Turbomachine Blade Row Edge Spacing for Flow Separation
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Solution Overview
Problem
The maximum deflection of a turbomachine blade row is limited by flow separation at the blade profile and boundary layer separation on the hub and housing side walls, which restricts aerodynamic load capacity, and existing solutions like double-row blade arrangements do not fully optimize flow conditions.
Innovation Solution
A turbomachine design with blade row groups featuring adjacent blade rows where the trailing edges of the upstream row and leading edges of the downstream row have a varying circumferential edge spacing starting from the main flow path center, adapting to changing flow conditions and reducing separations in the side wall area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant axial edge distance is maintained between blade rows, then manufacturing is simplified, but flow separation occurs in the side wall area due to boundary layer effects
Solution Approach 1:
The patent applies local quality by varying the axial edge distance specifically in the side wall area (near hub and housing) while maintaining a constant distance in the main flow path center region. This localized modification addresses boundary layer separation in the side wall area without complicating the overall blade arrangement, thus resolving the contradiction between manufacturing simplicity and flow attachment reliability.
2Reliability
If the meridional distance between blade edges increases from the main flow path center toward side walls, then flow separation in the side wall area is reduced, but the blade contouring becomes more complex
Solution Approach 1:
The patent segments the axial edge distance into two distinct zones: a first axial edge distance in the side wall area and a second axial edge distance in the main flow path center region. This segmentation allows optimization of flow attachment in the side wall area while maintaining simpler blade contouring in the main flow path, thus resolving the contradiction between flow attachment reliability and blade contouring complexity.
3Adaptability or versatility
If double-row blade arrangements are used, then deflection capability is increased, but flow separation issues persist in the side wall area
Solution Approach 1:
The patent applies local quality by implementing different axial edge distances for different radial positions within the double-row blade arrangement. Specifically, the first axial edge distance is used in the side wall area to prevent boundary layer separation, while the second axial edge distance is used in the main flow path center to maintain deflection capability. This localized differentiation resolves the contradiction between deflection capability and flow attachment in the side wall area.
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 flow through the blade rows without detachment, effectively addressing flow separation issues and improving the turbomachine's aerodynamic performance by adapting blade positioning to peripheral edge distances.
Implementation Method 1
the maximum deflection is limited by separation of a boundary layer flow on the hub and housing side walls
Implementation Method 2
the maximum deflection of a blade row of a turbomachine and thus its aerodynamic load capacity is limited on the one hand by flow separation at the blade profile
Data Source
AI summary
The turbomachine comprises a blade row group arranged in a main current path and two adjacent rows of blades, viewed in the main flow direction, each blade row having multiple blades (38,40). The rear edges (42) of the blades of the upstream blade row and the front edges (44) of the blades of the downstream blade row are arranged in the peripheral direction at an edge distance (U-1,U-2), which varies starting from a main flow path center (52) in the direction of both main flow limiters (54). The edge distance increases or decreases on both sides.