Combustion chamber length prediction for scramjet based on a quasi-one-dimensional model

At present, there have been a lot of studies on combustion chamber configurations of scramjet, and the prevailing method is to employ cavities or struts to create regional recirculation zones to achieve complete combustion. Few attentions are paid to the combustion chamber length. This paper, from the perspective of chemical kinetics, aims to study the factors affecting the combustion chamber length required for complete combustion, and the effect of chamber length on engine performance. To achieve this purpose, a one-dimensional model with finite-rate chemistry has been established. The chamber length is computed from the occurrence of the peak in species’ concentration. The results show that dynamic pressure and elevation have impacts on the required chamber length. The fuel itself also plays an important role. Hydrogen, compared to other fuels, has a quite short ignition delay time and, therefore, the chamber length for complete combustion is quite short. Restricted chamber length inevitably worsens engine performance because of incomplete combustion.