Using CEQUEL for Thermochemistry Calculations in a Graduate Rocket Propulsion Course at UAH

Advanced projects in rocket propulsion classes often require the calculation of thermochemical properties of the combustion gases and nozzle performance. While there are several codes available to do thermochemical calculations, difficulties often arise in interfacing the code results into the detailed trade study calculations of notional propulsion systems. The objective of this paper is to illustrate the use of a spreadsheet and Python-based code for a solid-fuel ramjet design project. The scope includes propellant characterization, time-dependent calculation of thermochemical properties, internal ballistics, and flight performance analysis. The code Chemical Equilibrium in Excel (CEQUELTM) provided these on-demand calculations. The students evaluated different candidate solid fuels for an air-breathing ramjet concept and used the code to calculate the recovery properties of the inlet air, chamber properties, and nozzle performance into a flight simulation that compared range and time to target for each configuration. The paper illustrates the use of CEQUEL in both a spreadsheet approach as well as a Python-based implementation. Students could learn and successfully implement this program into their class project. The CEQUEL program allowed students to incorporate detailed thermochemical calculations into their time-dependent simulations without having to resort to table lookups or parametric curve fits of the thermochemical results. The code is an excellent fit for instructional courses in propulsion as well as research projects.