AMPS Aeroelastic Model Reduces CFD Cost for Gas Turbine Flutter
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Solution Overview
Problem
Current methods for predicting rotor flutter in gas turbine engines are computationally expensive and require numerous large-scale calculations, limiting their efficiency and practicality for initial engine design, especially in modern aircraft with more flexible structures that are prone to flutter.
Innovation Solution
The Aeroelastic Model Using Principal Shapes of Modes (AMPS) reduces the number and size of computational fluid dynamics (CFD) calculations by defining a smaller set of principal shapes that span the structural mode shapes, capturing aerodynamic damping and structural coupling, and using linear superposition to construct an aerodynamic coupling matrix for predictive flutter analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct method with full CFD calculations is used for flutter prediction, then prediction accuracy and applicability to broader problems is improved, but computational cost and calculation time increases significantly
Solution Approach 1:
The patent segments the complete set of structural mode shapes into a reduced set of principal shapes that capture the essential aerodynamic behavior. By dividing the full mode shape space into dominant principal shapes, the method reduces the number of CFD calculations needed while maintaining prediction accuracy for flutter analysis.
Solution Approach 2:
The patent extracts only the most critical principal shapes from the complete set of structural modes that are most relevant to flutter prediction. This extraction allows the method to focus computational resources on the essential modes that drive aerodynamic damping, eliminating the need to compute all possible mode shapes.
2Loss of time
If reduced order models are used for flutter prediction, then computational cost and calculation time is reduced, but range of applicability and prediction accuracy is limited
Solution Approach 1:
The patent creates a universal set of principal shapes that can represent various structural modes across different rotor configurations and operating conditions. These principal shapes serve multiple functions: they capture aerodynamic damping, represent structural coupling, and adapt to different blade count and configuration scenarios, making the method widely applicable.
Solution Approach 2:
The patent uses parameter changes by adjusting the number and combination of principal shapes used in the model based on the specific problem requirements. The method can adapt the principal shape set to match different rotor configurations, blade counts, and operating conditions, maintaining both accuracy and computational efficiency across varied applications.
3Weight of moving object
If more flexible structures are used to reduce aircraft weight, then aircraft weight is reduced, but risk of flutter increases
Solution Approach 1:
The patent applies preliminary action by performing flutter prediction analysis during the design phase before actual engine operation or testing begins. By using the principal shapes method to predict aerodynamic damping and identify potential flutter conditions early in the design process, engineers can modify the structure proactively to prevent flutter issues before they occur during operation.
Data Source
AI summary
The Aeroelastic Model using the Principal Shapes of modes (AMPS) is a method used to predict flutter in gas turbine engines. Modern gas turbine engines often include rotors with flexible disks and/or significant blade geometry variations. The AMPS method accounts for the varying blade mode shapes associated with flexible disks as well as changing blade geometry, providing accurate flutter predictions for a large number of modes from a relatively small number of CFD (computational fluid dynamics) simulations. The AMPS method includes determining a smaller set of principal shapes that approximates a larger set of structural modes of interest. Using linear superposition, aerodynamic forces associated with the vibration of the principal shapes can be used to construct the full aerodynamic coupling matrix associated with the structural modes of interest. An eigenvalue equation is solved to determine a damping distribution associated with the structural modes of interest. The damping distribution is predictive of flutter.