Centrifugal Compressor Impeller Secondary Flow Reducers
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Solution Overview
Problem
Centrifugal compressors face inefficiencies due to secondary flows near impeller blades, which require additional work and can compromise downstream components, and existing design changes to address this issue are costly and difficult to implement.
Innovation Solution
The integration of secondary flow reducers on impeller blades, which include ribs that intersect the blade surfaces to define first and second surfaces and a third surface between them, coincident with ideal streamlines to reduce secondary flows and maintain the overall shape of the impeller design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If impeller blade shape is modified to reduce secondary flows, then compressor efficiency is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention divides the impeller blade into functional segments by adding secondary flow reducers (ridges) that partition the blade surface into distinct flow zones. These ridges segment the boundary layer into regions of different flow characteristics, allowing independent control of secondary flow patterns without redesigning the entire blade geometry. This segmentation approach reduces secondary flows while maintaining the overall blade design framework.
Solution Approach 2:
The invention applies local modifications to specific regions of the impeller blade where secondary flows are most problematic. The secondary flow reducers are strategically positioned at locations where boundary layer separation and transverse flow migration occur, providing localized flow control. This allows efficiency improvement without requiring global changes to the blade shape, thereby limiting complexity increases.
2Productivity
If impeller blade shape is modified to reduce secondary flows, then compressor efficiency is improved, but ease of manufacture deteriorates
Solution Approach 1:
The secondary flow reducers are designed as separate, discrete ridges that can be manufactured independently and then integrated onto the impeller blade. This segmentation allows for simplified manufacturing processes compared to creating entirely new blade geometries, as each ridge can be produced using standard machining or additive manufacturing techniques and then attached or integrated into the existing blade structure.
Solution Approach 2:
The invention allows for preliminary manufacturing of the base impeller blade using existing designs and processes, followed by the addition of secondary flow reducers in a subsequent manufacturing step. This preliminary action approach enables manufacturers to produce the main blade structure first, then add the flow-control features, thereby maintaining ease of manufacture for the primary component while achieving efficiency improvements through the added features.
3Loss of energy
If secondary flow reducers are added to impeller blades, then secondary flows are reduced, but device complexity increases
Solution Approach 1:
The invention extracts the secondary flow control function from the main impeller blade design by adding separate, distinct ridge structures. Rather than incorporating flow control directly into the blade airfoil shape, the secondary flow reducers are added as separate elements that perform the specific function of reducing secondary flows. This extraction allows the main blade design to remain simple while the added features provide the desired flow control.
Solution Approach 2:
The secondary flow reducers are designed to perform multiple functions simultaneously: they reduce secondary flows, control boundary layer separation, and maintain overall flow attachment to the blade surface. This multi-functionality means that a single added feature provides multiple benefits, justifying the increase in device complexity by delivering compounded performance improvements rather than requiring multiple separate modifications.
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 effectively reduces secondary flows, enhances flow uniformity, and improves compressor performance by minimizing loss coefficients and increasing work and flow coefficients, while being easily integratable with existing designs at a lower cost.
Implementation Method 1
The secondary flow reducer defines ideal streamlines coincident with the third surface. In this way, the secondary flow reducer serves to redirect process fluid flow in a manner that reduces secondary flows and enhances flow uniformity.
Data Source
Figure 1
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AI summary
An impeller (46) includes a hub (62) having a direction of rotation, a plurality of impeller blades 60 extending from the hub (62), each blade having a downstream end (721), an upstream end (68), a leading surface (74) facing the direction of rotation of the hub, and a trailing surface (76) facing opposite to the direction of rotation of the hub. The impeller (46) further includes a secondary flow reducer (80) extending towards the downstream end (72) and the upstream end (68) of the at least one of the plurality of impeller blades (60), the secondary flow reducer (80) defining first and second surfaces intersecting one of the leading surface and the trailing surface of the at least one of the plurality of impeller blades as well as a third surface between the first and second surfaces.