Enhanced Atomization of Viscous Liquids Using Insights from Global Instabilities of Two-Phase Countercurrent Mixing Layers

利用两相逆流混合层整体不稳定性的见解增强粘性液体的雾化

• 批准号: 2023932
• 负责人: Vinod Srinivasan
• 金额: $ 51.1万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023932&HistoricalAwards=false
• 关键词: Enhanced; Atomization; Viscous; Liquids; Using

Atomization refers to the process of breaking up a liquid stream into a collection of droplets, which are then usually sprayed into a fluid flow or onto a surface to form a coating. Atomization occurs in a variety of industrial and natural systems. Consumers are familiar with many products that have been produced using a spraying technique, such as powdered milk, infant formula, and painted surfaces, or are deployed using a spraying operation, such as hair spray, automotive fuel injectors, and nasal inhalers. The sprays are designed to atomize the fluids into fine droplets that improve products by enhancing efficiency, reducing costs, and minimizing wastes. In many cases of practical interest, the fluids that are sprayed are highly viscous, which poses problems to achieving fine sprays and increases the energy used to produce a spray. Often, sprays of highly viscous fluids produce extremely large droplets that diminish the effectiveness of the atomization process. This project will use a combination of experiments, theory and numerical simulation to study the atomization process. The research team will use a model flow system and examine the instability in the flow that is the start of atomization. Undergraduate students will be recruited to the research team through the University of Minnesota's Research Experience for Undergraduates program. The researchers will create a traveling exhibit that will be used at science fairs for middle-schoolers to acquaint youngsters with principles of fluid dynamics applied to atomization.This project will investigate the performance of a newly designed atomizer nozzle that dramatically reduces energy consumption, while enabling the atomization of highly viscous fluids into sprays of fine droplets. The project will use a combination of theory, experiments and computational fluid dynamics to identify the mechanisms responsible for the enhanced performance, which will enable design enhancements to further improve energy efficiency. The hypothesis is that a two-phase counterflow mixing layer established inside the nozzle is responsible for high levels of turbulent mixing, creating a two-phase mixture that emerges from the nozzle directly as a spray. The experiments involve characterization of the spray as a function of liquid viscosity, counterflowing air-liquid mass flow and momentum ratios, and nozzle internal geometry. In parallel, the research team will use experiments on planar countercurrent mixing layers that allow optical access to examine in detail the dynamics of a liquid-air interface with counterflow velocity profiles. Experiments will also be performed at the X-Ray facility at Argonne National Labs to elucidate the density profile inside the nozzle. These experiments will be accompanied by a detailed linear stability analysis to identify the presence of absolutely unstable profiles in the mixing layer, which may appear in experiments as self-sustained oscillations. High-resolution Direct Numerical Simulations (DNS) will clarify the physics of mixing inside the nozzle and provide design guidance to engineering practitioners in atomization processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

雾化是指将液体流分解成液滴的过程，这些液滴通常被喷射到流体中或在表面上形成涂层。雾化发生在各种工业和自然系统中。消费者熟悉许多使用喷涂技术生产的产品，如奶粉、婴儿配方奶粉和喷漆表面，或使用喷涂操作进行部署，如发胶、汽车燃油喷油器和鼻吸入器。喷雾器的目的是将液体雾化成细小的液滴，通过提高效率、降低成本和减少浪费来改善产品。在许多实际情况下，被喷射的流体是高粘性的，这给实现精细喷雾带来了问题，并增加了用于产生喷雾的能量。通常，高粘性流体的喷雾会产生极大的液滴，从而降低雾化过程的有效性。本项目将采用实验、理论和数值模拟相结合的方法对雾化过程进行研究。研究小组将使用一个模型流动系统，并检查流动中的不稳定性，这是雾化的开始。本科生将通过明尼苏达大学本科生研究经验项目被招募到研究团队。研究人员将制作一个巡回展览，用于中学生的科学展览，让青少年了解应用于雾化的流体动力学原理。该项目将研究一种新设计的雾化器喷嘴的性能，该喷嘴可以显著降低能耗，同时将高粘性流体雾化成细滴喷雾。该项目将结合理论、实验和计算流体动力学来确定提高性能的机制，这将使设计改进能够进一步提高能源效率。假设建立在喷嘴内部的两相逆流混合层负责高水平的湍流混合，产生两相混合物，直接从喷嘴中喷射出来。实验包括表征喷雾作为液体粘度，逆流空气-液体质量流量和动量比的函数，以及喷嘴内部几何形状。与此同时，研究小组将使用平面逆流混合层的实验，该实验允许光学访问，以详细检查具有逆流速度分布的液气界面的动力学。实验也将在阿贡国家实验室的x射线设备上进行，以阐明喷嘴内的密度分布。这些实验将伴随着详细的线性稳定性分析，以确定混合层中绝对不稳定剖面的存在，这些剖面可能在实验中表现为自持续振荡。高分辨率直接数值模拟（DNS）将阐明喷嘴内混合的物理特性，并为雾化过程的工程实践者提供设计指导。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Visualization of Internal Flow Dynamics in Counterflow Atomizers Using X-Ray Diagnostics and Laser Shadowgraphy

使用 X 射线诊断和激光阴影成像技术实现逆流雾化器内部流动动力学的可视化

• 发表时间: 2022
• 期刊: ILASS-Americas 32nd Annual Conference on Liquid Atomization and Spray Systems
• 作者: Hoxie, A.;Srinivasan, V.;Johnson, E.;Kastengren, A.
• 通讯作者: Kastengren, A.

An in situ adaptive tabulation based approach to multi-component transcritical flow simulation

基于原位自适应制表的多组分跨临界流模拟方法

• 发表时间: 2021
• 期刊: 12th U.S. National Combustion Meeting
• 作者: Zhang, Hongyuan;Yang, Suo.
• 通讯作者: Yang, Suo.

Multi-component transcritical flow simulation based on in situ adaptive tabulation of vapor-liquid equilibrium solutions

基于汽液平衡解原位自适应制表的多组分跨临界流模拟

• DOI: 10.2514/6.2021-0549
• 发表时间: 2021
• 期刊: AIAA Scitech 2021 Forum
• 作者: Zhang, Hongyuan;Yang, Suo
• 通讯作者: Yang, Suo

Multicomponent Effects on the Supercritical CO2 Systems: Mixture Critical Point and Phase Separation

多组分对超临界 CO2 系统的影响：混合物临界点和相分离

• DOI: 10.1007/s10494-022-00335-9
• 发表时间: 2022
• 期刊: Turbulence and Combustion
• 作者: Zhang, Hongyuan;Yi, Ping;Yang, Suo
• 通讯作者: Yang, Suo

Investigation of transcritical shock-droplet interaction using vapor-liquid equilibrium (VLE)-based CFD simulation

使用基于气液平衡 (VLE) 的 CFD 模拟研究跨临界冲击-液滴相互作用

• 发表时间: 2022
• 期刊: ILASS-Americas 32nd Annual Conference on Liquid Atomization and Spray Systems
• 作者: Zhang, Hongyuan;Yang, Suo
• 通讯作者: Yang, Suo