Asymmetric Pre-Exit Thrust Reverser Door Gap
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Solution Overview
Problem
Existing pre-exit pivot door thrust reversers for turbofan gas turbine engines face challenges in efficiently redirecting exhaust streams for effective reverse thrust during landing, as they often require complex and costly configurations to maintain aerodynamic integrity and ensure proper door alignment.
Innovation Solution
A pre-exit thrust reverser design featuring an upper and lower pivot assembly with offset centers of rotation and asymmetrical door lengths, where the upper door length is greater than the lower door length, allowing the upper trailing edge to extend aft of the lower trailing edge in the deployed state, creating a gap for leakage and enhancing reverse thrust while maintaining a cylindrical exhaust tube configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pre-exit pivot door thrust reversers are designed with symmetrical door lengths and centered pivot assemblies, then manufacturing and assembly are simplified, but aerodynamic integrity is compromised and reverse thrust efficiency is reduced
Solution Approach 1:
The patent applies asymmetry by configuring the upper pivot assembly with a center of rotation positioned aft of the center of rotation of the lower pivot assembly. The upper reverser door has a greater door length than the lower reverser door, creating an asymmetrical arrangement that generates a leakage stream between the doors during deployment. This asymmetry improves reverse thrust efficiency and aerodynamic integrity by allowing controlled exhaust flow through the gap while maintaining proper door alignment during operation.
2Reliability
If close tolerances are maintained between mating reverser doors, then aerodynamic integrity is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent converts the potential harm of gap formation between reverser doors into a beneficial leakage stream. By positioning the upper pivot assembly center of rotation aft of the lower pivot assembly center of rotation and creating an asymmetrical door length configuration, the design intentionally allows a controlled gap to form during deployment. This leakage stream enhances reverse thrust efficiency by directing exhaust flow through the gap, while eliminating the need for expensive close tolerances between mating doors.
3Productivity
If asymmetrical door lengths are used with offset pivot assemblies, then reverse thrust efficiency is enhanced through leakage stream creation, but device complexity increases
Solution Approach 1:
The patent applies local quality by creating different configurations for the upper and lower pivot assemblies and their associated reverser doors. The upper pivot assembly has its center of rotation positioned aft relative to the lower pivot assembly, and the upper reverser door has a greater length than the lower door. This localized asymmetry creates a specific leakage stream pattern in the critical region between the doors during deployment, enhancing reverse thrust efficiency without requiring complete asymmetry throughout the entire thrust reverser system.
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
This design improves the efficiency of reverse thrust generation by creating a leakage stream that enhances reverse thrust while maintaining aerodynamic integrity and reducing the need for close tolerances between mating reverser doors, thus simplifying the system and potentially lowering costs.
Implementation Method 1
creating a gap for leakage and enhancing reverse thrust while maintaining a cylindrical exhaust tube configuration
Data Source
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AI summary
A pre-exit thrust reverser includes an upper reverser door (202) pivotally mounted to a frame and having an upper trailing edge (232), a lower reverser door (204) pivotally mounted to the frame and having a lower trailing edge (234) and an exhaust duct (208) fixedly mounted to the frame. The upper trailing edge is configured to extend aft of the lower trailing edge when the thrust reverser assumes a deployed state.