Adjustable Mixer Fairing Nozzle for Gas Turbine Fan Efficiency
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Solution Overview
Problem
Current gas turbine engines with fixed or variable area nozzles face inefficiencies in fan operation at varying flight conditions, particularly at low pressure ratios and high airspeeds, leading to potential fan surge and reduced efficiency.
Innovation Solution
A nozzle arrangement featuring a mixer duct with a movably mounted mixer fairing that adjusts the output flow areas of both the bypass and mixer nozzles, as well as the throat area of the mixer duct inlet, allowing for simultaneous alteration of nozzle areas to optimize fan efficiency across different flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed area nozzle is used, then the device complexity is reduced, but the fan efficiency deteriorates at varying flight conditions
Solution Approach 1:
The patent applies a movable mixer fairing that can change position relative to the bypass duct and engine core, transforming the fixed nozzle structure into a dynamic one. The fairing moves between retracted and extended positions to adjust the mixer duct geometry and nozzle exit areas, enabling the system to adapt to varying flight conditions and maintain optimal fan efficiency without excessive complexity.
2Productivity
If the nozzle area is reduced to improve efficiency at high airspeeds, then the fan efficiency improves, but the risk of fan surge increases
Solution Approach 1:
The movable fairing creates a dynamic nozzle system that adjusts geometry based on flight conditions. At high airspeeds, the fairing retracts to reduce nozzle area and improve efficiency, while at lower speeds it extends to maintain larger effective area and prevent surge, thus dynamically balancing efficiency and safety margins.
Solution Approach 2:
The system changes the geometric parameters of the mixer duct by moving the fairing, which simultaneously alters the nozzle exit areas and throat area. This parameter adjustment allows optimization of the working line to maintain appropriate margins against fan surge across different operating conditions while improving efficiency at high airspeeds.
3Productivity
If a variable area nozzle is added to improve fan efficiency, then the fan efficiency improves, but the device complexity increases
Solution Approach 1:
The movable mixer fairing serves multiple functions simultaneously: it adjusts the mixer duct geometry, controls the nozzle exit areas for both bypass and core flows, and modifies the throat area. This multi-functionality reduces the need for separate adjustment mechanisms for each parameter, thereby limiting the increase in device complexity while achieving variable area control.
4Productivity
If the mixer fairing is moved to alter nozzle areas, then the fan efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The patent implements a movable rather than fully adjustable mechanism. The fairing moves between discrete positions (retracted and extended) rather than requiring continuous adjustment capability, which simplifies the manufacturing requirements while still achieving the necessary geometric changes to optimize the fan working line across different operating conditions.
Data Source
AI summary
A gas turbine engine comprising: a bypass duct having a bypass nozzle; an engine core having a core nozzle; and, a mixer duct defined by a mixer fairing and having a mixer nozzle, wherein the mixer duct is arranged to receive an airflow from the bypass duct through a mixer duct inlet and an airflow from the engine core, when in use, and the geometry of the mixer duct is selectively adjustable by moving the mixer fairing relative to the bypass duct and engine core in use.