Turbine Blade Sweep Angle for Secondary Flow Control
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Solution Overview
Problem
One-piece bladed disks for turbine engines face challenges in controlling secondary flows and maintaining aerodynamic performance due to small radial airfoil height and 'plunging' flow passages, which affect mechanical strength and efficiency.
Innovation Solution
The airfoil profile features a positive sweep angle increasing from the root to 20-40% radial height, then decreasing, and a dihedral angle that transitions from negative to positive, optimizing fluid flow distribution and reducing secondary flows by aligning forces for improved aerodynamic efficiency and static stress management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the radial airfoil height is kept small, then the blade fits within the plunging flow passage geometry, but secondary flows increase and aerodynamic performance decreases
Solution Approach 1:
The patent applies local quality by varying the sweep angle along the radial height of the airfoil. The leading edge has a positive sweep angle that increases from the root to a first radial height (20-40% of total height) and then decreases to the tip, while the trailing edge has a different sweep angle profile. This creates locally optimized flow control at different radial positions, managing secondary flows in the root zone while maintaining aerodynamic efficiency at the tip, thus resolving the contradiction between small airfoil height and aerodynamic performance.
2Ease of manufacture
If the leading edge sweep angle increases continuously from root to tip, then manufacturing is simplified, but secondary flows are not adequately controlled and aerodynamic efficiency is reduced
Solution Approach 1:
The patent applies parameter changes by modifying the sweep angle parameter along the radial height of the airfoil. Instead of a continuous increase from root to tip, the sweep angle increases to a maximum at 20-40% radial height and then decreases toward the tip. This parameter variation optimizes the balance between manufacturability (maintaining reasonable geometric complexity) and aerodynamic performance (controlling secondary flows and improving efficiency).
Solution Approach 2:
The patent applies local quality by creating different sweep angle zones: a first zone from the root to 20-40% radial height with increasing positive sweep angle, and a second zone from that height to the tip with decreasing sweep angle. This local differentiation allows optimized flow control in specific zones while maintaining overall geometric feasibility for manufacturing.
3Volume of moving object
If the flow passage is designed as plunging type, then the engine structure is compact, but flow control becomes difficult and aerodynamic performance is reduced
Solution Approach 1:
The patent applies local quality by implementing position-dependent sweep angles on both the leading and trailing edges of the airfoil. The leading edge has a positive sweep angle profile that peaks at 20-40% radial height, while the trailing edge has a different profile. This local geometric optimization compensates for the plunging passage geometry, improving flow control and aerodynamic performance in specific zones without changing the overall compact engine structure.
Solution Approach 2:
The patent applies dimensionality change by introducing sweep angle variations in the circumferential direction (around the engine axis) to compensate for the plunging passage geometry. By varying the sweep angle along the radial height and around the circumference, the patent creates a three-dimensional flow control strategy that manages secondary flows in the plunging passage while maintaining compact engine volume.
Data Source
AI summary
A turbine engine blade comprising an airfoil extending axially between a leading edge and a trailing edge and extending radially between a root and a tip. The leading edge of the airfoil presents a sweep angle that is positive and that increases continuously from the root to a first radial height of the airfoil situated in the range 20% to 40% of the total radial height of the airfoil as measured from the root to the tip, and decreases continuously from this first radial height of the airfoil to the tip.