Numerical investigation on the effect of variation of upper wall divergence angle of parallel fuel injection scramjet combustor performance

Abstract

Numerical investigation of Scramjet combustor is performed with the help of center lobed strut to act as a parallel fuel injector. The geometry of the combustor plays a major role to get the enhanced combustion performance in scramjet engine due to the absence of rotating parts. Keeping this idea, the behavioral impact of upper wall divergence angle inside the supersonic combustor and their outcome have been studied by allocating three models. The supersonic free stream air is used as an oxidizer and sonic speed hydrogen as a combustible fuel to complete the chemical reaction during the combustion. Experimental model has been selected for the purpose of comparison and validation. The grid independence analyze has also been done. Ansys 14.0 - Fluent solver is opted for numerical investigation. The computational results show substantial conclusions. The mixing behavior follow the similar pattern in all the models and reaches up to 100% but the behavior of mixing length is found lesser in case of one and two degree upper wall divergence angled combustor model. The mixing length is found 41 mm for both one and two degree angle model whereas 51 mm mixing length has been captured in case of three degree divergence angled model. Initially the rapid combustion is observed in one degree angle of divergence model among all cases. However, the maximum combustion efficiency reaches 95.3% in case of two degree angle of divergence at the upper wall. Which signifies the greater impact of combustor geometry on the scramjet engine performance.

Keywords

• Divergence angle
• Parallel fuel injection
• Combustion efficiency
• Mixing efficiency, Dlr scramjet model