Abstract: Large axial-flow fans have found wide applications in many fields, such as the fans used for boilers in power stations, the fans in ventilation systems for coal mines and the fans for wind tunnels. The power consumption of those large axial-flow fans is often high up to several thousand kilo-Watts. Because of this, the aerodynamic performance improvement of the axial-flow fans becomes momentous and essential. The inlet box is an integral part of axial-flow fans, and a well-designed inlet box could effectively improve fan efficiency. However, the inlet box is a complicated part, and the existing inlet box design method severely depends on the design experience. In this study, we propose a structure optimization design system based on a surrogate model technique for researching the critical structure parameters of the inlet box and accomplishing aerodynamic performance optimization. As for this expensive optimization problem (Numerical simulation is substantially time-consuming), the design system contains twice optimization procedures by using the Response Surface Methodology (RSM) with the orthogonal design method. The optimization object is an existing large axial-flow fan. The optimization objective is the total pressure efficiency of the fan, and the total pressure rise is the restriction condition. At first, seven structure parameters of the inlet box are conducted as the optimization variables, and we compute the variety ranges of each parameter through the design experience and previous study. We generate twenty different inlet boxes connect with the same impeller and outlet pipe by the orthogonal design method and calculated fan aerodynamic performance by CFX software. After the first optimization, we find the key structural parameters by the sensitivity analysis and the reselect variables total of 25 cases are adopted in a further RSM optimal process. The ultimate surrogate model estimates the fan with the optimal inlet box has a better aerodynamic characteristic and a 7% total pressure efficiency rise. Finally, we compare the aerodynamic characteristics of the ultimate design fan and the initial fan by CFD simulation. The flow field certificates that optimal inlet box leads more uniform airflow into the fan impeller, and the turbulent flow in the impeller flow passage has been effectively restrained. Compared with the initial design, the numerical aerodynamic performance of the optimal fan shows that: the total pressure efficiency is 6.5% higher than that of the initial impeller, and the pressure rise is 3% higher than that of the initial impeller. The result demonstrates that some most critical parameters of the inlet box structure decide the aerodynamic performance, and the inlet box optimization effectively increases the fan efficiency in the meanwhile.  

 

Keywords: Inlet box; Axial-Flow Fan; Structure Optimization; Response Surface Methodology


Inlet Box Structure Optimization of a Large Axial-Flow Fan Using Response Surface Methodology

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

IMECE2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.