3D打印浓缩风能装置用于风洞试验安全性分析

通过3D打印技术可以方便快捷地制作出浓缩风能装置风洞试验模型,但必须对其安全性进行分析。该文采用流固耦合分析方法,对利用3D打印技术按1:4.5的比例制作的浓缩风能装置模型用于风洞试验的安全性进行分析。首先通过计算流体力学软件对流体场进行网格无关性分析,然后对流体场进行仿真模拟,得出了浓缩风能装置模型在风洞中的风速分布,其结果表明,浓缩风能装置叶轮安装平面6点风速平均值为流场入口风速的1.40倍,该倍率与参考文献中的实际测量平均倍率1.38倍非常接近,这说明按1:4.5的比例制作的浓缩风能装置模型用于该文所述尺寸风洞按该文中的设置进行模拟计算是正确的。然后将该模型表面风压分布作为载荷加载到此模型上,得到该模型在风洞中所受最大应力为3.5385 MPa,远小于所选3D打印材料的拉伸强度40.2 MPa和弯曲强度67.8 MPa,且最大偏移量仅为1.8675 mm,因此采用文中所选3D打印材料通过3D打印技术制作风洞试验模型是安全的。

Security analysis of 3D-printed wind-energy concentration device in wind tunnel test

Wind-energy concentration device model can be efficiently made by 3D (three-dimensional) printers, but its security must be tested. This research adopts a fluid-solid interaction (FSI) method to study the security of the 3D printed wind-energy concentration device model in wind tunnel tests. At first, by using the CAD (computer aided design) software, a solid field model of a wind-energy concentration device is created with a proportion of 1:4.5. Then the solid field model is imported into the finite element analysis software. Based on the size of the wind tunnel, a cubic area of 20 m × 3 m × 3 m (length × width × height) is established, and the concentration device model has the same axial line with the length direction. Then by the Boolean subtraction method, a geometric fluid field is built through subtracting the solid field area in the box area. The interface between the fluid field and the concentration device model is just fluid-solid interaction interface. And the fluid field is simulated and calculated with the help of the CFD (computational fluid dynamics) software. An SSTk-ω turbulence model is adopted. In terms of the meshes, a non-uniform tetrahedron meshing is applied. Different numbers of meshes are meshed and the grid independence test is performed. This research takes air as the fluid medium. The temperature is 273.15 K and the pressure is 101325 Pa. The density, velocity, viscosity, thermal conductivity coefficient, constant-pressure specific heat capacity, mass flow rate, turbulent kinetic energy (k value) and specific dissipation rate (ω) are 1.293 kg/m3, 30 m/s, 1.72×10-5 kg/(m·s), 0.0244 W/(m·K), 1005 J/(kg·K), 349.11 kg/s, 1.3336 m2/s2 and 150.6047 s-1, respectively. This research adopts the mass flow inlet and pressure flow outlet. Surface roughness of the wind-energy concentration device model is set to 0.3 mm. When the component residual reaches 1.0×10-4 kg/s, the equation is thought to converge and the distribution of the wind speed in the fluid field is gained. The results show that the mean wind speed of 6 points on the mounting plane of wind turbine in the concentration device is 1.40 times the inlet wind velocity of the whole flow field, proximate to the average time of 1.40 in the actual measurement in the references. This shows that when applied in the wind tunnel with the size and design described in the paper, the simulative calculation based on the 1:4.5 design proportion of wind-energy concentration device model is correct. In the structural static module, the whole solid field is divided into tetrahedral meshes, each structural unit being 0.002 m. The stress cloud plot and the solid field deformation plot are gained after the distribution of wind pressure is loaded on the wind-energy concentration device model. The plots show that the maximum stress area lies on the outer edge of the diffusion pipe, with a maximum stress of 3.5385 MPa. This is far less than the tensile strength of 40.2 MPa and the bending strength of 67.8 MPa in the candidate DSM Somos Imagine 8 000 type photosensitive resin used in the 3D printing. And the maximum deformation is just 1.8675 mm. Therefore, this material satisfies the specifications of strength and resilience and can be adopted in the 3D printing of the wind-energy concentration device model used for the testing of flow field in the wind tunnel.