Computational Study of Transverse Slot Injection in Supersonic Flow (original) (raw)
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Predictions of Axial and Transverse Injection into Supersonic Flow
2001
CFD calculations are performed on a swept ramp injecting fuel axially, and on a two-hole transverse fuel injection downstream of a backward-facing step, both into a supersonic turbulent flow. The resulting complex flowfields are predicted using a cubic k-ε turbulence closure. Comparisons with experimental data show very good agreement. A discussion of the main flow features is presented. The fast computational convergence demonstrates the readiness of the method for the design cycle.
Numerical Exploration of Staged Transverse Injection into Confined Supersonic
Defence Science Journal, 2011
Staged transverse sonic injection into supersonic flow in a confined environment usually employed in scramjet combustor has been explored numerically using an indigenously developed three-dimensional Reynolds Averaged Navier Stokes solver with Roes scheme and k-w turbulence model. Simulations were carried out for both without injection and with injection in Mach 2 flow behind a backward-facing step in a rectangular duct. Simulation captured all finer details of flow structures including recirculation bubble behind a backward-facing step, barrel shocks and Mach discs caused due to transverse injection and reattachment of shear layer in the downstream wake region. K-w turbulence model with compressibility correction performed extremely well in predicting the overall behaviour of the flow field. The jet from the second injector was found to penetrate more in the free-stream due to the loss of free-stream total pressure across the barrel shock of the first injection point. Excellent agreement of computed profiles of various flow parameters at different axial locations in the duct with experimental results and other numerical results available in the literature demonstrate the robustness and accuracy of the indigenously developed code.
Numerical Simulation of Wall Injection with Cavity in Supersonic Flows of Scramjet Combustion
International Journal of Soft Computing and Engineering
A supersonic combustion ramjet engine (scramjet) is one of the most promising air-breathing propulsive systems for future hypersonic vehicles, and it has drawn the attention of an ever increasing number of researchers. This work involves an application of computational fluid dynamics to a problem associated with the flow in the combustor region of a scramjet. A cavity wall injector is an integrated fuel injection approach, and it is a new concept for flame holding and stabilization in supersonic combustors. The presence of a cavity on an aerodynamic surface could have a large impact on the air flow surrounding it, and this makes a large difference to the performance of the engine, namely it may improve the combustion efficiency and increase the drag force. The objective of the work was to design the four wall injector model with cavity using gambit, study the combustion processes of air- fuel (h2) mixture for the wall injector models with inlet air at Mach number 2 and inlet fuel at Mach number 2 and compare the performance of the different wall injector models. There are several key issues that must be considered in the design of an efficient fuel injector. Of particular importance are the total pressure losses created by the injector and the injection processes that must be minimized since the losses reduce the thrust of the engine. In this analysis, the two-dimensional coupled implicit Reynolds averaged Navier-Stokes (RANS) equations, the standard k-ε Turbulence model, sst-kω Turbulence and the eddy-dissipation reaction model have been employed to investigate the flow field in a hydrogen-fuelled scramjet combustor with a cavity design and to analyze the combustion processes. Numerical results are obtained with the fluent solving sst-kω Turbulence model to have the best results of all models. The grid independent test was also carried out. The profiles of static pressure, static temperature, and two components of velocity and mole fraction of hydrogen at various locations of the flow field are presented. Computed values using sst-kω turbulence model are found to have good overall agreement with results obtained from literature reviews and some discrepancies were observed for static pressure and static temperature in the vicinity of the jets due to unsteadiness in the shock system.
2010
Effect of confinement has been investigated numerically for superson.:c turbulent flow past backwardfacing step in a nonreacting scram jet combustor. Flow struc:tlre downstream of the backward facing step has been studied by considering various configurations with different combustor heights as well as unconfinedflow. Staged transverse sonic mjectors with different combustor heights are also considered to find out the effect of confinement on the penetration, spreading and other flow features in the flow field. Three dimensional Navier Stokes equations along with k-f. turbulence model are solved using a commercial CFD so/ tware. The simulation captures all essential features of the flow. Good comparisons of various flow profiles have been obtained between experimental and computed values. Although confinement creates complicated shock reflections in the combustor, the length of the recirculation bubble behind the backward facing step remains almost constant. For the injection .~ase,...
Journal of Thermal Science, 2003
A numerical investigation has been performed on supersonic mixing of hydrogen with air in a Scramjet (Supersonic Combustion Ramjet) combustor and its flame holding capability by solving Two-Dimensional full Navier-Stokes equations. The main flow is air entering through a finite width of inlet and gaseous hydrogen is injected perpendicularly from the side wall. An explicit Harten-Yee Non-MUSCL Modified-flux-type TVD scheme has been used to solve the system of equations, and a zero-equation algebraic turbulence model to calculate the eddy viscosity coefficient. In this study the enhancement of mixing and good flame holding capability of a supersonic combustor have been investigated by varying the distance of injector position from left boundary keeping constant the backward-facing step height and other calculation parameters. The results show that the configuration for small distance of injector position has high mixing efficiency but the upstream recirculation can not evolved properly which is an important factor for flame holding capability. On the other hand, the configuration for very long distance has lower mixing efficiency due to lower gradient of hydrogen mass concentration on the top of injector caused by the expansion of side jet in both upstream and downstream of injector. For moderate distance of injector position, large and elongated upstream recirculation can evolve which might be activated as a good flame holder.
Computation of supersonic turbulent flowfield with transverse injection
Applied Mathematics and Mechanics, 2002
Three dimensional steady flowfield generated by transverse sonic injection into a supersonic flow was simulated by solving the Favre-averaged Navier-Stokes equations using the weighted essentially nonoscillatory (WENO ) schemes and Jones-Launder k-e model. Results indicate that in the upstream of the square injection there exist two main recirculation regions and the primary vortex induces the horseshoe vortex region. In the downstream there is a low pressure region which conduces a pair of helical vortex.
Computational Analysis of Transverse Sonic Injection in Supersonic Crossflow Using RANS Models
Journal of Fluids Engineering, 2020
Transverse injection at sonic speed from a rectangular slot into a supersonic crossflow is numerically explored with an indigenously developed parallel three-dimensional (3D) Reynold-averaged Navier–Stokes (RANS) solver for unstructured grids. The RANS models used for turbulence closure are the one-equation Spalart–Allmaras (SA) model and the two-equation shear stress transport (SST) model. For each model, the influence of compressibility corrections is assessed. Due to the presence of shock-turbulent boundary layer interaction (STBLI) in the flow, various STBLI corrections are assessed for both the models. Most of the simulations are two-dimensional (2D), but three-dimensional simulations are also performed to investigate the mismatch between the experimental dataset and the numerical results. The SA model is less sensitive to STBLI corrections, but some improvement in its prediction of the separation distance is found with the compressibility corrections. The SST model results are...
Effect of location of a transverse sonic jet on shock augmented mixing in a SCRAMJET engine
Aerospace Science and Technology
Transverse sonic injection into supersonic cross flow is a well-established technique to inject fuel into a SCRAMJET combustor. A SCRAMJET combustor with a backward facing step acting as a flame-holder has been used for this study. The jet is placed at various locations downstream of the step, where each location represents a distinct flow region. Three-dimensional simulations have been performed using Menter's SST model in our in-house parallel 3-D RANS unstructured grid CFD solver. In such a SCRAMJET configuration, mixing between air and fuel is augmented by shocks generated by the under-expanded jet injected into the supersonic cross flow, hence the jet location is expected to be critical. The performance and mixing of the combustor has been quantified for each of the distinct configurations. The length of the combustor required for complete mixing has also been estimated for the different cases. It is observed that the mixing and performance are strongly affected by the location of the jet in the combustor flowfield. From the results presented in this paper, the optimal location for the jet is somewhat before the end of the recirculation region behind the backward facing step.
The Implication of Injection Locations in an Axisymmetric Cavity-Based Scramjet Combustor
Energies
This paper presents the effect of cavity-based injection in an axisymmetric supersonic combustor using numerical investigation. An axisymmetric cavity-based angled and transverse injections in a circular scramjet combustor are studied. A three-dimensional Reynolds-averaged Navier–Stokes (RANS) equation along with the k-ω shear-stress transport (SST) turbulence model and species transport equations are considered for the reacting flow studies. The numerical results of the non-reacting flow studies are validated with the available experimental data and are in good agreement with it. The performance of the injection system is analyzed based on the parameters like wall pressures, combustion efficiency, and total pressure loss of the scramjet combustor. The transverse injection upstream of the cavity and at the bottom wall of the cavity in a supersonic flow field creates a strong shock train in the cavity region that enhances complete combustion of hydrogen-air in the cavity region compa...
Computation of transverse injection into supersonic crossflow with various boundary layer thickness
2017
Supersonic turbulent multispecies flow with transverse jet injection is numerically investigated. On the basis of the developed model the pattern of the vortex system formation is studied in detail. As a result, new vortices formed in the recirculation zone ahead of the jet are identified as well as their effect on the mixing layer. The effect of the boundary layer thickness on the vortex system is also studied, and the value of the boundary layer thickness, for which there is an additional multi-structural separation zone ahead of the jet, is determined. The formation of the lateral vortex pairs generated by the upstream vortices, convection of these vortex systems downstream and their effect on the mixing layer are revealed in dependence of the boundary layer thickness.