Turbocharger Diffuser Center Body for Swirl Management
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Solution Overview
Problem
Radial turbocharger turbines face efficiency losses due to high exit swirl at off-design operating conditions, leading to increased kinetic energy and angle of incidence losses, particularly under transient conditions, due to size constraints and varying swirl angles.
Innovation Solution
A compact turbocharger turbine diffuser design featuring a center body with de-swirl vanes and annular guide vanes that increase the mean diameter of the exhaust gas stream, reducing tangential velocity and angle of attack, and a wastegate system for improved flow diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional conical diffuser design is used, then efficiency is high when dealing with zero or low levels of inlet swirl, but significant separation of the flow and inefficient diffusion occurs when dealing with high inlet swirl
Solution Approach 1:
The diffuser is segmented into multiple sections with different wall angle configurations. The first section has a first wall angle optimized for low swirl conditions, while the second section has a second wall angle optimized for high swirl conditions. This segmentation allows the diffuser to adapt to varying inlet swirl angles throughout the operating range, preventing flow separation and maintaining diffusion efficiency across all conditions.
2Ease of operation
If de-swirl vanes with leading edge angle matched to flow swirl angle are used, then swirl management is effective at a small range of operating conditions, but high angle of incidence losses occur at operating conditions not close to the design condition
Solution Approach 1:
The diffuser employs variable wall angles instead of fixed de-swirl vanes. The first section has a shallower wall angle that adapts to low swirl conditions, while the second section has a steeper wall angle that adapts to high swirl conditions. This dynamic geometric adaptation eliminates the need for fixed-angle vanes, thereby preventing high angle of incidence losses across the full operating range while maintaining effective swirl management.
3Volume of moving object
If the turbocharger size is reduced to meet package constraints, then installation is feasible, but efficiency losses increase due to insufficient diffuser length for proper diffusion
Solution Approach 1:
The diffuser utilizes the radial dimension by implementing sections with different wall angles at different radial positions. The first section has a first wall angle and the second section has a second wall angle, creating a three-dimensional flow path that maximizes diffusion efficiency within the limited axial space. This dimensional approach allows adequate diffusion length to be achieved within compact turbocharger dimensions.
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 design effectively reduces kinetic energy and angle of incidence losses across a wide range of operating conditions, enhancing efficiency and managing swirling flows within package constraints.
Implementation Method 1
The diffuser is configured to reduce airflow velocity. To accomplish this, the cross-sectional area of the diffuser increases from an upstream end of the diffuser to the downstream end of the diffuser. Because the mass flow rate through the diffuser is constant, this increased cross-sectional area provides for decreased velocity, decreased dynamic pressure, and increased static pressure.
Implementation Method 2
the presence of the center body increases the mean diameter of the exhaust gas stream. With free vortex flow, the angular momentum of the tangential portion of the flow remains constant, and thus the increase in mean diameter decreases the tangential velocity of the exhaust stream.
Data Source
Figure 1
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Figure 4
AI summary
A turbocharger turbine having housing walls defining a diffuser. Within the diffuser, a center body (221) is supported by de-swirl vanes (241) extending from the diffuser wall. The center body forms a de-swirl passageway having an increasing mean diameter of flow from an upstream end (225) of the center body to a leading edge (243) of the de-swirl vanes. A trailing edge (245) of the de-swirl vanes is near the downstream end (233) of the center body. Annular-type guide vanes surround the center body within the de-swirl passageway. A wastegate system is configured to vent wastegate flow into the diffuser through injection ports on the de-swirl vanes, annular guide vanes and/or center body.