Variable Outlet Guide Vanes for Gas Turbine Fan Airflow Distortion

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbine engine fan assemblies experience operability issues due to variations in intake airflow and pressure fluctuations, leading to inefficiencies and losses in fan inlet air direction and thrust generation.

Innovation Solution

A fan assembly with a circumferentially arranged fan duct, an inlet fan, and an outlet guide vane assembly featuring variable-pitch outlet guide vanes and actuation assemblies that adjust the direction of fan exit air to minimize losses caused by distortions and pressure fluctuations, using a control system to rotate the vanes to optimal angles based on operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the outlet guide vane assembly uses fixed-pitch vanes, then the structure is simple, but the ability to compensate for airflow distortions and pressure fluctuations is limited

Engineering Contradiction:

Improveability to compensate for airflow distortionsVSAvoidstructure of outlet guide vane assembly

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The outlet guide vanes are designed with variable pitch capability, allowing them to rotate about their leading edge pitch axes to different angles depending on operating conditions. This dynamic adjustment enables the vanes to adapt to varying airflow distortions and pressure fluctuations, resolving the contradiction between adaptability and structural simplicity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The pitch angle of the outlet guide vanes is changed as a variable parameter based on operating conditions. By adjusting the pitch angle, the system can optimize performance across different operating regimes, transforming a static structure into an adaptive one without completely redesigning the assembly

Inventive Principle:

Principle #35Parameter changes

2Loss of energy

If the leading edge portion redirects fan exit air in a single direction, then the control mechanism is simple, but losses from airflow distortions are not minimized

Engineering Contradiction:

Improvelosses from airflow distortionsVSAvoidcontrol mechanism of outlet guide vane

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The outlet guide vane is segmented into a leading edge portion and a trailing edge portion that can rotate independently about different pitch axes. This segmentation allows each portion to be controlled separately to optimize airflow direction and minimize losses, rather than moving the entire vane as a single unit

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the outlet guide vane (leading edge and trailing edge) are given different rotational capabilities about different pitch axes. This local differentiation allows each section to address specific airflow distortion patterns, improving energy efficiency without requiring complete redesign of the control mechanism

Inventive Principle:

Principle #3Local quality

3Productivity

If the fan assembly operates without outlet guide vanes, then the device complexity is reduced, but thrust efficiency and operability under varying conditions deteriorate

Engineering Contradiction:

Improvethrust efficiencyVSAvoidfan assembly structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The outlet guide vane assembly serves multiple functions: it redirects fan exit air, compensates for airflow distortions, adjusts for pressure fluctuations, and optimizes thrust generation. By consolidating these functions into a single assembly with variable-pitch capability, the system achieves high productivity without proportionally increasing overall complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution effectively redirects fan exit air to reduce losses and improve thrust efficiency by compensating for airflow distortions and pressure variations, enhancing the overall performance and operability of the gas turbine engine.

Implementation Method 1

The outlet guide vane assembly is configured to adjust a direction of the fan exit air received from the plurality of fan blades... the leading edge portion and the trailing edge portion are configured to rotate to a first arrangement... so as to redirect the fan exit air in a first direction and to minimize losses created by distortions in fan inlet air

Methodology Applied

Scientific EffectAerodynamic flow redirection:

Data Source

PatentUS11686211B2Variable outlet guide vanes

Publication Date: 2023.06.27 ROLLS ROYCE CORP

AI summary

A fan assembly includes a fan duct, an inlet fan, and an outlet guide vane assembly. The inlet fan forces fan exit air toward an aft end of the fan duct. The outlet guide vane assembly is located in the fan duct downstream of the inlet fan and adjusts a direction of the fan exit air, and includes a plurality of outlet guide vanes and a plurality of actuation assemblies that control rotation of the outlet guide vanes about a pitch axis. The outlet guide vanes include a leading edge portion and a trailing edge portion rotatably coupled to an axially aft edge of the leading edge portion. The actuation assembly rotates the leading edge portion and the trailing edge portion to minimize losses created by distortions in fan inlet air and created by the leading edge portion redirecting the fan exit air in the first direction.