Geared Turbofan Engine Mount Layout to Reduce Case Distortion
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Solution Overview
Problem
Conventional engine mounting configurations for turbofan gas turbine engines on aircraft pylons result in large 'punch loads' that distort the engine cases and increase clearance between static and rotating blade tips, affecting engine performance and fuel burn.
Innovation Solution
A novel engine mounting configuration using a forward and aft mount system that eliminates thrust links, incorporating a gear train with a gear reduction ratio greater than 2.3 and a fan variable area nozzle to adjust fan nozzle exit area, minimizing distortion and optimizing engine operation across various flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional engine mounting configuration with long thrust links is used, then thrust loads are effectively coupled to the pylon, but large punch loads distort the engine cases and increase blade tip clearance
Solution Approach 1:
The patent removes the traditional long thrust links from the engine mounting configuration. By extracting this component, the harmful punch loads that caused case distortion and increased blade tip clearance are eliminated, while thrust loads are still effectively managed through alternative mounting structures
Solution Approach 2:
The engine mounting system is divided into separate functional components: forward mounts and aft mounts that independently support different aspects of engine loads. This segmentation allows optimized load paths that prevent concentrated punch loads on the engine cases while maintaining effective thrust coupling to the pylon
2Productivity
If gear train with high gear reduction ratio is used, then fan speed is reduced for improved efficiency, but system complexity increases
Solution Approach 1:
The gear train acts as an intermediary mechanism between the high-speed low-pressure turbine and the fan. It provides the necessary speed reduction and torque multiplication while isolating the fan from direct high-speed rotation, thereby improving fan efficiency without requiring the fan to operate at excessively high speeds
3Adaptability or versatility
If fan variable area nozzle is used, then fan pressure ratio is optimized for different flight conditions, but device complexity increases
Solution Approach 1:
The fan nozzle is designed with variable area capability that allows it to dynamically adjust its opening based on flight conditions. This dynamic adjustment optimizes the fan pressure ratio for different operating regimes (takeoff, cruise, etc.) while the nozzle mechanism itself remains relatively simple in structure
Data Source
AI summary
A gas turbine engine may include propulsor means for providing propulsion, reduction means for reducing a rotational speed of an output that drives the propulsor means relative to an input, and expansion means for driving the input of the reduction means. Static support means may support a bearing system that rotatably supports the expansion means and the propulsor means. The support means may support a forward engine mount at a first engine mount location axially near the reduction means relative to an engine axis when the engine is mounted. The support means may support an aft engine mount at a second engine mount location.