A scramjet engine refers to a ramjet engine in which fuel is burned in supersonic airflow. When using hydrocarbon fuel, the flight number of the scramjet engine is below 8. When using liquid hydrogen fuel, the flight number can reach 6 to 25. The supersonic or hypersonic airflow expands to the lower supersonic speed of Mach 4 in the inlet, and then the fuel is injected from the wall and/or protrusions in the airflow, mixed with air and burned in the supersonic combustion chamber, and finally, the burned The gas is discharged through the expanding nozzle.
U.S. scramjets
Hypersonic aircraft (winged and wingless aircraft that fly more than 5 times the speed of sound) are the strategic development direction of future military and civilian aircraft, known as It is the third revolution in aviation history after propellers and turbojet propulsion aircraft. The scramjet engine is the primary key technology for realizing hypersonic aircraft and is one of the hot areas in which countries around the world have been competing for development since the 21st century.
At present, the scramjet engines developed more abroad include sub-combustion/scramjet dual-mode ramjet engines and sub-combustion/scramjet dual-combustion chamber ramjet engines. The sub-combustion/scramjet dual-mode ramjet engine can operate in two modes: sub-combustion and scramjet. When the engine flight M number is greater than 6, supersonic combustion is achieved, and when the Mach number is lower than 6. Achieve subsonic combustion. Currently, both the United States and Russia are studying this type of engine, and NASA is conducting flight tests of this type of engine. The inlet duct of the sub/scramjet dual combustion chamber ramjet engine is divided into two parts: one part guides part of the incoming flow into the subsonic combustion chamber, and the other part guides the rest of the incoming flow into the supersonic combustion chamber. This engine is suitable for single-use aircraft such as cruise missiles.
Although the scramjet engine has many advantages and is the best air-breathing power for hypersonic aircraft, it cannot independently complete the entire process from takeoff to hypersonic flight. Therefore, combined power has been proposed concept, the Mach number range of this solution is 0-15, and is used for manned aerospace aircraft that can take off and land on the ground. The combined scramjet engines that have been studied abroad mainly include turbine/scramjet and rocket/scramjet. This combined engine could power reusable space planes that take off and land from the ground in the 21st century.