Geared Turbofan Core Split Power Ratio

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Solution Overview

Problem

Gas turbine engines face efficiency decreases due to high fan blade tip speeds as fan diameters increase, leading to compressibility effects, and existing designs struggle to optimize both thermal and propulsive efficiencies simultaneously.

Innovation Solution

A gas turbine engine design featuring a two-spool or three-spool architecture with a gear arrangement between the low pressure spool and the fan, including multiple compressor stages and turbine stages, optimized power and pressure ratios, and advanced materials for turbine blades, to enhance efficiency and reduce mechanical stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fan diameter is increased to improve fuel consumption, then propulsive efficiency is improved, but fan blade tip speed increases causing compressibility effects and efficiency decrease

Engineering Contradiction:

Improvefuel consumptionVSAvoidfan blade tip speed

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The low pressure spool is segmented into two separate compressors (first and second compressor sections) with different rotational speeds. The first compressor section rotates at a lower speed while the second compressor section rotates at a higher speed, allowing each to operate at optimal points and preventing excessive fan blade tip speeds while maintaining large fan diameter benefits

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts the rotational speeds of the two compressor sections independently through the gear arrangement, allowing the fan to rotate at a speed that optimizes propulsive efficiency while the compressors operate at speeds that prevent compressibility effects. This dynamic control enables the system to adapt to different operating conditions

Inventive Principle:

Principle #15Dynamics

2Productivity

If fan diameter is increased to improve fuel consumption, then propulsive efficiency is improved, but mechanical stresses on the engine increase

Engineering Contradiction:

Improvefuel consumptionVSAvoidmechanical stress

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

By segmenting the low pressure spool into two separate compressor sections that can rotate independently, the mechanical load is distributed across two smaller compressors rather than one large compressor. This reduces the mechanical stress on individual components while still achieving the required compression ratio through the series arrangement of the two compressors

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A gear arrangement acts as an intermediary between the two compressor sections and the fan, allowing independent speed control and load distribution. The gear system mediates the mechanical stresses by providing a flexible transmission path that can accommodate different operating conditions and reduce peak stresses on any single component

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If a gear arrangement is added between the low pressure spool and fan, then fan speed can be optimized, but device complexity increases

Engineering Contradiction:

Improvefan speed controlVSAvoidsystem complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The gear arrangement is merged with the existing two-spool architecture by integrating it into the connection between the first and second compressor sections. Rather than adding a completely separate transmission system, the gear arrangement utilizes the existing rotational dynamics and structural framework, thereby reducing the increase in overall system complexity while still providing independent fan speed control

Inventive Principle:

Principle #5Merging (Combining)

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 design achieves higher overall efficiency, improved propulsive and thermal efficiencies, and a more compact engine with increased fuel efficiency and reduced size, while maintaining high fan blade and turbine efficiencies.

Implementation Method 1

gear arrangement between the low pressure spool and the fan

Methodology Applied

Scientific EffectGear mechanism: Gear

Implementation Method 2

compressor section, including at least a first compressor section and a second compressor section

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

turbine section includes at least one turbine to drive the second compressor section and a fan drive turbine to drive at least a gear arrangement

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

combustion section where it is mixed with fuel and ignited

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS11578651B2Geared turbofan arrangement with core split power ratio

Publication Date: 2023.02.14 RTX CORP

AI summary

A propulsor section includes a propulsor having a plurality of blades rotatable about an engine longitudinal axis. A compressor section includes a low pressure compressor and a high pressure compressor. A turbine section includes a low pressure turbine that drives the propulsor through an epicyclic gear arrangement, and includes a second turbine that drives the high pressure compressor. A power ratio is provided by the combination of a first power input of the low pressure compressor and a second power input of the high pressure compressor. The power ratio is defined by the second power input divided by the first power input. The power ratio is equal to, or greater than, 1.0 and less than, or equal to, 1.4.