双喷管差动式小推力测量装置的设计与分析

Design and Analysis of a Double Nozzles Small Thrust Difference Measuring Device

关键词:  小推力  喷管推力差  测量装置  弧形弹簧片  灵敏系数 

Key words:  Small thrust  Nozzle thrust difference  Measuring device  Curve leaf spring  Sensitivity coefficient

摘要:

为了研究喷管型面对小推力火箭发动机推力性能的影响,设计并建设了双喷管差动式小推力测量装置及其附属设备。在测量装置中,基准喷管和待测喷管同轴反向设置,通过测量结构应变来直接测量两个喷管的推力差。对测量装置进行了简化模型理论分析,导出其灵敏系数理论公式。依据该公式进行关键参数设计,确定合理的灵敏系数,指导试验系统设计,以保证测量精度。验证性试验表明测量装置可以测量牛级推力差,标定曲线线性较好,以基准喷管推力作为比较对象,推力差的相对扩展不确定度为0.5%。推力差与基准喷管推力的比值越小,以基准喷管推力为比较对象的相对测量不确定度越小。测量装置可以用于小推力火箭发动机喷管性能分析及优化的试验研究。 

Abstract:

Double nozzles small thrust difference measuring device and its accessory facilities are presented,which can be used to study the effects of nozzle contour on the thrust performance of small thrust rocket engine. The reference nozzle and the testing nozzle are set coaxially in reverse directions in the measuring device. The small thrust difference between the two nozzles can be obtained by measuring the structure strain caused by the thrust difference. Theoretical analysis of the measuring device was made with simplified models. Theoretical formula of the measuring device sensitivity coefficient was deduced. Based on the formula, key parameters were designed and reasonable sensitivity coefficient was determined. The theoretical formula can be used to guide the design of the test system. The results of the validation experiment show that the small thrust difference which is only several Newtons can be obtained, and the calibration curve has good linearity. The relative expanded uncertainty of the thrust difference is about 0.5% compared with the reference nozzle thrust in the experiment. Further more, the relative expanded uncertainty will be smaller when the ratio of the thrust difference to the reference nozzle thrust is smaller. The measuring device can be applied to the experiment study for nozzle performance analysis and optimization design.