Key points for the silent design of drone blades in aerial photography
The key points of silent design for the blades of aerial photography drones
mainly include the following aspects:
First, optimize the shape of the blades
Key point analysis:
Swept-back tip design: By adopting swept-back tips, the working performance of the forward blades at Mach numbers can be improved, the time when aerodynamic drag increases can be delayed, and noise generation can be reduced at the same time.
Wingtip treatment: For instance, the DJI Mavic Pro Platinum Edition unmanned aerial vehicle adopts a redesigned 8331 propeller. By adding "inclined wingtips" to adjust the blade design, the blade is curved in the middle and directed backward at the tip, which not only enhances aerodynamic efficiency but also significantly reduces aerodynamic noise.
Second, the selection of blade materials
Key point analysis:
Composite material application: The blades are made of reinforced composite materials such as carbon fiber and glass fiber. These materials have excellent properties such as high specific strength, high specific modulus, high damping and designability, which help to reduce the vibration and noise of the blades during rotation.
Lightweight design: Under the premise of ensuring structural strength, by optimizing material usage and design, the weight of the blades is reduced, which helps to lower the inertial force during rotation and thereby reduce noise.
Third, the design of the blade structure
Key point analysis:
Application of toothed structure: For instance, in the unmanned aerial vehicle blades designed by Fengyi Technology, multiple teeth arranged along the blade length are added to the trailing edge of the blade, altering the structure of the tail vortex and effectively reducing the far-field radiation of noise.
Wing design: Special wings are designed at the tip of the blade. By reintegrating the airflow in the flow field, the noise at the top is further reduced.
Fourth, optimization of the motor and electronic speed controller
Key point analysis:
FOC sinusoidal wave drive architecture electronic control: Compared with the traditional square wave control, the FOC sinusoidal wave drive architecture electronic control makes the motor phase current sinusoidal and continuously changing, without sudden changes in commutation current, reducing electromagnetic noise.
Motor and blade matching: Select the appropriate combination of motor and blade to ensure sufficient thrust is provided while reducing noise generation.
Fifth, the number and layout of the blades
Key point analysis:
Increasing the number of blades: Under the condition that the total thrust remains unchanged, increasing the number of blades can reduce the load on each individual blade, thereby reducing noise. For instance, compared with four-axis unmanned aerial vehicles (UAVs), eight-axis UAVs bear less load per blade under the same load, which helps to reduce noise.
Optimize the layout of the blades: By rationally arranging the blades, the mutual interference between the blades and the airflow disorder can be reduced, thereby lowering the noise.
Sixth, closed propeller design
Key point analysis:
Annular propeller: For instance, the annular propeller developed by the Lincoln Laboratory of the Massachusetts Institute of Technology minimizes the drag effect of the rotating air tunnel (i.e., vortex) generated at the blade tip through a closed structure, thereby reducing noise.
Application prospects: This closed propeller design is not only applicable to unmanned aerial vehicles but also to other aircraft that require noise reduction.
Practical application suggestions
Comprehensive consideration: In the silent design of aerial photography drones, multiple aspects need to be comprehensively considered, including the shape, material, structure of the blades, optimization of the motor and electronic adjustment, the number and layout of the blades, as well as the design of the closed propeller.
Flight test: Verify the effect of the silent design through flight tests, and make necessary adjustments and optimizations based on the test results.
User feedback: Collect user feedback to understand their noise perception during use and provide references for subsequent silent design.
In summary, the silent design of aerial photography drones is a complex process involving multiple aspects, which requires comprehensive consideration of various factors to achieve the best noise reduction effect.
