Off-Center Cooling Bore Reaming for Gas Turbine Rotor Cracks
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Solution Overview
Problem
Gas turbine engines face issues with material creep and cracking due to thermal stresses, and existing reaming methods for cooling bores require extensive downtime and high transport costs, as they cannot be performed in situ and affect efficiency by allowing excessive cooling air passage.
Innovation Solution
A cooling bore guide system comprising a cutter guide and guide lock allows for off-center reaming of rotor cooling bores without removing the rotor from service, using a semicircular cutter guide and guide lock to create an enlarged portion that reduces thermal stresses while maintaining efficiency by only increasing the bore diameter in the affected areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard reaming methods are used to enlarge cooling bores, then cracking issues are addressed, but extensive downtime and high transport costs occur
Solution Approach 1:
The rotor is serviced in-situ at the gas turbine location rather than being transported to external workshops. The cooling bore guide system is installed directly on the rotor while it remains mounted in the gas turbine, allowing the rotor to service itself without removal, thereby eliminating transport and extensive setup downtime.
Solution Approach 2:
The cooling bore guide is pre-assembled with cutter guides and guide locks before being installed on the rotor. The guide locks are positioned in adjacent cooling bores beforehand to ensure proper alignment and stability during the reaming operation, enabling quick deployment without extensive on-site preparation.
2Reliability
If cooling bore diameter is increased to address cracking, then thermal stress issues are reduced, but gas turbine efficiency decreases due to excessive cooling air passage
Solution Approach 1:
Instead of uniformly enlarging the entire cooling bore, the invention applies reaming only to specific localized sections where cracking has been detected. The cooling bore guide positions the cutting tool to remove material only in the affected areas, maintaining the original bore diameter in non-cracked sections and thus preserving gas turbine efficiency while still addressing thermal stress issues in damaged zones.
Solution Approach 2:
The reaming operation is applied partially rather than completely - only the portions of cooling bores that show signs of cracking are enlarged. This partial action approach provides sufficient relief for thermal stress management in affected areas without the excessive material removal that would occur with full-bore reaming, thereby minimizing the impact on gas turbine efficiency.
3Duration of action of stationary object
If cooling bores are reamed to prevent cracking, then component lifetime is extended, but transport costs and workshop requirements increase
Solution Approach 1:
The rotor is serviced in-situ at the gas turbine location rather than being transported to external workshops. The cooling bore guide system is installed directly on the rotor while it remains mounted in the gas turbine, allowing the rotor to service itself without removal, thereby eliminating transport and extensive setup downtime.
Solution Approach 2:
The cooling bore guide system is designed to be adaptable to different rotor configurations and cooling bore arrangements. The guide locks can be positioned in adjacent cooling bores to provide stable support for various bore patterns, making the system universally applicable to different gas turbine rotor designs without requiring custom tooling for each configuration.
4Manufacturing precision
If standard reaming methods are used, then cooling bores can be enlarged, but the rotor must be removed from service and transported to workshops
Solution Approach 1:
The cooling bore guide acts as an intermediary device that bridges the cutting tool and the rotor cooling bores. It includes cutter guides that fit into selected cooling bores and guide locks that engage adjacent bores, creating a stable reference framework that enables precise reaming operations directly on the installed rotor without removal or external workshop equipment.
Solution Approach 2:
The invention transitions from external workshop-based reaming to in-situ reaming by adding the dimensional aspect of on-machine tooling. The cooling bore guide system provides the necessary rigidity and positioning capability directly on the gas turbine rotor, enabling precision work in the original installation context rather than requiring removal to a different location.
Data Source
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AI summary
The present application provides a cooling bore guide (120) for reaming an enlarged portion (100) into a cooling bore (280) of a rotor (45). The cooling bore guide (120) may include a cutter guide (130) for insertion into the cooling bore (280) and a guide lock (140) for insertion into an adjacent cooling bore (290).