Turbomachine Compressor Shrouds with Independent Suspension

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Solution Overview

Problem

Existing multistage turbomachine compressors face challenges in optimizing radial clearances between moving blades and the casing due to varying operating temperatures, rotor speeds, and radial vibration speeds across different compression stages, leading to inefficiencies and wear, as prior solutions like double-walled casings with rigidly connected inner walls limit independent adjustment of these clearances.

Innovation Solution

A multistage turbomachine compressor design featuring independently suspended shrouds for each annular row of moving blades and stator vanes within a double-walled casing, allowing for adjustable radial clearances tailored to each stage's specific conditions, ensuring optimal efficiency and operability by allowing independent adjustment of radial clearances based on weight, dimension, and temperature differences across stages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If compression stages are secured to one another via the inner wall of the casing, then structural stability is improved, but the ability to adjust radial clearances independently for each stage deteriorates

Engineering Contradiction:

Improvestructural stabilityVSAvoidindependent adjustment capability

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The inner wall of the casing is segmented into multiple independent shrouds, each surrounding a specific compression stage. Each shroud can be adjusted independently while remaining structurally connected to the outer wall through flexible suspension means, thus resolving the contradiction between structural stability and independent adjustability.

Inventive Principle:

Principle #1Segmentation

2Ease of manufacture

If radial clearances are adjusted uniformly across all compression stages, then manufacturing complexity is reduced, but compressor efficiency deteriorates due to inability to account for stage-specific variations

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcompressor efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

Each shroud is designed with specific local characteristics including varying weights, radial dimensions, and suspension stiffnesses tailored to the requirements of each compression stage. This allows optimal radial clearances to be achieved for each stage while maintaining a relatively simple overall manufacturing approach through modular shroud design.

Inventive Principle:

Principle #3Local quality

3Reliability

If the inner wall is made rigid to maintain structural integrity, then reliability is improved, but the ability to adapt to varying thermal and vibrational conditions across stages deteriorates

Engineering Contradiction:

Improvestructural integrityVSAvoidthermal and vibrational adaptation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The inner wall is transformed from a rigid structure to a dynamic one through the introduction of flexible suspension means (hairpins) that allow each shroud to move independently in response to thermal expansion and vibrational conditions. This maintains structural integrity while enabling adaptation to varying stage-specific conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The suspension means are designed with specific stiffness parameters and thermal expansion characteristics that allow the shrouds to adjust their positions dynamically. By varying the stiffness and thermal properties of each suspension means, the system adapts to different thermal and vibrational conditions across compression stages while maintaining overall structural reliability.

Inventive Principle:

Principle #35Parameter changes

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 compressor efficiency and turbomachine operability by enabling precise adjustment of radial clearances, minimizing friction and wear, and maintaining gas flow continuity, thereby improving performance across varying operating speeds.

Implementation Method 1

suspension means that are flexible or deformable, and referred to as hairpins

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

By injecting air into the casing, it is also possible to ventilate the hairpins so as to modify their thermal expansion and thereby adjust the radial clearances

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS7651317B2Multistage turbomachine compressor

Publication Date: 2010.01.26 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A multistage compressor for a turbomachine, in particular an airplane turboprop or turbojet, the compressor comprising a double-walled casing having an inner wall made up of shrouds surrounding respective annular rows of moving blades and annular rows of straightening stator vanes, said shrouds being connected to the outer wall of the casing by independent suspension means enabling the radial clearances between the outer ends of the moving blades and the shrouds of the inner wall of the casing to be adjusted independently from one compression stage to another.