Turbomachine Blade Top Portion Z-Profile Rim Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Movable blades in turbomachines face issues with weight and stress distribution due to non-aligned center of gravity and excessive stress on the blade, leading to reduced lifetime, and existing designs either increase weight or fail to effectively transmit forces between adjacent blades.
Innovation Solution
A top portion with a Z-shaped profile and outwardly projecting rims, where the second rim is connected to the downstream wiper and has a downstream portion extending to the upstream wiper, set back relative to the first segment, and coated with anti-wear material to protect against wear and improve contact forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the first subportion of the platform is made thicker to improve bearing forces between blades, then the strength and force transmission is improved, but the weight of the blade increases
Solution Approach 1:
The platform is segmented into two subportions with different thicknesses: a first subportion of greater thickness extending axially from the upstream wiper to the third segments of the side edges, and a second subportion of smaller thickness extending axially after the first subportion to the downstream wiper. This segmentation allows the thick section to provide necessary bearing forces only where needed (along the second segments for twisting stress) while the thinner section reduces overall weight.
Solution Approach 2:
The platform exhibits local quality variation through its two-subportion structure, where the first subportion has greater thickness to provide local reinforcement for bearing forces and force transmission, while the second subportion has smaller thickness to reduce weight. This localized thickness variation optimizes the balance between strength requirements and weight reduction.
2Device complexity
If the center of gravity of the platform is not aligned with the center of gravity of the airfoil, then the structural design is simplified, but extra stresses are exerted on the blade reducing its lifetime
Solution Approach 1:
The invention adjusts the geometric parameters of the two subportions, particularly the axial extension lengths and circumferential positions, to position the platform's center of gravity in alignment with the airfoil's center of gravity. This parameter optimization eliminates extra stresses while maintaining the functional requirements of the platform structure.
3Strength
If the side edges are made taller to improve force transmission between blades, then the bearing forces are improved, but the weight and complexity of the blade increases
Solution Approach 1:
The side edges are segmented into first and third segments that are substantially parallel and closer together, with a second intermediate segment extending obliquely between them. This segmentation allows the side edges to provide adequate bearing surface area for force transmission while maintaining a more compact overall height, thus reducing weight compared to uniformly taller side edges.
Data Source
AI summary
A movable blade for a turbomachine, the blade including at its distal end a top portion including opposite first and second side edges and upstream and downstream sealing wipers. Each of the first and second side edges has a substantially Z-shaped profile between the upstream and downstream wipers. On a side of the first side edge, the platform includes a first outwardly projecting rim not connected to either of the upstream and downstream wipers. The platform includes a second outwardly projecting rim, the second rim including a downstream portion connected to the downstream wiper and extending along the second edge, and an upstream portion extending the downstream portion as far as the upstream wiper, and set back relative to the second side edge.