高效能微型电喷射推进技术基础理论研究

Currently, the development of electrospray propulsion technology is focused on further reducing the onset voltage and improving the thrust resolution, specific impulse, and propulsion efficiency. Intrinsically, those propulsive performance is determined by the structure and size of nozzles as well as the liquid ejection mode. In this project, we will conduct both theoretical modelling and experiments to investigate the physical process of nanoscale liquid ejection driven by electric field. The fundamental mechanisms affecting the onset voltage, charge-to-mass ratio, and multi-electrospray performance will be unveiled. In detail, theoretically, we will develop the theoretical model of onset voltage and the molecular dynamics (MD) simulation model of nanoscale jet. The coupled effects of electric field, flow field, surface and fluid properties, and nozzles’ structure and size on liquid ejection will be clarified. Furthermore, effective approaches to tune pure droplet or pure ion emission regime will be determined. Experimentally, we employ high-precision nano-fabrication and characterization technology of the focused ion beam and the transmission electron microscope to realize high-precision and reproducible fabrication of stable nanopores on silicon nitride thin film. Single nozzle electrospray experiments will be performed to validate and improve the developed theoretical onset voltage model and MD models to achieve accurate prediction of propulsive performance in real operating conditions. To reduce the effects of electrostatic shielding, multi-nozzle electrospray experiments will be conducted to optimize the distribution and the spacing of nozzles. Those work in this project will contribute to providing scientific guidance for the design and development of high-performance electrospray propulsion systems.

现阶段电喷射推进技术发展的重点是进一步降低启动电压，提高推动力精度、比冲和推进效率，而这些推进性能主要取决于喷孔结构尺寸及流体喷射模式。本项目以纳喷射物理过程为研究对象，采用理论模拟与实验相结合的手段，解析启动电压、电荷质量比、多孔喷射规律的影响机制。理论方面，将建立纳尺度启动电压理论模型和纳喷射分子动力学模型，明确电场、流场、壁面特性、流体特性、喷孔结构尺寸相互耦合对流体喷射的影响，提出液滴喷射或纯离子喷射的有效调控方法。实验方面，选用氮化硅薄膜材料作为纳米喷孔加工材料，使用聚焦离子束和透射电子显微镜高精度纳米加工与表征技术，实现稳定纳米孔的高精度、可重复制造。通过单孔电喷射实验，完善启动电压模型和纳喷射分子动力学模型，实现对真实工况中推进系统性能的准确预测。开展多孔阵列喷射实验，优化纳米孔分布和孔隙，降低静电屏蔽影响。这些工作的开展将为设计和开发高效能电喷射推进系统提供基础理论指导。

现阶段电喷射推进技术发展的重点是进一步降低启动电压，提高推动力精度、比冲和推进效率，而这些推进性能主要取决于喷孔结构尺寸及流体喷射模式。本项目以纳喷射物理过程为研究对象，采用理论模拟与实验相结合的手段，解析启动电压、喷射模式、多孔喷射规律的影响机制。理论方面，首先确定流体从纳米通道释放所需临界压力随管道孔径、亲疏水性、管道形貌变化的规律，建立流体释放压力的理论模型，并通过实验验证理论结果；其次提出了纳尺度启动电压理论模型和纳喷射分子动力学模型，明确电场、流场、壁面特性、流体特性、喷孔结构尺寸相互耦合对流体喷射的影响，提出液滴喷射或连续喷射的有效调控方法。实验方面，选用玻璃毛细管作为纳米喷孔加工材料，使用拉制仪加工制造玻璃基纳米孔，通过单孔电喷射实验，完善启动电压模型和纳喷射分子动力学模型，实现对真实工况中推进系统性能的准确预测。缩小喷孔孔径，大幅降低喷射启动电压，并通过调控离子浓度，实现液滴或连续喷射。通过有限元模拟优化阵列式喷孔间距，利用增材制造方法加工阵列式静电喷射推进器，开展多孔阵列喷射实验，优化纳米孔分布和孔隙，降低静电屏蔽影响。这些工作的开展将为设计和开发高效能电喷射推进系统提供基础理论指导。