Axially Offset Guide Vane Cascade for Turbomachine Mass Flow
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Solution Overview
Problem
Conventional guide vane cascades in turbomachines experience unfavorable mass flow distribution under partial load, leading to increased load on the rotating blade cascade due to aerodynamically unfavorable configurations, particularly in the radially inner region.
Innovation Solution
The guide vane cascade features a tandem configuration in the radially outer region and a divergent channel in the radially inner region, achieved by axially offsetting guide vanes and matching their profiles and adjustment angles, which redistributes the mass flow radially outward, improving aerodynamics and reducing load on the rotating blade cascade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If guide vanes are arranged in a conventional configuration without axial offset, then the structure is simpler, but unfavorable mass flow distribution occurs under partial load leading to increased load on the rotating blade cascade
Solution Approach 1:
The guide vane cascade is segmented into two distinct groups: first guide vanes and second guide vanes with axially offset rotation axes. This segmentation allows independent optimization of flow control in different radial regions, enabling the tandem configuration that redistributes mass flow favorably under partial load conditions.
Solution Approach 2:
The invention introduces axial offset between the rotation axes of the two guide vane groups, adding an axial dimension to the traditional radial arrangement. This dimensional change creates the tandem configuration that generates the divergent channel, enabling mass flow redistribution from the radially inner to the radially outer region.
2Reliability
If guide vanes are axially offset to create tandem configuration, then mass flow distribution is improved radially outward, but the radially inner region experiences higher interface loading and blockage losses
Solution Approach 1:
The invention converts the potentially harmful concentrated mass flow in the radially inner region into a beneficial distributed flow pattern. By creating the divergent channel through axial offset, the high interface loading and blockage in the inner region act as a diffusor that redistributes mass flow radially outward, transforming local losses into system-wide flow improvement.
Solution Approach 2:
The invention changes the geometric parameters of the guide vane arrangement by introducing axial offset between the rotation axes of the two vane groups. This parameter change transforms the flow channel geometry from a conventional single-row configuration to a tandem configuration with a divergent channel, fundamentally altering the mass flow distribution pattern.
3Reliability
If guide vanes are adjusted to form divergent channel in radially inner region, then mass flow is redistributed radially outward, but the configuration becomes more complex
Solution Approach 1:
The tandem configuration of guide vanes with axial offset serves multiple functions simultaneously: it creates the divergent channel for mass flow redistribution, acts as a diffusor to reduce concentrated loading, and maintains adjustable guide vane functionality for variable flow conditions. This multi-functionality justifies the increased structural complexity.
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
This configuration enhances mass flow distribution radially outward, reducing load and profile losses in the radially inner region while maintaining a favorable tandem configuration in the outer region, thus improving the performance of the downstream rotating blade cascade.
Implementation Method 1
In the radially inner region, first and second guide vanes form a divergent channel, the latter representing a diffusor
Implementation Method 2
Radially inner interface loading and blockage or profile losses will be correspondingly high
Data Source
AI summary
The present invention relates to a guide vane cascade for a turbomachine, which has guide vanes that are mounted adjustably about an axis of rotation, so as to change an inflow angle each time, wherein a first guide vane and a second guide vane arranged on the pressure side thereof, referred to a longitudinal axis of the turbomachine, are arranged with an axial offset, namely, the axis of rotation of the second guide vane is offset axially toward the back, wherein the first guide vane and the second guide vane are provided such that, in an adjusted state, they form together a tandem configuration in a radially outer region but together they delimit a divergent channel in a radially inner region.