Non-uniform Blade Spacing in Rotary Machines to Dampen Wakes

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Solution Overview

Problem

Rotating turbine blades in gas turbine engines create wakes and bow waves that cause vibration, premature wear, and damage to stationary structures, as well as resonant behavior due to their periodic nature.

Innovation Solution

Implementing a non-uniform spacing of blades and vanes in rotary machines, achieved through differently sized spacers between adjacent blades and vanes, or differently sized bases, to reduce the periodic generation of wakes and bow waves, thereby dampening their impact on structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform blade spacing is used in the rotor, then the manufacturing and assembly process is simple, but wakes and bow waves are periodically generated causing vibration, premature wear, and damage to stationary structures

Engineering Contradiction:

Improveblade spacing uniformityVSAvoidvibration and wear from wakes

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by implementing non-uniform blade spacing in the rotor, where at least one blade is positioned at a different circumferential distance from adjacent blades compared to other blade spacings. This asymmetric arrangement disrupts the periodic generation of wakes and bow waves, thereby reducing vibration and premature wear of stationary structures while maintaining acceptable manufacturing complexity through controlled variations in spacing.

Inventive Principle:

Principle #4Asymmetry

2Object-affected harmful factors

If non-uniform blade spacing is implemented, then resonance and vibration are reduced, but the manufacturing and assembly complexity increases

Engineering Contradiction:

Improveresonance and vibrationVSAvoidblade spacing configuration

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies local quality by implementing non-uniform blade spacing only in specific locations rather than throughout the entire rotor. At least one blade is positioned at a different circumferential distance from adjacent blades, creating localized variations in spacing that are sufficient to disrupt periodic wake generation and reduce resonance, while minimizing the overall complexity increase compared to completely non-uniform configurations.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If non-uniform blade and vane spacing is used, then the periodic nature of wakes and bow waves is reduced, but the manufacturing precision requirements increase

Engineering Contradiction:

Improveperiodic wake generationVSAvoidblade and vane positioning

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry to both rotor blades and stator vanes by implementing non-uniform spacing arrangements. The rotor has at least one blade at a different circumferential distance from adjacent blades, and the stator has at least one vane at a different circumferential distance from adjacent vanes. This asymmetric configuration in both stages effectively disrupts the periodic nature of wake and bow wave generation, reducing resonance while maintaining reasonable manufacturing precision through controlled, non-random spacing variations.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS8678752B2Rotary machine having non-uniform blade and vane spacing

Publication Date: 2014.03.25 GE INFRASTRUCTURE TECH LLC

AI summary

A system, including a rotary machine including: a stator, a rotor configured to rotate relative to the stator, wherein the rotor comprises a plurality of blades having a non-uniform spacing about a circumference of the rotor.