Open Rotor Blade Pitch Control for Excitation Load Mitigation

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Solution Overview

Problem

Open rotor aeronautical engines face challenges with airfoil excitation phenomena that cause aerodynamic forces affecting operational performance and structural requirements, leading to excitation loads on airfoils, bearing assemblies, and support structures.

Innovation Solution

Implementing a control system with sensors to determine airfoil excitation phenomena and excitation loads, using electronic controllers to adjust the pitch angles of airfoils and modify fuel flow to compensate for these loads, thereby augmenting and compensating for excitation loads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the outer nacelle is removed to facilitate a larger fan, then fan size and propulsive efficiency are improved, but off-axis airflow causes airfoil excitation loads and structural issues

Engineering Contradiction:

Improvepropulsive efficiencyVSAvoidairfoil excitation loads

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the airfoil pitch angles dynamically adjustable through pitch change assemblies. The control system continuously monitors excitation loads and adjusts pitch angles in real-time to compensate for off-axis airflow effects, transforming a static structure into a dynamically adaptive system that maintains stability despite removed nacelle protection

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of airfoil pitch angle to compensate for excitation loads. By varying the pitch angle parameter in response to detected excitation conditions, the system adjusts aerodynamic forces to counteract harmful effects of off-axis airflow, resolving the contradiction between improved propulsive efficiency and reduced excitation loads

Inventive Principle:

Principle #35Parameter changes

2Reliability

If excitation loads are compensated by adjusting airfoil pitch angles, then structural fatigue is reduced, but device complexity increases due to pitch change assemblies and control systems

Engineering Contradiction:

Improvecycle fatigue resistanceVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback through sensors that detect airfoil excitation phenomena and feed this information to the control system. The control system processes this feedback and adjusts pitch change assemblies accordingly, creating a closed-loop system that reduces structural fatigue while managing complexity through intelligent control rather than purely mechanical solutions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system performs multiple functions: it monitors excitation loads, determines appropriate compensation actions, and actuates pitch change assemblies. This multi-functional approach consolidates what could be separate complex systems into a unified control architecture, reducing overall device complexity while maintaining reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If real-time control is implemented to mitigate excitation loads, then operational performance is improved, but energy consumption increases due to active control mechanisms

Engineering Contradiction:

Improveoperational performanceVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by implementing control only when excitation loads are detected above certain thresholds. The system uses sensors to monitor conditions and activates pitch change assemblies only when compensation is needed, rather than continuously operating, thereby reducing energy consumption while maintaining operational performance

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The control system operates periodically based on detected excitation conditions rather than continuously. By monitoring and acting only when excitation phenomena occur, the system reduces energy consumption associated with constant actuation while maintaining the reliability benefits of load compensation during actual operating conditions

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12491988B2Controlling excitation loads associated with open rotor aeronautical engines

Publication Date: 2025.12.09 GENERAL ELECTRIC CO POLSKA SP ZOO

AI summary

An open rotor aeronautical engine may include a core engine, a plurality of unducted airfoils, and a pitch change assembly. The pitch change assembly may include an ensemble actuator assembly and a unitary actuator assembly. The ensemble actuator assembly may have one or more ensemble actuators and a unison ring that is movable by actuation of the one or more ensemble actuators to collectively change a pitch angle of the plurality of unducted airfoils. The unitary actuator assembly comprising a plurality of unitary actuators respectively coupled to a corresponding one of the plurality of unducted airfoils, the plurality of unitary actuators respectively movable to change the pitch angle of the corresponding one of the plurality of unducted airfoils.