Gas Turbine Stator Vane End Wall Shaping for Flow Control
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Solution Overview
Problem
Conventional methods for suppressing secondary flows and horseshoe-shaped vortices near the leading edge of gas turbine stator vanes are ineffective, leading to increased total pressure loss and vane loading.
Innovation Solution
The stator vane design features inward and outward convexed shapes on the end walls, strategically positioned near the leading edge to control fluid velocity and prevent vortex formation, with vertex positions optimized between 30% to 80% of the radial position to minimize flow passageway narrowing and abrupt velocity changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional axially asymmetrical end wall shaping is used to suppress secondary flows, then total pressure loss is reduced in the region between pressure and suction surfaces, but horseshoe-shaped vortex augmentation near the leading edge cannot be suppressed
Solution Approach 1:
The end wall shape is segmented into multiple regions: a first region with a convexed shape near the leading edge to suppress horseshoe vortices, and a second region with a concaved shape in the intermediate portion to suppress secondary flows. This segmentation allows each region to address specific flow problems independently, resolving the contradiction between suppressing horseshoe vortices and reducing total pressure loss.
Solution Approach 2:
Different portions of the end wall are given different local shapes tailored to their specific functional requirements. The leading edge region receives a convexed shape for vortex suppression, while the intermediate region receives a concaved shape for secondary flow control. This local differentiation enables simultaneous achievement of both vortex suppression and total pressure loss reduction.
2Reliability
If the vertex of the convexed end wall shape is positioned too close to the leading edge, then horseshoe vortex suppression is improved, but flow passageway narrowing and abrupt velocity changes increase
Solution Approach 1:
The convexed shape is applied partially rather than extending to the very leading edge. The vertex is positioned at an optimized distance from the leading edge, providing sufficient vortex suppression while avoiding excessive flow passageway narrowing. This partial application balances vortex control with velocity stability.
Solution Approach 2:
The position of the vertex of the convexed shape is optimized as a key parameter. By adjusting this parameter to an optimal distance from the leading edge, the design achieves effective horseshoe vortex suppression while maintaining gentle velocity changes and avoiding flow passageway narrowing.
3Force
If the end wall shape is designed to suppress secondary flows, then vane loading is reduced, but the complexity of end wall shaping increases
Solution Approach 1:
The end wall employs axially asymmetrical shaping with convexed and concaved portions at different locations. This asymmetry is strategically designed to control flow patterns and reduce vane loading while maintaining manufacturability. The asymmetrical shape directly addresses the secondary flow problem without requiring overly complex geometries.
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 effectively suppresses secondary flows and horseshoe-shaped vortices, reducing total pressure loss and enhancing turbine efficiency by maintaining gentle velocity changes and reducing impulse wave losses.
Implementation Method 1
a flow of fluid streaming near an end wall of the vane, that is, a secondary flow, at a cross section perpendicular to a main flow of gas
Implementation Method 2
augmentation of a horseshoe-shaped vortex occurring near the leading edge
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Provided is a gas turbine stator vane effective for suppressing a secondary flow in a region sandwiched between a suction surface side and a pressure surface side, as well as for suppressing augmentation of a horseshoe-shaped vortex occurring near a leading edge of the vane.