Numerical investigation of blade tip grooving effect on performance and dynamics of an axial flow fan

Appropriate changes to the blade tip structure can effectively improve fan performance. The performance of the OB-84 axial fan with different grooved blade tips is simulated using Fluent. The effects of various tip structures on the flow field, losses distribution, and noise characteristics are investigated. Analysis of static structure and vibration characteristics is performed with the Ansys finite element analysis module. Simulated results show that for the grooved blade tips, both the total pressure rise and shaft power of the fan decrease, but the efficiency improves distinctly; the grooved blade tip structure perturbs the flow and vortex fields and impedes the development of the leakage flow; this eventually results in the reduction of mixing losses between the leakage flow and mainstream. Blade tip case 4 produces the maximum efficiency with an increase of 1.07% at design volume flow rate, and case 7 obtains the lowest shaft power compared with the original tip. Grooved blade tips amplify the fan noise, so measures should be taken to control the noise. Analysis of dynamic characteristics reveals that the distortion and fracture failure of the blade as well as resonance of the impeller would not occur by adopting grooved blade tips.

[1]  Chunxi Li,et al.  Numerical investigation of impeller trimming effect on performance of an axial flow fan , 2014 .

[2]  M. H. Mohamed,et al.  Optimization of blade pitch angle of an axial turbine used for wave energy conversion , 2013 .

[3]  Li Chunxi,et al.  The performance of a centrifugal fan with enlarged impeller , 2011 .

[4]  Jun Hu,et al.  Investigations on the Effects of Inflow Condition and Tip Clearance Size to the Performance of a Compressor Rotor , 2014 .

[5]  W. Neise,et al.  Experimental Study of Tip Clearance Losses and Noise in Axial Turbomachines , 1997 .

[6]  Guillermo Paniagua,et al.  Blade Tip Shape Optimization for Enhanced Turbine Aerothermal Performance , 2014 .

[7]  Zhu Jian-hong.  Optimization design of turbine blade tip clearance shapes , 2009 .

[8]  Sang Woo Lee,et al.  Aerodynamic performance of winglets covering the tip gap inlet in a turbine cascade , 2012 .

[9]  T. Fukano,et al.  The effects of tip clearance on the noise of low pressure axial and mixed flow fans , 1986 .

[10]  Ali Ameri,et al.  Effect of Squealer Tip on Rotor Heat Transfer and Efficiency , 1998 .

[11]  J. Park,et al.  Effects of turbine blade tip shape on total pressure loss and secondary flow of a linear turbine cascade , 2012 .

[12]  Chun Li,et al.  Comparison of leakage performance and fluid-induced force of turbine tip labyrinth seal and a new kind of radial annular seal , 2014 .

[13]  C. P. Lee,et al.  Analysis of Some Improved Blade Tip Concepts , 2006 .

[14]  S. Ekkad,et al.  Effect of Blade Tip Geometry on Tip Flow and Heat Transfer for a Blade in a Low Speed Cascade , 2003 .

[15]  Douglas C. Rabe,et al.  Experimental Investigation of Stepped Tip Gap Effects on the Performance of a Transonic Axial-Flow Compressor Rotor , 1997 .

[16]  Hyung Hee Cho,et al.  Heat transfer and film cooling effectiveness on the squealer tip of a turbine blade , 2014 .

[17]  W. Neise,et al.  ROTATING BLADE FLOW INSTABILITY AS A SOURCE OF NOISE IN AXIAL TURBOMACHINES , 1997 .

[18]  N. Cumpsty,et al.  Tip Leakage Flow in Axial Compressors , 1991 .

[19]  P. Moin,et al.  Prediction and analysis of rotor tip-clearance flows using large-eddy simulation , 2004, 2004 Users Group Conference (DOD_UGC'04).

[20]  Ying-zi Jin,et al.  Effect of tip flange on tip leakage flow of small axial flow fans , 2014 .

[21]  Reza S. Abhari,et al.  Flow Physics and Profiling of Recessed Blade Tips: Impact on Performance and Heat Load , 2008 .

[22]  Masato Furukawa,et al.  Effects of the Tip Clearance on Vortical Flow and Its Relation to Noise in an Axial Flow Fan , 2003 .

[23]  He Weifeng,et al.  Influence from the blade installation angle of the windward axial fans on the performance of an air-cooled power plant , 2013 .

[24]  A. E. Filios,et al.  Broadband noise radiation analysis for an HAWT rotor , 2007 .

[25]  Takanori Uchida,et al.  Behavior of the Blade Tip Vortices of a Wind Turbine Equipped with a Brimmed-Diffuser Shroud , 2012 .

[26]  Zheng Qun.  Effect of Squealer Tip Geometry on Rotor Blade Aerodynamic Performance , 2013 .

[27]  Motoo Kuroumaru,et al.  Structure of Tip Clearance Flow in an Isolated Axial Compressor Rotor , 1989 .

[29]  Qun Zheng,et al.  Aero-thermal performance improvements of unshrouded turbines through management of tip leakage and injection flows , 2014 .