Diode Laser Sensor for Scramjet Inlets

The supersonic combustion ramjet (scramjet) engine is one of the more promising high-speed flight propulsion technologies. One of the reasons for this is the simplicity of the engine design, having no moving parts and requiring no external ignition source, and the fact that scramjets do not need to provide their own oxidizer. Despite this simplicity, several obstacles to the use of scramjet propulsion systems have become apparent, including the ability to produce sufficient fuel-air mixing at high speed, large total pressure losses, reduction in specific impulse with increasing flight Mach number, and the sensitivity of combustion to inlet temperature. This last problem can be very significant.