Rotary Blade Lean Angle Inflection for Clearance Flow
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Solution Overview
Problem
The performance of rotary machine blades, such as those in turbochargers, is compromised by clearance flows due to differential pressures, and existing solutions to reduce these flows can lead to a decrease in performance or increase in losses.
Innovation Solution
The rotary machine blade incorporates a clearance flow suppressing blade portion with a lean angle that has one or more inflection points, where the inflection point closest to the blade end turns from negative to positive, directing secondary flows to reduce clearance flows without altering the blade's circumferential shape, and can be formed in specific regions or shapes to enhance effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a plate is added to reduce leakage flow vortex on the rotor blade tip, then clearance flow is reduced, but the throat area reduces and performance decreases or loss increases
Solution Approach 1:
The invention changes the geometric parameters of the rotor blade by introducing inflection points in the lean angle distribution along the blade span. Specifically, the lean angle transitions from negative to positive near the blade tip, which modifies the secondary flow pattern and reduces clearance flow without requiring additional plates or changing the circumferential blade shape, thereby avoiding throat area reduction and associated losses.
2Object-generated harmful factors
If the circumferential shape of the blade tip is changed to reduce clearance flow, then clearance flow is reduced, but the throat area reduces and performance decreases
Solution Approach 1:
The invention applies a localized modification to the blade geometry by introducing inflection points in the lean angle distribution specifically in the region near the blade tip (span height of 70% or more). This local change in the lean angle profile affects only the secondary flow and clearance flow in that specific region, while maintaining the overall blade shape and throat area, thus preserving performance while reducing clearance flow.
3Object-generated harmful factors
If a plate is added to reduce leakage flow, then clearance flow is reduced, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the need for additional plates or auxiliary structures by directly modifying the rotor blade geometry itself. The inflection points in the lean angle distribution create the desired secondary flow effect inherently within the blade structure, removing the need for separate clearance flow control devices and simplifying the overall system.
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 configuration efficiently reduces clearance flows without decreasing performance or increasing losses, improving the efficiency of the rotary machine blade and turbocharger.
Implementation Method 1
A secondary flow can be directed to flow in a direction where a clearance flow between the blade end and a shroud is reduced without changing the circumferential shape of the blade by the clearance flow suppressing blade portion being included
Data Source
AI summary
A rotary machine blade (31) equipped with a clearance flow suppression blade section (34), the lean angle of which has one or more inflection points, and which is formed such that when the direction from a positive-pressure surface (31a) to a negative-pressure surface (31b) is taken as the normal direction, an inflection point (P1) of the lean angle positioned farthest toward the blade end (33) changes from the negative to the positive direction in the direction away from the blade end (33).