Turbine Rotor Ferrule Cooling Air Separation
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Solution Overview
Problem
Turbine rotors in turbomachines face challenges with flange separation and high stresses in inter-disk bolted joints due to increasing operating temperatures and rotation speeds, and the inclusion of cooling air supply mechanisms complicates the design, especially in spool and drilled rotor types, where labyrinth rings are not feasible or add weight.
Innovation Solution
A turbine rotor design featuring first and second annular ferrules, where the second ferrules are radially coupled to disks and form spaces communicating with blade root recesses, allowing direct cooling air entry through calibrated through-holes without mixing with hot air streams, and incorporating features like annular ribs, protrusions, and snap rings for secure assembly and reduced mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a labyrinth ring is added to cooledisks rotor to supply cooling air, then cooling function is improved, but rotor weight increases substantially
Solution Approach 1:
The invention extracts the cooling air supply function from the traditional labyrinth ring structure and relocates it to the ferrule component. The ferrule, which already exists as a coupling element between disks and blades, is modified to include cooling air supply features, thereby eliminating the need for a separate labyrinth ring in spool rotors and reducing overall rotor weight.
Solution Approach 2:
The ferrule is designed to perform multiple functions simultaneously: it serves as the mechanical coupling element connecting disks and blades, and also as the cooling air supply mechanism. By integrating these functions into a single component, the invention eliminates the need for additional dedicated cooling structures that would increase weight.
2Reliability
If a labyrinth ring is added to drilled rotor to supply cooling air, then cooling function is improved, but device complexity increases
Solution Approach 1:
The invention merges the cooling air supply function with the existing ferrule structure in drilled rotors. Instead of adding a separate labyrinth ring, the ferrule is designed with integrated cooling features including through-holes and radial coupling to disks, thereby combining mechanical coupling and cooling air delivery into a single integrated component.
Solution Approach 2:
The ferrule serves dual purposes: as the structural coupling element between disks and blades, and as the cooling air distribution system. This multi-functionality eliminates the need for additional dedicated cooling structures, reducing overall device complexity.
3Reliability
If cooling air is supplied through conventional means, then cooling is provided, but cooling air mixes with hot stream air reducing cooling efficiency
Solution Approach 1:
The ferrule acts as an intermediary structure that delivers cooling air directly to the disk and blade root coupling portions through radially coupled pathways. This intermediary delivery system isolates the cooling air from the hot mainstream gas flow, preventing mixing and maintaining cooling air temperature effectiveness.
Solution Approach 2:
The cooling air supply is localized directly at the critical coupling portions between disks and blade roots. The ferrule delivers cooling air precisely where it is needed through through-holes and radial pathways, creating a localized cooling zone that prevents hot air mixing and maximizes cooling efficiency at the most stressed areas.
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 cooling efficiency by directly delivering cooling air to critical areas without heating, reduces mass and complexity, and prevents flange separation, thereby extending the lifespan of blade and disk coupling portions.
Implementation Method 1
each first ferrule includes through-holes which enable air to enter this space, and then the recesses, intended to cool the portion which couples its disk and the blade roots held in these recesses
Data Source
AI summary
A turbine rotor is fitted to a turbomachine and includes disks each containing a coupling portion with recesses each holding a root of a blade, and coupled to one another by a first annular ferrule attached to one of them close to the recesses, and second rotationally coupled ferrules, which are respectively coupled radially to the disks, which each consists of at least two semi-annular sectors, and which form with the associated disk a space which communicates with the recesses of the coupling portion of this latter disk. In addition, each first ferrule includes through-holes enabling air to enter this space, and then the recesses, intended to cool the coupling portion which couples its disk and the blade roots.