Variable Geometry Nozzle Flap Control for Turbojet Nacelles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable geometry nozzles in turbojet engines face high unavailability due to simple breakdowns like flap blockages, where each flap is actuated by a motorized electromechanical actuator, leading to system-wide failures when one actuator or flap is blocked.
Innovation Solution
A method for controlling the nozzle that detects the state of each flap, allowing operation in a normal mode when all flaps are operational or a degraded mode when one or more are blocked, by compensating with functional flaps to ensure the nozzle opens as commanded, with each functional flap opening beyond its nominal position based on the number of blocked flaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If each flap is actuated by a motorized electromechanical actuator, then the nozzle can be controlled in different phases of flight, but the system becomes vulnerable to complete failure when one actuator or flap is blocked
Solution Approach 1:
The nozzle is divided into multiple independent flaps (typically 4-6 flaps), each actuated by its own motorized electromechanical actuator. This segmentation allows the system to maintain partial functionality even when individual flaps or actuators fail, as the remaining functional flaps can still adjust the nozzle geometry to some extent
Solution Approach 2:
The control system continuously monitors the position and status of each flap and actuator before critical failure occurs. When a flap is detected to be blocked or malfunctioning, the system proactively compensates by adjusting the position of other flaps to achieve the desired nozzle opening, preventing complete system failure
2Device complexity
If flexible shafts are used to interconnect actuators for synchronization, then the number of position sensors can be reduced, but the system becomes vulnerable to complete blocking when one actuator fails
Solution Approach 1:
Instead of using flexible shafts to mechanically couple all actuators together, the system segments the actuation system into independent units. Each actuator is controlled independently by the control system, which processes sensor data and sends individual control signals. This eliminates the mechanical coupling vulnerability while maintaining synchronization through electronic control
Solution Approach 2:
The system employs feedback mechanisms where position sensors (such as potentiometers or encoders on each actuator) continuously report the actual position of each flap to the control system. The control system uses this feedback information to detect blocked flaps and calculate compensatory adjustments for other flaps, ensuring the nozzle achieves the commanded opening despite individual failures
Data Source
Figure 1~4
AI summary
The present invention concerns a method for controlling a variable geometry nozzle equipping a turbojet nacelle, said nacelle comprising a variable geometry nozzle (10) comprising a downstream section ended by a plurality of flaps (12) that are mounted movable in such a way as to vary the ejection section of the nozzle. The method according to the invention is remarkable in that it is designed to control the nozzle (10) in a normal mode when the flaps (12) are detected to be in an operational state, or in a degraded mode when at least one flap is detected to be in a blocked state by the detection means, in which degraded mode the method consists of controlling the opening of one or more flaps in the operational state beyond the nominal opening of same in order to compensate for said at least one blocked flap, so as to ensure an opening of the nozzle (10) corresponding to said initial opening control.