Computational Fluid Dynamics (CFD, Computational Fluid Dynamics) is a powerful tool for simulating and analysing fluid flow and its interaction with solid boundaries. During the design process of an axial fan, CFD can be used to optimise the performance of the fan in terms of increasing efficiency, reducing noise, enhancing stability and predicting and improving thermal management.
1. Design process
Requirements definition: Firstly, clarify the application scenario of the fan, the desired performance index (e.g. flow rate, pressure, efficiency, etc.), and the operating conditions (temperature, humidity, etc.).
Preliminary design: Determine the basic parameters of the fan based on empirical data and theoretical calculations, including the number of blades, blade angle, diameter, etc.
Geometric modelling: Creation of a 3D model of the turbine and its surroundings, including components such as the impeller, casing, etc. This stage requires an accurate representation of the actual shape and dimensions of each component.
Meshing: The model is divided into small cells (grids) suitable for numerical solution. A high quality mesh is essential to accurately capture the flow characteristics. Typically, the density of the mesh is higher near walls and complex geometries.
Setting Boundary Conditions: Set boundary conditions such as inlet velocity, outlet pressure, rotational velocity, etc. according to the actual situation.
Select turbulence model: Choose a suitable turbulence model to describe the motion of the fluid. Commonly used models include k-ε model, k-ω SST model and so on.
Solution process: Use CFD software to solve the Navier-Stokes system of equations to simulate the fluid flow inside the fan.
Result analysis and optimisation:
Analyse the pressure distribution, velocity vector diagram, vortex structure, etc. of the flow field.
Adjust the design parameters, such as blade angle, thickness, pitch, etc., according to the simulation results to optimise the fan performance.
Repeat the above steps until the design requirements are met.
2. Key Technical Points
Selection of turbulence model: Different application scenarios may require different turbulence models, and the correct selection of turbulence model is very important to obtain reliable simulation results.
Multi-disciplinary optimisation: In addition to hydrodynamics, factors such as mechanical strength and material selection should also be considered to achieve multi-objective optimisation.
Dynamic effects analysis: Considering that axial fans usually operate at high speeds, it is also necessary to analyse rotor dynamics, such as vibration patterns and noise generation mechanisms.
Thermal management: For applications involving heat exchange, special attention needs to be paid to the simulation of heat conduction and convection heat transfer.
3. Application examples
Industrial ventilation systems: CFD optimisation of the design to ensure efficient operation of the entire system while reducing energy consumption.
Air conditioning and refrigeration equipment: To improve the design of fans, increase energy efficiency and reduce noise.
Aircraft engines: To help design efficient intake and exhaust systems and improve overall engine performance.
