Visualization of shock structures in converging nozzles with novel chevron configurations

Visualisation of compressible jet from converging nozzles with passive mixing enhancements has been done using an economical shadowgraph setup. A biconvex lens has been used to collimate light from an LED (point source) and the collimated beam is passed normal to the jet axis. A DSLR camera is used to capture the shock structures being visualized through shadowgraphy. The test nozzles have been designed with passive mixing enhancements, namely chevrons, which are shown to be effective in noise reduction by previous numerical studies as noted from literature survey. Nozzle A is a baseline nozzle with circular cross-section. Nozzle B is a 6-chevron nozzle. Nozzle C is a 6- chevron nozzle with a comparatively thinner lip section. Nozzle D is similar to nozzle C, with the chevrons tilted in an angle with respect to the nozzle axis on the plane of the nozzle wall. All the nozzles have a penetration angle of 10 degrees into the jet issuing from the nozzles. Comparative analysis of shock structures in jet from the different nozzles has been done and results are provided.