Development of Next Generation Wiping Air Knifese

在连续热浸镀锌中，在钢板基材的每一侧使用高速平面空气射流，称为“气刀”，以控制锌涂层的厚度。这些射流在移动的钢板上的冲击，在钢板浸入锌液后，导致多余的锌液被擦回到锌液中。迄今为止，只有单槽射流用于镀锌工业和其他热加工应用，如玻璃回火、复杂表面加热、涡轮叶片冷却和电子设备冷却。这项研究工作的目标是开发由多个槽射流组成的新型气刀几何形状，可以设计成在钢板上产生特定和所需的压力梯度和剪切应力分布组合，从而促进在广泛的镀锌工艺参数下实现卓越的涂层重量控制。使用多个狭缝射流而不是单个射流，也有望减少钢带上的压力波动，从而提高涂层质量和重量一致性，并降低气刀产生的噪音。进一步预计，使用多喷嘴技术将比目前使用单喷嘴技术产生更低的涂层重量，从而克服当前单喷嘴技术的这一限制。该Engage提案涉及该项目的第一阶段，所请求的资金将用于建立多槽喷气机设施和测量技术。将设计、制造和调试由多槽射流冲击板组成的多功能测试设备。这个初始阶段还将包括大量使用激光多普勒测速和粒子图像测速以及压力传感器和麦克风，以建立研究射流发展阶段、板上压力和剪切应力分布以及板上速度和压力振荡所需的实验技术。该项目完成后，申请实验室将拥有必要的设施，与ArcelorMittal （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.