SUPERSONIC NOZZLE TEST USING HIGH PRESSURE COMPRESSOR

Abstract

Design procedures of the supersonic converging-diverging nozzle along with visualization of the supersonic compressible flow using the optical methods (shadowgraph and schlieren) is presented. CD nozzle was designed using the online MATLAB code [17] giving more emphasis on the diverging section. Subsonic flow at the circular inlet was augmented to the sonic velocity at the rectangular throat. Further the flow becomes supersonic at the diverging section which was also rectangular in cross section. The design of planar nozzle was made such that flow properties remains the same along the planes between the walls. Significant pressure ratio, creating sonic flow at the throat and a bigger pressure difference is what causes the usual shock wave to originate within the diverging segment. Back pressure's influence causes it to go from the throat to the outlet region as the pressure gradient rises. According to the ambient pressure, a further rise in the pressure differential can result in a flow that is either perfectly expanded or under-expanded. The experimental setup was designed in such a way that the thrust from the nozzle don’t interfere with the flow visualization process. The flow shows high gradient in pressure, temperature and density. The flows visualized using these optical methods were as expected. The property of shadowgraph photography to de-emphasize the less abrupt flow made the visualization of flow characteristics easier.