Blisk Blade Root Profile for Vibratory Force Resistance
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Solution Overview
Problem
Existing one-piece bladed discs in turbomachinery face challenges in resisting static and vibratory forces, shocks from ingested solid bodies, and achieving uniform gas flow distribution, particularly under intense conditions like supersonic flight, due to limitations in blade root profile design.
Innovation Solution
The blades feature continuously increasing dihedral and sag angles approaching the hub, with specific angle profiles in the root zone to enhance aerodynamic performance and mechanical resistance, and a deflection angle that maximizes near the hub, ensuring improved gas flow distribution and mechanical stress management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional blade profiles are used in one-piece blisks, then manufacturing is simpler, but resistance to static and vibratory forces deteriorates
Solution Approach 1:
The patent applies local quality by implementing specific angle variations (dihedral angle α and sag angle β) only in the root zone of the blades (approximately 20-30% of blade height from the hub), while the rest of the blade maintains conventional profile. This localized modification enhances mechanical resistance at the critical root area without complicating the entire blade structure
Solution Approach 2:
The patent changes geometric parameters in the blade root zone by continuously increasing the dihedral angle α and sag angle β from hubward, with the deflection angle reaching a maximum of at least 20° near the hub connection. These parameter modifications improve stress distribution and vibratory resistance without requiring complete redesign of the blade
2Strength
If blade root profile is modified to improve mechanical resistance, then strength improves, but aerodynamic performance deteriorates
Solution Approach 1:
The invention confines the complex angle variations to the root zone (20-30% of blade height), ensuring that the aerodynamic portions of the blade (tip and middle sections) maintain their optimized airfoil shapes. This localized approach preserves overall aerodynamic efficiency while enhancing root mechanical properties
Solution Approach 2:
The patent employs continuous curvature in the angle variations within the root zone, using smooth transitions for the dihedral and sag angles rather than abrupt changes. This curvature approach maintains favorable flow characteristics while providing mechanical reinforcement
3Reliability
If angle variations are increased in root zone, then gas flow distribution improves, but manufacturing precision requirements deteriorate
Solution Approach 1:
The patent specifies continuous variation of angles in the root zone, avoiding abrupt changes or discontinuities. This smooth curvature approach facilitates manufacturing by eliminating sharp corners and sudden transitions, reducing precision requirements while maintaining improved gas flow distribution
Data Source
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AI summary
The invention relates to a one-piece blisk comprising blades (2), the leading edge (3) of said blades having highly-variable sweep angles and dihedral angles which increase towards the connection to the hub (1) in order to improve the mechanical strength of the assembly and to obtain a good distribution of the gas flow over the full height of the blade.