Annulus Duct Wall Recesses for Fluid Flow Machine Boundary Layer Control
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Solution Overview
Problem
The aerodynamic loadability and efficiency of fluid flow machines like blowers, compressors, and pumps are limited by boundary layer growth and separation in the rotor and stator blade tip areas, leading to instability and inefficiency due to the lack of effective solutions in current technologies.
Innovation Solution
The introduction of a variable stator with an inlet guide vane assembly and strategically designed recesses in the annulus duct wall, allowing for adjustable angles and optimized shaping to influence the boundary layer, reducing re-flow phenomena and instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If casing treatments with chambers and angular slots are used in the annulus duct wall, then stability of the fluid flow machine is improved, but efficiency is reduced
Solution Approach 1:
The invention applies different structural features at different locations: recesses are positioned specifically in the blade tip area where boundary layer separation occurs, while other areas maintain their original design. This localized intervention stabilizes the boundary layer without disrupting the overall flow pattern, thus improving stability while minimizing efficiency loss
Solution Approach 2:
The recesses act as intermediary structures that mediate between the blade tip and the casing wall. They provide a controlled space for the boundary layer to interact with the casing, preventing direct adverse interaction between the separated boundary layer and the casing surface, thereby stabilizing flow without significant energy penalty
2Loss of energy
If the annulus duct wall is modified with recesses to influence the boundary layer, then efficiency is improved, but device complexity increases
Solution Approach 1:
The annulus duct wall is segmented into different zones: areas with recesses in the blade tip region and areas without recesses elsewhere. This segmentation allows the invention to apply complexity only where necessary (at the blade tips) while maintaining simplicity in other regions, thus improving efficiency without excessive overall complexity
Solution Approach 2:
Instead of modifying the entire annulus duct wall, the invention applies recesses only partially - specifically in the blade tip area where boundary layer separation occurs. This partial action provides the necessary efficiency improvement while avoiding the complexity that would result from comprehensive 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 approach enhances the boundary layer management, leading to improved stability and efficiency, with potential cost and weight reductions of 10-20% and efficiency gains of 0.2-0.5% across various fluid flow machines.
Implementation Method 1
The aerodynamic loadability and the efficiency of fluid flow machines such as blowers, compressors, pumps and fans, is limited in particular 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 has a flow path provided by a casing (1) and a rotating shaft (2), in which rows of rotor blades (3) and stator blades (4) are arranged, and includes at least one annular groove-type recess (5) being disposed in a blade (3, 4) tip area in an annulus duct wall of the casing (1) and/or the shaft (2). An upstream end point (E) of the recess (5) in a flow direction is set at a distance (e)>0 forward of a forward blade tip point (A), and a downstream end point (F) of the recess (5) is set at a distance (f) rearward of point (A), where: 0.5 L>(f)>0, and L is a distance between point (A) and a rearward blade tip point (B).