Turbine Blade Platform Contours for Friction Reduction
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Solution Overview
Problem
Turbine engines experience significant frictional losses due to the high velocity of the working fluid flowing over the surface area of the platform in rotating turbomachinery, leading to reduced efficiency.
Innovation Solution
A flow directing assembly with non-axisymmetrical troughs positioned between neighboring airfoils, extending from the leading edges to the trailing edges, which reduces frictional losses by increasing the volume of the fluid flow passage and decreasing fluid velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the working fluid flows at high velocity through the turbine, then power output is increased, but frictional losses on the platform surface increase
Solution Approach 1:
The invention introduces a third dimension (radial depth) to the platform surface by forming troughs or scalloped areas. This dimensional change increases the flow passage volume without expanding the planar footprint, thereby reducing fluid velocity and frictional losses while maintaining power output capability
Solution Approach 2:
The invention changes the geometric parameters of the flow passage by creating non-axisymmetrical troughs with specific radial depths, circumferential positions, and axial extents. These parameter modifications optimize the balance between fluid velocity reduction (lowering frictional losses) and maintaining sufficient flow capacity for power generation
2Loss of energy
If the flow passage volume is increased to reduce fluid velocity and frictional losses, then the platform surface area must be expanded, but this increases the device complexity
Solution Approach 1:
The invention applies local modifications (troughs or scalloped areas) at specific circumferential positions between airfoils rather than uniformly across the entire platform. This localized approach increases flow volume where most beneficial while minimizing structural complexity and manufacturing difficulty
Solution Approach 2:
The troughs are designed as non-axisymmetrical features with optimized radial depths and circumferential positions. This asymmetry allows the flow passage volume to be increased efficiently in critical regions without requiring symmetric expansion that would increase overall device 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
The implementation of these troughs decreases frictional losses, enhances engine efficiency, and offers additional benefits such as reduced shock loss, improved thermal characteristics, and enhanced cooling of turbine blades.
Implementation Method 1
frictional losses occur, particularly as the working fluid flows over the surface area of the platform
Implementation Method 2
the inner wall of one or more of the flow passages comprises means for reducing frictional losses between the flow through the turbine engine and the inner wall
Data Source
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AI summary
A flow directing assembly (150) for use in a turbine engine (100) comprising: a plurality of circumferentially spaced blades (152), each of the blades (152) including a radial projecting airfoil (154) with a concave pressure side (160) and a convex suction side (162) that extend from a platform (156); and a plurality of flow passages (164), each flow passage (164) defined by the airfoils (164) of neighboring blades (152) and an inner wall (157) formed by abutting platforms (156) of neighboring blades (152), the inner wall (157) forming the inner radial boundary of the flow passage (164); wherein the inner wall (157) of one or more of the flow passages (164) comprises means for reducing frictional losses between the flow through the turbine engine (100) and the inner wall (157). The means for reducing frictional losses may comprise a non-axisymmetrical trough (170) positioned between neighboring airfoils (154) that is configured to reduce frictional losses.