Turbomachine Flow Path with Circumferentially Varying Outer Periphery
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Solution Overview
Problem
In turbomachines, the interaction between air flow and airfoils results in non-uniform pressure fields, causing time-varying stresses on rotor blades that can compromise their structural integrity due to material failure.
Innovation Solution
A circumferentially varying outer periphery in the annular flow path of turbomachines is designed to reduce vibratory stresses on rotor blades, featuring a series of alternating peaks and troughs that create a non-axisymmetric pattern, reducing the magnitude of these stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional axisymmetric flow path is used, then the structure is simple and easy to manufacture, but the rotor blades experience high vibratory stresses due to non-uniform pressure fields
Solution Approach 1:
The patent applies asymmetry by introducing a circumferentially varying outer periphery with alternating peaks and troughs, breaking the conventional axisymmetric geometry. This asymmetric flow path configuration modifies the pressure distribution to reduce vibratory stresses on rotor blades, directly addressing the technical contradiction between structural integrity and geometric complexity.
Solution Approach 2:
The patent implements local quality by creating localized variations in the outer periphery geometry (peaks and troughs) rather than uniform changes throughout. These localized geometric modifications target specific regions to alter pressure fields locally, reducing stresses on rotor blades while maintaining overall flow path functionality.
2Reliability
If the outer periphery is made axisymmetric, then manufacturing is easier, but the pressure field remains non-uniform causing material failure
Solution Approach 1:
The patent replaces the axisymmetric outer periphery with an asymmetric configuration featuring circumferential peaks and troughs. This asymmetric geometry creates a more uniform pressure field that reduces vibratory stresses and prevents material failure, while the manufacturing complexity is managed through the periodic nature of the variation.
Solution Approach 2:
The patent changes the geometric parameters of the outer periphery by introducing circumferential variations in radius (peaks and troughs). This parameter modification transforms the pressure field characteristics, converting it from non-uniform to more uniform, thereby improving reliability against material failure.
3Stress or pressure
If a circumferentially varying outer periphery is implemented, then vibratory stresses are reduced by 10-20%, but the flow path geometry becomes more complex
Solution Approach 1:
The patent uses asymmetric geometry with circumferential peaks and troughs to modify the pressure field and reduce vibratory stresses by 10-20%. The stress reduction is achieved through the asymmetric configuration that creates a more uniform pressure distribution, accepting increased geometric complexity as a trade-off.
Solution Approach 2:
The patent employs curved variations in the outer periphery (peaks and troughs) rather than sharp transitions. These smooth curvatures help manage the complexity of the flow path geometry while achieving the desired stress reduction, as the continuous curved surfaces maintain better flow characteristics compared to abrupt geometric changes.
Data Source
Figure 1
Figure 2
Figure 3~4A
AI summary
A turbomachine includes an annular flow path section (57) between a plurality of radially extending stator blades (64) and a plurality of radially extending rotor blades (66). At least a portion (70) of the flow path section (57) has a circumferentially varying outer periphery.