Nacelle Translating Cowl Panel for Wing Slat Clearance
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Solution Overview
Problem
There is a need for a nacelle design that optimizes aerodynamic performance while maintaining tight clearance tolerances between moveable portions of the wing, such as the leading edge slat, and the nacelle, particularly during reverse thrust operations, without compromising the translational movement of the transcowl to avoid interference.
Innovation Solution
The design incorporates a selectively operated reverse thruster nacelle with a transcowl panel that moves transversely to expose a cascade for reverse thrust airflow, accompanied by an automatic translating panel that coordinates with the transcowl movement to maintain a variable clearance space with the leading edge slat, and a hinged access panel with asymmetric or irregular shapes to provide clearance and access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the nacelle diameter is increased to optimize aerodynamic performance with high bypass ratio engines, then the airflow bypass region is increased, but the clearance between the nacelle and the wing's leading edge slat is reduced
Solution Approach 1:
The patent applies the dynamics principle by making the cowl panel movable rather than fixed. The cowl panel can translate in the longitudinal direction to adjust the nacelle's effective diameter, allowing the aircraft to optimize airflow bypass region when needed while maintaining safe clearance distances when the leading edge slat is in positions that require greater spacing. This dynamic adjustment resolves the contradiction between maximizing aerodynamic performance and maintaining safety clearances.
2Object-affected harmful factors
If the cowl panel is made movable to maintain clearance with the leading edge slat, then the clearance tolerance is preserved, but the aerodynamic performance may be compromised
Solution Approach 1:
The movable cowl panel enables dynamic adjustment of the nacelle configuration to maintain optimal aerodynamic performance while preserving required clearance tolerances. The panel can be positioned to ensure safe spacing from the leading edge slat during critical operations while allowing the nacelle to achieve its optimal aerodynamic shape during normal flight conditions.
Solution Approach 2:
The system performs preliminary action by proactively adjusting the cowl panel position in response to leading edge slat movement commands or detected slat positions. This anticipatory adjustment ensures clearance requirements are met before potential conflicts arise, rather than reacting to prevent damage after the fact.
3Object-affected harmful factors
If a fixed clearance structure is used to maintain distance from the leading edge slat, then the clearance is maintained, but the translational movement of the transcowl is restricted
Solution Approach 1:
Rather than using a fixed clearance structure that would restrict transcowl movement, the patent employs a dynamic cowl panel system that can translate independently. This allows the main transcowl to move freely for thrust reverser operation while the cowl panel adjusts its position to maintain clearance from the leading edge slat, thus preserving both clearance maintenance and operational flexibility.
Solution Approach 2:
The cowl is segmented into the main transcowl structure and the movable cowl panel. This segmentation allows the main transcowl to perform its primary function of covering and exposing the thrust reverser cascade, while the separate cowl panel handles the clearance maintenance function by translating independently to avoid the leading edge slat.
4Force
If the leading edge slat is moved downward to create drag during landing, then the drag is increased, but the risk of contact with the nacelle increases
Solution Approach 1:
The movable cowl panel system performs preliminary action by detecting or anticipating leading edge slat deployment and proactively adjusting the cowl panel position to increase clearance. This preventive adjustment occurs before the slat reaches positions that would create contact risk, allowing the aircraft to safely utilize the full drag capability of the leading edge slat without compromising safety.
Solution Approach 2:
The cowl panel acts as an intermediary element between the nacelle and the leading edge slat. When the slat moves downward to create drag, the cowl panel can translate to maintain an intermediate clearance zone, allowing both the drag-generating slat movement and the safe spacing to coexist without direct contact between the slat and nacelle structure.
Data Source
AI summary
A nacelle for a jet engine having a selectively operated reverse thruster which redirects air flow to a cascade during a reverse thrust operation, the nacelle including a fancowl panel configured as a stationary partial cover for a jet engine; and a translating cowl panel configured to move transversely during a reverse thrust operation so as to expose a cascade for emitting reverse thrust airflow. In exemplary embodiments, a moveable automatic translating panel, or a rotatable hinge panel, or an extension portion of the fancowl is used to preserve clearance with an aircraft wing in a nacelle clearance area.