Gas Turbine Rotor Blade Locking Sheet Metal Strip
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Solution Overview
Problem
Existing rotor arrangements for gas turbines, which use solid pins for axial locking of rotor blades, result in increased weight and stress on the rotor blades during operation, and require higher bending forces for assembly.
Innovation Solution
A rotor arrangement that uses a locking sheet metal strip with two bent tongues to engage an annular groove on the rotor disk and a root groove on the rotor blade, providing axial fixation without the need for solid pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid pin is used as a locking element, then the axial positioning of rotor blades is secure, but the weight of the rotor blade assembly increases significantly
Solution Approach 1:
The patent replaces the solid pin with a thin-walled cylindrical shell structure that acts as a locking element. This thin-walled structure provides sufficient axial locking capability while significantly reducing the weight compared to a solid pin, directly resolving the contradiction between reliability of positioning and weight of the assembly.
2Reliability
If a solid pin is used as a locking element, then the axial locking is effective, but the bending force required for assembly increases
Solution Approach 1:
The thin-walled cylindrical shell structure requires significantly less bending force during assembly compared to a solid pin. The thin-walled construction allows the locking element to be more easily deformed and installed into the rotor blade assembly while still providing effective axial locking when in position.
3Strength
If a solid pin is used as a locking element, then the structural strength is high, but the stress on rotor blade roots increases during operation
Solution Approach 1:
The thin-walled cylindrical shell distributes the locking forces more evenly across the attachment slot interface, reducing stress concentration at the rotor blade roots. While the wall is thin, the cylindrical geometry and strategic positioning maintain sufficient strength for axial locking while lowering the overall stress burden on the blade roots during operation.
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 solution reduces the weight added to the rotor blades, decreases the bending force required for assembly, and provides a reliable and safe operational construction by utilizing centrifugal forces to maintain the position of the locking tongues.
Implementation Method 1
As the bending edge extends radially, centrifugal forces acting onto the lateral tongues cannot bend the tongues back. This leads to a reliable and safe construction from an operational perspective.
Data Source
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AI summary
The invention relates to a rotor arrangement (RA) comprising a rotor arrangement (RA) for a rotor of a gas turbine, comprising - at least one rotor disk (RD) comprising attachment slots for carrying rotor blades (RB) and an annular groove (AG) having an annular opening towards the outward direction and - rotor blades (RB) having an airfoil (AF) and a blade root (BR) and assembled in an attachment slot (AS), wherein each of the assembled blade roots (BR) comprises a root extension (RE) with a root groove (RG), said root groove (RG) facing the annular groove (AG) when the rotor blade (RB) is assembled in the attachment slot (AS), and wherein for each assembled rotor blade (RB) a locking element is provided, the locking element engaging the annular groove (AG) of the rotor disk (RD) and the root groove (RG) of the respective rotor blade (RB). For the provision of a light and an easy mountable locking element, preferably all locking elements are embodied as a locking sheet metal strip (LSMS), which comprises two bended tongues (BT) embracing the respective root extension (RE).