uncertainty is about 6.4% in this test.

     

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