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.
CFD Analysis of a Hydrogen Fueled Mixture in Scramjet Combustor with a Strut Injector by Using Fluent Software
In this study, k-ε model has been used to examine supersonic flow in a model scramjet combustor. The configuration used is similar to the DLR (German Aerospace Center) scramjet model and it is consists of a one-sided divergent channel with a wedge-shaped flameholder at the base of which hydrogen is injected. Here, we investigate supersonic cold flow with hydrogen injection. For the purpose of validation, the k-ε results are compared with experimental data for temperature at the bottom wall. In addition, qualitative comparisons are also made between predicted and measured shadowgraph images. The k-ε computations are capable of predicting cold flow simulations well and good.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.