Turbojet Nacelle Thrust Reverser Control Sector
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Solution Overview
Problem
Existing bypass turbojet engine nacelles with thrust reverser systems face aerodynamic losses due to control tie-rods passing through the cold air annular flow path, which is not optimized without a fixed front frame and results in reduced efficiency.
Innovation Solution
The design includes a movable cowl with a control sector sliding in a transverse plane, connected to a return device that drives the pivoting flaps to close the annular flow path, with flap tie-rods outside the flow path, eliminating the need for a fixed front frame and enhancing aerodynamic efficiency by using a single control sector and various return devices such as racks, pinions, and cables to manage the flaps' movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control tie-rods are used to connect pivoting flaps to the fixed front frame, then the flaps can be controlled to close the annular flow path, but the tie-rods pass through the cold air annular flow path causing aerodynamic losses
Solution Approach 1:
The control tie-rods are extracted from the annular flow path and relocated to the outer periphery, where they connect the control sector to the pivoting flaps without interfering with the cold air flow. This eliminates the aerodynamic losses caused by tie-rods passing through the flow path while maintaining reliable flap control.
Solution Approach 2:
A control sector is introduced as an intermediary element that receives control signals from the cowl and distributes them to multiple pivoting flaps via tie-rods. This allows centralized control while keeping the tie-rods positioned outside the annular flow path, resolving both the control reliability and aerodynamic efficiency requirements.
2Ease of operation
If a fixed front frame is used to support the control mechanism, then the pivoting flaps can be controlled, but the structure becomes more complex and aerodynamic efficiency is reduced
Solution Approach 1:
The movable cowl is given multiple functions: it serves as both the aerodynamic cover and the control mechanism support structure. The control sector is integrated into the cowl, eliminating the need for a separate fixed front frame and reducing structural complexity while maintaining full flap control capability.
Solution Approach 2:
Instead of having a fixed front frame support the control mechanism, the invention inverts the approach by using the movable cowl itself as the support structure. This eliminates the fixed frame requirement and simplifies the overall nacelle structure.
3Ease of operation
If multiple tie-rods are used to control each pivoting flap individually, then precise flap control is achieved, but the number of components increases and aerodynamic losses increase
Solution Approach 1:
Multiple flap control functions are merged into a single control sector that rotates to control all pivoting flaps simultaneously. This reduces the number of independent control mechanisms from multiple individual tie-rod systems to a unified rotational control system, decreasing component count while maintaining precise control.
Solution Approach 2:
The control sector serves as a universal control element that can control multiple pivoting flaps through its rotational movement. A single rotational input at the control sector translates to coordinated movement of all connected flaps, reducing the overall complexity of the control system.
Data Source
AI summary
A turbofan engine nacelle includes a thrust reverser system provided with at least one movable cowl retracting towards a rear reverse-jet position, tilting pivoting flaps which at least partially close an annular flow duct, and opening lateral openings of this annular flow duct equipped with reverser grids. Each movable cowl includes a control sector that slides in a transverse plane, a deflection device linking a fixed part of the nacelle to this control sector in order to make it slide towards a reversal position when the movable cowl retracts, and flap connecting rods linking this control sector to the pivoting flaps, which tilt these flaps, closing the annular flow duct, when the control sector slides towards its reversal position.