Variable Fan Nozzle Inflatable Bladder for Bypass Airflow Control
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Solution Overview
Problem
Conventional gas turbine engines experience inefficient operation and increased mechanical stress during take-off and landing due to pressure pulsations across the fan, leading to higher fuel consumption and reduced life expectancy, as they are designed for specific cruise conditions and struggle to control bypass airflow effectively across a wider range of flight conditions.
Innovation Solution
A variable fan nozzle system featuring an inflatable bladder with selectively variable internal fluid pressure, which controls the cross-sectional area of the bypass passage through movable flaps, allowing for enhanced control of bypass airflow and pressure ratio management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fan size and bypass airflow ratio are designed for cruise conditions, then the pressure ratio across the fan is maintained during cruise, but pressure pulsations occur during take-off and landing causing fan flutter and mechanical stress
Solution Approach 1:
The patent applies the dynamics principle by implementing a variable geometry bypass duct system that can dynamically adjust its cross-sectional area using movable flaps and adjustable seals. This allows the bypass airflow area to be modified in real-time according to different flight conditions (cruise, take-off, landing), enabling the engine to maintain optimal pressure ratios across all operating regimes rather than being fixed for cruise only. The dynamic adjustment capability resolves the contradiction by making the system adaptable while maintaining reliability through consistent pressure ratio control.
Solution Approach 2:
The patent employs parameter changes by varying the bypass airflow area parameter through movable flaps and adjustable seals in the bypass duct. By changing this geometric parameter in response to different flight conditions, the system maintains the pressure ratio parameter within the desired range across all operating conditions. This resolves the contradiction between reliability (maintaining proper pressure ratio) and adaptability (handling different flight conditions) through controlled parameter modification.
2Productivity
If conventional fixed geometry bypass ducts are used, then the engine structure is simple, but the engine cannot efficiently control bypass airflow across different flight conditions leading to increased fuel consumption
Solution Approach 1:
The variable geometry bypass duct system uses movable flaps and adjustable seals that can change the duct's cross-sectional area dynamically. This dynamic capability allows the engine to optimize bypass airflow for different flight conditions, improving overall engine efficiency and fuel consumption while accepting increased structural complexity. The productivity gain comes from the ability to maintain optimal airflow characteristics across all operating regimes.
Solution Approach 2:
The variable geometry bypass duct system serves multiple functions: it controls bypass airflow area, maintains pressure ratios, reduces fan flutter, and improves efficiency across different flight conditions. This multi-functionality justifies the increased complexity by providing comprehensive performance optimization that a simple fixed geometry duct cannot achieve.
3Duration of action of stationary object
If the bypass airflow is not controlled during take-off and landing, then the engine structure remains simple, but pressure pulsations cause fan flutter and reduced life expectancy
Solution Approach 1:
The adjustable seals and movable flaps in the bypass duct create a dynamic control system that can modify the bypass airflow area in real-time. During take-off and landing, this system actively adjusts to prevent pressure pulsations and fan flutter, thereby protecting the fan and extending its life expectancy. The added complexity of the dynamic control system is justified by the significant improvement in component durability.
Solution Approach 2:
The variable geometry bypass duct system provides beforehand cushioning by proactively controlling bypass airflow to prevent pressure pulsations before they can cause fan flutter and damage. The adjustable seals and flaps are positioned and configured in advance to maintain proper pressure ratios during critical operations like take-off and landing, cushioning the fan against harmful mechanical stresses before they occur.
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 enables efficient fan operation across various flight conditions by maintaining optimal pressure ratios, reducing mechanical stress and fuel consumption, and extending the life expectancy of the fan by dynamically adjusting the bypass airflow.
Implementation Method 1
The inflatable bladder of the nozzle section has a contained internal fluid pressure that is selectively variable to influence the bypass airflow
Data Source
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AI summary
A variable fan nozzle for use in a gas turbine engine includes a nozzle section, such as an inflatable bladder, associated with a fan bypass passage for conveying a bypass airflow. The nozzle section has an internal fluid pressure that is selectively variable to influence the bypass airflow.