Design of de Laval nozzle for additive manufacturing and 3D printing

Centerline有限公司是一家总部位于安大略省温莎的私人持股公司，为汽车、航空航天和国防工业提供先进的生产技术。CENTERLINE生产商用超音速冷喷涂系统，这是一种高速材料沉积过程，在该过程中，未熔化的细小粉末颗粒(通常直径为10-50微米)通常在压缩气体超音速射流中加速至200至1000米/S的速度。当与目标表面碰撞时，固体颗粒变形并结合在一起，迅速形成一层沉积材料。Centerline正在考虑将这项技术扩展到添加剂制造的可能性。 加法制造是一种三维(3D)打印过程，它通过构建层来从数字模型创建实体对象。这一过程是通过使用3D计算机辅助设计(CAD)来创建数字模型来实现的，该数字模型被切片成非常薄的横截面，称为层。在打印过程中，3D打印机会构建连续的材料层，直到对象完成。相比之下，传统的制造技术或减法制造涉及通过切割或钻孔系统地从散装形状中去除材料。与传统的制造方法相比，添加剂技术在许多应用中提供了优势。零件可以用任何几何复杂性来成形。 Centerline现有的冷喷嘴提供了大约4.0毫米的斑点尺寸。为了获得更好的制造分辨率和制造复杂的物体，需要将光斑尺寸减小到1.0 mm或更小。可以通过缩小当前的De Laval喷嘴设计来实现这一目标。考虑到商业化的潜力，CenterLine希望对类似于小得多的喷嘴组件的模型的流体流动特性进行数值评估。将在温莎大学进行详细的计算流体力学(CFD)研究，以评估收敛-扩张喷管(De Laval喷管)的性能。

CenterLine Ltd. is a privately held Windsor, Ontario, based corporation, providing advanced production technologies to the automotive, aerospace and defence industries . CenterLine produces commercial supersonic Cold Spray Systems, which is a high-rate material deposition process in which small, non-melted powder particles (typically 10 - 50 µm in diameter) are normally accelerated to velocities between 200 to 1000 m/s in a supersonic jet of compressed gas. Upon impact with a target surface, the solid particles deform and bond together, rapidly building up a layer of deposited material. Centerline is considering the possibility of extending this technology to additive manufacturing. Additive manufacturing is a three-dimensional (3D) printing process that builds layers to create a solid object from a digital model. The process is achieved by using a 3D computer-aided design (CAD) to create a digital model that is sliced into very thin cross-sections called layers. During the print process, the 3D printer builds up successive layers of material until the object is finished. By contrast, the traditional manufacturing techniques or subtractive manufacturing involve the systematic removal of material from bulk shapes by cutting or drilling. Additive technologies offer advantages in many applications compared to the traditional manufacturing methods. Parts can be formed with any geometric complexity. CenterLine's existing cold spray nozzle offers a spot size of about 4.0 mm. It is required that the spot size be reduced to 1.0 mm or less for a better manufacturing resolution and for producing intricate objects. It may be possible to achieve this objective by scaling down the current de Laval nozzle design. Considering the potential for commercialization, CenterLine would like to evaluate numerically the fluid flow characteristics of a model that resembles a much smaller nozzle assembly. A detailed computational fluid dynamics (CFD) investigation, will be carried out at University of Windsor to assess the performance of the convergent-divergent nozzle (de Laval nozzle).