Active Control of Liquid Jet Breakup for Advanced Manufacturing

液体喷雾和气雾剂在从食品和化学加工到网状制造和制药的各种制造环境中发挥着重要作用。对于每种应用，喷雾中液滴的理想大小及其所需的动量各不相同。然而，目前，液滴是在剧烈和混乱的散体流体破碎事件中产生的，这使得液滴的预测和控制变得困难。因此，改进对液滴大小和轨迹的实时控制可能对先进的制造和加工方法产生重大影响。这个项目？S的目标是展示一种产生、操纵和控制液滴的新方法。其概念是开发一种控制方法，将简单的毛细喷流分解成具有可预测和可变大小和动量的液滴。虽然在所有复杂的喷雾中，毛细射流的破碎机理并不完全相同，但它也可以作为开发其他液滴和喷雾应用的控制策略的模型。多年来，人们一直在研究液体射流在理想扰动下分解成均匀的液滴。然而，在实际系统中，执行器动力学使得很难产生纯激励，从而将分解性能限制在小液滴尺寸范围内。在所提出的工作中，我们探索了通过控制输入到扰动源的波形来扩大破裂性能窗口的可能性，以抑制干扰成分。该研究首先确定了典型的压电式致动器在纯正弦输入下的响应动力学。然后，反问题解产生抑制不良响应模式所需的非正弦输入波，并确保致动器仅以一个主频率扰动射流。随后在液体射流上对这种开环控制性能进行了实验验证。然后，该项目开发了一种实时识别方法，以允许根据所需的输出液滴行为对输入波形进行修正和调整。因此，该项目有两个组成部分：(1)利用扰动毛细射流的动态特性开发可应用控制技术的系统模型的控制部件；(2)开发可通过传感器和执行器反馈回路激励和控制的毛细射流破碎系统和控制装置的实验部件，以验证控制结果。

Liquid sprays and aerosols play an important role in a myriad of manufacturing environments, from food and chemical processing to netshape manufacturing and pharmaceuticals. For each application, the ideal size of the droplets in the spray and their desired momentum varies. Currently, however, liquid droplets are generated during a vigorous and chaotic breakup event from a bulk fluid, making prediction and control of droplets difficult. Improved real-time control of droplet size and trajectory could therefore have significant impacts on advanced manufacturing and processing methods. This project?s goal is to demonstrate a novel approach for generating, manipulating, and controlling droplets. The concept is to develop a control methodology for adjusting the breakup of a simple capillary jet into droplets with predictable and variable size and momentum. While the mechanism for capillary jet breakup is not identical in all complex sprays, it can serve as a model for the development of control strategies for other droplet and spray applications as well.The breakup of liquid jets into uniform droplets in response to ideal perturbations on the jet has been studied for many years. In practical systems, however, actuator dynamics make it difficult to create a pure excitation, thereby limiting the breakup performance to a small range of droplet sizes. In the proposed work, we explore the possibility of expanding the breakup performance window by controlling the input waveforms to the perturbation source in order to suppress disruptive components. The study begins by identifying the response dynamics of a typical piezoelectric actuator to a pure sinusoidal input. An inverse problem solution then produces the non-sinusoidal input wave needed to suppress undesirable response modes and ensure that the actuator perturbs the jet with only one dominant frequency. Experimental verification of this open-loop control performance on a liquid jet follows. The project then develops a real-time identification approach to allow corrections and adjustments to the input waveform in response to the desired output droplet behavior. Hence, the project has two elements: (1) a control component that uses the dynamic features of the perturbed capillary jet to develop a system model to which control techniques can be applied and (2) an experimental component that develops a capillary jet breakup system and control apparatus that can be stimulated and controlled via sensor and actuator feedback loops in order to verify the control findings.