Development of a Novel Shadowgraph Technique for Unsteady Flow Phenomena Studies in a Pulsejet Engine

A novel shadowgraph flow visualisation technique has been developed and used to visualise key regions of a pulsejet flow field which are spatially separated. Schlieren and shadowgraph techniques are ideal flow visualisation techniques that can be used where large density gradients exist in a flow field. Conventional Schlieren and shadowgraph arrangements use a pair of collimating mirrors along with the light source and the knife edge. The present technique has the advantage of using four mirrors of the same focal lengths and overcomes the shortcoming of the requirement of a large diameter collimating mirror for covering the flow field which is either large in size or separated by a distance. The technique developed has been effectively demonstrated in capturing the unsteady flow field in a valveless pulsejet engin