Gas Turbine Rotor Balancing Flange Protuberance Design
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Solution Overview
Problem
Existing methods for balancing gas turbine engine rotors, such as material removal and addition of balancing weights or rings, often result in increased weight and stress concentrations due to the need for oversized balancing flanges to accommodate various unbalance corrections, limiting the effectiveness and efficiency of rotor balancing.
Innovation Solution
A method involving the creation of a protuberance on an annular balancing flange by non-axisymmetrically removing material from the flange, rather than machining a traditional notch, to correct unbalance, allowing for customized corrections with reduced weight penalty and increased balancing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If material is removed by milling a groove into the rotor surface to correct unbalance, then unbalance correction is achieved, but high stress areas are created in the rotor
Solution Approach 1:
The patent applies asymmetry by creating a protuberance (adding material) instead of removing material to create unbalance correction. The protuberance is positioned at a specific location on the balancing flange with asymmetric geometry relative to the rotor axis, generating the required unbalance correction without creating stress concentrations associated with groove machining.
2Adaptability or versatility
If the rotor is over dimensioned to ensure sufficient depth of material for groove formation, then unbalance correction capability is improved, but significant weight is added to the rotor
Solution Approach 1:
The patent inverts the conventional approach by adding material (protuberance) rather than removing material (groove). This allows the balancing flange to be precisely dimensioned without requiring excessive material depth, as the protuberance can be created with minimal additional material or even by redistributing existing material, thereby avoiding significant weight penalties.
Solution Approach 2:
The patent changes the balancing parameter from negative (material removal depth) to positive (protuberance height). This allows for more efficient material utilization where the protuberance height can be precisely controlled to provide the required unbalance correction without requiring the balancing flange to be over-dimensioned to accommodate deep groove machining.
3Reliability
If balancing weights or rings are added to the rotor to correct unbalance, then unbalance correction is achieved, but significant weight is added to the rotor
Solution Approach 1:
The patent merges the balancing function with the existing balancing flange structure by creating a protuberance directly on the flange. This eliminates the need for separate balancing weights or rings, as the protuberance itself provides the unbalance correction. The balancing function is integrated into the flange geometry rather than being added as a separate component, thereby avoiding significant weight addition.
Data Source
AI summary
A gas turbine engine rotor including a disc adapted to be mounted for rotation about an axis, the disc including an annular balancing flange integrally connected thereto, the balancing flange having a first radial dimension around a first arc angle and a second radial dimension greater than the first radial dimension around a second arc angle, the second arc angle corresponding to 360 minus the first arc angle, the second arc angle being less than 180 degrees, the balancing flange around the second arc angle defining a protuberance, the protuberance being defined through machining of the balancing flange, the protuberance compensating for an unbalance of the rotor.