Axial Flow Blade Fluid Passage for Wake Noise Reduction

Solution Overview

Problem

Existing axial flow fluid apparatuses face challenges in reducing noise and vibration caused by wake interference between moving and stationary blade rows, with previous solutions either increasing apparatus size or complicating mechanisms.

Innovation Solution

The axial flow fluid apparatus incorporates a fluid passage within the blades to jet fluid from the positive pressure surface to the negative pressure surface or trailing edge, utilizing differential pressure to weaken the wake and reduce noise and vibration without external air introduction or complex mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the spacing between the moving blade row and the stationary blade row is widened to weaken the wake, then the noise or vibration is reduced, but the axial length of the apparatus becomes long and the weight or apparatus size increases

Engineering Contradiction:

Improvenoise or vibrationVSAvoidaxial length

Core Design Contradiction:

Object-affected harmful factorsVSLength of moving object

Solution Approach 1:

The patent applies preliminary action by forming a fluid passage in advance within the moving blade to jet fluid toward the velocity defect region before the wake fully develops and interferes with the stationary blade. This proactive approach weakens the wake early in its formation, reducing noise and vibration without requiring increased spacing between blade rows, thereby avoiding the penalty of increased axial length.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary substance (fluid) that is jetted through the moving blade to the velocity defect region. This intermediary fluid acts as a mediator that fills the wake and reduces the velocity defect, thereby weakening the wake's harmful effects on the stationary blade without requiring physical separation or increased spacing between blade rows.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a mechanism is added to introduce external air into the velocity defect region to weaken the wake, then the noise or vibration is reduced, but the mechanism becomes complicated

Engineering Contradiction:

Improvenoise or vibrationVSAvoidmechanism complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies self-service by utilizing the existing fluid flow and pressure differential within the apparatus to jet fluid through the moving blade to the velocity defect region. The system uses its own internal fluid dynamics to weaken the wake without requiring external air introduction mechanisms or additional complex components. The fluid passage is formed within the blade structure itself, eliminating the need for separate air introduction systems.

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If the spacing between the moving blade row and the stationary blade row is widened, then the wake becomes weaker and noise or vibration is reduced, but the apparatus weight increases or the apparatus must be enlarged

Engineering Contradiction:

Improvenoise or vibrationVSAvoidapparatus weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The patent applies preliminary action by forming a fluid passage in advance within the moving blade to jet fluid toward the velocity defect region before the wake fully develops and interferes with the stationary blade. This proactive approach weakens the wake early in its formation, reducing noise and vibration without requiring increased spacing between blade rows, thereby avoiding the penalty of increased axial length.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary substance (fluid) that is jetted through the moving blade to the velocity defect region. This intermediary fluid acts as a mediator that fills the wake and reduces the velocity defect, thereby weakening the wake's harmful effects on the stationary blade without requiring physical separation or increased spacing between blade rows.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach effectively reduces noise and vibration by weakening the wake within the apparatus, enhancing operational efficiency without increasing weight or complexity.

Implementation Method 1

utilizing differential pressure to weaken the wake and reduce noise and vibration

Methodology Applied

Scientific EffectDifferential pressure: Pressure Gradient

Data Source

PatentUS8133008B2Axial flow fluid apparatus and blade

Publication Date: 2012.03.13 IHI CORP

AI summary

An axial flow fluid apparatus axially provided with a plurality of blade rows having a plurality of blades arranged around a shaft is provided. A fluid passage for jetting a fluid to a downstream velocity defect region resulting from a blade is formed in at least one of blades constituting a blade row installed on the upstream side of the plurality of blade rows so as to lead from a positive pressure surface to a negative pressure surface or a trailing edge.