Adjustable Counterweights for Stable Partially Bladed Rotor Testing

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Solution Overview

Problem

Gas turbine engines face challenges during the development phase of new blades due to limited availability and high cost, leading to mass centroid offset and asymmetrical mass moments of inertia, causing instability and vibrations during rotor tests.

Innovation Solution

A counter weight system for rotor modules, comprising a root, main body, and side portions with adjustable plates, is used to balance the mass and inertia, achieving a zero nominal imbalance and symmetrical moments of inertia, allowing for efficient testing of limited blade configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a partially bladed rotor is used for testing, then blade availability requirements are reduced and testing cost is decreased, but mass centroid offset and asymmetrical mass moments of inertia are introduced causing rotor instability

Engineering Contradiction:

Improvetesting costVSAvoidrotor stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

Counterweights are added to the rotor assembly to offset the mass centroid displacement caused by the missing blades. The counterweights are positioned and sized to create a balancing moment that compensates for the asymmetrical mass distribution, thereby restoring rotor stability during rotation.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent intentionally introduces asymmetrical counterweights to compensate for the asymmetrical blade configuration. By deliberately creating a controlled asymmetry in the counterweight distribution, the system achieves dynamic balance that mirrors the blade asymmetry, stabilizing the rotor despite the partial blade configuration.

Inventive Principle:

Principle #4Asymmetry

2Stability of the object's composition

If traditional fixed counter weight bodies are used, then rotor balance can be achieved, but manufacturing flexibility and adaptability are reduced

Engineering Contradiction:

Improvemass balanceVSAvoidweight adjustment flexibility

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The counterweight system is divided into modular components that can be independently adjusted. Instead of a single fixed counterweight body, the system uses segmented counterweights or adjustable mass elements that can be repositioned or reconfigured to achieve different balance requirements for various blade configurations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The counterweight system transitions from a static, fixed configuration to a dynamic, adjustable configuration. The counterweights can be moved, added, or removed to adapt to different testing scenarios and blade configurations, providing flexibility while maintaining mass balance through controlled adjustment.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250341438A1Apparatus and method for partially bladed rotor test

Publication Date: 2025.11.06 RTX CORP

AI summary

A counter weight for use with a rotor module, including: a root portion; a main body portion that extends away from the root portion; a pair of side portions each extending from opposite sides of the main body portion; and at least one plate secured to one of the opposite sides of the main body portion in order to adjust a weight of the counter weight.