Supersonic combustion

To understand the difference in stagnation pressure losses between subsonic and supersonic combustion one must consider sonic conditions in isoergic and isentropic flows that is, one must deal with, as is done in fluid mechanics, the Fanno and Rayleigh lines. Following an early NACA report for these conditions, since the mass flow rate (puA) must remain constant, then for a constant area duct the momentum equation takes the form... 

In the case of supersonic combustion ramjet devices, instantaneous ignition must occur because the flow time in the constant area duct that comprises the ramjet chamber is short. As noted in Chapter 1, supersonic combustion simply refers to the flow condition and not to any difference in the chemical reaction mechanism from that in subsonic ramjet devices. What is unusual in supersonic combustion because of the typical flow condition is that the normal ignition time is usually longer than the reaction time. To assure rapid ignition in this case, many have proposed the injection of silane (SiH4), which is... 

ENHANCEMENT OF LIQUID HYDROCARBON SUPERSONIC COMBUSTION USING EFFERVESCENT... 

Supersonic combustion depends considerably (along with the kinetics) on the intensity of turbulent mixing. The significant factors in supersonic mixing enhancement are (1) the decrease in mixing intensity in supersonic flows, and... 

It can be seen from Fig. 23.3 that the values of the pressure along the length of the combustor are higher almost everywhere in the case of the elliptic nozzles, i.e., enhancement of supersonic combustion took place when kerosene was injected through elliptic nozzles. Figure 23.3 shows that at the aft of the combustor, a flow separation occurred for the case ER = 0 (due to overexpansion of the flow). It is also seen from Fig. 23.3 that after some induction and delay... 

Supersonic combustion enhancement can be analyzed using the local characteristics — normalized difference of pressure rise due to combustion for elliptic and round nozzles, i.e.. 

The investigation showed efficient supersonic combustion of a liquid hydrocarbon fuel when using effervescent sprays and elliptic nozzles for the injection of the fuel. In the future, it would be interesting to study the possibilities of supersonic combustion enhancement using the elliptic nozzles drilled at the base of NASA swept wedges. 

Figure 25.1 Regimes of turbulent combustion 1 — offshore flares, 2 — spark-ignition engines, 3 — supersonic combustion, Kl — turbulent kinetic energy referred to laminar ratio of kinematic viscocity to chemical time, — Damkohler number based on Kolmogorov scale, Ld — integral scale referred to thickness of laminar deflagration...

Beach, H. L., Jr. 1992. Supersonic combustion status and issues. In Major research topics in combustion. Eds. M. Y. Hussaini, A. Kumar, and R. G. Voigt. New York Springer-Verlag. 1-15. 

Ibid, pp 1075-79 Y) J.R. Richard et al, "Spontaneous Ignition and Combustion of Sodium Droplets in Various Oxidizing Atmospheres at Atmospheric Pressure , 12thSymp-Combstn, Poitiers, France, July 14-20, 1968 (Published in 1969), pp 39-48 Z) A. Ma ek J. McKenzie Semple, "Experimental Burning Rates and Combustion AA) F.J. Kosdon, "Combustion of Vertical Cellulosic Cylinders in Air , Ibid, pp 41-43 (8 refs) BB) Louis Viaud, Supersonic Combustion Research by ONERA , Ibid, pp 197-98 Note ONERA stands for "Office National... 

CC) A. Ferri H. Fox, "Analysis of Fluid Dynamics of Supersonic Combustion Process Controlled by Mixing , Ibid, pp 198-200 DD) J. Swithenbank N. Chigier, Vortex Mixing in Supersonic Combustion , Ibid, p 204... 

Early Supersonic Combustion Studies at NACA and NASA , HthSympCombstn (1967)> pp 729-37 21) F.S. Billig, "Design of... 

Storable Propellant Fuels in Supersonic Combustion Ramjets , USP 3811280 (1974) CA 81, 79922 (1974) [A method is suggested for the decompn of UDMH into a H-contg gas which is then oxidized into a supersonic combstn mode by injection into a supersonic airstream. The crucial portion of the procedure consists of mixing enough oxidizer with the fuel to vaporize and crack the fuel into the H-rich gas, eg, RFNA and UDMH in a wt ratio of 0.09] 7) N.J. 

The combustion of flammable gaseous hydrocarbon mixtures may be divided into two processes deflagration, or subsonic combustion, and detonation, or supersonic combustion. Some of the experimental and theoretical aspects of propagation, stabilization, unsteady phenomena, and chemical phenomena of deflagration and detonation are reviewed. The significance of flow parameters in dealing with hydrocarbon combustion is discussed. A brief review of pertinent, important work recently performed in these fields is presented. 

NASP was to be used as an experimental vehicle to test high-risk technologies for Reagan s Strategic Defense Initiative, but also to ferry men and equipment to future space stations more economically than could be done with the Space Shuttle. It would take off like a conventional airplane. Hydrogen-fueled, air-breathing scramjet (supersonic combustion ram jet) engines would push it at speeds of up to Mach 25 to the almost-vac-uum of near space, where rocket power would provide the final push needed to reach a space station. 

Yu, K.H., K. J. Wilson, and K.C. Schadow. 2001. Effect of flame-holding cavities on supersonic combustion performance. J. Propulsion Power 17(6).T287-95. 

Anderson, T. J., and Eckbreth, A. C. "Simultaneous CoherentAnti-StokesRamanSpectroscopy Measurements in Hydrogen-Fueled Supersonic Combustion." Journal of Propulsion 8, no. 1 (1992) 7. 

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