Ramjet supersonic-combustion

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... 

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. 

Supersonic combustion ramjet engines for hypersonic vehicles must provide enough distance for fuel to ignite. An ignition delay of 1 millisecond, for a flow moving at 2,000 meters per second, means an ignition distance of 2 meters. 

Ken Yu s group at the University of Maryland extended the previously reported work [3] to include four sets of experimental and analytical studies to identify key physical mechanisms for controlling mixing and combustion processes in ramjet and scramjet combustors (Chapter 16). In a supersonic mixing-enhancement experiment, the practicality of utilizing passive acoustic excitation as a means to enhance mixing in scramjets is assessed. 

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