SCRAMJET

Space was always a dream for man. There was always a passion for human beings since the time of antiquity to fly like a bird. Here the passion takes precedence. His dream has no limits. It leads him to do lot of experiments to foray the Milky Way. Some may have failed but finally he succeeded in his attempts and that pave the way for Aeronautical Technology.

One thing has always been true about rockets: The farther and faster you want to go, the bigger your rocket needs to be. Rockets combine a liquid fuel with liquid oxygen to create thrust. Take away the need for liquid oxygen and your spacecraft can be smaller or carry more pay load.

During and after World War II, tremendous amounts of time and effort were put into researching high-speed jet- and rocket-powered aircraft. The Bell X-1 attained supersonic flight in 1947, and by the early 1960s, rapid progress towards faster aircraft suggested that operational aircraft would be flying at "hypersonic" speeds within a few years. Except for specialized rocket research vehicles like the North American X-15 and other rocket-powered spacecraft, aircraft top speeds have remained level, generally in the range of Mach 1 to Mach 2.

That's the idea behind a different propulsion system called "SCRAMJET", or Supersonic Combustion Ramjet: The oxygen needed by the engine to combust is taken from the atmosphere passing through the vehicle, instead of from a tank onboard. The craft becomes smaller, lighter and faster. Researchers predict scramjet speeds could reach 15 times the speed of sound. An 18-hour trip to Tokyo from New York City becomes a 2-hour flight.

The university of Queensland’s Hyshot team, Australia reported in 1995, the first development of a scramjet and in 2002 successfully tested the first ever scramjet system. It had a speed of Mach 7, or seven times the speed of sound.

SCRAMJET

A scramjet (supersonic combustion ramjet) is a variant of a ramjet air breathing combustion jet engine in which the combustion process takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to forcefully compress and decelerate the incoming air before combustion (hence ramjet), but whereas a ramjet decelerates the air to subsonic velocities before combustion, airflow in a scramjet is supersonic throughout the entire engine. This allows the scramjet to efficiently operate at extremely high speeds: theoretical projections place the top speed of a scramjet between Mach 12 and Mach 24, which is near orbital velocity

The scramjet is composed of three basic components: a converging inlet, where incoming air is compressed and decelerated; a combustor, where gaseous fuel is burned with atmospheric oxygen to produce heat; and a diverging nozzle, where the heated air is accelerated to produce thrust. Unlike a typical jet engine, such as a turbojet or turbofan engine, a scramjet does not use rotating, fan-like components to compress the air; rather, the incredible speed of the aircraft moving through the atmosphere causes the air to compress within the nozzle. As such, very few moving parts are needed in a scramjet, which greatly simplifies both the design and operation of the engine. In comparison, typical turbojet engines require inlet fans, multiple stages of rotating compressor, and multiple rotating turbine stages, all of which add weight, complexity, and a greater number of failure points to the engine. It is this simplicity that allows scramjets to operate at such high velocities, as the conditions encountered in hypersonic flight severely hamper the operation of conventional turbo machinery.

Scramjet engines are a type of jet engine, and rely on the combustion of fuel and an oxidizer to produce thrust. Similar to conventional jet engines, scramjet-powered aircraft carry the fuel on board, and obtain the oxidizer by the ingestion of atmospheric oxygen (as compared to rockets, which carry both fuel and an oxidizing agent). This requirement limits scramjets to suborbital atmospheric flight, where the oxygen content of the air is sufficient to maintain combustion.

CONCLUSION

Scramjet programme is a fast developing field in the present world. There are many applications with scramjet. It provides a cheaper and efficient access to space. Scramjet has the potential for supersonic or hypersonic transportation. Scramjet technologies are also used for military applications. But scramjet technologies still need developments. Scramjet in future will provide us cheaper and faster access to any part in this universe. Also the craft will become smaller and lighter and can carry more payloads.