应用于激波风洞的半导体应变天平技术研究

对于有效试验时间仅有十至几十毫秒的激波风洞，常规应变天平和压电天平无法满足高精度气动力测量要求。半导体应变计的应变灵敏度远大于常用的金属电阻应变计，但其温度系数比金属电阻应变计高出2个数量级。针对此问题，设计了温度自补偿的半导体应变计并应用于等强度梁试验，结果表明:温度自补偿能够有效改善半导体应变计的温度效应，可将温度漂移降低至0.2% FS。在此基础上，设计了一杆高频响六分量半导体应变天平，通过天平、支杆一体化等设计，将测力试验系统的一阶固有频率提升至100 Hz以上。天平静态校准结果表明:该天平的综合加载误差达到国军标合格指标，综合加载重复性达到国军标先进指标。激波风洞B-2标模测力验证试验结果表明:在有效试验时间内，该天平可获得一个周期以上的输出信号，风洞试验结果与气动手册参考值、CFD计算值吻合较好。

Research on semiconductor strain gage balance technology applied in shock tunnel

The conventional strain balance or piezoelectric balance cannot meet the requirements of high precision aerodynamic measurement in the shock tunnel, as the effective test time is very short. The strain sensitivity of the semiconductor strain gage is much higher than that of the foil strain gage, but its temperature coefficient is two orders of magnitude greater than that of the foil strain gage. This paper designed a temperature-self-compensation semiconductor strain gage, and applied it on equal strength beam experiments. The results show that the temperature self-compensation technology can effectively improve the temperature effect of the semiconductor strain gage, and the temperature drift of the semiconductor strain gage is reduced down to 0.2% FS after temperature compensation. In this paper, a six-components balance with high frequency response is designed for the shock tunnel, and the results of calibration show that the combining loading repeatability and combining loading error of the balance meet the requirements of the national military standards. The balance can acquire more than one signal during effective test time as the inherent frequency of the test system is more than 100 Hz, and the results of the shock tunnel test are in good agreement with reference values of the aerodynamic manual and CFD results.