Computational study of SCRAM Jet combustor with a co-axial strut fuel injector
The geometric configuration of Supersonic Combustion Ramjet (SCRAM) is relatively simple when compared to gas turbine engines as there are no moving parts, but the flow physics associated with it is quite complex. At high speeds of flight the residence time of the atmospheric air in the combustion chamber is very low it is of the order of milliseconds, within this short time the fuel injected in to air must efficiently mix and react to release energy in the combustion chamber. The Combustor length and Weight can be minimized and Thrust produced can be maximized by rapid and effective mixing of fuel and oxidizer. The present study focuses on using coaxial type fuel injectors and studies the characteristics of SCRAM Jet Engines. From the results obtained it is observed that the turbulence kinetic energy of the coaxial jets is improved by the four times at the point of fuel injection when compared with the circular jet injector. As Turbulent kinetic energy is one of the parameter indicating the mixing of the fuel and oxidized (air), it is concluded that by employing the coaxial strut fuel injectors the mixing of fuel and oxidized can be enhanced.
The CFD Analysis of Turbulence Characteristics in Combustion Chamber with Non Circular Co-Axial Jets
Co-Axial jets have applications in areas where the mixing of two fluid jets are necessary, the two fluid jets can be effectively mixed by producing the turbulence flow. Turbulence is a chaotic behavior of the fluid particles that comes in to picture when the inertia force of the flow dominates the viscous force and it is characterized by the Reynolds Number. Co-axial jets are effective in producing the turbulence. In the present study the free compressible turbulent coaxial jet problem will be computed using CFD, and compare with different non circular coaxial jets based on constant hydraulic diameter and mass flow rate. Turbulence characteristics of combustion chamber with circular coaxial and non circular coaxial jets are determined and
Review of shock-induced supersonic combustion research and hypersonic applications
This article focuses on research in supersonic combustion and combustion kinetics in high-speed flow between 1959-1968, and the application of the experimental results to hypersonic propulsion. The analysis discusses both advantages and problems for premixing the fuel and employing shock-induced combustion as an ignition method for a scramjet flying at a high Mach number. The experimental tests are discussed, including implications to the chemical kinetics of the high-velocity combustion process. The conditions were confined to relatively low pressure, less than 2 atm (200 kPa). The results were considered to be mainly applicable for high-altitude scramjet flight, at low static pressure, where chemical reaction distances will be long. At these lower pressures, "shock-induced combustion" may be the predominant effect in a scramjet application, and it has some advantages that are discussed. The relation between shock-induced combustion and "detonation" is also discussed. In addition, an attempt is made to resolve the conflicting experimental data published in the 1960s relating to "standing detonation waves" and shock-induced combustion.