Geared Turbofan Generator Speed and Power
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Solution Overview
Problem
Gas turbine engines with generators driven by the low speed spool face limitations in power generation due to the speed constraints of the low speed spool, resulting in limited power availability as a function of size and weight.
Innovation Solution
A gear reduction system is implemented between the fan and the first stage compressor, with the low pressure turbine driving a sun gear through a flexible input shaft, allowing the generator rotor to be driven at a higher speed, and the generator is located within the nose cone for improved accessibility and anti-icing benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a generator is driven by the low speed spool, then the generator can be positioned in the nose cone, but the power generation capability is limited due to speed constraints
Solution Approach 1:
A gear reduction system is introduced as an intermediary between the low speed spool and the generator. The low pressure turbine drives a sun gear through a flexible input shaft, which rotates a generator shaft at higher speed than the low speed spool, thereby enabling the generator to produce more power while still being driven by the low speed spool assembly
Solution Approach 2:
The gear reduction system changes the speed parameter of the generator shaft relative to the low speed spool. By reducing the gear ratio between the sun gear and the generator shaft, the generator operates at a higher rotational speed, increasing its power output capability without requiring the low speed spool itself to rotate faster
2Power
If the generator size and weight are increased to compensate for low speed, then more power can be generated, but the overall system becomes heavier and larger
Solution Approach 1:
Instead of increasing generator size to compensate for low rotational speed, the invention changes the operational parameter by using a gear reduction system to increase the generator's rotational speed. This allows a smaller, lighter generator to produce the same or greater power output, resolving the contradiction between power capability and weight
3Weight of moving object
If the generator size is reduced to decrease weight, then the system becomes lighter, but power generation capability decreases
Solution Approach 1:
The gear reduction system enables a smaller, lighter generator to maintain or exceed the power generation capability of a larger generator operating at lower speed. By changing the rotational speed parameter through mechanical advantage, the invention allows weight reduction without sacrificing power output
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
This configuration enables higher power generation per unit volume and weight, enhances anti-icing of the nose cone, and simplifies maintenance by allowing a smaller, lighter generator to be used, while utilizing existing lubrication for cooling.
Implementation Method 1
the low pressure turbine drives a sun gear in the gear reduction through a flexible input shaft
Implementation Method 2
A gear reduction system is implemented between the fan and the first stage compressor, with the low pressure turbine driving a sun gear in the gear reduction
Implementation Method 3
A generator (102) is located within the nose cone and includes a stator (113) and a rotor (124)
Implementation Method 4
utilizing existing lubrication for cooling
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A gas turbine engine (20) comprises a fan rotor (85), a lower speed compressor rotor (90) and a higher speed compressor rotor (96), and a lower speed turbine rotor (94) and a higher speed turbine rotor (98). The lower speed turbine rotor (94) rotates the lower speed compressor rotor (96), and rotates a gear reduction (88) to, in turn, rotate the fan rotor (85). The higher speed turbine rotor (98) rotates the higher speed compressor rotor (96). An electrical generator (102) is driven to rotate with one of the lower speed turbine rotor (94) and the fan rotor (85).