Axial Turbine Diffusor with Axial Waste-Gate Injection
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Solution Overview
Problem
Conventional exhaust turbine diffusors suffer from suboptimal pressure recovery, complexity, installation space issues, and increased costs, particularly due to the recirculation of waste-gate mass flow which disrupts the outflow from the turbocharger turbine, leading to efficiency losses and mechanical vibrations.
Innovation Solution
An exhaust turbine design featuring a diffusor with a non-constant opening angle and a waste gate duct that injects the waste-gate mass flow in a substantially axial direction, with a transition angle less than 5°, allowing for unhindered outflow and laminar expansion, reducing turbulence and hindrance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If waste-gate mass flow is recirculated into the exhaust system, then exhaust gas utilization is improved, but turbine outflow is disrupted causing efficiency losses and vibrations
Solution Approach 1:
The harmful recirculation path of waste-gate mass flow is extracted and separated from the main exhaust flow path. The waste-gate mass flow is directed through a separate outlet duct away from the turbine outlet, preventing disruption of turbine outflow while still allowing exhaust gas utilization in other ways.
Solution Approach 2:
A separate outlet duct serves as an intermediary pathway for the waste-gate mass flow. This mediator allows the waste-gate flow to be discharged without directly interacting with and disrupting the main turbine exhaust flow, thus resolving the conflict between exhaust gas utilization and turbine operating stability.
2Stress or pressure
If conventional diffusors are used, then pressure recovery is achieved, but complexity and installation space increase
Solution Approach 1:
The diffusor function is merged with the outlet duct structure. The outlet duct itself is designed with diffusor characteristics (increasing cross-sectional area in the flow direction), combining the pressure recovery function with the existing exhaust flow path rather than adding separate complex diffusor components.
Solution Approach 2:
The outlet duct serves multiple functions: it guides the waste-gate mass flow away from the turbine outlet, provides pressure recovery through its diffusor geometry, and simplifies the overall structure by eliminating the need for separate complex diffusor components. This multi-functionality reduces device complexity while maintaining pressure recovery.
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 ensures unhindered outflow of the exhaust mass flow, reduces turbine blade vibrations, and improves diffusor performance while allowing for a simple and cost-effective construction with minimal additional components.
Implementation Method 1
an axial turbine diffusor (1), which opens downstream, radially outward, at a non-constant diffusor opening angle
Implementation Method 2
allows for unhindered outflow and laminar expansion, reducing turbulence and hindrance
Implementation Method 3
a waste gate duct (13), through which a waste-gate mass flow can be injected into the exhaust mass flow in a substantially axial direction of flow
Implementation Method 4
a turbine wheel (7) having a plurality of rotor blades (8), and an exhaust outlet duct (12), which is arranged downstream of the rotor blades
Data Source
AI summary
An exhaust turbine includes a turbine wheel having a plurality of rotor blades, an exhaust outlet where the exhaust outlet is arranged downstream of the rotor blades and is delimited radial to the outside by an axial turbine diffusor. An exhaust mass flow can be output in an axial flow direction by the exhaust outlet duct and the axial turbine diffusor opens downstream, radially to the outside at a non-constant diffusor-opening angle, such that at a first diffusor-opening angle deviates from a second diffusor-opening angle by at least 1°. The exhaust turbine further includes a waste gate duct, the outlet region of which opens into the diffusor or directly downstream of the diffusor into the exhaust outlet duct. The waste gate duct is designed to generate a substantially axial flow direction of a waste gate mass flow at the outlet region of the waste gate duct.