Complex Screw Rotor Geometry for Radial Leakage Reduction

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Solution Overview

Problem

Conventional screw compressors have limitations in efficiency and performance due to constant rotor profiles and diameters, leading to radial leakage, blow holes, and suboptimal compression ratios.

Innovation Solution

The design introduces variable helical profiles and outer diameters for both male and female rotors, with sections transitioning to circular cross-sections, and the use of double helix configurations with curved transitions and pockets to enhance compression efficiency and reduce leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional constant rotor profiles and diameters are used, then the compressor structure is simple, but radial leakage increases and compression efficiency decreases

Engineering Contradiction:
Improverotor structure simplicityVSAvoidradial leakage
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The rotor profiles are designed with varying local characteristics - the outer diameter and helical profile parameters change along the axial length of the rotor. This allows different sections of the rotor to have optimized geometry for their specific function, reducing radial leakage in high-pressure regions while maintaining structural integrity throughout.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The rotor design transitions from static constant profiles to dynamic variable profiles where the outer diameter and helical parameters are functions of axial position. This dynamic geometry adapts to the changing pressure and flow conditions along the compression path, optimizing performance while managing leakage.

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If conventional constant rotor profiles are used, then manufacturing is easier, but compression ratio and efficiency are suboptimal

Engineering Contradiction:
Improverotor profile fabricationVSAvoidcompression efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The rotor design employs systematic parameter variations along the axial direction. The outer diameter, helical angle, and profile curvature are defined as varying parameters rather than constants, allowing optimization of compression efficiency and pressure ratio while maintaining manufacturability through defined functional relationships.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If variable helical profiles and outer diameters are introduced, then compression efficiency and pressure ratio increase, but rotor design and manufacturing complexity increases

Engineering Contradiction:
Improvecompression efficiencyVSAvoidrotor profile complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The rotor is divided into multiple axial sections, each with its own optimized helical profile and outer diameter parameters. This segmentation allows complex variable geometry to be managed through discrete sections with defined transition zones, balancing performance optimization with manufacturing feasibility.

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 configuration results in lower radial leakage, faster compression, higher efficiency, and increased internal pressure ratios, while simplifying the compressor design and reducing axial loads.

Implementation Method 1

the intermeshing male and female rotors form cells of varying sizes to first receive the inlet fluid and then compress, thus increasing the pressure of, the fluid as it moves toward the outlet

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP3368771B1Complex screw rotors
Publication Date: 2021.03.31 GARDNER DENVER INC
  • EP3368771B1 patent drawingFigure 1
  • EP3368771B1 patent drawingFigure 2
  • EP3368771B1 patent drawingFigure 3~4

AI summary

A compressor design includes a male rotor (10) having one or more helical lobes (12) and a female rotor (14) having one or more helical grooves (16). The male rotor is mounted on a first shaft and the female rotor is mounted on a second shaft. The male rotor is positioned in a first section of a chamber and the female rotor is positioned in a second section of the chamber. Fluid enters the chamber at an inlet, and when the rotors are driven, the lobes of the male rotor fit into the grooves of the female rotor, causing compression and movement of the fluid towards an outlet or discharge end where the compressed fluid is discharged. The configuration of the lobe and groove helix, the lobe and groove profile, and the outer diameter of the rotors can be varied in different combinations to form different rotors.