Experimental Analysis of Force Recovery and Response Time Using Strain Measurement Sensors in Stress Wave Force Balance

Severe problem of aerodynamic heating and drag force are inherent with any hypersonic space vehicle like space shuttle, missiles etc. For proper design of vehicle, the drag force measurement become very crucial. Ground based test facilities are employed for these estimates along with any suitable force balance as well as sensors. There are many sensors (Accelerometer, Strain gauge and Piezofilm) reported in the literature that is used for evaluating the actual aerodynamic forces over test model in high speed flow. As per previous study, the piezofilm also become an alternative sensor over the strain gauges due to its simple instrumentation. For current investigation, the piezofilm and strain gauge sensors have mounted on same stress force balance to evaluate the response time as well as accuracy of predicted force at the same instant. However, these force balance need to be calibrated for inverse prediction of the force from recorded responses. A reliable multi point calibration methodology has been used to recover the calibration force. Initially, a blunt bicone shaped scaled “DASA CTV” model has been fabricated in house along with three component stress wave balance. Further, a multi-point calibration experiment has been performed over a test model at nine different locations. In literature, there is no any evidence has been found that effect of various sensors during calibration or actual shock tunnel experiments on a recovered forces. Hence, a calibration experimental studies focus on various sensors mounted on stress wave force balance to understand its behavior and also recovery of calibration forces during the experiment.