1. Single-stage impeller stage
There is only impeller in single stage, which is characterized by low pressure and efficiency. In the absence of a rear guide, a portion of kinetic energy associated with the velocity of rotation at the outlet of the fan was not utilized and was lost in vain. The single stage fan has small total pressure coefficient but simple structure and convenient manufacture. It is mainly used in low pressure axial fan with low pressure and low power consumption. The range of specific rotation number is usually 205-490. The stage-blade hub is smaller than the general one.
2. impeller and rear flow guide
A rear flow guide is installed at the back of the impeller, the purpose of which is to make use of the impeller outlet to spin things, so as to increase the pressure of the fan, and the efficiency of the fan is also improved accordingly. Its characteristics are that the single-stage total pressure coefficient is larger, generally 0.15-0.72, and the efficiency is high, so this type of stage is widely used in axial fan. This type of axial fan usually has a specific speed of 90-305. The fan can be adjusted by changing the installation angle of impeller blade under the condition of stopping or running.
3. front flow guide and impeller
The fan has a blade mounting angle adjustable and a fixed front flow guide at the front of the impeller. In order to produce a negative speed of rotation before the inlet of the impeller and zero at the outlet of the impeller. The velocity field and pressure field at the inlet of the impeller are aggravated by the leading flow, and the average relative velocity of the impeller is increased, which results in the increase of the fan loss and the decrease of the efficiency. In addition, this type of axial fan noise is also increased.http://jnblower.com/