Cascade Thrust Reverser Flap Vibration Control
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Solution Overview
Problem
Vibration of thrust reversal flaps in aircraft turbojet engines disrupts aerodynamic flow and causes premature wear in direct jet situations, affecting braking efficiency and reliability.
Innovation Solution
A cascade thrust reverser design featuring a telescopic connecting rod mechanism with a spring and hooks that pre-stresses the thrust reversal flap in direct jet position, preventing unwanted vibrations by engaging and disengaging hooks as the cowl transitions between positions, and utilizing a hinged triangle to amplify tensile forces for counteracting air pressure forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thrust reversal flaps are mounted pivotally inside the sliding cowl in direct jet situation, then the cold air flow can be directed through deviation cascades for braking operations, but the flaps vibrate disrupting aerodynamic flow and causing premature wear of hinges
Solution Approach 1:
The patent applies preliminary action by pre-stressing the thrust reversal flap against the housing using a spring mechanism before the flap is needed for braking operations. This pre-applied force ensures the flap remains firmly seated and eliminates vibration during direct jet operation, while allowing the flap to pivot freely when needed for reverse jet operations.
Solution Approach 2:
The patent changes the physical state of the flap by applying a continuous pre-stressing force that alters its positional parameter. The spring mechanism maintains the flap in a specific position against the housing with sufficient force to eliminate vibration, while the mechanical design allows this parameter to change when the flap needs to pivot for thrust reversal operations.
2Object-affected harmful factors
If thrust reversal flaps are held firmly in direct jet position, then vibration is eliminated, but the mechanism becomes more complex requiring additional components
Solution Approach 1:
The patent applies self-service by designing a mechanism where the spring automatically pre-stresses the flap against the housing without requiring external actuation or complex control systems. The spring's inherent elastic force continuously applies the necessary pre-stress, and the mechanical linkage automatically allows the flap to pivot when needed, making the system self-regulating and eliminating the need for additional complex control mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively cancels vibration phenomena and ensures smooth operation by maintaining the flap in a pre-stressed locked position during direct jet mode, enhancing the durability and reliability of thrust reversal operations.
Implementation Method 1
a spring returning this stem in extension position with respect to the body
Implementation Method 2
the pre-stressing of this thrust reversal flap against this housing by the friction between this stem and this housing wall
Data Source
AI summary
The present disclosure relates to a cascade thrust reverser providing that when a sliding cowl and a flap are in a direct jet position, a hook is held in engagement with another hook and the flap is immobilized inside of a housing of the sliding cowl by a stem of a telescopic connecting rod subjected to pre-stress generated by a compressed spring located in the body of the connecting rod. When the sliding cowl starts to slide from the direct jet position toward the reverse jet position, the hooks disengage each other and the stem engages with an extension in the body of the connecting rod, so that the flap is rotated from the direct jet position toward the reverse jet position due to the tensile force exerted by the stem.