Secondary Flow Ducts for Fluid Machine Stability
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Solution Overview
Problem
Existing fluid-flow machines face limitations in aerodynamic loadability and efficiency due to boundary layer growth and separation in the rotor and stator blade tip areas, leading to high secondary losses and operational instabilities, particularly at higher loads, and existing casing treatments are either inefficient or require significant installation space and complex production measures.
Innovation Solution
A structural assembly comprising a support component and an insertion component, where the insertion component forms secondary flow ducts that are inserted into a recess of the support component, allowing for complex duct designs without the need for extensive casing modifications, and can be manufactured using methods like casting or printing, providing a spatially compact and sturdy solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional casing treatments (circumferential grooves, slots, or chambers) are used to manage boundary layers and improve stability, then operational stability is improved, but installation space at the periphery of the annular duct increases significantly
Solution Approach 1:
The secondary flow ducts are nested within the annular duct itself, utilizing the existing structural space rather than adding peripheral extensions. The ducts are positioned concentrically within the annular duct wall structure, allowing boundary layer management without increasing the overall footprint of the fluid-flow machine.
2Loss of energy
If complex secondary flow ducts are provided in the casing to effectively manage boundary layers, then aerodynamic efficiency and stability are improved, but manufacturing complexity and production cost increase
Solution Approach 1:
The complex three-dimensional secondary flow duct system is segmented into multiple linear duct sections that can be manufactured separately using standard machining operations. Each duct is divided into manageable segments corresponding to different portions of the annular duct, allowing for simplified production while maintaining the overall complex flow management functionality when assembled.
Solution Approach 2:
The duct system incorporates adjustable components that allow the flow paths to be dynamically configured or modified. This enables the same basic structure to adapt to different operational conditions and boundary layer patterns without requiring complete redesign or complex custom manufacturing for each specific application.
3Ease of manufacture
If circumferential grooves with rectangular or parallelogram cross-sections are used as casing treatment, then implementation is simple through machining, but effectiveness is restricted and does not provide sufficient stability improvement
Solution Approach 1:
The invention transitions from two-dimensional circumferential grooves to three-dimensional secondary flow ducts that extend both circumferentially and axially within the annular duct. This dimensional expansion allows the ducts to interact with boundary layers at multiple locations and angles, significantly enhancing their effectiveness in managing flow separation and improving stability while still using manufacturable geometries.
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 approach enhances the stability of fluid-flow machines by effectively managing boundary layers in the blade tip area, reducing secondary losses, and improving operational stability without the inefficiencies and space requirements of traditional casing treatments.
Implementation Method 1
The aerodynamic loadability and the efficiency of fluid-flow machines, in particular of fluid-flow machines such as blowers, compressors, pumps and fans, is limited by the growth and the separation of boundary layers in the rotor and stator blade tip area near the casing or the hub wall, respectively
Data Source
AI summary
A fluid-flow machine includes: a main flow path boundary and at least one row of relatively rotating blades with a gap existing between blade ends and the main flow path boundary. At least one secondary flow duct having one opening each is provided in the main flow path boundary at ends spaced apart in the flow direction, such that the secondary flow duct is connected to the main flow path via the two openings. The structural assembly has at least one support component and at least one insertion component. The support component includes a recess extending in the circumferential direction that receives the at least one insertion component such that the support component surrounds the at least one insertion component largely on its sides not facing the main flow path, and where the insertion component completely surrounds or forms at least one secondary flow duct.