Turbomachine Stator Vane Damping via Mass Variation
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Solution Overview
Problem
Existing turbomachine compressor rectifiers face mechanical stress issues, particularly at the leading and trailing edges of blades, which can lead to damage or breakage due to inadequate damping of vibrations.
Innovation Solution
An angular rectifier sector design with an outer shroud featuring axial end portions and a damping element that separates from the end portion during high vibration amplitudes, modifying the total moving mass and preventing resonance by changing the vibratory behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the leading and trailing edges of the blades are connected to thick and rigid parts of the outer shroud, then the structural strength is improved, but the mechanical stresses on the blade edges increase due to inadequate vibration damping
Solution Approach 1:
The patent applies the dynamics principle by making the connection zone between the blade and outer shroud movable rather than fixed. The blade edge is connected to the outer shroud through a damping element that allows relative movement, enabling the system to adapt to vibratory stresses dynamically. This movable connection reduces stress concentration on the blade edges while maintaining structural integrity.
Solution Approach 2:
The patent uses an intermediary element (damping element) between the blade edge and the outer shroud to resolve the contradiction. This damping element acts as a mediator that absorbs and dissipates vibratory energy, protecting the blade edge from high mechanical stresses while still providing adequate structural support. The intermediary element transforms the rigid connection into a controlled, stress-absorbing interface.
2Stress or pressure
If the rigidity at the root of the blades is reduced to optimize force transition, then the stress on blade edges is reduced, but sufficient damping at the connection zones is not provided to prevent breakage due to vibrations
Solution Approach 1:
The damping element serves as an intermediary component that simultaneously addresses both requirements: it reduces mechanical stress on the blade edges while providing adequate vibration damping. The damping element is specifically designed to absorb vibratory energy and dissipate it, preventing the transmission of harmful vibrations to the blade edges while maintaining a compliant connection that reduces stress concentration.
Solution Approach 2:
The patent applies parameter changes by modifying the mechanical properties of the connection zone. The damping element introduces controlled changes in stiffness and damping characteristics, allowing the connection to be neither too rigid nor too flexible. By adjusting the damping parameters of the intermediary element, the system achieves optimal stress reduction while maintaining sufficient vibration resistance.
3Reliability
If a damping element is added to modify the total moving mass and prevent resonance, then the vibratory behavior is improved, but the device complexity increases
Solution Approach 1:
The damping element is designed to perform multiple functions simultaneously: it provides vibration damping, modifies the total moving mass to prevent resonance, and maintains the structural connection between the blade and outer shroud. By integrating these multiple functions into a single component, the patent avoids the need for separate damping devices, mass modifiers, and connection elements, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the damping function with the structural connection function into a single integrated element. Rather than adding a separate damping device to an existing rigid connection, the damping element combines both the connection and damping roles, reducing the overall number of components. This merging approach achieves vibration damping and resonance prevention while minimizing the increase in structural complexity.
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
Effectively limits mechanical stresses on blade edges, reducing the risk of damage by damping vibrations and preventing resonance, thereby enhancing the durability of the rectifier sector.
Implementation Method 1
at least one added element forming a damper is adapted to come into contact with the end portion, and in that, beyond a given value of amplitude of vibration of the end portion, the damping element and the end portion are capable of moving relative to each other so as to vary the total moving mass which is fixed to the end portion and thus to modify the vibratory behavior of said end portion
Data Source
AI summary
A stator angular sector for a turbine engine compressor including: an outer shroud and an inner shroud, and at least one vane extending radially between the shrouds. The outer shroud includes first and second mounting mechanisms for mounting the stator angular sector on a casing of the engine, which mechanisms are oriented parallel to the axis in opposite directions and connected together by an intermediate portion. The outer shroud includes at least one axial end portion extending from the intermediate portion with which at least one damper-forming insert is configured to come into contact, such that beyond a given value for amplitude of vibration of the end portion, the damper insert and the end portion are configured to move relative to each other to vary total moving mass moving with the end portion, thereby modifying vibratory behavior of the end portion.