Axial Compressor Rotor Splitter Blades Hub Solidity

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Solution Overview

Problem

Turbomachinery compressors face challenges in achieving high pressure ratios with minimal stages while maintaining aerodynamic and structural performance, as reducing the number of compressor airfoils leads to airflow separation at the rotor hub due to reduced hub solidity and non-axisymmetric disk profiles.

Innovation Solution

Incorporating an axial compressor rotor with an array of compressor blades and alternating splitter blades, where the splitter blades have reduced dimensions and are positioned to maintain hub solidity, preventing airflow separation and minimizing frictional losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the number of compressor airfoils is reduced to minimize weight and simplify manufacturing, then weight and manufacturing complexity are reduced, but hub flow separation occurs due to reduced hub solidity

Engineering Contradiction:

Improverotor weightVSAvoidaerodynamic performance

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The rotor blade row is segmented into two distinct types of airfoils: compressor blades and splitter blades. The compressor blades perform the primary compression function, while the splitter blades, positioned between them, specifically address the hub flow separation problem. This segmentation allows each blade type to be optimized for its specific function while working together to solve the overall system problem.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The splitter blades are strategically positioned in the hub region where flow separation occurs, providing localized aerodynamic correction. Their reduced span (extending only partway radially from the hub) concentrates their effect where it is most needed - in the low-solidity hub region - without unnecessarily increasing weight across the entire rotor blade row.

Inventive Principle:

Principle #3Local quality

2Strength

If the disk is configured with a non-axisymmetric scalloped surface profile to reduce mechanical stresses, then structural performance is improved, but airflow separation is promoted due to increased through flow area and aerodynamic loading

Engineering Contradiction:

Improvedisk structural performanceVSAvoidaerodynamic performance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The splitter blades act as intermediary elements between the compressor blades and the scalloped disk surface. They modify the airflow in the hub region to counteract the adverse effects of the scalloped profile, effectively mediating between the structural requirements (scalloped disk) and aerodynamic requirements (prevent flow separation).

Inventive Principle:

Principle #24Intermediary (Mediator)

3Weight of moving object

If the chord dimension and span dimension of splitter blades are reduced compared to compressor blades, then weight is minimized, but the ability to prevent flow separation may be compromised

Engineering Contradiction:

Improvesplitter blade weightVSAvoidflow separation control

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The splitter blades have reduced span dimensions compared to full-span compressor blades, but this is compensated by their strategic positioning in the hub region where flow separation occurs. The local quality principle allows the splitter blades to be smaller overall while maintaining effectiveness in the specific region where they are needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The splitter blades extend only partially radially from the hub (reduced span), providing just enough aerodynamic action in the critical hub region to prevent flow separation. This partial action is sufficient to solve the problem without the excessive weight that would result from full-span blades.

Inventive Principle:

Principle #16Partial or excessive action

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 solution effectively increases rotor hub solidity, reduces aerodynamic loading, and suppresses airflow separation, maintaining performance while minimizing weight and manufacturing complexity.

Implementation Method 1

the accompanying reduced hub solidity tends to cause the airflow in the hub region of the rotor airfoil to undesirably separate from the airfoil surface

Methodology Applied

Scientific EffectAirflow separation: Flow Separation

Implementation Method 2

an array of airfoil-shaped axial-flow compressor blades extending radially outward from the flowpath surface

Methodology Applied

Scientific EffectAerodynamic compression: Compression

Data Source

PatentUS9874221B2Axial compressor rotor incorporating splitter blades

Publication Date: 2018.01.23 GENERAL ELECTRIC CO

AI summary

A compressor apparatus includes: a rotor having: a disk mounted for rotation about a centerline axis, an outer periphery of the disk defining a flowpath surface; an array of airfoil-shaped axial-flow compressor blades extending radially outward from the flowpath surface, wherein the compressor blades each have a root, a tip, a leading edge, and a trailing edge, wherein the compressor blades have a chord dimension and are spaced apart by a circumferential spacing, the ratio of the chord to the circumferential spacing defining a blade solidity parameter; and an array of airfoil-shaped splitter blades alternating with the compressor blades, wherein the splitter blades each have a root, a tip, a leading edge, and a trailing edge; wherein at least one of a chord dimension of the splitter blades at the roots thereof and a span dimension of the splitter blades is less than the corresponding dimension of the compressor blades.