Variable Geometry Turbocharger Nozzle Vane Asymmetric Flange Design
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Solution Overview
Problem
Conventional nozzle vanes in variable geometry turbochargers experience degraded performance at low power due to uneven exhaust gas flow into gaps around the rotational shaft, leading to inefficiencies in gas flow and performance.
Innovation Solution
A nozzle vane design with a flange portion that satisfies specific geometric expressions (R1<R2 and R4<R3) to improve exhaust gas flow around the center of rotation, and optionally features a convex arc-shaped edge portion to reduce turbulence and swirl, enhancing gas flow through the gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional nozzle vane with a flange portion at the end on the rotational shaft side is used, then the structure is simple and easy to manufacture, but the exhaust gas flow into the gap on the rotational shaft side is poor, degrading turbocharger performance at low power
Solution Approach 1:
The flange portion is designed with asymmetric geometry where R1 < R2 and R4 < R3, creating different curvature radii on opposite sides. This asymmetry directs exhaust gas flow preferentially into the gap on the rotational shaft side, resolving the uneven flow distribution problem while maintaining manufacturing simplicity
Solution Approach 2:
The flange portion introduces localized geometric features with specific curvature radii (R1, R2, R3, R4) at critical locations around the rotational shaft. This local modification of geometry optimizes exhaust gas flow into the gap region without requiring complete redesign of the entire nozzle vane structure
2Productivity
If the flange portion has a convex arc-shaped edge portion protruding to the exhaust gas passage, then turbulence and swirl are reduced improving gas flow, but the manufacturing complexity increases
Solution Approach 1:
The edge portion of the flange is designed with a convex arc shape that protrudes into the exhaust gas passage. This curved geometry smoothly guides exhaust gas flow, reducing turbulence and swirl effects while maintaining relatively simple manufacturing requirements through standard forming processes
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
The improved nozzle vane design enhances exhaust gas flow and reduces turbulence, thereby increasing the performance of variable geometry turbochargers, especially at low power conditions.
Implementation Method 1
the exhaust gas flowing from upstream on the suction surface and passing near the center of rotation easily flows into the gap between the shroud surface or the hub surface and the nozzle vane
Implementation Method 2
it is possible to effectively suppress the exhaust gas flowing along the exhaust-gas-passage-side flange surface and then into the gap on the rotational shaft side of the nozzle vane from being separated when it passes through the edge portion of the passage-side flange surface. Thus, the generation of turbulence and swirl caused by separation can be suppressed
Data Source
AI summary
A nozzle vane of a variable geometry turbocharger comprises: a nozzle vane body rotatably disposed in an exhaust gas passage defined between a shroud surface and a hub surface; and a flange portion provided on at least one of a shroud-side end surface or a hub-side end surface of the nozzle vane body, and formed around a center of rotation of the nozzle vane body. The flange portion is formed to satisfy the expression (i): R1<R2 or (ii): R4<R3, where R1 is the shortest distance from the center of rotation to an outer edge of the flange portion on the trailing edge side and on a suction surface of the nozzle vane, R2 is the shortest distance from the center of rotation to the outer edge of the flange portion on the leading edge side and on the suction surface of the nozzle vane, R3 is the shortest distance from the center of rotation to the outer edge of the flange portion on the leading edge side and on a pressure surface of the nozzle vane, and R4 is the shortest distance from the center of rotation to the outer edge of the flange portion on the trailing edge side and on the pressure surface of the nozzle vane.