Preliminary study of Temperature and Water Vapor Concentration in a Scramjet Combustor Using a Software for Spectra Simulation (original) (raw)
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Defence Science Journal, 2014
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FLUID PHENOMENA IN SCRAMJET COMBUSTION SYSTEMS1
D e p a r t m e n t of Aeronautics, United States A i r Force A c a d e m y , USAF A c a d e m y , Colorado 80840 D. i? Pratt D e p a r t m e n t of M e c h a n i c a l Engineering, ABSTRACT This paper reviews important advances in understanding and predicting the behavior of scramjet combustion systems since the classic article published in this series by Antonio F e d (1973). The review focuses on basic fluid phenomena and is divided into three distinct sections. The first briefly describes progress that has been made in the design and demonstration of practical scramjets around the world, especially in the US, the FSU, France, and Germany. The second provides a contemporary exposition of the aerothermodynamics of the dual-mode ramjetkcramjet combustion system, accounting for the role of the isolator in preventing unstart from either thermal choking or flow separation due to heat release. The third part summarizes the current state of knowledge regarding fuel-air mixing in dual-mode ramjetkcramjet combustors, especially the potential of axial vorticity to increase mixing effectiveness over that of lateral vorticity.
Numerical Investigations of Model Scramjet Combustors
In the present paper different types of scramjet (supersonic combustion ramjet) combustors are investigated. Thereby the main difference between the combustors is the way of injecting the fuel into the combustion chamber. The first investigated concept of fuel injection is the injection by strut injectors. Here the injection of fuel is realized by a lobed strut that is located in the middle of the combustion chamber. The second concept for fuel supply is the wall injection of hydrogen. Here the fuel is injected by several holes in the wall of the combustor. Both concepts of fuel injection have different advantages and disadvantages which are explained in detail. Although different performance parameters for both scramjet combustors are introduced this paper will not compare the different techniques among each other. Because of the high Reynolds numbers in scramjet combustors, the need to resolve the boundary layers and the necessity of detailed chemistry, the simulation of scramjets is extremely CPU time demanding.
Thermochemical Exploration of a Cavity Based Supersonic Combustor with Liquid Kerosene Fuel
2010
Thermochemical exploration of a liquid hydrocarbon fueled scram jet combustor is presented. Three dimensional Navier Stokes equations alongwith K-f. turbulence model and single step kerosene-air reaction kinetics are solved using commercial software. Various combustor configurations with different fuel injection cavities are analyzed. Simulations capture all the I essential features of the flow field. Good comparisons between computational and experimental surface pressure form the basis for further analysis. Parametric studies have been carried out with different droplet diameters to study its effect in the flow development. The numerical simulation also wnjirmed the experimental observation that the threshold value of length-todepth ratio for cavitY characterization is different for reacting and non-reacting flows.
Development of a Premixed Combustion Capability for Dual-Mode Scramjet Experiments (Invited)
53rd AIAA Aerospace Sciences Meeting, 2015
Hypersonic air-breathing engines rely on scramjet combustion processes, which involve high speed, compressible, and highly turbulent flows. The combustion environment and the turbulent flames at the heart of these engines are difficult to simulate and study in the laboratory under well controlled conditions. Typically, wind-tunnel testing is performed that more closely approximates engine testing rather than a careful investigation of the underlying physics that drives the combustion process. The experiments described in this paper, along with companion data sets being developed separately, aim to isolate the chemical kinetic effects from the fuel-air mixing process in a dual-mode scramjet combustion environment. A unique fuel injection approach is taken that produces a nearly uniform fuel-air mixture at the entrance to the combustor. This approach relies on the precombustion shock train upstream of the dual-mode scramjet combustor. A stable ethylene flame anchored on a cavity flameholder with a uniformly mixed combustor inflow has been achieved in these experiments allowing numerous companion studies involving coherent anti-Stokes Raman scattering (CARS), particle image velocimetry (PIV), and planar laser induced fluorescence (PLIF) to be performed.
Fuel-Air Mixing and Combustion in Scramjets
Activities in the area of scramjet fuel-air mixing and combustion associated with the Research and Technology Organization Working Group on Technologies for Propelled Hypersonic Flight are described. Work discussed in this paper has centered on the design of two basic experiments for studying the mixing and combustion of fuel and air in a scramjet. Simulations were conducted to aid in the design of these experiments. The experimental models were then constructed, and data were collected in the laboratory. Comparison of the data from a coaxial jet mixing experiment and a supersonic combustor experiment with a combustor code were then made and described. This work was conducted by NATO to validate combustion codes currently employed in scramjet design and to aid in the development of improved turbulence and combustion models employed by the codes.
Thermochemical exploration of hydrogen combustion in generic scramjet combustor
Aerospace Science and Technology, 2013
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International Journal of Hydrogen Energy, 2017
In the present research work, computational simulation of the double cavity scramjet combustor have been performed by using the two-dimensional compressible Reynolds-Averaged NaviereStokes (RANS) equations coupled with two equation standard ke 3 turbulence model as well as the finite-rate/eddy-dissipation reaction model. All the simulations are carried out using ANSYS 14-FLUENT code. Additionally, the computational results of the present double cavity scramjet combustor have been compared with experimental results for validation purpose which is taken from the literature. The computational outcomes are in satisfactory agreement with the experimentally obtained shadowgraph image and pressure variation curve. However, due to numerical calculation, the pressure variation curve obtained computationally is under-predicted in 5 locations. Further, analyses have been carried out to investigate the effect of variation of hydrogen injection pressure as well as the variation of air inlet temperature on the flow-field characteristics of scramjet engine keeping the Mach number constant. The obtained results show that the increase in hydrogen injection pressure is followed by the generation of larger vortex structure near the cavity regions which in turn helps to carry the injectant and also enhance the air/fuel mixing whereas the increase in the inlet temperature of air is characterised by the shifting of incident oblique shock in the downstream of the H 2 injection location. Again for T 0 ΒΌ 1500 K, the combustion phenomena remains limited to the cavity region and spreads very little towards the downstream of the combustor.
Simulation and Analysis of Flow Inside a Scramjet Combustor
Simulation of combustion in a supersonic stream inside the combustor with strut injection is carried out using a commercially available CFD package. Typical inlet conditions for a scramjet flight speed of Mach 6-7 are assumed at the isolator entrance i.e. Mach 2.5; and total temperature, T 0 =1500 K. Simulation of four cases, one with only airflow, the other with non-reacting hydrogen injection and the remaining two with two different equivalence ratios are carried out. The difference in the nature of results for these four cases was used to analyze flow field complexity for supersonic combustion. These cases were analyzed by using contour plots and X-Y graphs of area-averaged quantities. These quantities are plotted against distance from the combustor inlet. CFD results for the combustor geometry are compared with the experimental work. By this study, efforts are made to throw more light on design aspects related to geometry of combustor and ultimately the utility of CFD in the design process. The study also aims at collecting more facts related to supersonic combustion phenomena occurring inside the given combustor geometry.