Turbine Propeller Vibration Reduction via Tangential Offsets
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Solution Overview
Problem
Turbine engine propellers experience high vibrational amplitudes due to turbulence from coupling structures, leading to resonances and vibrational instabilities, which are costly and time-consuming to address during the design and fine-tuning phases.
Innovation Solution
A method that involves calculating and reducing the synchronous forced response of propeller aerodynamic profiles by determining tangential geometric offsets to minimize the generalized aerodynamic force associated with fundamental modes of vibration, allowing for early control of vibrational levels during the design phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the propeller operates in the turbulence generated by the coupling structure, then the turbine engine can function, but high vibrational amplitudes occur on the propeller airfoils
Solution Approach 1:
The patent modifies geometric parameters of the aerodynamic profiles (stacking offsets in the tangential direction) to change the phase of pressures exerted on the propeller, thereby reducing vibrational amplitudes while maintaining engine operation
Solution Approach 2:
The patent introduces asymmetric tangential offsets to the aerodynamic profiles relative to the propeller rotation axis, creating an asymmetric configuration that reduces synchronous forced response and vibrational amplitudes
2Object-affected harmful factors
If fine-tuning of the propeller disk is performed to reduce vibrational levels, then vibrational amplitudes decrease, but the design process becomes particularly protracted and costly
Solution Approach 1:
The patent applies tangential offsets to aerodynamic profiles during the initial design phase rather than performing iterative fine-tuning after engine tests, thereby reducing vibrational levels before the propeller enters the testing and adjustment cycle
Solution Approach 2:
The patent skips the traditional iterative fine-tuning process by directly implementing offsetted aerodynamic profiles in the design, thereby rushing through the design cycle without repeated testing and adjustment iterations
3Object-affected harmful factors
If the aerodynamic profiles are modified to reduce vibrations, then vibrational levels decrease, but aerodynamic performance may be compromised
Solution Approach 1:
The patent applies local tangential offsets to specific aerodynamic profiles at different radial positions on the propeller, allowing vibration reduction in specific areas while preserving overall aerodynamic performance through localized modifications
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
This approach effectively reduces vibrational levels without compromising aerodynamic performance or increasing weight, enabling more efficient design and fine-tuning of turbine engines by minimizing the modulus of the forced response to turbulence-induced vibrations.
Implementation Method 1
turbulence in the flow of gas along the turbine engine, generated by an obstacle close to said propeller
Implementation Method 2
vibrations on the aerodynamic profiles of a propeller sustaining a periodic excitation
Data Source
AI summary
A method for reducing the vibration levels capable of occurring, in a turbine engine including at least one propeller and one coupling structure of the turbine engine, because of the turbulence of aerodynamic origin generated by the coupling structure on the propeller. The method includes: defining an initial configuration of the aerodynamic profiles, calculating the synchronous forced response on the propeller as a function of the force of harmonic excitation generated by the coupling structure expressed in the form of a linear function of the generalized aerodynamic force for the mode in question, and determining a tangential geometric offset value θ of the individual aerodynamic profiles for stacked sections of one of the propeller or of the coupling structure in order to reduce the term corresponding to the generalized aerodynamic force. The combination of the sections with the tangential offsets therefore defines a new configuration of the aerodynamic profiles.