Bionic Investigation On Erosion Resistance Of Centrifugal Fan Blades

Centrifugal fans are widely used in various industries as a kind of turbomachinery. Most of the centrifugal fans are operating in dusty environments. The impingement of particles on the fan blade surfaces can cause erosion damage leading to the loss of blades aerodynamic performance and structural failure of the centrifugal fan. The methods currently used to protect the fan blades from erosion by using the wear resistance materials or developing effective surface treatment technology. Bionics is a frontier science developed rapidly in recent years. The bionic achievements have been used in wide range of engineering and technical fields. In this paper, the bionic idea was used to design the erosion resistance fan blades.In this paper, the desert scorpion (Androctonus australis) was selected as the research object. Desert scorpion is a typical animal living in sandy deserts, and may face erosive action of blowing sand at a high speed. The living habit of the desert scorpion indicates that the dorsal surface of mesosoma is the major site subjected to the sand erosion. The morphologies of the dorsal surface of mesosoma was studied by the use of stereomicroscope, and the surface profile curves of the tergite dorsal surface were analyzed by using the method of reverse engineering. Results showed that the erosion resistance characteristics of desert scorpion were realized by biological coupling. Based on the bionic coupling design principle, three kinds of bionic models for erosion resistance including two single factor bionic models and a coupling bionic model were proposed, and the mechanisms of the erosion resistance models were discussed.In order to understand the erosion resistance mechanisms of the single bionic models, the combination of experimental and computational research were carried out in this paper.Numerical simulations were conducted to predict the erosion performance of the single factor bionic test samples. The three dimensional two-phase flow field and the associated solid particle trajectories were determined in a particulate flow tunnel, and the erosion rates of the sample surfaces were computed. The results indicated that the bionic samples exhibited better erosion resistance than that of the smooth surface samples. Through the statistical analysis of relative impact parameters, which were impact velocity, impact angle and impact frequency, the reasons for the erosion resistance of bionic samples were got.The erosion tests were conducted in the simple erosion wind tunnel for groove surface bionic samples at various impact conditions. The erosion mass loss and the relative erosion rates (ER) were obtained at different inject angle and different particle size quartz sand at a confirmed inject velocity. The test results indicated that the groove surface bionic samples exhibited better erosion performance at 30°inject angle. In order to determine the effect of the groove dimensions on the erosion resistance of the groove surface bionic samples, the regressive analysis of orthogonal multinomial were performed under a certain erosion condition. The inject angle was 30°and the particle size was 150μm. The results of the range analysis showed that the factors which influence the erosion resistance in sequence were groove distance (D), groove wide (W) and groove height (H). D had the greatest effect on the erosion resistance while H had the smallest. The best combination of the factors resulting in the lowest erosion rate was: D=2mm, W=5mm, H=4mm. Through the regression analysis, the regression equation between ER and the groove dimensions (D, W, H) was obtained.The results obtained from numerical simulations and experimental study on the groove surface bionic samples indicated that the sample erosion resistance can be improved by designing the groove dimensions appropriately. In the present work, this method was used to design the erosion resistance centrifugal fan blades. The three dimensional two-phase flow fields of centrifugal fans with bionic-surface blades versus with ruled blades were simulated. The blades erosion performance of both two kinds of centrifugal fans were then analyzed and compared. It was found that the erosion rate of the bionic blades was lower than that of the ruled blades when the particle diameter was 20μm.