Turbine Scroll Assembly for Uniform Axial Turbine Inlet Flow
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Solution Overview
Problem
Rotary internal combustion engines experience non-uniform gas flow into the turbine, leading to decreased turbine efficiency and structural fatigue due to periodic excitation forces.
Innovation Solution
A turbine scroll assembly with a flowpath, scroll stator vanes, and an annular collection region that directs gas flow uniformly into an axial turbine, using non-axisymmetric designs and offset turbine stator vanes to stabilize the gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional scroll is used to organize combustion gases, then the turbine can receive gas flow, but the gas flow exhibits circumferential and radial nonuniformities that decrease turbine efficiency and cause periodic excitation forces
Solution Approach 1:
The scroll is divided into multiple flow channels, each serving a specific rotary unit. Each flow channel includes a flow straightener with vanes that segment the gas flow into controlled pathways, directing flow from each rotary unit separately into the turbine. This segmentation allows independent control and conditioning of flow from each source, reducing overall nonuniformities and pulsation effects on the turbine.
Solution Approach 2:
Flow straighteners are introduced as intermediary components between the scroll flow channels and the turbine inlet. These flow straighteners, equipped with vanes, act as mediators that condition the gas flow by reducing circumferential and radial nonuniformities before the flow enters the turbine. The flow straighteners absorb and mitigate the harmful pulsation effects, allowing smooth flow transmission to the turbine without directly modifying the turbine structure.
2Productivity
If combustion gases flow periodically from rotary units, then each unit can operate cyclically, but the collective flow creates pulsation that subjects the turbine to periodic excitation forces causing structural fatigue
Solution Approach 1:
Flow straighteners are positioned upstream in each flow channel to preliminarily condition the gas flow before it reaches the turbine. By placing flow control elements (vanes) in advance within the scroll structure, the system pre-reduces flow nonuniformities and pulsation effects before the periodic flow from cyclically operating rotary units reaches the turbine, preventing excitation forces from developing fully.
Solution Approach 2:
The periodic pulsation and nonuniform flow characteristics, which would normally be harmful to turbine structure, are converted into a beneficial controlled flow pattern. The flow straighteners with vanes transform the chaotic periodic pulsations into organized, smoother flow streams that maintain the necessary mass flow for productivity while eliminating the harmful excitation forces that cause structural fatigue.
3Power
If multiple rotary units are axially aligned driving a common shaft, then power output is increased, but the combined exhaust flow from multiple units exacerbates flow nonuniformities into the turbine
Solution Approach 1:
The exhaust system is segmented into individual flow channels, one for each rotary unit, with each channel equipped with its own flow straightener. This segmentation allows the combined exhaust from multiple high-power rotary units to be processed independently through separate controlled pathways, preventing the superposition of nonuniform flow patterns that would occur with a single mixed flow path.
Solution Approach 2:
After individual flow conditioning in separate channels with flow straighteners, the flows from multiple rotary units are merged in a controlled manner at the turbine inlet. The flow straighteners ensure that each contributing flow stream is pre-conditioned to uniformity standards, allowing their combination to result in a collectively uniform flow pattern rather than amplifying nonuniformities through random mixing.
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 solution enhances turbine efficiency and reduces structural stress by stabilizing the gas flow, minimizing pulsation and excitation forces.
Implementation Method 1
The flow channel may extend circumferentially around a center axis to a terminal end. The plurality of scroll stator vanes may be distributed circumferentially about the center axis and disposed within the flow channel
Implementation Method 2
The annular collection region may be disposed radially inward of the flow channel, and may extend circumferentially about and axially along the center axis. The annular collection region may be configured to receive gas flow from the flow channel
Implementation Method 3
The turbine stator vane assembly may be disposed proximate the scroll outlet and may include a plurality of turbine stator vanes distributed circumferentially about the center axis
Data Source
AI summary
An assembly is provided comprising a turbine scroll and a turbine stator vane assembly. The turbine scroll includes a flowpath, a flow channel, scroll stator vanes, and an annular collection region. The flowpath extends along the scroll from an inlet to an outlet. The flow channel defines an outer radial wall extending between axial sidewalls spaced widthwise. The flow channel extends circumferentially around a center axis to a terminal end. The scroll stator vanes are distributed circumferentially about the center axis and disposed within the flow channel. The annular collection region is disposed radially inward of the flow channel and extends circumferentially about and axially along the center axis. The annular collection region is configured to receive gas flow from the flow channel. The turbine stator vane assembly is disposed at the outlet and includes a plurality of turbine stator vanes distributed circumferentially about the center axis.