Corona, Dielectric Barrier and Sliding Discharges in the Flow Control and Environmental Protection: From Fundamental Studies to Optimization of Practical Devices

工业、医药和环境保护中的许多过程都涉及气体中的电放电。对于我们的社会来说，最重要的设备可能是静电除尘器，它可以清除许多工业过程中产生的粉尘颗粒，这样我们就可以呼吸到更清洁的空气。许多有毒物质也可以用这个过程分解。所有这一切都是可能的，因为气体放电会产生自由离子和活性化学物质。尘埃颗粒可以带电，它们的运动可以通过电力控制，确保它们被收集起来，而不是释放到大气中。 气体放电中产生的移动离子也会由于与中性分子的频繁碰撞而产生气体运动，这通常被称为二次电流体流动，或离子风。此外，从离子到气体分子的能量转移会局部提高其温度，产生冲击波，这也会影响气体流动。基于气体放电的实际设备的设计和优化需要对该过程有透彻的了解，并有能力预测该过程的所有电气、化学、热和空气动力学特性。 提出的研究计划的第一个目标是建立一套数值算法，可以用来模拟电晕、介质阻挡和滑动放电，假设过程的不同参数：放电间隙的几何形状、供电电压的极性和波形、以及环境气体的温度、压力和组成。之后，可以根据所需的精确度和可用的计算资源，使用适当的模型来研究不同的设备。商业软件包不能解决这个问题；它们通常是发散的，或者至少表现出很大的数值扩散。 有了可靠的模拟工具，就有可能研究和优化三个重要的实用设备：用于控制流动边界层的气体放电执行器、用于有机物的电液动力干燥器和用于亚微米颗粒的静电除尘器。在加拿大，很大一部分电力是由燃煤发电站产生的，这些发电站会产生大量的粉尘。有效地收集这些粉尘对我们社会的健康至关重要，对保护我们的环境也是至关重要的。用于边界层控制的执行器特性的改进可以极大地影响飞机和风力涡轮机行业。

Many processes in industry, medicine and environmental protection involve electrical discharges in gases. The most important devices for our society are probably electrostatic precipitators, which remove dust particles generated in many industrial processes so we may breathe cleaner air. Many toxic substances can also be decomposed using this process. All this is possible, because gas discharges produce free ions and active chemical species. The dust particles can be electrically charged and their motion can be controlled using electric forces, ensuring they are collected and instead of being released into the atmosphere. Moving ions generated in gas discharges can also produce gas motion due to frequent collisions with neutral molecules this is commonly called the secondary electrohydrodynamic flow, or ionic wind. Moreover, the energy transfer from ions to gas molecules can locally increase their temperature producing a shock wave, which also affects the gas flow. The design and optimization of practical devices based on gas discharges require a thorough understanding of the process and ability to predict all electrical, chemical, thermal and aerodynamic characteristics of the process. The first objective of the proposed research program is to create a set of numerical algorithms, which can be used to simulate the corona, dielectric barrier and sliding discharges, assuming different parameters of the process: geometry of the discharge gap, polarity and waveform of the supplied voltage, and temperature, pressure and composition of ambient gas. Later, appropriate models can be used to study different devices, depending on the required accuracy and available computing resources. Commercial software packages are not able to solve this problem; they are usually divergent, or at least exhibit a large numerical diffusion. Having a reliable simulation tool, it will be possible to investigate and optimize three important practical devices: a gas discharge actuator for controlling the flow boundary layer, electrohydrodynamic dryers of organic substances, and electrostatic precipitators for submicron particles. A large percentage of power in Canada is generated by coal-fired power stations, which produce enormous amounts of dust. Efficient collection of this dust is of paramount importance for the health of our society, but also to protecting our environment. Improved characteristics of actuators for the boundary layer control can tremendously affect aircraft and wind turbine industries.