Tungsten copper nozzle is the important part of thrust chamber. Its first half is shrunk to a narrow throat by the middle into small. And the expansion of rocket to the bottom after a narrow throat from small to large outward. The rocket body by high pressure gas into the nozzle of the first half, after passing through the narrow escape from the latter part of the larynx. This structure allows the air flow velocity due to changes in cross-sectional area of the discharge varies from the airflow to subsonic speed of sound, until accelerate to supersonic speed.
Rocket engine gas flow in the combustion chamber under pressure through the nozzle moves backward into the nozzle of the A1. At this stage, the gas movement follow the principle that moving fluid in the tube cross section at small velocity, large cross-section of the flow rate of the small, so the airflow accelerated constantly. In A2, the gas flow speed is further accelerated, 2-3 km / s, equivalent to 7-8 times the speed of sound, thus creating a great thrust. Besides, there is a similar design in the spray tube of missile.
1. Convergent nozzle: sectional area of the flow direction gradually reducing, in large mach flying, incomplete expansion will cause great loss of thrust;
2. Eject nozzle: consists of adjustable convergent main nozzle and a fixed or adjustable ejector. It is light and has simple structure, can maintain good performance over a wide range of flight, it has been widely used in many high performance aircraft;
3. Adjustable nozzle: mainly used for high-speed flight afterburning turbojet aircraft or military afterburning turbofan engine. Easy to adjust nozzle area ratio, may vary with flight conditions, and often in a fully expanded state.