Outer Guide Vane Profile for Unducted Rotor Flow Straightening

Solution Overview

Problem

Existing unducted turbine engines face issues with decreased aerodynamic performance, increased noise levels, and mechanical stresses at the blade tip due to the low solidity of outer guide vanes, which are exacerbated by loading the propeller at the blade head.

Innovation Solution

An outer guide vane design with a specific deviation profile ranging from 20° to 45° at the radially inner boundary and 10° to 40° at the tip, along with a decreasing and increasing deviation pattern across the blade height, to improve airflow straightening and reduce mechanical stresses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the propeller is loaded at the blade head to maximize work and increase flow deviation, then the driving thrust is improved, but the outer guide vane must make a strong deviation to re-axialize the air flow, which increases mechanical stresses and reduces aerodynamic performance

Engineering Contradiction:

Improvedriving thrustVSAvoidmechanical stresses at blade tip

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

The patent applies different deviation angles to different sections of the outer guide vane blade. The radially inner boundary has a higher deviation angle (20°-45°) to effectively straighten the flow, while the blade tip has a lower deviation angle (10°-40°) to reduce mechanical stresses. This local differentiation resolves the contradiction by optimizing each section for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the deviation parameter along the blade height, creating a gradient from higher deviation at the root to lower deviation at the tip. This parameter variation allows the vane to achieve both effective flow straightening and reduced mechanical stresses simultaneously.

Inventive Principle:

Principle #35Parameter changes

2Power

If the propeller is loaded at the blade head to increase flow deviation, then the driving thrust is improved, but the solidity of the outer guide vane at the blade tip is reduced, which decreases aerodynamic performance and increases noise level

Engineering Contradiction:

Improvedriving thrustVSAvoidnoise level

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent applies different deviation angles to different sections of the outer guide vane blade. The radially inner boundary has a higher deviation angle (20°-45°) to effectively straighten the flow, while the blade tip has a lower deviation angle (10°-40°) to reduce mechanical stresses. This local differentiation resolves the contradiction by optimizing each section for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the deviation parameter along the blade height, creating a gradient from higher deviation at the root to lower deviation at the tip. This parameter variation allows the vane to achieve both effective flow straightening and reduced mechanical stresses simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Power

If the propeller is loaded at the blade head to increase flow deviation, then the driving thrust is improved, but the lower solidity of the outer guide vane at the blade tip reduces its ability to straighten the flow, which decreases aerodynamic performance

Engineering Contradiction:

Improvedriving thrustVSAvoidaerodynamic performance

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The patent applies different deviation angles to different sections of the outer guide vane blade. The radially inner boundary has a higher deviation angle (20°-45°) to effectively straighten the flow, while the blade tip has a lower deviation angle (10°-40°) to reduce mechanical stresses. This local differentiation resolves the contradiction by optimizing each section for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the deviation parameter along the blade height, creating a gradient from higher deviation at the root to lower deviation at the tip. This parameter variation allows the vane to achieve both effective flow straightening and reduced mechanical stresses simultaneously.

Inventive Principle:

Principle #35Parameter changes

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

Enhances aerodynamic performance and reduces noise generation while minimizing mechanical stresses at the blade tip, thereby optimizing the thrust-generating assembly's efficiency.

Implementation Method 1

a deviation (δ) of the profile, corresponding to an absolute value of a difference between a tangent to the skeleton at the leading edge and a tangent to the skeleton at the trailing edge of the blade

Methodology Applied

Scientific EffectAerodynamic deviation: Aerofoil

Data Source

PatentUS20250354501A1Unducted thrust-generating assembly comprising an outer guide vane

Publication Date: 2025.11.20 SAFRAN AIRCRAFT ENGINES SAS

AI summary

The present invention relates to a flow-straightening stator (5) of an unducted thrust-generating assembly (3) comprising a plurality of blades (7) each having: —a tip (11) and a radially inner boundary (10) corresponding to an intersection between the blade (7) and a casing (8) of the turbine engine (1); —a skeleton (16); and—a deviation (S) of the profile, corresponding to an absolute value of a difference between a tangent to the skeleton (16) at the leading edge (14) and a tangent to the skeleton (16) at the trailing edge (15) of the blade (7), of between 20° and 450 at the radially inner boundary (10) of the blade (7) and between 10° and 40° at the tip (11) of the blade (7).