Development of Next Generation Wiping Air Knifese

在连续热镀锌中，在钢板基材的两侧使用高速平面喷气刀来控制锌层的厚度。这些射流冲击移动的钢板，使其浸入锌熔池后，使多余的熔融锌被擦回锌槽中。到目前为止，只有单槽喷嘴用于镀锌工业和其他热处理应用，如玻璃钢化、复杂表面的加热、涡轮叶片的冷却和电子设备的冷却。拟议的研究工作的目标是开发由多个缝隙喷嘴组成的新的气刀几何结构，这种喷口可以设计成在钢板上产生特定和所需的压力梯度和剪应力分布的组合，从而有助于在广泛的镀锌工艺参数下实现更好的涂层重量控制。使用多槽喷嘴，而不是单一喷嘴，预计还可以减少钢带上的压力波动，从而提高涂层质量和重量一致性，并减少气刀产生的噪音。还可以预期，使用多重喷射技术将允许产生比目前使用单一喷射技术可能的更低的涂层重量，从而克服当前单一喷射技术的这一限制。该项目提案涉及该项目的第一阶段，所申请的资金将用于建立多槽喷气设施和测量技术。将设计、制造和调试一个由多槽喷射器撞击平板组成的多功能测试设备。这一初始阶段还将包括密集使用激光多普勒测速仪和粒子图像测速仪以及压力传感器和麦克风，以建立所需的实验技术，以研究射流发展阶段、平板上的压力和剪应力分布以及平板上的速度和压力振荡。该项目完成后，申请实验室将拥有必要的设施，与安赛乐米塔尔(Dofasco)启动CRD项目，开发下一代擦拭气刀。

In continuous hot dip galvanizing, a high speed planar air jet, known as an "air knife", is used on each side of the sheet steel substrate to control the thickness of the zinc coating. The impingement of these jets on the moving steel sheet, after its immersion in a bath of molten zinc, causes the excess molten zinc to be wiped back into the zinc bath. To date, only single-slot jets are used in galvanizing industry and other thermal processing applications such as glass tempering, heating of complex surfaces, cooling of turbine blades and for the cooling of electronic devices. The objective of the proposed research work is to develop new air knife geometries consisting of multiple slot jets, which can be designed to produce specific and desired combinations of pressure gradient and shear stress distribution on the steel sheet and thereby facilitate superior coating weight control for a wide range of galvanizing process parameters. The use of multiple slot jets, instead of a single jet, is also expected to reduce pressure fluctuations on the steel strip which improves the coating quality and its weight consistency and reduces the noise generated by the air knives. It is further anticipated that use of the multiple jet technology will allow lower coating weights to be produced than is currently possible with the single jet technology, thereby overcoming this limitation of the current single jet technology. This Engage proposal deals with the first phase of this project and the requested funding will be used to establish a multiple-slot jet facility and measurement techniques. A versatile test facility consisting of a multiple-slot jet impinging on a plate will be designed, manufactured and commissioned. This initial phase will also include intensive use of Laser Doppler Velocimetry and Particle Image Velocimetry as well as pressure transducers and microphones to establish the experimental techniques needed to investigate the jet development stages, pressure and shear stress distributions on the plate, and the velocity and pressure oscillations on the plate. Upon completion of this project, the applicant laboratory will have the necessary facility to initiate a CRD project with ArcelorMittal (Dofasco) to develop the next generation wiping air knifes.