Turbofan Thrust Reverser With Segmented Cowl And Vane Arrangement
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Solution Overview
Problem
Existing ducted fan gas turbine engines face challenges in efficiently controlling fan stability and thrust reversal, particularly at lower pressure ratios, due to complex actuation mechanisms and safety concerns associated with variable area nozzles and thrust reversers.
Innovation Solution
A combined thrust reverser and variable area nozzle system featuring a stationary and movable cowl portion with a vane arrangement, allowing for three operational configurations that increase or decrease the total effective flow area, enabling efficient operation over a range of conditions with reduced actuation complexity and improved safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the aft cowl is translated rearwardly to increase the discharge area of the nozzle, then the discharge area increases, but the actuation mechanism becomes more complex and the risk of unintended deployment increases
Solution Approach 1:
The cowl is divided into a stationary portion and a movable portion that can be translated rearwardly. This segmentation allows the discharge area to be increased by moving only the movable portion, rather than translating the entire cowl assembly, thereby reducing the complexity of the actuation mechanism while still achieving the desired increase in discharge area.
Solution Approach 2:
The movable cowl portion can be dynamically positioned between different locations: a forward position for normal operation, an intermediate position to increase discharge area, and a rearward position for thrust reversal. This dynamic positioning capability allows the system to adapt to different operating conditions without requiring a completely complex actuation mechanism, as each position can be reached through controlled movement of the movable portion.
2Weight of moving object
If a single actuator varies the area of the discharge nozzle and provides thrust reversal, then engine weight is reduced, but the risk of unintended deployment during flight increases
Solution Approach 1:
By segmenting the cowl into stationary and movable portions, the system can use a single actuator to control the movable portion's position. This segmentation isolates the critical movement function to a smaller, more controllable component, reducing the overall system complexity and weight while maintaining safety through the limited range of motion of the movable portion alone.
Solution Approach 2:
The movable cowl portion is designed to be translatable only within specific predetermined ranges between defined positions (forward, intermediate, rearward). This preliminary definition of acceptable movement ranges prevents unintended deployment during flight, as the actuator cannot move the cowl beyond these pre-established safe zones, thereby maintaining reliability while using a simpler single-actuator system.
3Area of stationary object
If the cowl is translated a relatively long distance to produce large increases in discharge area, then the discharge area increases sufficiently, but the actuation mechanism becomes more complex
Solution Approach 1:
The cowl is segmented into a stationary portion and a movable portion. By translating only the movable portion rather than the entire cowl assembly, the system achieves the necessary increase in discharge area with a shorter, more manageable translation distance. This segmentation directly reduces the complexity of the actuation mechanism by minimizing the travel distance that must be controlled.
Solution Approach 2:
Instead of translating the cowl along its entire length (one-dimensional movement), the invention uses a localized translation of the movable portion in a specific dimension, creating an intermediate position that provides sufficient discharge area increase without requiring extreme translation distances. This dimensional approach to movement allows for efficient area modulation with reduced actuation complexity.
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 system achieves efficient operation by allowing a large increase in discharge area with minimal cowl translation, enhancing aerodynamic and acoustic efficiency while simplifying actuation and reducing the risk of unintended deployment during flight.
Implementation Method 1
a vane arrangement including a first set of turning vanes for channelling airflow from the duct in a rearward direction, and a second set of turning vanes for channelling airflow from the bypass duct in a forward direction
Implementation Method 2
the nacelle has a stationary cowl portion and a movable cowl portion which is translatable rearwardly relative to the stationary cowl portion to open an annular gap therebetween
Implementation Method 3
air entering the intake is accelerated by the fan to produce two air flows: a first air flow A into the core engine and a second airflow B which passes through the bypass duct to provide propulsive thrust
Implementation Method 4
The intermediate pressure compressor compresses the air flow A directed into it before delivering that air to the high pressure compressor where further compression takes place
Implementation Method 5
The compressed air exhausted from the high-pressure compressor is directed into the combustion equipment where it is mixed with fuel and the mixture combusted
Implementation Method 6
The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines before being exhausted through the nozzle to provide additional propulsive thrust
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A ducted fan gas turbine assembly has a thrust reverser assembly having a vane arrangement including a first set of turning vanes (37) for channelling airflow from the duct in a rearward direction and a second set of turning vanes (38) for channelling airflow from the bypass duct (30) in a forward direction. The thrust reverser assembly further has a plurality of blocker doors (41) which are deployable to block the bypass duct (30). The nacelle has a stationary cowl portion (32) and a movable cowl portion (33) which is translatable rearwardly relative to the stationary cowl portion (32) to open an annular gap (43) therebetween. The cowl portions (32, 33) cooperate with the thrust reverser assembly to provide three operational configurations. In the first operational configuration the gap (43) between the cowl portions (32, 33) is closed and the vane arrangement is stowed in the nacelle to prevent airflow from the duct (30) flowing therethrough. In the second operational configuration the first set of turning vanes (37) is positioned in the gap (43) opened between the cowl portions (32, 33) to form an annular secondary discharge nozzle from the bypass duct (30) for the duct airflow. In the third operational configuration the blocker doors (41) are deployed and the second set of turning vanes (38) is positioned in the gap (43) opened between the cowl portions (32, 33) to divert the duct airflow through the second set of turning vanes (38) and provide reverse thrust.