This paper proposes an analysis and design of air intake of scramjet engine for lower starting Mach number at M=3.5. In the current scenario, there are lots of researches have been carried out towards the vehicle with a combined propulsion system for getting high performance and efficiency while pursuing a very wide range of operating Mach number. Due to various propulsion systems, weight reduction is a very challenging task for this type of vehicle. So if we can somehow reduce the starting Mach number of scramjet engine then we can reduce the required propulsion system, as the bridge between the maximum possible velocity of the low-speed engine and the scramjet start velocity. In beginning, the basic geometry of hypersonic intake with shock structure is given followed by the theoretical equations of various design parameters at various sections of the scramjet engine. Next, various geometries of intake are constructed with a combination of a different number of ramps and with different ramp angles. Analysis of intake geometries against lower Mach number flow is carried out by CFD simulations and various flow parameters are measured. From these flow parameters, performance parameters are found and compare various intake geometries based on them.

Keywords : Lower starting Mach number, Hypersonic, Scramjet, Air-intake, Ramp angle, CFD.