Completed: The nozzle was assumed isentropic, and isentropic equations for compressible flow were used to determine the thermodynamic properties at the subsonic, sonic, and supersonic regions. To reach maximum propulsive efficiency, the exit pressure (Pexit) of the nozzle must match the ambient air pressure (Patm) and the flow must be choked. Choked flow assures that supersonic Mach numbers (M) will exist at the nozzle exit and constrains the Mach number at the throat to M=1. This was accomplished by using equations (4) in an iterative method to determine the mass flow rate at the throat when the M=1. Based on a desired exit Mach number of 1.6 and thrust of 5000 N was selected based on a goal height. With Pe equal Patm, equation (3) was simplified …show more content…
This allows for the determination of the exit mass flow rate and thus the mass flow rate at the throat. This flow rate can be related to the Mach number at the throat by equation (5) and the throat area can be determined. With equation (2) the exit area is determined. With the areas of each region and chamber pressure (determined by another student), a simulation of the nozzle was run at operating condition using the CD Nozzle Simulator (engApplets, Blacksburg, VA). This simulation will reveal any shock waves forming inside the nozzle that will decrease propulsive efficiency. Materials were chosen for the nozzle and combustion chamber after performing initial heat and stress analysis. Autodesk Inventor (Autodesk, San Rafael, CA) was used to 3D model the nozzle and to produce drawings for fabrication in the machine shop. Inventor was also used to simulate heat and dynamic loads through the nozzle. The combustion chamber was also drawn in Inventor and the parts assembled for