Centrifugal Impeller Blade with Opposing Inclination to Suppress Secondary Flow

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In centrifugal rotary machines, a secondary flow occurring in an axial direction away from the disc leads to accumulation of low-energy fluid, degrading performance by causing inefficient energy distribution and reduced compression efficiency.

Innovation Solution

The impeller design includes blades with specific sections inclined in opposite and forward directions to redirect secondary flows, dividing them into tangential and normal components, thereby preventing flow away from the disc and optimizing energy use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the blade is designed with conventional single-direction inclination, then the compression efficiency is maintained, but the secondary flow flowing away from the disc cannot be suppressed

Engineering Contradiction:

Improvesecondary flowVSAvoidenergy loss

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The blade is divided into multiple sections along the flow direction: a first section with a first inclination angle directing flow toward the disc, and a second section with a second inclination angle directing flow forward. This segmentation allows different parts of the blade to perform different functions - the first section suppresses secondary flow by redirecting it toward the disc, while the second section maintains compression efficiency by preserving forward flow direction.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of having the entire blade inclined in the forward direction (conventional design), the first section of the blade is inclined in the opposite direction (toward the disc) to counteract the harmful secondary flow. This inversion of the inclination direction in the critical region near the disc effectively suppresses the secondary flow that was previously flowing away from the disc.

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If the blade section is inclined toward the opposite direction of rotary direction, then secondary flow is suppressed, but compression efficiency may be reduced

Engineering Contradiction:

Improvesecondary flowVSAvoidcompression efficiency

Core Design Contradiction:

Object-affected harmful factorsVSPower

Solution Approach 1:

The blade is segmented into a first section for suppressing secondary flow and a second section for maintaining compression efficiency. The first section is inclined toward the disc to redirect secondary flow, while the second section continues in the forward direction to receive the pressing force of the fluid and maintain effective compression.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the blade are given different inclination characteristics suited to their local function. The first section near the disc has an inclination toward the disc to address the local problem of secondary flow accumulation, while the second section has an inclination toward the forward direction to optimize the local compression function where the fluid pressing force acts.

Inventive Principle:

Principle #3Local quality

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 effectively suppresses secondary flows, enhances energy distribution, and maintains compression efficiency by utilizing the fluid's pressing force, improving overall performance of the centrifugal rotary machine.

Implementation Method 1

the secondary flow is divided into a tangential direction component at a point at which the secondary flow comes into contact with the first section and a normal direction component that is a component perpendicular to the tangential direction component and pushing the secondary flow toward the first section

Methodology Applied

Scientific EffectFlow division into components:

Implementation Method 2

it is possible to receive a pressing force of the fluid from the forward direction of the rotary direction

Methodology Applied

Scientific EffectPressure force: Pressure Gradient

Data Source

PatentEP2918848B1Impeller for centrifugal rotary machine, and centrifugal rotary machine

Publication Date: 2018.06.06 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP

Figure 1
Figure 2
Figure 3

AI summary

An impeller for a centrifugal rotary machine has a plurality of blades (4) arranged at intervals in a circumferential direction on a face facing a direction of an axis of a disc (3) formed in a discoid shape about the axis, wherein the blades (4) each include a first section (10A) rising from the disc (3) and inclined toward an opposite direction of a rotary direction (R) as the distance from the disc and a second section (11A) continuing from the first section (10A) and inclined toward a forward direction of the rotary direction (R) as the distance from the disc (3) between the leading edges and the trailing edges in the blades (4).