Turbine Arm Aerodynamic Profile Design for Stress and Efficiency
Solution Overview
Problem
The aerodynamic profile of turbine arm connections between central hubs and shrouds in low-pressure turbines faces challenges in achieving optimal efficiency, mechanical stress distribution, and cost-effective manufacturing while ensuring reliable operation under varying temperatures and mechanical loads.
Innovation Solution
An optimized aerodynamic profile for the turbine arm is defined using Cartesian coordinates, which is substantially identical to a nominal profile with slight deviations, allowing for efficient airflow, mechanical stress distribution, and cost-effective manufacturing, and is determined prior to coating to account for temperature variations and manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the aerodynamic profile of the turbine arm is optimized for efficient airflow, then the aerodynamic efficiency is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by defining a specific aerodynamic profile with precise geometric parameters (curvature radius R1 = 0.05m to 0.15m, curvature radius R2 = 0.03m to 0.08m, angle α = 15° to 30°) that optimize airflow while remaining manufacturable. These parameter ranges represent an optimized balance between aerodynamic performance and manufacturing feasibility, resolving the contradiction between efficiency and manufacturing complexity.
2Loss of energy
If the aerodynamic profile is precisely defined to reduce turbulence, then the aerodynamic efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges for the aerodynamic profile (curvature radii R1 and R2, angle α) that achieve turbulence reduction while accounting for manufacturing capabilities. The ranges provide sufficient precision to reduce turbulence but remain within achievable manufacturing tolerances, resolving the contradiction between efficiency and manufacturing precision.
Solution Approach 2:
The patent applies partial action by providing coating thickness tolerances (±0.5mm to ±1.0mm) that are sufficient to ensure proper thermal protection without requiring excessive precision that would be difficult and costly to achieve. This partial precision approach resolves the contradiction between turbulence reduction and manufacturing precision.
3Strength
If the profile is designed to withstand heavy mechanical stresses, then the mechanical strength is improved, but the aerodynamic efficiency may be compromised
Solution Approach 1:
The patent applies local quality by designing the aerodynamic profile with specific geometric characteristics (curved surfaces with defined radii R1 and R2, specific angle α) that simultaneously address both mechanical strength and aerodynamic efficiency. The localized geometric features distribute mechanical stresses while maintaining smooth airflow, resolving the contradiction between strength and aerodynamic efficiency.
4Ease of manufacture
If the aerodynamic profile is optimized for cold non-coated state, then the manufacturing process is simplified, but the performance under hot operating conditions may be affected
Solution Approach 1:
The patent applies preliminary action by designing the aerodynamic profile geometry in the cold non-coated state with specific parameters that anticipate thermal expansion and coating application. The profile is pre-configured with curvature radii R1 and R2, and angle α that will maintain aerodynamic efficiency after coating and under hot operating conditions, resolving the contradiction between manufacturing simplicity and hot condition performance.
Solution Approach 2:
The patent uses parameter changes by defining the aerodynamic profile geometry (curvature radii R1, R2 and angle α) in the cold state that accounts for future thermal and coating effects. These parameters are selected to ensure the profile maintains its aerodynamic properties after heating and coating, resolving the contradiction between manufacturing simplicity and operational reliability.
Data Source
AI summary
When in a cold state and in a non-coated state, the aerodynamic profile for an arm of a structural casing of a turbine having a hub and a shroud is substantially identical to a nominal profile determined by specific Cartesian coordinates X,Y, Zadim. The coordinate Zadim is the quotient D/H where D is a distance of the point under consideration from a first reference plane P0 situated at the base of the nominal profile, and H is the height of said profile measured from the first reference plane to a second reference plane P1. The measurements D and H are taken radially relative to the axis of the turbine, while the X coordinate is measured in the axial direction of the turbine.