Gas Turbine Rotor Damper Wedge for Anti-Sticking Friction Damping
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Solution Overview
Problem
Conventional friction damping arrangements in gas turbine engine rotors often result in the damper sticking to the rotor due to friction, hindering relative sliding and reducing vibration damping effectiveness, as energy dissipation contributes to vibratory stress rather than mitigating it.
Innovation Solution
A gas turbine engine rotor design featuring a split ring and damper configuration, where the split ring is resiliently expandable under centrifugal load, radially engaging a lip or conical ramping surface to axially load the damper against a seat, ensuring kinetic friction and effective energy dissipation for damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the damper is fitted to the rotor groove conventionally, then the damper is held in position, but the damper sticks to the rotor by friction causing it to deform together with the rotor as one solid body, hindering relative sliding and reducing vibration damping effectiveness
Solution Approach 1:
A split ring is introduced as an intermediary component between the damper and the rotor. The split ring engages with the rotor groove and applies a radial loading force on the damper, creating an axial contact force that enables controlled kinetic friction. This intermediary mechanism allows the damper to maintain relative sliding capability while still being positioned securely, converting the harmful static friction into useful kinetic friction for energy dissipation.
Solution Approach 2:
The invention changes the friction parameter from static friction (sticking condition) to kinetic friction (sliding condition) by introducing the split ring mechanism. The split ring modifies the contact conditions between damper and rotor, transforming the interaction from a rigid bonded state to a controlled sliding state where kinetic friction can occur, thereby enabling effective vibration damping through energy dissipation.
2Loss of energy
If the damper is constrained to prevent sticking, then relative sliding is maintained, but the damper requires additional loading mechanisms to ensure sufficient kinetic friction for effective energy dissipation
Solution Approach 1:
The split ring is designed to automatically generate the required axial loading force on the damper through centrifugal action. As the rotor rotates, the split ring experiences centrifugal force that causes it to expand radially and engage with the rotor groove, which in turn applies the necessary contact force on the damper. This self-service mechanism eliminates the need for external spring loading or adjustable fastening devices, achieving sufficient kinetic friction through the rotor's own rotational motion.
Solution Approach 2:
The loading mechanism is made dynamic rather than static. The split ring's engagement force with the damper is not fixed but varies with rotor speed due to centrifugal effects. At operational rotational speeds, the centrifugal force generates adequate axial loading to ensure sufficient kinetic friction for energy dissipation, while allowing the system to adapt to different operating conditions without complex adjustment mechanisms.
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 design enhances friction damping by allowing relative sliding between the damper and rotor, effectively dissipating vibratory energy and reducing stress, while maintaining the damper's radial freedom to prevent sticking and ensure efficient operation.
Implementation Method 1
the split ring radially engaging the lip at the rated axial location and resiliently expandable radially outwardly under centrifugal load relative to the rotation axis
Implementation Method 2
expanding the split ring radially against the lip axially deflects the split ring toward the seat so as to axially load the damper against the seat
Implementation Method 3
relative sliding, or kinetic friction, of the damper relative to the rotor is hindered and, as a result, so is the vibration damping potency of the damper
Data Source
AI summary
A gas turbine engine rotor having an axis, comprising: a body about the axis having an inner surface, a seat having an outer seat edge at a first radial location surrounded by the inner surface at a second radial location, a lip along the inner surface having an inner lip edge spaced axially away from the seat to define a gap, the lip at a rated axial location between the inner lip edge and the seat facing toward the seat at a normal angle; a damper in the gap having first and second damper surfaces, the first damper surface adjacent the seat; and a split ring in the gap adjacent the second damper surface, having an outer ring edge spaced from the inner surface, engaging the lip at the rated axial location and resiliently expandable against the lip deflects the split ring to load the damper against the seat.