As a core component of industrial ventilation systems, the airtightness of a centrifugal fan square is crucial to its airflow. Airtightness directly determines the fan's operating efficiency and is closely related to energy consumption, equipment lifespan, and system stability. From structural principles to practical applications, the impact of airtightness on airflow can be analyzed from multiple dimensions.
Airtightness is the fundamental guarantee of a centrifugal fan square's performance. When the fan is running, the high-speed rotation of the impeller generates centrifugal force, drawing air in from the inlet and accelerating it before expelling it from the outlet. During this process, if there are sealing defects in the casing, such as air leaks at casing joints, excessive clearance between the drive shaft and the casing, or a poorly sealed access door, some airflow will escape directly from the leak point without the impeller performing work. This "internal short circuit" significantly reduces the fan's effective airflow because the actual volume of air delivered to the system is reduced, while the motor power does not decrease accordingly, resulting in energy waste. For example, in cleanrooms or laboratories requiring precise ventilation control, poor sealing may lead to unmet environmental parameters, affecting production processes or experimental results.
The impact of sealing on airflow is also reflected in system resistance matching. Centrifugal fan square designs are typically based on airflow-pressure curves under specific operating conditions, i.e., the balance between the airflow provided by the fan at different speeds and the system resistance. If the casing seal is insufficient, leaking airflow will alter the actual resistance distribution of the system. On one hand, a leak point is equivalent to an additional exhaust vent, leading to a decrease in the total system resistance. The fan may operate outside its design operating point, with airflow deviating from the expected value. On the other hand, if the leak occurs near the inlet, it may introduce external turbulent airflow, interfering with the flow field uniformity at the impeller inlet and further reducing fan efficiency. This dual effect is particularly pronounced in complex duct systems, potentially causing airflow fluctuations or even surge phenomena.
From an energy conversion perspective, sealing defects directly weaken the fan's energy transfer efficiency. The core function of a centrifugal fan is to convert the mechanical energy of the motor into the kinetic and pressure energy of the air. When the casing leaks, some mechanical energy is used to drive the leaking airflow instead of effectively performing work, leading to increased energy consumption per unit airflow. Under long-term operation, this not only increases operating costs but may also shorten equipment lifespan due to motor overload. For example, in ventilation systems requiring continuous operation, poor sealing may force the fan to operate under high load for extended periods, accelerating wear on transmission components such as bearings and belts, creating a vicious cycle.
The impact of sealing on airflow is also closely related to fan selection. During the design phase, engineers must select a suitable fan model based on system requirements, with airflow and pressure parameters calculated under ideal sealing conditions. If the sealing fails to meet standards during actual operation, the fan may not achieve its designed airflow, resulting in insufficient system performance. In this case, compensating for airflow loss by increasing the speed or replacing the motor with a larger one will not only increase initial investment and operating costs but may also trigger new vibration and noise problems. Therefore, sealing is a critical parameter that must be strictly controlled during fan selection and system design.
Maintenance is crucial for the continued effectiveness of sealing. During long-term operation, the outer casing sealing structure of a centrifugal fan square may gradually age and fail due to factors such as temperature changes, vibration, shock, and media corrosion. For example, packing seals may develop gaps due to wear, mechanical seals may leak due to damage to the sealing surface, and even welded joints may crack due to fatigue. Regular inspection and replacement of sealing elements, tightening of connecting bolts, and repair of surface defects are crucial for maintaining fan sealing performance and ensuring stable airflow. Neglecting maintenance can lead to a rapid decline in sealing performance and trigger sudden malfunctions.
The sealing performance of the centrifugal fan square casing has a decisive impact on airflow. It not only directly relates to the fan's effective work capacity and energy utilization efficiency but also profoundly affects the stability and economy of system operation. From design and selection to installation and commissioning, and then to daily maintenance, strict control of sealing performance is required at every stage to ensure that the fan continuously provides stable and efficient airflow output under complex operating conditions, meeting the stringent requirements of industrial production ventilation systems.
