Numerical and Experimental Study of the Performance for a Small Two-Stage Axial Fan.

• Main Authors: Hung-chi Li, 李虹錤
• Other Authors: Sheam-chyun Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/akfj7m

碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === Because of the rapid development of cloud-computing technology, the computing hardware needs to function reliably in a nonstop mode. Also, the demand on reducing computer size, especially the high-performance server, has generated a problem of more heat dissipation being crowded into less space. Moreover, most of the computers are installed inside a small and packed room, which forms a difficult obstacle for heat removing process. Accordingly, the cooling fans not only need to deliver sufficient air flow, but also provide adequate static pressure to overcome the high system resistance. To meet with this challenging request, this work aims to design a two-stage 4056 axial fan (40×40×56 mm3), which is used extensively to generate the high-pressure air stream for the thermal management of 1U server. First of all, the first-stage and second-stage rotors are designed and verified their performances via the CFD code Fluent separately. Later, with the aids of CFD tool, the detailed flow visualization and the comprehensive parametric study are executed on the complete 4056 fan, which is assembled by combining two rotors together in series. In addition, based on the flow pattern observed, a proper stator is proposed and installed between two impellers to enhance the aerodynamic performance of 4056 fan. The parameters considered here include the hub geometry, the blade shape, the blade angles, the blade numbers, the setting angles, the rotational speeds, and the dimensions of rotors and stator. Subsequently, an adequate parameter setting is obtained after the aforementioned design procedure. Thereafter, the prototype of optimized design is manufactured by the CNC machine to carry out the corresponding experimental performance verifications. To ensure a reliable outcome, the fan’s performance and noise tests are executed in AMCA and semi-anechoic chambers by following AMCA-210-99 and CNS-8753 codes. By comparing the experimental and numerical results, a remarkable agreement between these performance curves is observed for verifying the reliability of numerical simulation. Besides, under the same rotating speed and similar noise level, the aerodynamic performance of optimum fan is superior to the reference fan by 1.6% and 15.7% increases on its maximum flow rate and maximum static pressure, respectively. In summary, this study successfully establishes a reliable and systematic scheme to design the two-stage axial fan for the cooling management of 1U server or the related products. Besides, the corresponding performance influences caused by important fan parameters are analyzed and summed up for serving as the design reference for the two-stage axial fan.