Compact Accessory Gearbox Layout for Lower Gas Turbine Nacelle Drag
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Solution Overview
Problem
Gas turbine engines face challenges in reducing the size of accessory systems, leading to increased drag and nacelle volume, which affects efficiency and mobility, particularly in mobile platforms like aircraft.
Innovation Solution
A compact accessory gearbox system is designed with a unique gear train configuration that includes a towershaft, bevel gears, and accessory drive shafts with transverse axes of rotation, allowing for a compact and efficient arrangement that reduces the overall volume of the engine nacelle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional accessory systems are used in gas turbine engines, then the accessories can be positioned within the engine nacelle, but the nacelle volume increases and drag on the mobile platform increases
Solution Approach 1:
The patent applies dimensionality change by using bevel gears with transverse axes of rotation to rearrange the spatial configuration of the accessory drive system. The towershaft and multiple accessory drive shafts are positioned with their axes transverse to each other, creating a compact three-dimensional arrangement that reduces the overall nacelle volume required while maintaining all necessary accessory functions.
Solution Approach 2:
The patent implements nesting by arranging multiple accessory drive shafts and bevel gears in a nested configuration within the compact accessory gearbox. The first, second, and third accessory drive shafts are positioned with their axes transverse to the shaft axis, allowing them to be nested within the limited space of the gearbox housing, thereby minimizing the required nacelle volume.
2Volume of moving object
If accessory systems are reduced in size, then nacelle volume decreases, but the complexity of the gear train configuration increases
Solution Approach 1:
The patent applies segmentation by dividing the accessory drive system into multiple independent shafts (towershaft, first accessory drive shaft, second accessory drive shaft, third accessory drive shaft), each with its own bevel gear. This segmentation allows each component to be optimized independently while maintaining a compact overall configuration, reducing nacelle volume without excessive complexity increase.
Solution Approach 2:
The patent implements multi-functionality by using a single compact accessory gearbox to drive multiple accessories through the transverse shaft arrangement. The shaft and multiple accessory drive shafts with transverse axes enable a universal drive configuration that can power various accessories (generators, pumps, etc.) from a single gearbox, reducing overall system volume while maintaining functional versatility.
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 compact accessory gearbox system achieves a significant reduction in nacelle volume, enhancing mobility and efficiency by minimizing drag and optimizing space utilization within the engine nacelle.
Implementation Method 1
The towershaft includes a towershaft bevel gear at a distal end. The accessory system also includes a shaft including a first shaft bevel gear coupled to the towershaft bevel gear.
Data Source
AI summary
An accessory system for a gas turbine engine having a driveshaft is provided. The accessory system includes a towershaft coupled to the driveshaft and driven by the driveshaft. The accessory system also includes a shaft including a first shaft bevel gear coupled to a towershaft bevel gear. The shaft is rotatable by the towershaft. The accessory system includes a first accessory drive shaft having a first accessory bevel gear driven by the shaft. The accessory system also includes a second accessory drive shaft having a second accessory bevel gear driven by the shaft.