Integrally Bladed Rotor Fillet Geometry for Crack Containment
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Solution Overview
Problem
Current integrally bladed rotors for gas turbine engines face challenges in assembly, manufacture, and performance, particularly in preventing crack propagation and optimizing stress distribution, which affects engine efficiency and reliability.
Innovation Solution
The design incorporates a first fillet providing a smooth transition from the peripheral surface, with a second fillet radially outward, and a patch portion on the suction side at the leading edge, both featuring distinct radii to create a crack propagation boundary that prevents cracks from entering the rotor, enhancing structural integrity and reducing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If airfoils are integrally formed as part of the rotor, then the number of parts is reduced and fastening systems are eliminated, but crack propagation risks increase at the interface between the rotor and airfoils
Solution Approach 1:
The patent applies curvature by forming fillets at the interface between the rotor and airfoils. The first fillet has a first radius and the second fillet has a second radius, creating curved transition surfaces that eliminate sharp corners and stress concentration points. This curvature design prevents crack initiation and propagation at the integral interface, resolving the reliability issue while maintaining the simplicity of the integrated structure.
Solution Approach 2:
The patent applies local quality by creating distinct fillet regions with different radii at specific locations where the rotor meets the airfoils. The first fillet and second fillet have different radii tailored to their respective positions, providing localized stress distribution optimization. This allows the structure to maintain integral simplicity while having enhanced crack resistance at critical interfaces.
2Reliability
If separate airfoils are assembled to the rotor, then crack propagation can be isolated, but the number of parts increases and fastening systems are required
Solution Approach 1:
The patent uses fillet curvature to create smooth transitions at the integral interface between rotor and airfoils. By forming rounded corners with specific radii instead of sharp edges, the design prevents stress concentration that would lead to crack initiation, achieving crack propagation control without requiring separate assembled components or fastening systems.
3Ease of manufacture
If fillets with uniform radius are used at the rotor-airfoil interface, then manufacturing is simplified, but stress distribution is not optimized and crack propagation may occur
Solution Approach 1:
The patent applies local quality by specifying different radii for different fillet locations. The first fillet has a first radius and the second fillet has a second radius, with each radius optimized for its specific position at the rotor-airfoil interface. This localized differentiation optimizes stress distribution at each critical point while remaining manufacturable through standard forming processes.
Solution Approach 2:
The patent uses varied curvature radii in the fillets to optimize stress distribution. By creating curved surfaces with specific, different radii at different locations, the design achieves optimal stress flow patterns that prevent crack initiation, balancing manufacturing feasibility with mechanical strength requirements.
Data Source
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AI summary
An integrally bladed rotor (62; 102) for a gas turbine engine (20) includes a rotor portion (76; 120) with an outer periphery (64; 122). At least one airfoil (66; 106) includes a suction side (74; 112) and a pressure side (72; 114) extending between a leading edge (68; 108) and a trailing edge (70; 110). The at least one airfoil (66; 106) extends radially from the outer periphery (64) and has an airfoil thickness (82; 124) between the suction side (74; 112) and the pressure side (72; 114). A first thickness (84; 126) on at least one of the pressure side (72; 114) and suction side (74; 112) of the airfoil (66; 106) in addition to the airfoil thickness (82; 124) that extends radially from the outer periphery (64; 122) defines a crack propagation boundary (135). A method of fabricating an integrally bladed rotor (62; 102) for a gas turbine engine (20) is also disclosed.