Gas Turbine Blade Solidity Ratio Segmentation
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Solution Overview
Problem
Conventional gas turbine blade manufacturing processes struggle to balance aerodynamics, mechanical integrity, and economic attractiveness, particularly in achieving larger blades with efficient power output and reduced mass, due to limitations in wall thickness, centrifugal loads, and cooling efficiency.
Innovation Solution
The solution involves a gas turbine blade design with a machined zone from 80% to 85% of the span having solidity ratios below 35%, and then reverting to conventional levels in the lower half, combined with specific wall thickness and trailing edge thickness adjustments, achieved through machining techniques like milling or grinding, to optimize aerodynamics and mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the airfoil span and chord length are increased to achieve higher power output, then the power output increases, but the tensile loads and centrifugal loads increase proportionally
Solution Approach 1:
The airfoil is divided into multiple zones along the span: a first zone (0-70%) with conventional solidity ratios for mechanical strength, and a second zone (70-100%) with reduced solidity ratios for weight reduction. This segmentation allows different portions of the airfoil to serve different functions - the root portion maintains structural integrity while the tip portion reduces centrifugal loads.
Solution Approach 2:
Different solidity ratios are applied to different zones of the airfoil based on local requirements. The first zone (0-70% span) uses conventional solidity ratios (35-70%) to handle high tensile loads near the root, while the second zone (70-100% span) uses reduced solidity ratios (10-35%) to minimize centrifugal loads at the tip where aerodynamic performance is more critical.
2Strength
If the wall thickness is increased to maintain mechanical integrity, then the strength increases, but the mass increases adding unnecessary weight
Solution Approach 1:
The airfoil wall thickness is segmented into different zones: the first zone (0-70% span) maintains conventional wall thicknesses for structural strength, while the second zone (70-100% span) uses reduced wall thicknesses to minimize mass. This allows the blade to have adequate strength where needed while reducing overall weight.
Solution Approach 2:
Different wall thicknesses are applied locally to different zones of the airfoil. The root portion (first zone) has thicker walls to withstand high tensile stresses, while the tip portion (second zone) has thinner walls since the stresses are lower and aerodynamic efficiency benefits from reduced mass.
3Strength
If the solidity ratio is increased to reduce tensile loads, then the mechanical integrity improves, but the aerodynamic performance deteriorates due to excessive blockage
Solution Approach 1:
The airfoil span is segmented into two zones with different solidity ratio requirements. The first zone (0-70% span) uses conventional solidity ratios to handle mechanical loads, while the second zone (70-100% span) uses reduced solidity ratios to optimize aerodynamic flow and minimize energy losses from excessive blockage.
Solution Approach 2:
Different solidity ratios are applied to different zones: the root zone (first zone) has higher solidity for structural reasons, while the tip zone (second zone) has lower solidity for aerodynamic reasons, creating an optimized gradient that balances both requirements.
4Power
If the airfoil size is increased for higher power output, then the power output increases, but the manufacturing complexity increases due to taper requirements
Solution Approach 1:
The manufacturing process is segmented into two distinct zones: the first zone (0-70% span) uses conventional casting processes with standard taper requirements, while the second zone (70-100% span) uses advanced additive manufacturing techniques that can produce complex geometries without traditional taper constraints, simplifying the overall manufacturing of large airfoils.
Data Source
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AI summary
The present invention relates to a gas turbine blade (1) having a casted metal airfoil (2), said airfoil (2) comprising a main wall defining at least one interior cavity (9), having a first side wall (3) and a second side wall (4), which are coupled to each other at a leading edge (5) and a trailing edge (6), extending in a radial direction from a blade root (7) to a blade tip (8) and defining a radial span from 0% at the blade root (7) to 100% at the blade tip (8), wherein said main airfoil (2) has a radial span dependent chord length defined by a straight line connecting the leading edge (5) and the trailing edge (6) as well as a radial span dependent solidity ratio of metal area to total cross-sectional area, characterized in that solidity ratios in a machined zone of the airfoil (2) from 80% to 85% of span are below 35%, in particular all solidity ratios in said zone.