Variable Weight Dovetail Keys for Fan Rotor Balancing
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Solution Overview
Problem
Existing fan rotor balance weight configurations in turbomachinery are inadequate for removing unbalance caused by heavy blades, especially as fan bypass ratios increase, leading to potential mechanical loads and component failure.
Innovation Solution
Incorporating variable weight dovetail keys into the mechanical connection between fan blades and the rotor disk, allowing for precise adjustment of imbalance by inserting spacers with individually selected weights into dovetail slots, which form part of the mechanical joint, enabling more significant weight changes without disturbing the blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional trim bolts are used for balancing, then the rotor can be balanced to a limited extent, but the capability to remove unbalance caused by heavy blades is insufficient
Solution Approach 1:
The patent changes the weight parameter of the connection components (dovetail keys) to achieve balancing. By providing connection components with different weights, the system can compensate for blade weight variations more effectively than traditional trim bolts. The weight of the connection component is selected from a set of discrete weight values to achieve the desired balance.
Solution Approach 2:
The connection component serves multiple functions: it provides the mechanical connection between the blade and rotor disk, and simultaneously acts as a balance weight. This multi-functionality eliminates the need for separate trim bolts and enables greater weight adjustment capability for balancing.
2Reliability
If larger balance weights are used to correct heavy blade imbalance, then balancing capability improves, but the mechanical connection structure becomes more complex
Solution Approach 1:
The patent merges the connection function and the balancing function into a single component. The connection component (dovetail key) that mechanically connects the blade to the rotor disk also serves as the balance weight. This integration avoids the need for separate balance weights and complex installation procedures.
Solution Approach 2:
Instead of changing the structural complexity to achieve larger balance weights, the patent changes the weight parameter of the existing connection component. By selecting from a set of connection components with different weights, the system achieves greater imbalance correction capability without modifying the fundamental connection structure.
3Use of energy by moving object
If fan bypass ratio is increased to improve engine efficiency, then fan diameter increases, but the capability of existing balance weight configurations to remove unbalance decreases
Solution Approach 1:
The patent addresses the reduced balancing capability in high bypass ratio engines by changing the weight parameter of the connection components. The system provides connection components with a range of weight values, enabling effective balancing even when the fan diameter increases and the relative impact of balance weights decreases.
Data Source
AI summary
A turbomachinery rotor apparatus includes: a rotatable disk having an array of slots spaced around its periphery; an array of blades installed in the slots, wherein the blades have variable weights; and a plurality of connection components installed in the disk, each connection component forming a portion of a mechanical joint between one of the blades and its respective slot, wherein the connection components have variable weights.