Turbomachine Stator Side Wall Contouring for Flow Loss Reduction
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Solution Overview
Problem
Turbomachine blade cascades experience secondary flows and pressure losses due to the deflection of flow layers near the wall, leading to inefficiencies in gas and steam turbines.
Innovation Solution
The implementation of a blade cascade with circumferentially wavy side walls featuring elevations, depressions, and ribs with airfoil profiles, which influence primary pressure gradients and outflow angles, reducing secondary flow vortices and flow losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional straight side walls are used in blade cascades, then the structure is simple and easy to manufacture, but secondary flows and pressure losses increase due to deflection of flow layers near the wall
Solution Approach 1:
The patent applies curvature to the side walls by introducing circumferentially wavy contours with elevations and depressions, replacing straight side walls with curved surfaces that guide flow more effectively and reduce secondary flow vortices
Solution Approach 2:
The side wall contour is segmented into multiple features including elevations, depressions, and ribs with airfoil profiles, each serving to modify flow characteristics in specific regions to reduce overall pressure losses
2Loss of energy
If non-circumferentially symmetrical side wall contours are introduced to reduce secondary flows, then pressure losses are reduced, but the manufacturing complexity increases
Solution Approach 1:
The circumferentially wavy contour with smooth elevations and depressions provides a curved geometry that reduces secondary flows while maintaining manufacturability through established forming techniques
3Productivity
If elevations and depressions are added to the side wall to influence outflow angle, then flow alignment is improved, but the device complexity increases
Solution Approach 1:
Elevations and depressions are strategically positioned in the rear area of the side wall to locally modify outflow angle and influence subsequent grating inflow distribution, applying complexity only where needed to achieve flow control objectives
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 design reduces secondary flows and improves the alignment of the outflow angle, resulting in enhanced efficiency and reduced mixing losses for turbomachines.
Implementation Method 1
A primary or main flow guided through a flow channel is deflected parallel to the boundary wall by a lateral pressure gradient
Implementation Method 2
Since flow layers close to the wall are deflected more strongly than flow layers farther away from the wall due to their lower speed, a secondary flow or a channel vortex is formed that is superimposed on the main flow
Implementation Method 3
at least one rib having an airfoil profile with a pressure side and an opposite suction side
Implementation Method 4
an interaction of horseshoe vortices induced at the blade leading edge with one another and with a channel vortex is prevented or at least reduced
Data Source
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AI summary
A blade grid of a turbomachine is disclosed, the at least one side wall of which is corrugated in the circumferential direction and has at least one elevation and at least one depression, wherein at least one profile-like rib is integrated into or combined with the side wall, which has a blade profile with a pressure side and with an opposite suction side, as well as a turbomachine with such a blade grid.