Comparison of Operating Power Between High-Pressure Direct-Coupled Centrifugal Fans and Axial Flow Smoke Exhaust Fans

Comparison of Operating Power Between High-Pressure Direct-Coupled Centrifugal Fans and Axial Flow Smoke Exhaust Fans Some users and friends remain unclear about the differences between high-pressure direct-coupled centrifugal fans and axial flow smoke exhaust fans, unsure how to distinguish between these two types of equipment. In fact, there is a significant difference in the operating power of the two fans. Typically, the power output of a high-pressure direct-coupled centrifugal fan increases with rising airflow volume, whereas the operating power of an axial flow smoke exhaust fan decreases as airflow volume increases. When using a high-pressure direct-coupled centrifugal fan, all dampers should be fully closed before startup to prevent excessive DC from causing engine combustion. Conversely, during the startup of an axial flow smoke exhaust fan, its dampers must be fully open before gradually adjusting to the required airflow. The high-pressure direct-coupled centrifugal fan is a fluid-driving device. It is currently primarily used for ventilation and dust removal in various factories, tunnels, and buildings. It is also frequently employed as ventilation and induced draft equipment for boilers and light industrial furnaces, or for drying and ventilating stored grains, etc. Beyond these, the two fan types exhibit numerous other distinctions. For instance, the connection between a high-pressure direct-coupled centrifugal fan and its motor is primarily achieved through shaft coupling, whereas the axial fan is internally mounted. Comparatively, the former features a simpler structural design. Additionally, after installing a high-pressure direct-coupled centrifugal fan, the flow direction of the medium within the duct can be adjusted, whereas an axial smoke exhaust fan does not alter the flow direction of the medium within the duct. The so-called axial flow smoke exhaust fan is essentially a cyclone aligned with the fan blade axis, similar to an electric fan. The electromechanical fan outside an air conditioner is an axial flow smoke exhaust fan. Currently, axial flow smoke exhaust fans are primarily used in applications requiring high flow rates and low pressure. New Ideas, Insights, and Methods in the Aerodynamic Design of Shell-less Centrifugal Fans With the advancement of modern aerodynamic design methods for shell-less centrifugal fans, we have encountered new challenges during the development of high-performance fans, particularly through communication with frontline production management technicians. Simultaneously, the process of resolving these issues often sparks innovative ideas and approaches, continuously driving the evolution of modern design methodologies. Next, we will briefly introduce the selection of aerodynamic design methods for airflow, aiming to deepen our understanding. The aerodynamic design of shell-less centrifugal fan equipment is primarily based on the design flow rate requirements provided by the user. Moreover, the default operating condition is set to achieve high efficiency under such conditions. However, analysis of actual applications reveals that the operating point for many shell-less centrifugal fan units does not align with the aerodynamic design flow rate. The deviation in direction and magnitude is related to the specific speed. Typically, fans with specific speeds below 27—commonly termed low-specific-speed fans—often exhibit flow rates exceeding the original design conditions. Moreover, the deviation becomes more pronounced as the specific speed of the shell-less centrifugal fan decreases. Fans with medium specific speeds generally operate close to their original design conditions. When the specific speed exceeds 55, the operating flow rate falls below the original design flow rate. For such scenarios, we can initially adopt a flow-based aerodynamic design approach when selecting the startup design method. That is, when designing shell-less centrifugal fans, flow design and total pressure aerodynamic design should be conducted reasonably according to different user requirements. While optimizing design performance, the non-design performance of shell-less centrifugal fan equipment should also be considered.