Dynamic Compressor Shroud Clearance Control

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Solution Overview

Problem

Current axial compressors are costly to manufacture and operate, particularly for expendable applications, as material substitution alone is insufficient to achieve significant cost savings, and there is a need for improved designs that reduce manufacturing costs and prevent blade tip rub and leakage.

Innovation Solution

A compressor shroud assembly with a dynamically moveable shroud segment and actuator system that maintains a clearance gap between the shroud and blade tips, allowing for radial expansion and contraction of the shroud segment to control blade tip clearance, using a sensor to adjust the clearance based on operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If material substitution is used to reduce manufacturing cost, then cost is reduced, but manufacturing precision and reliability are compromised

Engineering Contradiction:

Improvemanufacturing costVSAvoidcomponent precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The shroud segment is made dynamically moveable rather than fixed, allowing it to adjust its position radially to maintain optimal blade tip clearance under varying operating conditions. This dynamic adjustment compensates for thermal expansion and manufacturing tolerances, maintaining precision without requiring expensive materials throughout the entire assembly.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameters of the shroud segment by enabling radial movement to adjust clearance gaps. This parameter adjustment allows the system to adapt to temperature and pressure changes, maintaining manufacturing precision through operational flexibility rather than relying solely on expensive materials with tight tolerances.

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If blade tip clearance is reduced to improve efficiency, then leakage is minimized, but blade tip rub and impingement risk increases

Engineering Contradiction:

Improveleakage lossVSAvoidblade tip clearance stability

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The actuator system provides active feedback control of the shroud segment position, sensing blade tip clearance conditions and automatically adjusting the shroud position to maintain optimal gap. This feedback mechanism prevents both excessive leakage and dangerous blade tip contact, dynamically optimizing the clearance under all operating conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The shroud segment transitions from a static to a dynamic component that can actively adjust its radial position. This dynamic capability allows the system to respond to changing operating conditions in real-time, maintaining safe clearance distances while minimizing leakage losses through continuous optimization.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If a fixed shroud design is used to simplify manufacturing, then device complexity is reduced, but adaptability to operating conditions is limited

Engineering Contradiction:

Improveshroud structure complexityVSAvoidclearance control capability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The shroud segment is designed with dynamic movement capability through the actuator mechanism, allowing it to adapt radially to different operating conditions such as thermal expansion and pressure changes. This dynamic feature provides adaptability without requiring complete redesign of the entire shroud structure, maintaining relative simplicity while adding functionality.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The shroud is segmented into movable and stationary portions, with only the specific segment requiring adaptability being made moveable. This segmentation allows the invention to add control capability to only where needed, rather than complicating the entire shroud structure, thus maintaining manufacturing simplicity while providing necessary adaptability.

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 solution reduces manufacturing costs, prevents blade tip impingement, and improves compressor efficiency by minimizing leakage, achieving cost savings and enhanced performance through simplified design and reduced fasteners and seal assemblies.

Implementation Method 1

The actuator operates to direct pressurized air into the annular chamber

Methodology Applied

Scientific EffectPressurized air flow: Pressure Gradient

Implementation Method 2

a sensor for measuring a clearance gap between the flowpath boundary member and the blade tips of the bladed disc and providing an output

Methodology Applied

Scientific EffectClearance measurement:

Data Source

PatentUS10794213B2Blade tip clearance control for an axial compressor with radially outer annulus

Publication Date: 2020.10.06 ROLLS ROYCE NORTH AMERICAN TECHNOLOGIES INC

AI summary

A compressor shroud assembly in a turbine engine having a dynamically moveable shroud for encasing a rotor segment. The rotor segment comprises a bladed disc. The compressor shroud assembly maintains a clearance gap between the shroud and the blade tips of the bladed disc. The assembly comprises a static compressor casing, a shroud mounted to the casing, and an actuator mounted to the casing. The shroud comprises a flowpath boundary member spaced radially inward from the casing, the flowpath boundary member being moveable relative to the casing in a radial direction. The actuator is coupled to the shroud for effecting the movement of the flowpath boundary member.