We set up a PIV experiment to demonstrate the feasibility of measuring the velocities and concentrations of particles during a simulation of an object entering the atmosphere.
A plasma is generated by the installation and solid particles are injected into the supersonic flow. The particles abrade the equipment that is more or less rapidly worn away depending on its composition and the experimental settings.
The PIV measurements use an pulsed laser (2x120mJ@532nm), a plane generator and a high resolution digital camera. In addition to a narrow interference filter (FWHM 3nm), it is necessary to use a liquid crystal shutter, synchronised to the camera and the laser, to diminish the strong thermal radiation from the measuring cylinder and so obtain usable images of particles with a very good signal to noise ratio. Images are processed using the PIV RT module to compute the velocity fields through the shock wave and also for detecting particles for concentration measurements.