Axially Permeable Chambers for Turbo Compressor Stability

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Solution Overview

Problem

Current circulation structures for turbo compressors, such as 'casing treatments' and 'hub treatments,' face challenges in stabilizing aerodynamic flow at rotor blade and hub vane ends, leading to compressor surging and inefficiencies, particularly at part and full load.

Innovation Solution

The introduction of axially permeable chambers upstream of annular chambers in the main flow direction, with radial recesses, which allow axial flow without circumferential connection, inhibits the formation of fission vortices and redirects high-loss fluid to influence rotor-side inflow, creating counter-rotation and relocating flow obstructions to annular chambers with circumferential connections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If conventional circulation structures (casing treatments or hub treatments) are used, then the aerodynamic stability at rotor blade ends is improved, but three-dimensional flow losses increase and efficiency decreases

Engineering Contradiction:
Improveaerodynamic stabilityVSAvoidthree-dimensional flow losses
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The circulation structure is divided into multiple axially permeable chambers arranged upstream of the annular chamber. These chambers are segmented in the axial direction and allow flow penetration, creating a distributed flow control mechanism that reduces three-dimensional losses while maintaining stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces chambers that are permeable in the axial direction (third dimension) rather than only in the circumferential direction. This axial permeability allows flow to pass through the chambers from front to back, creating a new flow path dimension that reduces three-dimensional flow losses while maintaining aerodynamic stability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If circulation structures are added to stabilize flow, then compressor surge limit is improved, but device complexity increases

Engineering Contradiction:
Improvecompressor surge limitVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The axially permeable chambers are integrated with the existing annular chamber structure, merging the new flow control function with the existing circulation structure. This combination achieves enhanced surge margin without requiring completely separate complex systems.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The circulation structure serves multiple functions: it stabilizes aerodynamic flow, controls surge margin, and reduces three-dimensional losses all through the same integrated chamber system. The axially permeable chambers and annular chamber work together to achieve multiple performance goals simultaneously.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Stability of the object's composition

If flow obstruction areas are present in the main flow channel, then circulation is achieved, but flow losses increase

Engineering Contradiction:
Improveflow circulationVSAvoidflow losses
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The axially permeable chambers act as intermediary flow paths that allow controlled interaction between the main flow channel and the circulation system. Flow can penetrate through these chambers, mediating between the high-speed main flow and the recirculation zones, reducing abrupt flow separations and associated losses.

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 configuration reduces three-dimensional flow losses, enhances operational stability, and improves efficiency, especially at full load, while maintaining simplicity and low manufacturing costs.

Implementation Method 1

a plurality of axially permeable chambers are positioned upstream of the or each annular chamber, viewed in the main flow direction of the main flow duct, with a radial recess being formed in relation to the main flow duct in the region of the axially permeable chambers

Methodology Applied
Scientific EffectAxial flow:

Implementation Method 2

A recirculation flow that forms uses high-loss fluid to influence the inflow of components on the rotor side, with the geometric properties of the chambers through which flow can take place in the axial direction without a circumferential connection generating a counter-rotation

Methodology Applied
Scientific EffectCounter-rotation:

Implementation Method 3

an annular chamber through which flow can flow in the circumferential direction, with the or each annular chamber being positioned downstream of the chamber through which flow can flow in the axial direction

Methodology Applied
Scientific EffectCircumferential flow:

Data Source

PatentEP2242931B1Circulation structure for a turbo compressor
Publication Date: 2016.11.02 MTU AERO ENGINES GMBH
  • EP2242931B1 patent drawingFigure 1~2
  • EP2242931B1 patent drawingFigure 3~4
  • EP2242931B1 patent drawingFigure 5~6

AI summary

A circulation structure for a turbo compressor, in particular for a compressor of a gas turbine, is disclosed. The circulation structure includes at least one annular chamber that can be traversed in a circumferential direction, is concentric with a shaft of the turbo compressor in the region of the free blade ends of a blade ring, and radially borders a main flow channel. Several chambers that can be traversed in an axial direction are situated upstream of the or each annular chamber, when viewed from the main flow direction of the main flow channel.