Variable Area Fan Nozzle Bladder System for Turbofan Engines
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Solution Overview
Problem
Conventional gas turbine engines with fixed geometry fan nozzles compromise performance across different flight conditions, and existing variable area nozzles increase engine weight, negating fuel efficiency gains.
Innovation Solution
A bladder system within the turbofan engine's nacelle assembly adjusts the fan nozzle exit area by inflating or deflating bladders, allowing for uniform or asymmetrical changes in the fan nozzle exit area, controlled by a valve system and positional measurement system, to optimize thrust efficiency and fuel economy across various flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed geometry fan nozzle is used, then the engine structure is simple, but the thrust efficiency and fuel economy are compromised across different flight conditions
Solution Approach 1:
The patent applies the dynamics principle by making the fan nozzle exit area variable rather than fixed. A bladder system with multiple inflatable chambers allows the nozzle area to be dynamically adjusted according to flight conditions (takeoff, cruise, landing), enabling the engine to optimize thrust efficiency and fuel economy across different operating regimes while maintaining relatively simple overall structure.
2Productivity
If a variable area fan nozzle is implemented, then the thrust efficiency and fuel economy improve, but the engine weight increases
Solution Approach 1:
The patent employs flexible shells and thin films by using a bladder system consisting of inflatable chambers made from flexible material. These bladders expand and contract to vary the nozzle exit area without requiring heavy mechanical actuators or complex variable geometry mechanisms, thereby achieving weight-efficient area modulation for optimized fuel economy across flight conditions.
Solution Approach 2:
The patent applies pneumatics and hydraulics by utilizing pressurized air from the engine's bypass stream to inflate and deflate the bladder chambers. This pneumatic actuation eliminates the need for external motors, linkages, or heavy mechanical control systems, significantly reducing the weight penalty while enabling effective variable area control for improved fuel efficiency.
3Adaptability or versatility
If existing variable area nozzle mechanisms are used, then the fan nozzle exit area can be changed, but the overall engine weight increases to the extent that fuel efficiency gains are negated
Solution Approach 1:
The patent applies segmentation by dividing the bladder system into multiple independent inflatable chambers arranged around the nozzle perimeter. This segmentation allows selective inflation or deflation of individual chambers to achieve precise control over the nozzle exit area, providing adaptability for different flight conditions while keeping each individual chamber lightweight and manageable.
4Productivity
If symmetrical bladder adjustment is used, then thrust efficiency is maximized, but asymmetrical fan nozzle exit area cannot be achieved
Solution Approach 1:
The patent applies local quality by enabling independent control of each bladder chamber's inflation or deflation state. This allows the system to transition from symmetrical adjustment (all bladders moved uniformly for maximum thrust efficiency) to asymmetrical adjustment (selective bladder control for vectored bypass flow), providing local adaptability in different operational modes while maintaining the capability for optimized symmetrical operation when needed.
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 solution maximizes thrust efficiency and fuel economy by varying the fan nozzle exit area, maintaining efficient fan operation across takeoff, cruise, and landing conditions while minimizing weight penalties, and ensures fail-safe operation by defaulting to a takeoff/landing configuration in case of pressure loss.
Implementation Method 1
A bladder system within the turbofan engine's nacelle assembly adjusts the fan nozzle exit area by inflating or deflating bladders
Implementation Method 2
controlled by a valve system and positional measurement system
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A turbofan engine (10) includes a variable area fan nozzle (42) which effectively changes the physical area and geometry within a fan bypass flow path (40) to manipulate the pressure ratio of the bypass flow with a multitude of bladders (52A...52D) circumferentially located about a core cowl (12). A method of varying such a fan nozzle exit area with a bladder system is also disclosed.