In this research paper, passive method has been considered to improve the mixing and combustion efficiency of scramjet combustor. Modified and innovative strut injector designs have been developed from the reference of DLR scramjet. Strut is the mechanical component which is placed in the flow stream of supersonic airflow and used to inject the fuel. The newly introduced strut injector models are named as rocket and double arrow shape strut injectors. Numerical analysis of computational domains with innovative strut injectors has been carried out by considering the ANSYS - FLUENT 15.0, which is a numerical simulation tool. Shear stress transport model (SST k-omega model) has been considered for turbulence modeling under high speed flows. From the numerical results, it is observed that the compressed air entered into the combustion chamber is at higher pressure than the basic DLR scramjet model and it reduces the ignition delay. It is also found that both the rocket and double arrow strut models increases the boundary layer separation and vortex formation and therefore it enhances the better mixing of fuel and air and finally it improves the combustion efficiency. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.