​New Concepts, Insights, and Methods in 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 in our interactions with frontline production management technicians. Simultaneously, the process of addressing these challenges often sparks fresh ideas and approaches, continuously driving the evolution of contemporary design methodologies. Next, we will briefly introduce the selection of aerodynamic design methods for airflow, hoping 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.