The shape of the duct fan blade directly determines the flow state of the airflow. When the traditional straight blade is running, the airflow is easy to separate at the edge of the blade, forming vortices, resulting in energy loss and reduced efficiency. The blades with airfoil design can effectively reduce air resistance, reduce vortex generation, and improve the smoothness of airflow and the lift coefficient of the fan by simulating the streamlined structure of the aircraft wing. For example, the swept-back blade can delay the separation of airflow, so that the fan can maintain stable performance at high speed; the swept-forward blade can enhance the axial guidance ability of the airflow and improve the overall efficiency of the fan.
The blade angle is an important parameter for regulating the pressure and flow of the duct fan. When the blade angle increases, the direction of the force of the airflow on the blade surface changes, and the pressure generated by the fan increases accordingly, but it also causes the blade load to increase and increase energy consumption. Conversely, reducing the blade angle can reduce the pressure and increase the flow. In practical applications, the blade angle needs to be accurately adjusted according to the ventilation needs. For example, in a duct system with a long ventilation distance and high resistance, the blade angle can be appropriately increased to increase the pressure; in a scenario where rapid ventilation is required, the blade angle can be reduced to increase the flow.
The choice of the number of blades has a complex effect on the performance of duct fans. Increasing the number of blades can improve the stability of the fan and make the airflow more uniform, but it will also increase the interference between the blades, resulting in increased airflow turbulence, increased wind resistance and noise. Conversely, reducing the number of blades can reduce wind resistance and increase fan speed, but it may increase airflow fluctuations and affect the output stability of the fan. Generally speaking, small duct fans use 3-5 blades to reduce noise while ensuring a certain air volume; large industrial duct fans use 6-8 blades to ensure sufficient pressure and stability.
Irrational blade structure design is one of the main reasons for excessive noise in duct fans. Factors such as the roughness of the blade surface, the irregular shape of the blade edge, and the gap between the blade and the pipe can cause vibration and noise in the airflow. By optimizing the smoothness of the blade surface, adopting a streamlined blade edge design, and accurately controlling the gap between the blade and the pipe, noise can be effectively reduced. In addition, introducing damping materials in the blade structure or adopting an asymmetric blade design can further suppress vibration and reduce noise.
With the help of aerodynamic simulation software, numerical simulation and optimization of duct fan blade structure is an important means in modern design. By establishing a three-dimensional model of the blade, simulating the airflow under different working conditions, and analyzing parameters such as pressure distribution, velocity vector and vortex intensity, designers can intuitively understand the problems existing in the blade structure and make targeted improvements. For example, by adjusting the curvature, torsion angle and thickness distribution of the blade, the pressure distribution on the blade surface can be more uniform, thereby improving the overall performance of the fan.
The performance of the blade material directly affects the structural strength and operating efficiency of the duct fan. Although traditional metal blades are strong, they are heavy, which increases the rotational inertia of the fan and leads to increased energy consumption. With the development of composite materials, lightweight and high-strength materials such as carbon fiber and glass fiber reinforced plastics are gradually used in blade manufacturing. These materials are not only light in weight, but also have good corrosion resistance and fatigue resistance, which can effectively reduce the operating cost of the fan while improving the structural stability and service life of the blade.
After completing the optimization of the blade structure design, the optimization effect needs to be verified through actual testing. We manufacture optimized blade samples and install them on duct fans for performance testing. We measure the fan's air volume, air pressure, power, noise and other parameters and compare them with the data before optimization. Through repeated testing and adjustment, we continuously improve the blade structure design to ensure that the optimized duct fan can meet the needs of actual applications and achieve maximum performance improvement.
