Design and analysis of velocimetry for supersonic sled system

Abstract

Knowledge of precise velocity profile of aerospace bodies is essential in research programs-especially now when operating speeds are going much beyond supersonic regimes. Not much research has been reported on velocimetry of such systems. It was therefore considered essential to carry out in-depth study and research of various feasible techniques for high velocity measurements of bodies moving on rail system at supersonic speeds to give fillip to various research programs in defence and space domain. The research centre, where the testing of such systems is carried out, has a precision rail track on which the test articles such as parachutes, unmanned aerial vehicles, missiles and fuses etc are test run at required high speeds. It provides a unique environment for captive flight testing and enables experimentation at high velocities and accelerations for short durations. The research, elaborated in this thesis, was carried out at this facility. While considering various techniques for determining velocity, it was realized that velocity could not be directly measured by any of the known techniques on the rail system. On the other hand, there were several techniques for velocity derivation from other parameters. Out of these, three such techniques were shortlisted for carrying out in depth studies. The identified techniques were based on different primary measurements of - position, acceleration and pressure-which, finally lead to the derivation of velocity. Literature published half a century ago points to the use of position based measurements in rocket sled applications on the rails on which magneto inductive sensor were deployed. Thereafter, the field remained un-explored. It was found that magneto-inductive sensor output falls with the increase in velocity and it was not usable at speeds beyond 500 m/s. Simulation of such a system was carried out to understand the reasons for the problem. The outcome of the research was non-obvious.