Axial-Flow Trough Wall Configuration for Secondary Flow Loss Reduction
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Solution Overview
Problem
In axial-flow machines like gas turbine engines, the reduction of blade thickness leads to flow separation and strong vortices near pressure surfaces, causing significant pressure losses due to interactions with boundary layers, which conventional methods fail to adequately mitigate.
Innovation Solution
A radial wall configuration featuring a trough between blades, with a centerline curvature matching the blade's camber line, positioned between the leading and trailing edges, and optimized amplitudes and profiles to reduce secondary flow losses, including convex and concave profiles near the leading and trailing edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If blade thickness is reduced to make the blade more lightweight, then weight is reduced, but flow separation is generated in the vicinity of pressure surfaces causing strong vortices and pressure loss
Solution Approach 1:
The radial wall is designed with non-uniform curvature: a first curvature in the vicinity of the leading edge and a second curvature in the vicinity of the trailing edge. This local variation in wall geometry modifies the boundary layer characteristics at different positions along the blade, suppressing flow separation and vortex generation while maintaining the lightweight thin-profile blade design.
2Loss of energy
If a slope is provided on the radial wall to moderate the pressure gradient, then secondary flow loss is reduced, but the invention addresses a different mechanism (vortex generation from flow separation) that requires a more complex wall configuration
Solution Approach 1:
Instead of a uniform slope, the invention employs varying curvatures at specific locations (leading edge and trailing edge regions), creating localized flow control zones that address vortex generation from flow separation while maintaining overall structural simplicity.
Solution Approach 2:
The invention utilizes curved surfaces with different curvatures at different positions along the radial wall. The first curvature near the leading edge and second curvature near the trailing edge create smooth flow transitions that suppress vortex generation, replacing the need for complex multi-component structures.
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 effectively reduces secondary flow losses and improves the performance of gas turbine engines by minimizing vortex generation and turbulence near the wall surfaces.
Implementation Method 1
a boundary layer grows on the wall. In the boundary layer on the wall, a secondary flow having a different velocity component from a main flow is generated
Implementation Method 2
a flow separation tends to be partially generated in the vicinity of each pressure surface of the blades
Implementation Method 3
a strong vortex having a different flow direction/axis from the main flow is generated
Data Source
AI summary
A wall configuration of an axial-flow machine which can reduce the secondary flow loss is provided. A trough is formed between a blade and another blade in the blade row and extends in at least an axial direction of the blade row. The region where the trough is formed is axially between a leading edge and a trailing edge of the blade. A center line of the trough has a curvature in the same direction as a camber line of the blade. A maximum amplitude of the trough is located adjacent to an axial center of the blade or located axially between the axial center and the leading edge of the blade.