Turbomachinery Rotor Blade Protrusion for Lacing Wire Stress Reduction
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Solution Overview
Problem
Turbine blades in highly pulsating gas flows require additional damping/stiffness, which is achieved by lacing wires, but these cause stress and disrupt gas flow efficiency, and conventional bosses to mitigate stress further reduce efficiency.
Innovation Solution
A turbomachinery rotor blade design with protrusions downstream and/or upstream of the hole for the lacing wire, reducing stress without thickening the blade inboard or outboard, thereby minimizing gas stream disruption and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a boss is added around the hole in each blade to reduce stresses, then the blade strength is improved, but the gas stream flow is disrupted and aerodynamic efficiency is reduced
Solution Approach 1:
The invention applies local quality by positioning protrusions at specific locations (upstream and downstream of the hole) rather than creating a complete boss around the hole. This localized approach provides stress support only where inertial loads are most significant, while leaving the rest of the blade surface smooth to maintain aerodynamic efficiency.
Solution Approach 2:
The boss structure is segmented into discrete protrusions located only at critical stress points (upstream and downstream of the hole) rather than forming a continuous circular boss. This segmentation allows stress reinforcement where needed while minimizing interference with gas stream flow over the majority of the blade surface.
2Strength
If the blade is thickened inboard or outboard of the hole to reduce stress, then the blade strength is improved, but the gas stream disruption is increased and aerodynamic performance is reduced
Solution Approach 1:
The invention uses local quality by creating protrusions only at specific locations (upstream and downstream of the hole) rather than thickening the blade inboard or outboard. This provides targeted stress support while maintaining smooth blade surfaces in regions critical for aerodynamic performance.
Solution Approach 2:
The solution moves from two-dimensional planar thickening (inboard/outboard) to a three-dimensional configuration where protrusions extend from the blade surface in the direction of gas flow. This dimensional change allows stress reinforcement without blocking the gas stream path.
Data Source
AI summary
A turbomachinery rotor blade is provided having an aerofoil body, and a hole penetrating the aerofoil body from a suction surface to a pressure surface thereof. The hole is suitable to receive a lacing wire. The blade further has a protrusion from the suction or pressure surface. The protrusion extends in a downstream direction from a downstream side of the hole and/or extends in an upstream direction from an upstream side of the hole, thereby disturbing the suction or pressure surface to locally thicken the aerofoil body adjacent the hole. The maximum radial extent of the protrusion in the radially outward direction of the blade is radially coterminous with the outboard side of the hole, and the maximum radial extent of the protrusion in the radially inward direction of the blade is radially coterminous with the inboard side of the hole.