Variable Geometry Turbine Vane Rib for Leakage Control
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Solution Overview
Problem
Variable geometry turbochargers experience significant efficiency losses due to leakage flow through vane slots as the inlet passageway width is reduced, leading to increased pressure differential and turbulence, which affects turbine performance.
Innovation Solution
The introduction of a rib structure on the vanes that circumscribes the vane surfaces, directing any leakage flow radially or tangentially, reducing axial leakage and improving mixing with main exhaust gas flow, thereby minimizing efficiency losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet passageway width is reduced to maintain gas velocity at low flow rates, then turbine efficiency is improved, but leakage flow through vane slots increases causing efficiency losses
Solution Approach 1:
The vane structure is segmented by adding ribs that divide the vane surfaces into multiple sections. These ribs create separate flow paths that prevent leakage flow from bypassing the vanes through the slots, thereby reducing energy losses while maintaining the reduced inlet passageway width configuration
Solution Approach 2:
The ribs act as intermediary structures between the vanes and the leakage flow path. By introducing these intermediate elements, the patent blocks the direct leakage path through the vane slots and redirects the flow through the intended vane passages, reducing efficiency losses without requiring a larger inlet passageway
2Speed
If the inlet passageway width is reduced to optimise gas flow velocity, then gas velocity is maintained, but pressure differential increases causing turbulence
Solution Approach 1:
The rib structures segment the flow passages and create multiple smaller flow channels. This segmentation distributes the pressure differential across multiple paths, reducing the intensity of turbulence generated by the pressure drop while maintaining the high gas velocity required for efficient turbine operation at low flow rates
Data Source
AI summary
A variable geometry turbine comprises a turbine wheel (5) supported in a housing (1) for rotation about a turbine axis. An annular inlet passage (9) is defined between first and second radial inlet surfaces, one of said first and second inlet surfaces being defined by a moveable wall member (40). A substantially annular array of vanes (41) is provided which extend across the inlet passageway (9); each vane (41) being fixed to said first inlet surface. Each vane (41) has first and second major vane surfaces (45, 46) having a chordal length extending between a radially outer leading vane edge (47) and a radially inner trailing vane edge (48), the first major vane surface (45) facing generally away from the axis and the second major vane surface (46) facing generally towards the axis. A rib (43) extends across at least a substantial portion of the chordal length of at least one of the first and second major vane surfaces (45, 46) of one or more vanes (41) of the array.