Jet Engine Fan Blade Leading Edge Sweep Optimization
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Solution Overview
Problem
Current turbojet fan blade geometries face challenges in achieving optimal aerodynamic performance, mechanical strength, and noise reduction while meeting high-speed operational demands and stress requirements.
Innovation Solution
A turbojet fan blade design featuring a leading edge with a sag angle greater than or equal to +28° between 60% and 90% radial height, and a deflection angle difference of less than 10° between 15% and 45% radial height, ensuring improved aerodynamic and acoustic performance while maintaining mechanical robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the leading edge has a large sag angle (>=+28°) in the radial height range of 60%-90%, then the specific flow rate increases (maximum >210 kg/s/m²), but excessive rear deflection at tip sections may compromise aeromechanical stability
Solution Approach 1:
The patent applies different sag angle values to different radial sections of the blade. The leading edge has a sag angle of at least +28° in the radial height range of 60%-90% to maximize flow rate, while the sag angle at the tip section (radial height >90%) is limited to less than +15° to maintain aeromechanical stability. This local differentiation resolves the contradiction between maximizing productivity and ensuring reliability.
2Productivity
If the leading edge sag angle varies significantly, then aerodynamic performance may improve, but the acoustic signature deteriorates due to increased turbulence propagation in the wake
Solution Approach 1:
The patent carefully controls the sag angle parameter distribution along the radial height to optimize both aerodynamic performance and acoustic signature. By setting the sag angle to at least +28° in the 60%-90% radial range and limiting the angle difference to less than 10° between specific radial heights, the design achieves maximum specific flow while significantly reducing turbulence propagation and improving acoustic characteristics.
3Productivity
If the leading edge deflection varies rapidly, then flow capacities may increase, but mechanical strength decreases due to increased stress concentrations
Solution Approach 1:
The patent applies different deflection characteristics to different radial sections. The leading edge has controlled deflection with angle difference less than 10° in the 15%-45% radial range to reduce stress concentrations and improve mechanical strength, while achieving maximum specific flow greater than 210 kg/s/m² in the 60%-90% radial range where high flow capacity is prioritized.
4Power
If the blade is designed for high rotation speeds to increase power output, then productivity increases, but mechanical stresses become most severe compromising reliability
Solution Approach 1:
The patent optimizes the sag angle parameter distribution to enable high rotation speed operation. By setting the sag angle to at least +28° in the 60%-90% radial range and controlling the angle difference to less than 10°, the blade achieves maximum specific flow greater than 210 kg/s/m² while maintaining aeromechanical stability and reducing stress concentrations, allowing high power output with improved reliability.
Data Source
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AI summary
The invention relates to a blade for the fan of a jet engine. The leading edge of the blade has a sweep angle greater than or equal to +28° in a part of the blade that is situated at a radial height of between 60% and 90% of the total radial height of the blade as measured from its root to its tip, and the difference (delta1) in sweep angle of the leading edge is less than 10° between a radial height of minimum sweep (Hmin) corresponding to a minimum sweep situated in that part of the blade of between 20% and 90% of the radial height of the blade, and a radial height (Hmin+10) measured at 10% above this radial height of minimum sweep.