Impeller Blade Morphology for Centrifugal Compressor Efficiency

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Solution Overview

Problem

Centrifugal compressors suffer from inefficiencies in fluid compression due to gaps between impeller blades and the shroud, as well as fluid near the hub not being effectively compressed, leading to decreased performance and higher fuel costs.

Innovation Solution

The impeller design features blades with a curved root and tip portion and a substantially linear mid-portion, which creates a pressure differential and radial body forces to draw low-energy air from gaps and near the hub towards the mid-portion for efficient compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional impeller blades with linear or simple curved profiles are used, then the manufacturing is simple, but fluid compression efficiency is poor due to churning and shearing in gap and hub regions

Engineering Contradiction:

Improveblade manufacturing simplicityVSAvoidfluid compression efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The impeller blades are designed with curved profiles instead of linear or simple curved shapes. Specifically, the blades have a first curved portion near the hub, a second curved portion near the tip, and a substantially linear mid-portion, creating a complex curved geometry that optimizes fluid flow paths and eliminates churning and shearing effects in inefficient regions

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

Different portions of the blade have different geometric characteristics optimized for their specific functions: the root portion has a first curvature to address hub region flow, the mid-portion is substantially linear for efficient compression, and the tip portion has a second curvature to address gap region flow. This local optimization of blade geometry throughout its length resolves the contradiction between manufacturing simplicity and compression efficiency

Inventive Principle:

Principle #3Local quality

2Device complexity

If impeller blades extend without curved tip portions, then the blade structure is simpler, but fluid in the gap between blade tip and shroud churns or shears instead of compressing efficiently

Engineering Contradiction:

Improveblade geometry complexityVSAvoidenergy loss from fluid churning and shearing

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The tip portion of each blade is designed with a second curved portion that extends beyond a radial line from the axis of rotation. This curved tip geometry modifies the flow pattern in the gap region between the blade tip and shroud, preventing churning and shearing motions that cause energy loss, and instead directing fluid into efficient compression paths

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Productivity

If impeller blades have curved root and tip portions with linear mid-portion, then fluid compression efficiency is improved, but the blade design and manufacturing become more complex

Engineering Contradiction:

Improvecompression efficiencyVSAvoidblade morphology complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The blade is divided into three distinct segments along its length: a root portion with a first curved profile, a mid-portion that is substantially linear, and a tip portion with a second curved profile. Each segment is optimized independently for its specific function, allowing the complex overall geometry to be broken down into manageable sections that can be manufactured using standard techniques while achieving superior compression efficiency

Inventive Principle:

Principle #1Segmentation

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 airflow and compression efficiency, increasing the working mass of air and reducing fuel costs by ensuring more effective use of fluid energy within the compressor.

Implementation Method 1

creates a pressure differential and radial body forces to draw low-energy air from gaps and near the hub towards the mid-portion

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Implementation Method 2

creates a pressure differential and radial body forces to draw low-energy air from gaps and near the hub towards the mid-portion

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

The impeller, which includes a plurality of blades extending from a hub, rotates to accelerate the fluid. The pressure associated with the fluid increases as the fluid is accelerated by the blades

Methodology Applied

Scientific EffectKinetic energy conversion:

Data Source

PatentUS10221858B2Impeller blade morphology

Publication Date: 2019.03.05 ROLLS ROYCE CORP

AI summary

According to one aspect, an impeller comprises a hub and a plurality of blades extending from the hub. At least one blade includes a curved root portion proximal the hub, a curved tip portion disposed at an outer blade location, and a mid-portion intermediate the root portion and the tip portion. The mid-portion is substantially linear.