Annular Wiper with Radial Projection for Turbomachine Sealing

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Solution Overview

Problem

Thermal spraying for coating wipers in turbomachines is often uncertain or impossible due to geometrical arrangements, and existing coatings can be abrasive, leading to damage when wipers contact abradable materials.

Innovation Solution

A thermomechanical turbomachine part with a wiper of varying radial height, featuring radially projecting portions and a discontinuous profile, which acts as a cutting tool to engage abradable materials without the need for thermal spraying coatings, using a machining method involving a machine tool and U-shaped staples for extra thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal spraying is used to coat wipers with abrasive deposit, then wiper protection is improved, but manufacturing complexity and uncertainty increase due to geometrical constraints

Engineering Contradiction:

Improvewiper protectionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and removes the thermal spraying coating process entirely from the wiper system. Instead of applying protective coatings through complex thermal spraying, the patent uses the wiper's own material properties and geometric design (varying radial height with cutting portions) to achieve protection and sealing functionality, thereby eliminating manufacturing uncertainty related to coating deposition.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Rather than protecting the wiper by coating it with abrasive material (conventional approach), the invention inverts the approach by making the wiper itself from abrasive or cutting material with specific geometric features (radially projecting portions) that actively engage with and protect against the abradable sealing surface through controlled cutting action.

Inventive Principle:

Principle #13The other way round (Inversion)

2Duration of action of stationary object

If thermal spraying is used to deposit coating, then wiper durability is improved, but ease of manufacture deteriorates due to strict geometric requirements

Engineering Contradiction:

Improvewiper durabilityVSAvoidease of manufacture

Core Design Contradiction:

Duration of action of stationary objectVSEase of manufacture

Solution Approach 1:

The wiper is designed with self-service characteristics where its own structure (radially projecting portions of varying height) and material properties (abrasive or cutting material) enable it to maintain durability through controlled engagement with the sealing surface. The wiper's geometry allows it to self-regulate its interaction with the abradable material without requiring external coating processes.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention changes the critical parameters from coating deposition parameters (spray angle, distance, temperature) to wiper geometric parameters (radial height variation, projecting portion shape and distribution). This parameter transformation simplifies manufacturing by focusing on achievable geometric features rather than controlling complex thermal spraying processes.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If continuous blade wiper is used, then sealing function is improved, but harmful factors increase due to contact damage with abradable material

Engineering Contradiction:

Improvesealing functionVSAvoidwiper damage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The continuous blade wiper is segmented into distinct radially projecting portions with varying heights around the circumference. This segmentation creates discrete cutting elements rather than a continuous contact surface, allowing the wiper to engage the abradable material in a controlled cutting manner that prevents damage while maintaining sealing effectiveness through the distributed projecting portions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the wiper have different local qualities - the radially projecting portions are made of abrasive or cutting material with specific geometric features for engaging the sealing surface, while other portions may have different characteristics. This local differentiation allows the wiper to perform sealing functions in some areas while protecting against damage through controlled cutting action in specific localized regions.

Inventive Principle:

Principle #3Local quality

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

The wiper effectively cuts into abradable materials without thermal spraying, ensuring durability and functionality without the risks associated with abrasive coatings, and can be fabricated in various locations within the turbomachine.

Implementation Method 1

the wiper does not form a continuous blade of constant height, and because of the presence of distinct projecting portions, i.e. because of a wiper transverse profile having an outer outline that is not circular, it serves not only to perform a sealing function, but also acts like a 'cutting tool'

Methodology Applied

Scientific EffectMechanical cutting:

Data Source

PatentUS7857581B2Annular wiper for a sealing labyrinth, and its method of manufacture

Publication Date: 2010.12.28 SAFRAN AIRCRAFT ENGINES SAS

AI summary

The invention provides a thermomechanical turbomachine part that is circularly symmetrical about a longitudinal axis, in particular a rotor, the part including at least one annular wiper for a sealing labyrinth. In characteristic manner, the wiper presents height in the radial direction that varies around its circumference by forming a plurality of projecting portions.