Gas Turbine Rotor Balancing via Nested Cavity Weights
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Solution Overview
Problem
Current methods for balancing gas turbine rotors, such as redistribution, removal, and addition of weight, are inadequate in achieving precise balance, particularly at high rotational speeds, leading to vibrations and stress issues, with existing weight addition methods being time-consuming and insufficient for restoring balance in larger assemblies.
Innovation Solution
A balanced rotor component with an axial slot and cavity system that houses a complementary profiled balance weight, allowing for precise placement and reduced stress concentration, utilizing a dovetail or fir-tree slot with a radially matching weight that can slide circumferentially and has obtuse angle lateral sides to prevent contact with slot walls at high stress points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If weight is added to correct rotor imbalance, then balancing precision is improved, but the complexity of the balancing apparatus and time consumption increase
Solution Approach 1:
The balance weight is nested within a cavity in the rotor component, with the weight positioned inside a defined space bounded by forward and rearward walls. This nested configuration allows the balancing apparatus to add weight without requiring external attachment mechanisms, thereby improving balancing precision while minimizing apparatus complexity and installation time.
2Ease of manufacture
If balance weight is placed in contact with slot walls at high rotational speeds, then weight distribution is simplified, but stress concentration and component durability worsen
Solution Approach 1:
The lateral sides of the balance weight are designed to be asymmetric relative to the slot walls, with intentional spacing that prevents contact at high stress points. This asymmetric positioning ensures that the weight does not concentrate stress on the slot walls during rotation, thereby maintaining component durability while still achieving effective weight distribution for balancing.
Solution Approach 2:
The balance weight features a localized radially inner surface that matches the base of the axial slot, providing precise weight distribution at the critical interface. This local quality match ensures optimal contact and weight distribution where needed, while the lateral sides are deliberately spaced from slot walls to avoid stress concentration, thus resolving the contradiction between manufacturing simplicity and component strength.
3Manufacturing precision
If traditional weight addition methods are used, then balancing capability is improved, but working time and productivity are reduced
Solution Approach 1:
The balance weight is pre-configured with a radially inner surface that matches the axial slot base, and the weight is designed to be inserted into a pre-defined cavity with forward and rearward walls. This preliminary preparation of both the slot and weight geometry enables rapid installation without requiring time-consuming fitting or adjustment procedures, thereby improving productivity while maintaining high balancing capability.
Data Source
AI summary
A balanced rotor component for a gas turbine engine having a aerofoil with a root and an rotor with an axial aerofoil root slot. The aerofoil root has a cavity which holds a balance weight. The cavity is open along at least one wall and the balance weight is spaced from the slot wall to minimise stress concentrations.