Variable Pitch Bladed Disc Asymmetry for Noise Reduction

Solution Overview

Problem

Turbine engine propellers with uniformly distributed blades generate significant noise during take-off and approach phases, limiting acoustic certification and application due to the emergence of tone components over wide band noise levels, causing discomfort to the human ear.

Innovation Solution

A bladed wheel with variable pitch blades, where each blade has a unique tilt and axis rotation, distributing acoustic energy across multiple frequencies to reduce noise emergence and perceived discomfort, allowing for untuning of blade interactions and maintaining the same geometrical shape for all blades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If blades are uniformly distributed with identical geometrical pitch, then manufacturing is simplified and aerodynamic efficiency is maintained, but noise lines emerge prominently causing discomfort and limiting acoustic certification

Engineering Contradiction:

Improveblade manufacturing simplicityVSAvoidnoise lines and acoustic discomfort

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by introducing different blade tilts for different blades within the same bladed wheel. Specifically, at least one first blade has a first tilt and at least one second blade has a second tilt that is different from the first tilt. This asymmetric configuration disrupts the uniform periodicity that causes tone components, thereby reducing acoustic discomfort while maintaining manufacturing feasibility through standardized tilt mechanisms.

Inventive Principle:

Principle #4Asymmetry

2Adaptability or versatility

If variable pitch control is implemented uniformly for all blades, then aerodynamic adaptability is improved, but noise reduction is limited due to persistent tone components

Engineering Contradiction:

Improveaerodynamic adaptabilityVSAvoidtone components and noise

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by assigning different tilt angles to different blades (first blades with first tilt, second blades with second tilt) while maintaining the same variable pitch control mechanism for all blades. This localized differentiation in tilt configuration disrupts the periodicity that generates tone components, enabling noise reduction while preserving aerodynamic adaptability through uniform pitch control.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If blade tilts are made unique for each blade, then noise lines are distributed across multiple frequencies reducing discomfort, but device complexity increases

Engineering Contradiction:

Improvenoise distribution and discomfortVSAvoidblade configuration complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent applies local quality by introducing different tilts for different blades (first blades with first tilt, second blades with second tilt) while maintaining the same variable pitch control mechanism for all blades. This localized differentiation in tilt configuration disrupts the periodicity that generates tone components, enabling noise reduction while preserving aerodynamic adaptability through uniform pitch control.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies asymmetry by introducing different blade tilts for different blades within the same bladed wheel. Specifically, at least one first blade has a first tilt and at least one second blade has a second tilt that is different from the first tilt. This asymmetric configuration disrupts the uniform periodicity that causes tone components, thereby reducing acoustic discomfort while maintaining manufacturing feasibility through standardized tilt mechanisms.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11591913B2Variable pitch bladed disc

Publication Date: 2023.02.28 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A variable-pitch bladed disc including a plurality of blades, each at a variable pitch in relation to a rotation axis of the blade and each having a root, the plurality of blades including at least one first blade and at least one second blade, a plurality of rotor connecting shafts, each having a root and a tip, each root being mounted at the tip of a corresponding rotor connecting shaft by way of a pivot so as to allow each blade to rotate about the blade rotation axis, the first blade having a first blade inclination, such that the first blade is inclined in a fixed manner with respect to the blade rotation axis of the first blade, and the second blade having a second blade inclination different from the first blade inclination.