Counter-rotating Tip Turbine Compressor Reduces Length

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional turbofan engines have a complex elongated structure due to axial flow, which complicates packaging, while tip turbine engines with direct axial compressor rotor drive face increased length and weight with more compressor stages.

Innovation Solution

A tip turbine engine design featuring a compressor case with radially inward outer compressor airfoils and counter-rotating inner airfoils, driven by a gear system, allowing increased compression without additional airfoils and eliminating a stage of outer airfoils, reducing engine length and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of compressor stages is increased to improve compression efficiency, then compression efficiency is improved, but engine length and weight increase

Engineering Contradiction:

Improvecompression efficiencyVSAvoidengine length

Core Design Contradiction:

ProductivityVSLength of moving object

Solution Approach 1:

The patent applies counter-rotation of the compressor rotor relative to the compressor case. The compressor case rotates in one direction while the compressor rotor rotates in the opposite direction, creating enhanced compression through the relative motion between the two rotating components. This inversion approach allows achieving higher compression efficiency without proportionally increasing the number of compressor stages, thereby reducing engine length.

Inventive Principle:

Principle #13The other way round (Inversion)

2Productivity

If the number of compressor stages is increased to improve compression efficiency, then compression efficiency is improved, but engine weight increases

Engineering Contradiction:

Improvecompression efficiencyVSAvoidengine weight

Core Design Contradiction:

ProductivityVSWeight of moving object

Solution Approach 1:

By implementing counter-rotation between the compressor case and compressor rotor, the patent achieves enhanced compression efficiency through the relative rotational motion. This approach provides an alternative to simply adding more compressor stages, thereby avoiding the associated weight penalty of additional components while maintaining or improving compression performance.

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If more compressor stages are added to increase compression, then compression is improved, but the number of parts increases

Engineering Contradiction:

ImprovecompressionVSAvoidnumber of parts

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The counter-rotation mechanism utilizes the relative motion between two rotating components (compressor case and compressor rotor) to generate compression. This approach achieves enhanced compression without requiring additional discrete compressor stages, thereby reducing the total number of parts and simplifying the overall compressor architecture.

Inventive Principle:

Principle #13The other way round (Inversion)

4Power

If conventional axial flow design is used, then thrust-to-weight ratio is achieved, but engine structure becomes elongated and complex

Engineering Contradiction:

Improvethrust-to-weight ratioVSAvoidengine structure

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent implements counter-rotation of the compressor components, where the compressor case and compressor rotor rotate in opposite directions. This innovative approach achieves enhanced compression and maintains thrust-to-weight ratio while avoiding the elongated and complicated engine structure associated with conventional multi-stage axial compressors.

Inventive Principle:

Principle #13The other way round (Inversion)

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 design enhances compression efficiency, reduces engine length and weight, and decreases the number of parts, achieving a thrust-to-weight ratio comparable to conventional engines with a significantly shorter package.

Implementation Method 1

at least one gear couples the rotation of the turbine and fan to an axial compressor rotor from which extend radially outwardly a plurality of inner compressor airfoils

Methodology Applied

Scientific EffectGear mechanism: Gear

Data Source

PatentUS8061968B2Counter-rotating compressor case and assembly method for tip turbine engine

Publication Date: 2011.11.22 RTX CORP

AI summary

A tip turbine engine (10) provides an axial compressor (22) having a compressor case (50) from which extend radially inwardly a plurality of outer compressor airfoils (54). The compressor case (50) is directly driven by the rotation of the turbine (32) and fan (28), while at least one gear (77) couples the rotation of the turbine (32) and fan (28) to an axial compressor rotor (46) having a plurality of inner compressor airfoils (52). In this manner, the axial compressor rotor (46) is driven in a direction opposite the direction of the outer compressor airfoils (54), thereby increasing the compression provided by the compressor without increasing the number of airfoils. The outer compressor airfoils (54) are formed on a plurality of outer airfoil assemblies (56) each having an arcuate substrate (58) from which the outer compressor airfoils (54) extend. Each of the outer compressor airfoil assemblies (56) includes more than one axially-spaced stage of outer compressor airfoils (54). For assembly, the outer compressor airfoil assemblies (56) are moved toward the axial compressor rotor (46) and then inserted into the compressor case (50).