What is the relationship between air pressure, airflow, power, and rotational speed in axial-flow fire ventilation fans?

Typically, the rotational speed of an axial flow fire fan—which can be directly measured using an octopus meter—is denoted by the letter N. This value is usually expressed in revolutions per minute (rpm). Generally, small axial flow fire fans rotate at high speeds and are directly connected to the motor. In contrast, large axial flow fire fans rotate at slower speeds, and their connection to the motor often uses a belt drive. In this way, the fan’s speed can be adjusted by changing the diameter of the pulleys. The relationship between them can be expressed by the formula n1/n2 = d2/d1. In this formula, n1 and n2 represent the speeds of the axial flow fire fan and the motor, respectively. d1 and d2 represent the diameters of the fan and motor pulleys, respectively. Based on this relationship, if you wish to change the speed of the axial flow fire fan, you simply need to change the diameters of the fan and motor pulleys. In other words, when the speed of the axial flow fire fan changes, the corresponding performance parameters and characteristic curves will also change. This is because the fan exhibits different characteristic curves at various speeds. By adjusting the rotational speed of the axial flow fire fan, it can be observed that the corresponding performance parameters change under certain conditions. As the speed of the axial flow fire fan changes, the airflow changes in direct proportion to the square of the speed. The change in static pressure is proportional to the square of the speed ratio. The change in force is proportional to the cube of the speed ratio. From the above explanation, it can be seen that when the speed of the axial flow fire fan changes, the actual output must be recalculated. At the same time, please check whether the original motor is overloaded.