M E T H O D O L O G Y

Hand calculations, along with Computational Fluid Dynamics (CFD) and CAD software will be used to optimize and simulate the thrust output of two different types of rocket nozzles, namely the conical (pictured below, left) and bell (pictured below, left) models. After analyzing the results of the nozzles' computational analysis, the highest-ranking model will be determined.

1) Steps a-e below will be repeated for each of the six nozzle designs; slight variations of this general procedure will be made for each model, as shown in our Project Summary.

a. Using Autodesk Fusion, model the geometry for the rocket nozzle in 2D, carefully considering the expansion ratio, which determines the thrust output; hand calculations must be done prior to modeling to match the exit pressure and ambient pressures of Titan, Earth, and Saturn individually respectively. Space should be made on the exit side for later measurement of exhaust. Export this file in .scdoc form for use in Ansys Fluent. 

b. In Ansys Fluent’s Geometry menu, define the dimensions of the bell-shaped rocket nozzle’s 2D geometry using the Sketch tool, including the inlet, converging, diverging, and exhaust regions; divide them using the Face Split tool. 

c. Generate a default mesh for the model, using the Face Meshing tool afterwards to increase its accuracy. The mesh should be made fine in the Sizing menu, with the maximum size depending on the bell-shaped nozzle’s 2D geometry. Further size the mesh by setting the number of divisions in the Edge menu, adding bias to each edge. 

d. In the Setup and Solution menu, select density-based solver. Turn on energy calculations before selecting the realizable, K-epsilon-2 model in the Viscous Model menu. Air should be the measured material in the Fluid menu, set as an ideal gas; its viscosity is to be calculated using Sutherland’s law for simplicity and accuracy. Set the boundary conditions of each edge, including the pressure and temperature of the inlet and outlet regions. External values are determined by the studied celestial bodies' environmental conditions. The turbulent kinetic energy and turbulent dissipation rate should then be set to second order upwind. 

e. Continuing in the Setup and Solution menu, begin a standard initialization computed from the nozzle’s inlet before setting the number of iterations and running the calculation. Display and save the Mach number, velocity, pressure, and temperature contour results, along with all other results provided by Ansys Fluent. 

2) To determine the cause of differing exit velocities, the contour graphs and various values produced by the simulations must be studied. Areas of thrust loss are to be pinpointed visually and analytically; different types of flows caused by the nozzle designs lead to these thrust losses, and they are to be evaluated for their effect on thrust efficiency.

3) Relative to each celestial body, the efficiencies of the generated bell and conical rocket nozzles will be compared to one another based on their respective exit velocities.