Blisk Trailing Edge Thickening for Gas Turbine Surge Control
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Solution Overview
Problem
Prior art integrally bladed rotors experience undesirable aerodynamic surging, an unstable airflow effect that negatively impacts fan operation in gas turbine engines.
Innovation Solution
The design incorporates a thicker portion at the trailing edge and radially inner span of the airfoil, with a fillet merging the airfoil into the hub, where the thicker portion extends for less than 50% of the span and axial distance, and increases in thickness towards the hub, maintaining a limited material addition to reduce surge while minimizing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the blade thickness is increased at the trailing edge and radially inner span to reduce surge, then the aerodynamic stability is improved, but the blade weight increases
Solution Approach 1:
The patent applies local quality by increasing the blade thickness only in specific regions (trailing edge and radially inner span) rather than uniformly across the entire blade. This localized thickening reduces surge in critical areas while minimizing overall weight increase. The thicker portion is confined to less than 50% of the span and less than 50% of the axial distance, ensuring targeted aerodynamic improvement without excessive material addition.
2Reliability
If a thicker portion is added to the airfoil to reduce surge, then the aerodynamic performance is improved, but the material usage increases
Solution Approach 1:
The invention implements local quality by concentrating the thicker portion at the trailing edge and radially inner span where surge is most problematic. This localized approach improves aerodynamic performance in critical regions while limiting material usage. The thicker portion is restricted to specific dimensional boundaries (less than 50% of span, less than 50% of axial distance) to optimize the balance between surge reduction and material efficiency.
3Reliability
If the blade thickness is increased to prevent surge, then the aerodynamic stability is improved, but the blade complexity increases
Solution Approach 1:
The patent applies local quality by introducing geometric complexity only in specific regions (trailing edge and radially inner span) rather than throughout the entire blade. This localized thickening with fillets merging into the hub provides surge control where needed while maintaining simpler geometry in other areas, thus limiting overall blade complexity.
Solution Approach 2:
The invention uses curvature principles by employing fillets to merge the thicker portion smoothly into the hub and airfoil. These curved transitions eliminate sharp geometric discontinuities, reducing stress concentrations and simplifying manufacturing while maintaining the aerodynamic benefits of the localized thickening.
Data Source
Figure 1
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Figure 3A~3B
AI summary
An integrally bladed rotor (80) for a gas turbine engine (20) comprises a hub (82) centered about an axis and having a plurality of blades (84) extending radially outwardly of the axis across a span. Each of the blades (84) includes an airfoil extending between a leading edge (86) and a trailing edge (88), and having a pressure side (85) and a suction side (89). The airfoil has a thicker portion (94) at the trailing edge (88), and at a radially inner portion of the span, and over a limited percentage of the span, such that the thicker portion (94) does not extend beyond 50 percent of the span. An axial distance is defined between the trailing edge (88) and the leading edge (86). The thicker portion (94) extends for less than 50 percent of the axial distance, and is on the pressure side (85).