TRANSACTION ON CONTROL AND MECHANICAL SYSTEMS, VOL. 1, NO. 3, PP . 114-124, JUL., 2012. RECEIVED: 15, MAY, 2012; REVISED: 20, JUN., 2012; ACCEPTED: 14, JUL., 2012; PUBLISHED: 10, AUG., 2012. Abstract: The supersonic combustion of hydrogen using diamond-shaped strut injector along with two-dimensional non-premixed combustion model is presented in this paper. The present work stresses on the k-ω which has been used for modeling the turbulence and single step finite rate chemistry. In this process, a PDF approach is created and this method needs solution to a high dimensional PDF transport equation. As the combustion of hydrogen fuel is injected from the diamond-shaped strut injector, it is successfully used to model the turbulent reacting flow field. From the present work it has been observed that, the maximum temperature occurred in the recirculation areas which is produced due to shock wave -expansion and the fuel jet losses concentration and after passing successively through such areas, temperature decreased slightly along the axis. From the maximum mass fraction of OH, it is seen that there is very little amount of OH around 0.0035 were found out after combustion. By providing strut injector, expansion wave is created which caused the proper mixing between the fuels and air which resulted in complete combustion. Keywords: Diamond-shaped strut injector, Implicit formulation method, k-ω, Mach number, scramjet, supersonic combustor, two-dimensional 1. INTRODUCTION In the present scramjet engines the combustor length is generally of the order of 300 mm and the residence time of the mixture is of the order of milliseconds. Strut injectors are located at the channel axis and directly inject the fuel into the core of the air stream which is possible without the induction of strong shock waves. Moreover, additional momentum is added by parallel fuel injection increasing the engine thrust. Problems occur in the mixing of the reactants, flame stability and completion of the combustion within the limited combustor length which occurs due to high speed of the supersonic flow in the combustion chamber. The flow field in the scramjet combustor is highly complex which shows that, when the flight speed is low, the kinetic energy of the air is not enough to be used for the optimal compression. In a supersonic combustion ramjet or scramjet, the flow is compressed and decelerated using a series of oblique shock waves. A scramjet engine is well Dr.K.M.Pandey, Professor, Department of Mechanical Engineering,NIT Silchar, Assam, India. (kmpandey2001@yahoo.com) Sukanta Roga, M. Tech in Thermal Engineering, Department of Mechanical Engineering, NIT Silchar, Assam, India (sukanta.me42@gmail.com) known as hypersonic air-breathing engine in which heat release due to combustion process occurs in the supersonic flow relative to the engine. Therefore, the flow velocity around the scramjet remains supersonic and thereby it does not require mechanical chocking system [1] . Scramjet is a signifier for Supersonic Combustion Ramjet which is a type of jet engine aimed to operate in the high velocity regime usually it is related with rockets. Both are designed to be used for supersonic flight; however a Scramjet allows the flow through the engine to remain supersonic, whereas in a Ramjet the flow is slowed to subsonic levels before it enters the combustor which is the main difference between Scramjet and the Ramjet. Figure 1 shows a basic generic Scramjet design. It works by injecting fuel into a flow of supersonic air. The air is at sufficiently high temperature and pressure for the fuel to combust and the ensuing mixture is discharged from the engine at a higher pressure. The Scramjet engine is composed of four main sections i.e., the inlet, isolator, combustor and exhaust [2] . Fig.1. Generic Scramjet engine K.M. Pandey et al. [3-4] describe that there are many types of Fuel Injectors for Scramjet Engines. The fuel that is used by scramjets is usually either a liquid or a gas. The fuel and air need to be mixed about stoichiometric proportions for efficient combustion. The main problem of scramjet fuel injection is that the air flow is quite fast which shows that, there is minimal time for the fuel to mix with the air and ignite to produce thrust which require about milliseconds. Hydrogen is the main fuel used for combustion. The main important aspect in designing scramjet engines is to enhance the mixing and thus reducing the combustor length. A number of options are available for injecting fuel and enhancing the mixing of the fuel and air in high speed flows typical of those found in a scramjet combustor which are as follows. CFD Analysis of Supersonic Combustion Using Diamond-Shaped Strut Injector With K-ω Non-Premixed Combustion Model K.M. Pandey 1 and S. Roga 2