Compact Accessory Gear Train for Lower-Drag Gas Turbine Nacelles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engines have large accessory systems that increase the size of the engine nacelle, leading to increased drag on mobile platforms, necessitating a compact accessory system to reduce nacelle size.
Innovation Solution
A compact accessory gearbox with a unique gear train configuration and adapter system that arranges accessories in a compact, axi-symmetric layout, reducing the overall size of the nacelle by optimizing the arrangement of drive shafts and gears within the gearbox.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional accessory systems are used in gas turbine engines, then accessories can be driven effectively, but the engine nacelle size increases leading to increased drag
Solution Approach 1:
The patent applies multi-axis gear arrangements where drive shafts and gears are positioned at different angles (first axis, second axis, third axis) to create a three-dimensional compact layout. This spatial reconfiguration allows accessories to be driven effectively while reducing the overall nacelle footprint, thereby decreasing drag without sacrificing functionality
Solution Approach 2:
The compact accessory gearbox nests multiple gears and drive shafts within a reduced housing volume. The bevel gears and drive shafts are arranged concentrically and at various angles to maximize space utilization, enabling the accessory system to maintain its driving capability while occupying significantly less space in the nacelle
2Length of stationary object
If accessory systems are compacted to reduce nacelle size, then drag decreases, but the arrangement of drive shafts and gears becomes more complex
Solution Approach 1:
The patent employs asymmetric gear arrangements where drive shafts are positioned at specific non-uniform angles relative to each other. The bevel gears are configured with different pitch angles and tooth configurations to optimize the compact layout, creating an asymmetric but highly efficient power transmission path that reduces nacelle dimensions while managing complexity through deliberate geometric design
3Volume of stationary object
If multi-axis gear arrangements are used to compact the accessory gearbox, then nacelle size is reduced, but manufacturing and assembly become more difficult
Solution Approach 1:
The accessory gearbox is divided into modular sections with standardized interfaces. Each module contains specific gear trains and drive shaft configurations that can be manufactured and tested independently before final assembly. This segmentation allows complex multi-axis arrangements to be built from simpler, pre-fabricated components, reducing manufacturing and assembly difficulty while maintaining the compact volume
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
An accessory system for a gas turbine engine having a driveshaft with an axis of rotation is provided. The system includes a towershaft coupled to the driveshaft and rotatable about a towershaft axis of rotation. The towershaft includes a towershaft bevel gear. The system includes a primary shaft including a first bevel gear and a second bevel gear that each revolve about a primary shaft axis of rotation. The first bevel gear is coupled to the towershaft bevel gear. The system includes a secondary shaft including a third bevel gear and a fourth bevel gear that each revolve about a secondary shaft axis of rotation. The third bevel gear is coupled to the second bevel gear. The system includes a tertiary shaft including a fifth bevel gear that revolves about a tertiary shaft axis of rotation. The fifth bevel gear is coupled to the fourth bevel gear.