1. Field of the Invention
Embodiments of the present invention relate to aircraft engine thrust reversers. More particularly, embodiments of the present invention relate to cascade thrust reversers for use with an aircraft engine with a short fan duct.
2. Description of the Related Art
Many commercial jet aircraft include turbofan jet engines as the main source of propulsion. This type of engine includes a nacelle that surrounds an intake fan and a turbine engine. The intake fan brings air into the engine and a portion of the airstream enters the turbine engine, which is combusted to provide thrust. The rest of the airstream bypasses the turbine engine and flows through a fan duct that surrounds the turbine engine within the nacelle. The airstream exiting the fan duct also provides thrust.
The engine may also include a thrust reverser to provide reverse thrust during landing in order to slow the aircraft when the aircraft is on the ground. A turbofan jet engine often includes a cascade-type thrust reverser. The cascade thrust reverser typically includes a plurality of cascades that are positioned around the circumference of the interior of the nacelle along the path of the fan duct. When the thrust reverser is deployed, a portion of the nacelle is translated rearward, typically by actuators, to expose the cascades. Roughly at the same time, a plurality of blocker doors that are located on the interior of the nacelle along the path of the fan duct are positioned to block the path of the air flowing along the fan duct and divert it through the cascades, which provides reverse thrust.
It is desirable to reduce the aerodynamic drag on the engine as well as the weight of the engine, which in turn reduces the fuel consumption and increases the range of the aircraft. One way to do this is to shorten the length of the fan duct and in turn, the nacelle, which reduces the surface area and the weight of the engine. However, the components of the thrust reverser (e.g., cascades, actuators, etc.) generally require a certain length to perform to a desired specification. Once this specification is determined, the nacelle and fan duct must then be positioned around these components. Simply reducing the size of the components to fit within a shortened fan duct length leads to diminished or altered performance of the thrust reverser as well as possibly impacting the operating stability of the turbofan jet engine.