Active Control of Liquid Jet Breakup for Advanced Manufacturing

液体喷雾剂和气溶胶在从食品和化学加工到净成形制造和制药的无数制造环境中发挥着重要作用。 对于每种应用，喷雾中液滴的理想尺寸及其所需动量都各不相同。 然而，目前，液滴是在大量流体的剧烈和混乱的破碎事件期间产生的，使得液滴的预测和控制变得困难。 因此，改进液滴尺寸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？的目标是展示一种新的方法来产生，操纵和控制液滴。 这个概念是开发一种控制方法，用于调整一个简单的毛细管射流分裂成具有可预测的和可变的大小和动量的液滴。 虽然毛细管射流破碎的机理在所有复杂喷雾中并不相同，但它也可以作为其他液滴和喷雾应用控制策略发展的模型。液体射流在理想扰动下破碎成均匀液滴的问题已经研究了很多年。 然而，在实际系统中，致动器动力学使得难以产生纯激励，从而将破碎性能限制在小范围的液滴尺寸。 在所提出的工作中，我们探讨了通过控制扰动源的输入波形来扩展破碎性能窗口以抑制破坏性成分的可能性。 研究首先确定一个典型的压电致动器的响应动力学的纯正弦输入。 逆问题的解决方案，然后产生的非正弦输入波需要抑制不希望的响应模式，并确保致动器扰动射流只有一个主频率。 以下是对液体射流开环控制性能的实验验证。 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校正和调整。 因此，该项目有两个要素：（1）一个控制组件，它使用扰动的毛细管射流的动态特征来开发一个系统模型，控制技术可以应用于该系统模型;以及（2）一个实验组件，它开发一个毛细管射流破碎系统和控制装置，可以通过传感器和致动器反馈回路进行激励和控制，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.