Views: 0 Author: Site Editor Publish Time: 2022-04-01 Origin: Site
The fan is a machine that relies on the input mechanical energy to increase the gas pressure to guide the flow of the gas. It is a driven fluid machine. The working principle of the fan is basically the same as that of the turbo compressor, but because the gas flow rate is low and the pressure change is not large, it is generally not necessary to consider the change of the gas specific volume, that is, the gas is treated as an incompressible fluid.
Fans are divided into axial flow fans, centrifugal fans and oblique flow (mixed flow) fans according to the flow direction of the airflow after entering the impeller.
The airflow enters the rotating vane channel, and the gas is compressed and flows radially under the action of centrifugal force.
The centrifugal fan is based on the principle of converting kinetic energy into potential energy, using a high-speed rotating impeller to accelerate the gas, then decelerate and change the flow direction, so that the kinetic energy is converted into potential energy (pressure). In a single-stage centrifugal fan, the gas enters the impeller from the axial direction, the gas changes to the radial direction as it flows through the impeller, and then enters the diffuser. In a diffuser, the gas changes the direction of flow causing a deceleration, which converts kinetic energy into pressure energy. The pressure increase occurs mainly in the impeller, and secondly in the diffusion process. In a multi-stage centrifugal fan, a recirculator is used to move the airflow to the next impeller, creating a higher pressure.
After the airflow enters the fan impeller axially, the fan flows along the axial direction in the flow channel of the rotating blade. Compared with centrifugal fans, axial flow fans have the characteristics of large flow, small volume and low pressure head, so attention should be paid to the occasions with dust and corrosive gases.
When the impeller rotates, the gas enters the impeller axially from the air inlet, and is pushed by the blades on the impeller to increase the energy of the gas, and then flows into the guide vane. The guide vanes turn the deflected airflow into an axial flow, and at the same time guide the gas into the diffuser, further convert the kinetic energy of the gas into pressure energy, and finally introduce it into the working pipeline.
In the impeller of the fan, the direction of the airflow is between the axial flow, which is approximately along the cone flow, so it can be called a diagonal flow (mixed flow) fan. The pressure coefficient of this fan is higher than that of the axial fan, and the flow coefficient is higher than that of the centrifugal fan.
When the impeller rotates, the gas enters the impeller axially from the air inlet, and the Bailey beam is pushed by the blades on the impeller to increase the energy of the gas, and then flows into the guide vane. The guide vanes turn the deflected airflow into an axial flow, and at the same time guide the gas into the diffuser, further convert the kinetic energy of the gas into pressure energy, and finally introduce it into the working pipeline.