Experimental investigation of hysteresis phenomenon for scramjet engine

Scramjet and ramjet propulsion are developing technologies for a future generation of hypersonic atmospheric and space vehicles. Unfortunately, scramjet engines are susceptible to a highly detrimental operation mode called unstart, which would cause an abrupt drop of both engine thrust and specific impulse and unsteady aerodynamic and thermal loads. The direct-connected experiment system runs in a blowdown mode. The high-pressure air was supplied by a big enough chamber, which can ensure that the effective run time reaches about 1 min. An air heating system, in which compressed air was heated by the combustion of alcohol, was located upstream of the supersonic nozzle. In the air heating system, additional oxygen was supplied to keep the oxygen content equal to that in the atmosphere. It is installed at the center of the combustor upper wall next to the downstream of the strut. The plasma torch is turned off as long as the ignition is successful, and so it works for less than 1 s in the ignition period of every experiment.