What is thrust reversal ? What are the methods of thrust reversal ?
Thrust reversal is used to reverse thrust by the diversion of the aircraft’s engine thrust to provide a break or deceleration. Thrust reversal system is used to slow down the aircraft after touch down to make landing distances shorter. In bed weather brakes of the landing gear is not so effective so a thrust reversal system is needed to be more safer.
Types of thrust reversal systems:
In a jet engine aircraft, thrust reversal is done by using thrust reversing systems. These are target type thrust reversal, clam-shell type, and cold stream type thrust reversal. Target type thrust reversal uses a bucket type doors to reverse the flow of hot air through the engine exhaust. In a clam-shell type thrust reversal system, the normal exit of the engine is closed and ducts are opened to provide thrust directed forward. This system only affects fan airflow and it does not affect the main engine line. This type of thrust reversal is mainly used in turbofan engines.
The other type of thrust reversal system is of cold-stream type. These are used in high by-pass turbofan engines. Here air from the bypass duct is redirected by using blocker doors to produce a reverse thrust. This redirects exhaust air from both the fan and the engine core.
In a propeller-driven aircraft reverse thrust can be obtained by using a controllable-pitch propeller which can change the angle of the propeller blades.