###### Abstract  
To overcome the technical challenges of the multi-blade centrifugal fan, such as low efficiency and insufficient total pressure, the blades of the fan were optimally designed in this study. The flow field of the multi-blade centrifugal fan with a single-arc blade and an airfoil blade was simulated and compared using Computational Fluid Dynamics (CFDs). Under steady-state conditions, the total pressure, velocity field distribution, and aerodynamic performance of a multi-blade centrifugal fan were analyzed. The numerical results showed that there were vortices, secondary flows, and boundary layer separation phenomena in the flow passage of the single-arc multi-blade centrifugal fan. Based on the lift-to-drag ratio theory of airfoil in aerodynamics, four different airfoil blades were designed for the multi-blade centrifugal fan. The study found that the lift-to-drag ratio of the airfoil blades was positively correlated with the fan efficiency; among them, the A-type airfoil exhibited the highest lift-to-drag ratio within the 0-10 degree angle of attack range. The three-dimensional simulation results indicated that, except for the initial operating point B, the A-type airfoil showed higher fan efficiency under other operating conditions, and its total pressure curve was the most stable. In addition, the use of airfoil blades effectively suppressed the aforementioned adverse flow phenomena and improved the flow within the blade passage. Experimental verification further confirmed the effect of airfoil blades on improving fan performance: compared to single-arc blades, the efficiency of the multi-blade centrifugal fan increased by 3-7% after using airfoil blades, and the upper limit of high-efficiency flow increased from 450 m\({}^{3}\)/h to 650 m\({}^{3}\)/h. Meanwhile, the total pressure and power of the airfoil fan were also significantly improved. The results of this work are significant for guiding the optimal design of the fan. multi-blade centrifugal fan; airfoil; flow field; lift-to-drag ratio; computational fluid dynamics simulation; k-\(\epsilon\) turbulence model; SST k-\(\omega\) turbulence model +
Footnote †: journal: applied sciences  
Article  
A. Y.  
ventilation performance and reduce energy loss, it is essential to enhance the efficiency of multi-blade centrifugal fans by conducting in-depth investigations into their internal flow characteristics and continually optimizing their structural designs [5]. The stability of the internal flow field is a pivotal issue affecting the aerodynamic performance of centrifugal fans. With the rapid advancement of computer technology, computational fluid dynamics (CFD) has found extensive applications in various fields, including aerospace, oil and gas, and turbine design [6]. Many scholars employ CFD technology to analyze the flow field in their research on centrifugal fans. For instance, [PERSON] et al. [7] used the Realizable k-\(\varepsilon\) model for numerical simulation to investigate the flow state within the flow channel, identifying phenomena such as secondary flow and reflux. [PERSON] et al. [8] explored the impact of an oblique cut on the leading edge of a blade on the performance of a squirrel cage fan, revealing that an optimal oblique cutting angle could enhance inlet flow conditions, thereby shifting the fan's performance curve toward higher flow rates. Similarly, [PERSON] et al. [9] employed the Realizable k-\(\varepsilon\) turbulence model for numerical simulation to examine the three-dimensional flow inside centrifugal blowers. Additionally, some scholars have delved into the flow regime of rotating machinery under varying operating conditions [10; 11; 12]. By analyzing the eddy current state within the fan flow field, they discussed energy loss in the fan flow channel, concluding that impeller loss is closely associated with the occurrence of separation flow in the blade flow channel--the more severe the separation, the greater the impeller loss. [PERSON] et al.