Corrugated Disk Web for Deliberate Mistuning in Turbomachine Blades
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Solution Overview
Problem
Existing methods for deliberately mistuning bladed wheels in turbomachines to prevent flutter often degrade aerodynamic performance, leading to unfavorable effects on turbomachine efficiency.
Innovation Solution
A bladed wheel design featuring a disk with a corrugated web that introduces deliberate detuning by modifying the geometry of the disk, creating frequency separation between blades without altering the blades' geometry or material, thereby stabilizing the wheel against flutter while maintaining aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blades with different natural frequencies are introduced by modifying blade geometry or material, then deliberate mistuning is achieved and flutter is reduced, but aerodynamic performance is degraded
Solution Approach 1:
The invention segments the mistuning function between the blades and the disk. The blades remain identical and aerodynamically optimized, while the disk web is corrugated to modify the natural frequencies of the blade assembly. This segmentation allows the blades to maintain optimal aerodynamic geometry while the disk provides the frequency modulation needed for mistuning.
Solution Approach 2:
The corrugated disk web acts as an intermediary element that transfers vibrational energy between blades and introduces deliberate frequency differences. Instead of modifying the blades directly, the corrugated web mediates the dynamic interaction, coupling the blades in a way that creates frequency disparity and stabilizes against flutter while preserving blade aerodynamics.
2Reliability
If blade geometry or material is modified to achieve frequency separation, then deliberate detuning is achieved, but manufacturing complexity increases
Solution Approach 1:
The invention separates the frequency modulation function from the blade manufacturing process. All blades remain identical and can be manufactured using standard processes, while the frequency differentiation is achieved through the corrugated disk web, which is manufactured separately and assembled with the identical blades.
Solution Approach 2:
Instead of modifying each blade individually to achieve frequency separation, the invention inverts the approach by keeping blades identical and modifying the disk structure. The corrugations in the disk web create the frequency differences indirectly, reversing the conventional approach of direct blade modification.
3Stability of the object's composition
If conventional deliberate mistuning methods are used, then flutter stability is improved, but aerodynamic efficiency is reduced
Solution Approach 1:
The invention applies local quality changes to the disk web rather than the blades. The corrugations are localized to specific regions of the disk web, creating spatially varying stiffness that modifies natural frequencies locally. This allows frequency modulation without affecting the overall aerodynamic quality of the blades.
Solution Approach 2:
The invention changes physical parameters of the disk web (geometry, stiffness distribution through corrugations) to achieve frequency separation. By modifying the disk web parameters rather than blade parameters, the aerodynamic performance parameters of the blades remain unchanged, resolving the contradiction between stability and efficiency.
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 stabilizes the bladed wheel against flutter by increasing aero-elastic damping without impacting the blades' aerodynamic performance, achieving the desired frequency separation and minimizing manufacturing complexity.
Implementation Method 1
Bladed wheels are subject to multiple vibrational phenomena, the sources of which can be aerodynamic and/or mechanical.
Implementation Method 2
Such a frequency disparity allows stabilizing the bladed wheel with respect to flutter by increasing its aero-elastic damping.
Implementation Method 3
Flutter is linked to the interaction between the blades and the fluid passing through them. In fact, when the turbomachine is operating, the blades, while the fluid is passing through them, modify its flow. In return, the modification of the flow of the fluid passing through the blades has the effect of exciting them in vibration.
Data Source
AI summary
A bladed wheel of a turbomachine includes a disk extending around a longitudinal axis, in a median plane, and blades distributed regularly around the longitudinal axis and extending radially from the disk. The disk includes a web corrugated alternately upstream and downstream of the median plane, so as to introduce a deliberate detuning of the bladed wheel.