Rotor Blade Compound Lean Contour Vibration Detuning
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Solution Overview
Problem
Gas turbine engines experience airfoil vibration issues due to resonance between engine order frequencies and natural resonance frequencies, leading to component damage, reduced efficiency, and noise, which existing dampers and designs fail to adequately address.
Innovation Solution
The rotor blade features a compound lean contour at the trailing edge, comprising positive and negative lean sections that increase local bending stiffness, detuning the natural frequency of the blade to avoid resonance with engine order frequencies and reducing fluid leakage, thereby preventing harmful vibrations and enhancing engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If attachable dampers are used to manage vibration, then vibration control is improved, but device complexity and component reliability are worsened due to additional parts that can fail
Solution Approach 1:
The invention extracts the vibration control function from separate attachable dampers and integrates it directly into the airfoil structure through a contoured trailing edge. The contour itself acts as the damping mechanism, eliminating the need for additional damper components and their associated fasteners and mounting hardware.
Solution Approach 2:
The invention merges the structural airfoil with the vibration damping function by incorporating a contoured trailing edge directly into the airfoil. This combines what were previously separate components (airfoil and damper) into a single integrated structure, reducing part count and potential failure points.
2Object-affected harmful factors
If attachable dampers are used to manage vibration, then vibration control is improved, but component reliability is worsened due to additional failure points
Solution Approach 1:
The invention removes the separate damper components and their associated mounting hardware, retaining only the essential vibration control function integrated into the airfoil structure. This eliminates multiple potential failure points related to fasteners, mounting brackets, and separate damper units.
Solution Approach 2:
The airfoil structure serves its own vibration control needs through the contoured trailing edge, eliminating the need for separate vibration control components. The structure is self-sufficient for both aerodynamic function and vibration management.
3Object-affected harmful factors
If natural frequency is detuned to avoid resonance, then harmful vibrations are reduced, but blade stiffness characteristics must be precisely controlled
Solution Approach 1:
The invention applies a contoured trailing edge at a specific location on the airfoil to locally modify bending stiffness. This localized contouring achieves the desired frequency detuning effect without requiring precise control of the entire blade structure, simplifying manufacturing tolerances.
Solution Approach 2:
The invention changes the geometric parameters of the trailing edge contour to achieve the desired natural frequency detuning. By adjusting the contour shape, the bending stiffness and consequently the natural frequency can be tuned to avoid resonance conditions.
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 compound lean contour effectively shifts the natural frequency of the rotor blade beyond the operating speed range, preventing resonance-induced vibrations and improving engine efficiency by reducing fluid leakage, thus extending component lifespan and performance.
Implementation Method 1
High amplitude vibration can arise when engine order frequencies (determined by the rotational speeds of the gas turbine) coincide with airfoil natural resonance frequencies
Implementation Method 2
the contoured trailing edge, which increases local bending stiffness at the trailing edge, detunes the natural frequency of the rotor blade
Implementation Method 3
In addition, the compound lean contour reduces fluid leakage across the blade tip, improving engine efficiency
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A rotor blade comprises a blade platform and an airfoil. The airfoil comprises a blade tip, a leading edge, and a trailing edge with a stiffening compound lean contour. The blade tip is radially opposite the blade platform, and defines a blade span between the blade itself and the blade platform. The leading and trailing edges extend from the blade platform to the blade tip to define blade chords between the leading edge and the trailing edge. The compound lean contour comprises a positive lean section located at the lean tip, and extending along a lean axis to a lean end. The negative lean section is located radially inward of the positive lean section, and extends along the lean axis to the lean end.