| Centrifugal fan is a common machine widely used in almost every civil and national industry. According to statistics, the electronic consumption of either type of centrifugal fan and pump accounts for one third of the total power generated in this country, and the consumption of industrial centrifugal fan itself stands approximately5%of total power generation. Since the demand of centrifugal fan is increasing rapidly, the energy consumption of raw material manufacturing is rising as well. Thus, considering the aspects of energy-saving and intensity of resources, it is very important to design a centrifugal fan with low cost and high efficiency.The design methods and theories of fluid machinery are majorly obtained from abundant experiments, which could deliver better basically technical factors of centrifugal fan. However these experiments not only consume a lot of capital input and time, also cannot ensure the fluid status of the fan’s inside part. On the other hand, the CFD (Computational Fluid Dynamics) could more accurately illustrate the details of fluid movement, such as the time-variant attributes of velocity field, pressure field and temperature field. It would not only accurately predict the monolithic performance of a fan, also easily find the problems of the products and engineering design based on the analysis of fluid. As a result, it will reduce the unpredictable risk, dependency on experiments in design, design cycle and cost. Therefore, CFD is more widely used in fan design instead of traditional centrifugal fan experiments.This paper used Solidworks to set up a complete model of DFY32F-C4A centrifugal fan and used Fluent to analyze its internal air flow in3D. It also employed unstructured mesh and RNG k-ε turbulent flow model to investigate the machine and its meridian plane, revolution surface, blade surface and other important parts’static pressure, dynamic pressure, velocity vector and velocity gradient, and then compare each factor to obtain new fluid status. The results show:the intensity of pressure and flow velocity in the fan’s fluid field was nonaxisymmetrical, which is because the machine’s Non-axial symmetry; the area of volute outlet was too big so that the low pressure at the outlet generated too much counterflow, which caused the low wind pressure at the fan’s outlet and low efficiency; as a result of the rotational flow in volute, the air flow was influenced; there were phenomenon like vortex, outflow-jet flow and secondary flow, which increased the noise of the fan and reduced its efficiency. These results are so important that they will contribute a lot to the research of the vibration and noise control of centrifugal fan. Then through the calculation of different flow operating conditions of the fan, the fan’s total pressure and efficiency under each flow operating conditions were captured and so were the P-Q curve and η-Q curve. Compared with the experiment data, the paper analyzed the source of measurement error between simulation value and experiment value. At last it made proper modifications to the fan’s aeration tank, current collector and volute, and then generated three modification design plans. It carried out simulated calculation for each design, drew P-Q curve and η-Q curve after modification, calculated energy loss of each component and then took comparison with original machine. The conclusion is the improved fan’s performance was a little worse than the original fan, but it significantly reduced cost. Thus it can be considered to use it at the best flow operating condition point replacing original machine.The paper provided profound references for companies to improve the fan structures, flow field movement and enhance the fan efficiency and design innovation. |
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