| With the development of industrial technology, the application range of the fan expands. The requirements about flow field characteristics and stability get higher. Impeller is the core component of fan, directly affecting the overall performance of the fan. In consideration of the complex and difficult traditional design method, long experiment period and high experiment cost of impeller, a geometric design method is introduced in this paper by using numerical simulation to analyze the internal flow field and structural strength. Due to the fact that impeller is manufactured by ball-end cutter, there will be scallop height on the hub. Therefore, research of the influence of the scallop height on flow field has very important significance for finding a balance between efficiency and precision.Firstly, the basic knowledge of impeller, the mathematical principles of blade design and modeling are introduced. A geometric design method of the blade is presented. The characteristics of Bezier curve and its application in the impeller’s meridional plane design are discussed. The B-Spline curve is used to design the vane camber angle and the thickness of the blade. Based on MATLAB, the model of impeller is displayed.Secondly, the numerical simulation method of computational fluid dynamics is explained. Each fluid region such as impeller, volute is built by UG. The grid is divided by ICEM, and the numerical simulation of the whole fan is carried on by FLUENT. Then the flow field of different axial section and the path line drawing of the fan are obtained.Thirdly, the method of finite element analysis and its main calculation steps are discussed. A brief introduction of APDL is given. The3-d model of impeller, established in UG, is imported to ANSYS. Centrifugal force is applied to execute strength analysis in order to get the displacement and stress. APDL technology is adopted to apply the aerodynamic load on the blade surface of impeller, for the sake of analysis of coupling of fluid and solid. Both of the simulation results above are analyzed and compared.Finally, the forming principle and mathematical description of scallop height are introduced. As the use of periodic boundary is discussed, the models of channels with different scallop heights can be established. With the CFD method, the flow field of channels with scallop height is simulated. Then the pressure distribution of hub with different scallop heights is obtained and the effect of scallop height on the flow field of offset face of hub can be analyzed. |
