Turbomachine Compressor Abradable Shroud Design
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Solution Overview
Problem
Current turbomachine low-pressure compressor designs face issues with fragile shroud parts, misalignment of abradable elements, pressure drops, and complex maintenance due to axial bulk and flange positioning, which affect performance and ease of assembly/disassembly.
Innovation Solution
The compressor features annular grooves around moving blades for an abradable material element with an internal diameter greater than the theoretical vane diameter, allowing for equidistant flange placement and optimized axial dimensions, enabling better shock resistance and alignment compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the flanges are positioned upstream of the rotor blades to provide sufficient distance from welds, then the structural strength and stress resistance are improved, but the axial bulk of the compressor increases
Solution Approach 1:
The patent repositions the flange junction plane from an upstream location to a downstream location, beyond the trailing edges of the rotor blades. This spatial reconfiguration in the axial dimension allows the flanges to maintain sufficient distance from welds for stress resistance while reducing the overall axial bulk of the compressor by eliminating the need for extended upstream flange projections.
2Reliability
If the abradable element is tightly fitted to the shroud, then the radial clearance control is improved, but the alignment precision deteriorates due to potential misalignment after flange tightening
Solution Approach 1:
The patent specifies that the annular groove for the abradable element has an internal diameter greater than the external diameter of the theoretical vein. This parameter change creates a deliberate clearance between the groove and the abradable element, allowing the element to be self-aligned by the moving blades during operation while maintaining reliable radial clearance control through the compliant abradable material.
3Length of stationary object
If the shroud parts are designed with minimal axial dimension, then the axial bulk is reduced, but the structural reliability deteriorates as the parts become fragile
Solution Approach 1:
The patent positions the flange junction plane downstream of the rotor blades, which preliminarily reinforces the shroud structure in the critical region where moving blades pass. This repositioning provides earlier structural support before the blades reach the blade tips, preventing fragile shroud parts from breaking while maintaining minimal axial dimensions.
4Productivity
If the compressor stages are designed for optimal aerodynamic performance, then the turbomachine performance is improved, but the maintenance complexity increases due to imposed assembly direction
Solution Approach 1:
The patent creates an asymmetric design where the flange junction plane is positioned downstream rather than upstream, breaking the conventional symmetry of compressor stage assembly. This asymmetric configuration allows maintenance personnel to access and service compressor stages from either upstream or downstream directions, providing operational flexibility while preserving optimal aerodynamic performance through proper flange positioning.
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 the structural integrity and reduces axial size, improves airflow alignment, and simplifies maintenance by allowing for equal external diameters of moving blades and theoretical passages, thus enhancing turbomachine performance and operational efficiency.
Implementation Method 1
an annular groove for mounting an element made of abradable material, this annular groove having an internal diameter greater than the external diameter of the theoretical vein in this part of the casing
Data Source
Figure 1~2
AI summary
The compressor (10) has a cylindrical case (16) formed with annular ferrules (20, 22) that hold annular rows of straightening vanes (14). The ferrules have cylindrical edges (26, 28) to carry annular flanges (30, 30'), arranged at equal distance from the ferrules, for fixing the ferrules between the edges. The edges form an annular groove around movable vanes (12) placed between the ferrules for assembling an abradable element, where the internal diameter of the groove is higher than the external diameter of a theoretical vein in a part of the case.