CAREER: Towards Understanding and Control of Surface-Impinging Particle-Laden Flows

在各种工程应用中产生了充满分散固体颗粒的气流，其中它们与材料表面的相互作用可以导致积极或消极的结果。积极的结果包括喷涂涂层和冷喷涂增材制造，而消极的结果包括表面侵蚀和沉积，影响飞机推进系统，风力涡轮机和航天器在多尘大气中的性能。实现多相相互作用过程的控制受到连续气相和分散颗粒之间的动量和能量传递过程的基本流体动力学理解的差距的限制，这随后驱动颗粒和材料表面之间的相互作用结果。PI将推行综合研究和教育计划，以实现三个具体目标：1）在受气相影响的颗粒状况和当颗粒撞击固体表面时的碰撞结果之间建立联系，2）使用该联系来开发控制方案以利用流体注入到边界层中来减轻表面损伤，3）通过为本科生和高中生开设实践火箭学和空气动力学课程，推进航空航天教育，学校的学生以及针对公众的冲击波传播巡回展览。这项工作的总体目标是解决知识与流体动力学在影响颗粒负载气流的表面撞击过程中所起的关键作用有关的差距。将在激波管装置中的受控条件下研究脉冲加速的单粒子，其中，粒子运动和温度测量将用于研究非稳态粒子阻力和传热，并评估现有模型。粒子与固体表面碰撞的超高速成像将用于将碰撞结果映射到以无量纲温度和动能为特征的状态图。将在多相热叶栅装置中进行状态图的验证，并尝试通过在表面边界层中进行流体喷射来控制表面损伤，该装置在翼型表面上产生连续的颗粒负载流。该研究计划将作为通过外联活动进行航空航天教育的平台，包括：一个实验室组成部分混合火箭纳入本科推进课程，一个迷你课程的空气动力学和推进的K-8学生，一个中学暑期研究导师计划，以及一个互动的冲击波演示，它被纳入一个巡回展览，参观学校和州博览会，以促进科学该奖项反映了NSF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。

Gas flows laden with dispersed solid particles are generated in a variety of engineering applications where their interaction with material surfaces can lead to positive or negative outcomes. Positive outcomes include spray coatings and cold spray additive manufacturing, while negative outcomes include surface erosion and deposition affecting the performance of aircraft propulsion systems, wind turbines, and spacecraft in dusty atmospheres. Achieving control of the multiphase interaction process is limited by gaps in fundamental fluid dynamical understanding of momentum and energy transfer processes between the continuous gas phase and dispersed particles, which subsequently drives the interaction outcome between the particles and material surfaces. The PI will pursue an integrated research and education program to achieve three specific goals: 1) establish a connection between gas phase-influenced particle conditions and collision outcomes when the particles impact a solid surface, 2) use this connection to develop a control scheme to mitigate surface damage utilizing fluidic injection into the boundary layer, and 3) advance aerospace education through implementation of hands-on rocketry and aerodynamics courses for undergraduate and high-school students as well as a traveling exhibit on shockwave propagation aimed at the general public.The overall goal of this work is to address knowledge gaps pertaining to the critical role played by fluid dynamics in influencing surface impingement processes by particle-laden gas flows. Impulsively-accelerated single particles will be studied at controlled conditions in a shock tube setup, wherein, particle motion and temperature measurements will be used to study unsteady particle drag and heat transfer, and evaluate existing models for the same. Ultra-high-speed imaging of particle impact with a solid surface will be used to map collision outcomes to a regime map characterized by non-dimensional temperature and kinetic energy. Validation of the regime map and attempts to control surface damage through fluidic injection in the surface boundary layer will be pursued in a multiphase hot cascade setup generating continuous, particle-laden flow over an airfoil surface. The research program will serve as a platform for aerospace education through outreach activities including: a laboratory component on hybrid rockets incorporated into an undergraduate propulsion course, a mini-course on aerodynamics and propulsion for K-8 students, a middle-school summer research mentorship program, and an interactive shock wave demonstration incorporated into a traveling exhibit that visits schools and state fairs to further science education.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.