Open Rotor Guide Vane Pitch Control for Excitation Load Mitigation
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Solution Overview
Problem
Open rotor aeronautical engines experience 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 sensors to determine airfoil excitation phenomena and excitation loads, with electronic controllers providing control commands 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
Engineering Contradiction Analysis
1Productivity
If the outer nacelle is removed to facilitate a larger fan, then the fan size increases and propulsive efficiency improves, but off-axis airflow causes airfoil excitation phenomena and excitation loads on airfoils and support structures
Solution Approach 1:
The patent applies dynamics by making the airfoil pitch angles adjustable and variable during operation. The control system dynamically modifies pitch angles of individual airfoils based on detected excitation loads, transforming a static structure into a dynamic one that can adapt to changing flow conditions and mitigate excitation phenomena.
Solution Approach 2:
The patent changes the parameter of airfoil pitch angle to compensate for excitation loads. By varying the pitch angle of individual airfoils based on detected excitation conditions, the system modifies aerodynamic parameters to counteract harmful excitation effects while maintaining propulsive efficiency from the larger fan configuration.
2Reliability
If control systems are implemented to compensate for excitation loads, then excitation loads are mitigated and engine longevity is extended, but device complexity increases
Solution Approach 1:
The patent implements feedback by using sensors to detect airfoil excitation phenomena and feeding this information to a control system. The control system then adjusts airfoil pitch angles based on the detected excitation loads, creating a closed-loop feedback mechanism that automatically mitigates excitation effects and extends engine longevity.
Solution Approach 2:
The control system performs self-service by automatically detecting excitation loads through sensors and independently adjusting airfoil pitch angles to compensate for these loads. This self-regulating mechanism reduces the need for external intervention and simplifies operation while extending engine life.
3Use of energy by moving object
If fuel flow is modified to compensate for excitation loads, then propulsive efficiency improves and specific fuel consumption reduces, but control precision requirements increase
Solution Approach 1:
The patent changes fuel flow parameters in response to detected airfoil excitation loads. The control system modifies fuel flow rates to individual combustors based on excitation conditions, optimizing combustion efficiency and reducing specific fuel consumption while adapting to varying operational conditions.
Data Source
AI summary
An open rotor engine includes a core engine, a plurality of guide vanes positioned within or extending from the core engine; and a pitch change assembly operably coupled to the plurality of guide vanes. The pitch change assembly includes one or more actuators configured to change a pitch angle of respective ones of the plurality of guide vanes, and a plurality of linkage arms that are respectively movable by actuation of at least one of the one or more actuators. The plurality of linkage arms are directly or indirectly coupled to a corresponding one of the plurality of guide vanes. The plurality of linkage arms may have a length that differs from one another, and such length may orient a displacement or a range of motion of the respective linkage arm to an envelope of rotation about a guide vane axis that differs as between the plurality of guide vanes.