Degree Name

BS in Mechanical Engineering


Mechanical Engineering Department


John G. Fabijanic


The Rayleigh Test Apparatus is a device that will be used to test the thermodynamic properties of Nitrous Oxide to assess the feasibility of using this fluid as a coolant for a hybrid rocket aero spike. The aero spike is intended to redirect the propulsion flow as it leaves the engine to create a more efficient flow pattern at low and high altitudes. However, there are issues of overheating which leads to melting of the aero spike. For this reason, the use of nitrous oxide (N2O) as a coolant is being explored. N20 is being considered because it is already present as an oxidizer in many hybrid rockets. By redirecting the N2O through the inside of the aero spike it will cool the aero spike and then be used as the oxidizer in propulsion. Since there is currently little information on the thermodynamic properties of N2O, it is essential to know the possible outcomes of using this fluid as a coolant. N2O decomposes exothermically releasing, pound for pound, twice the energy as TNT; this characteristic is obviously not favorable inside a cooling system. By knowing the heat transfer coefficient of N2O, it can be ensured that decomposition of the N2O does not occur inside the aero spike. This achieved by choosing a proper flow rate of N2O to avoid decomposition while maximizing the amount of thermal energy removed from the aero spike.