Turbine Engine Spool Power Transfer for Lower Idle Thrust

Solution Overview

Problem

Modern turbofan engines experience excessive idle thrust and fuel flow due to increased engine speed for higher accessory power demands, leading to increased maintenance costs and fuel consumption.

Innovation Solution

A system that mechanically links a low pressure spool to a high pressure spool in a turbine engine using a power transfer unit and clutch, allowing power transfer from the low pressure spool to the high pressure spool, thereby reducing idle thrust and fuel flow by modulating power and speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If engine speed is increased to meet higher accessory power demands, then electrical power output is improved, but idle thrust and fuel flow increase excessively

Engineering Contradiction:

Improveelectrical power outputVSAvoidfuel flow

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The engine is divided into two independent spool systems (high-pressure spool and low-pressure spool) that can operate at different speeds. The high-pressure spool drives the fan and produces thrust, while the low-pressure spool drives the accessories. This segmentation allows the accessory-driven low-pressure spool to operate at higher speeds for increased power output without necessarily increasing the speed of the high-pressure spool and fan, thereby reducing excessive idle thrust and fuel flow.

Inventive Principle:

Principle #1Segmentation

2Power

If engine speed is increased to meet higher accessory power demands, then electrical power output is improved, but idle thrust increases excessively

Engineering Contradiction:

Improveelectrical power outputVSAvoididle thrust

Core Design Contradiction:

PowerVSForce

Solution Approach 1:

The engine is divided into two independent spool systems (high-pressure spool and low-pressure spool) that can operate at different speeds. The high-pressure spool drives the fan and produces thrust, while the low-pressure spool drives the accessories. This segmentation allows the accessory-driven low-pressure spool to operate at higher speeds for increased power output without necessarily increasing the speed of the high-pressure spool and fan, thereby reducing excessive idle thrust and fuel flow.

Inventive Principle:

Principle #1Segmentation

3Power

If a power transfer unit is added to mechanically link spools, then power transfer capability is improved, but device complexity increases

Engineering Contradiction:

Improvepower transfer capabilityVSAvoiddevice complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

A power transfer unit is introduced as an intermediary mechanism between the low-pressure spool and high-pressure spool. This unit includes a clutch that can selectively engage or disengage the mechanical connection, allowing controlled power transfer from the low-pressure spool to the high-pressure spool. The clutch acts as a mediator that enables flexible power distribution while maintaining the ability to operate in different modes (connected or disconnected), thus managing the complexity through controlled engagement rather than permanent mechanical linkage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11333077B2Systems and methods for transferring mechanical power in a turbine engine

Publication Date: 2022.05.17 THE BOEING CO

AI summary

A system (166) for transferring mechanical power in a turbine engine (150/151) including a low pressure spool (162) and a high pressure spool (156) includes a power transfer unit (168) coupled between an output shaft (172) of the low pressure spool (162) and a drive shaft (174) of the high pressure spool (156) to mechanically link the low pressure spool (162) to the high pressure spool (156), and a clutch (170) coupled to the power transfer unit (168), wherein the clutch (170) is configured to transfer power produced from the low pressure spool (162) to the high pressure spool (156).