Variable-Pitch Propeller Blade Closure Means for Turbomachine Noise Reduction

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Solution Overview

Problem

Unducted fan turbine engines experience high operating noise levels and reduced propulsive efficiency due to aerodynamic interactions between counter-rotating propellers, particularly caused by turbulence at the base of variable-pitch vanes during specific flight phases like take-off and landing, where empty spaces between the vane base and hub exacerbate turbulent activity.

Innovation Solution

The vanes are equipped with retractable closure means that can occupy either a deployed position to fill the empty space between the vane base and the hub, or a retracted position, effectively reducing turbulence and noise by conforming to the hub shape, thereby improving aerodynamic performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable-pitch vanes are mounted on the hub to adjust angular pitch for different operating conditions, then the adaptability of the propeller is improved, but empty spaces are formed between the vane base and hub which increase turbulence and noise

Engineering Contradiction:

Improveangular pitch adjustment capabilityVSAvoidturbulence and noise at vane base

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The vane assembly is segmented into the vane body and a separate closure element. The closure element can be deployed to fill the empty space between the vane base and hub, or retracted to allow variable pitch adjustment. This segmentation allows the system to achieve both adaptability through pitch change and turbulence reduction through selective closure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The closure element is designed to be movable between deployed and retracted positions. This dynamic capability allows the system to adapt its configuration based on operating conditions: retracted during pitch adjustment for versatility, and deployed during operation to eliminate turbulence and noise from empty spaces.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the vanes are fixed at certain angular pitches for specific flight phases, then the propulsive efficiency is improved, but the turbulence at the vane base increases due to empty spaces, causing noise emissions

Engineering Contradiction:

Improvepropulsive efficiencyVSAvoidnoise emissions from turbulence

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The closure element is deployed in advance to fill the empty space between the vane base and hub before the propeller operates at a fixed pitch angle. This preliminary action prevents turbulence and noise from developing during the flight phase, maintaining both propulsive efficiency and low noise emissions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The empty space that causes harmful turbulence is converted into a beneficial feature by filling it with the closure element. This transforms the problematic void into a streamlined configuration that improves aerodynamic performance and reduces noise, turning a harmful condition into a beneficial one.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-generated harmful factors

If the closure means are deployed to fill the empty space, then the turbulence is reduced and noise is minimized, but the device complexity increases

Engineering Contradiction:

Improveturbulence and noise reductionVSAvoidstructure with retractable closure means

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

Instead of modifying the entire propeller system, the closure element is applied locally only at the base of each vane where the empty space problem occurs. This localized solution addresses the specific turbulence and noise issue without requiring complex modifications throughout the entire propeller structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The closure element acts as an intermediary component between the vane base and the hub. It fills the gap without requiring direct modification of either the vane or hub structures, providing a simple mechanical solution that reduces turbulence and noise while adding minimal complexity to the overall system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9481449B2Blade, particularly variable-pitch blade, propellor comprising such blades and corresponding turbomachine

Publication Date: 2016.11.01 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A blade, configured to be mounted on a hub of a turbomachine propeller so that an empty space is defined between a base of the blade and a face of the hub facing the base. The blade includes a retractable blanking mechanism configured to reversibly occupy at least one of following two positions: a deployed position in which the retractable blanking mechanism at least partially closes off the empty space; and an extreme retracted position in which the retractable mechanism is kept out of the empty space.