The thermodynamic analysis of a ramjet engine

Ramjets are an engine used in aircraft that require high altitude and high speed. It works with the Brayton cycle. In this study, the performance evaluation of a ramjet engine has been made by making thermodynamic analysis. The necessary mathematical models were established on MATLAB. In the performance analysis, the effects of parameters such as altitude, Mach number, diffuser and nozzle exit cross-sections and fuel type on thrust, specific thrust, thrust efficiency, thermal efficiency, and total efficiency were investigated theoretically. As a first step, the results were obtained at 15 km altitude and 4.0 Mach number while the areas of all engine stations were constant. Then, the effect of changing these parameters on changing performance parameters under changing mach number, altitude and field conditions was investigated. For a ramjet engine, a graph of the total efficiency increased slightly and then decreased with the increase of mach number at constant altitude. The thrust produced accordingly has the same curve. For a ramjet engine, the thrust generated decreases with increasing altitude. It has been observed that as diffuser outlet cross section A2 increases, total efficiency increases, fuel consumption and thrust generated decrease. Likewise, it was found that as nozzle outlet cross section A6 increased, the total efficiency increased and the fuel consumption and thrust produced decreased. The effect of fuel type (specific heat value of the fuel) on total efficiency, thrust efficiency, thermal efficiency and thrust can be almost negligible.