本研究探討不同電極模組以及其排列方式，在單/雙級方管電液動泵的放電特性、流場現象和效能影響，首先選定Zhang之單級EHD泵及Mazumder之雙級EHD泵設計作為參考模型，並改動其模型之電極模組配置方式，經實驗方法進行完整的性能測試和討論分析，接著將其與參考模型之特性做比較。本研究探討之設計參數為1、3、7根電極模組，於單級EHD泵上，其電極模組僅配置於管內單一壁面，且電極的安裝方式為內嵌壁面式，而雙級EHD泵之電極模組排列方式又分同面式和非同面式兩種。彙整分析相關實驗結果發現，隨著操作電壓的增加電場作用力也有所提升，同時觀察到增加放電電極根數可使EHD泵之流量增加；雖然增加放電電極可使體積流率進一步提升，但放電電極密度過高時使電場作用彼此互相影響，也導致體積流率受到限制。另外在檢視高密度的電極模組也發現，此EHD設計能夠將氣體分子有效推送至遠的距離並保持較高之風速。
至於在流場現象部分，由於單級EHD泵的電極模組安裝規劃之故，造成在靠近電極面側之風速較大，而遠離電極面側之風速較微弱，其中3根電極模組之單級EHD泵擁有最佳之流量4.82 L/s。雙級同面式EHD泵方面，以3根電極模組有最佳流量6.19 L/s，至於非同面式電極配置能令流量稍微增加些，也以3根電極模組有最大流量6.42 L/s。於效率表現部分，效率與操作電壓成反比，其中單級EHD泵，在26kV時，三種電極模組皆有最佳效率，且以1根電極模組所產生之10.12 L/s/W為最佳；而雙級EHD泵在上下級電壓皆26kV時，同面式EHD泵1根電極模組能夠產生最佳效率5.68 L/s/W，而非同面式EHD泵3根電極模組能夠產生最佳效率5.72 L/s/W。且因為雙級同面式EHD泵之電極模組安裝方式與單級EHD泵相同，皆配置於同一壁面上，故流場形態與單級EHD泵相同，在靠近電極面側壁面有較大之風速分佈；而雙級非同面式EHD泵之電極模組安裝於兩不同壁面上，故在兩側安裝電極之壁面處均有較明顯之風速。

This study investigates the discharge characteristics, flow field phenomena, and performance efficiencies of the single- and two-stage EHD pumps within a square channel with asymmetric electrodes. For convenient demonstration, electrode module is installed near the wall to perturb the boundary layer on single wall of this 4-plate tube. The parameters of electrode modules considered here include electrode numbers (1, 3, and 7) and installation on the same or the opposite plate for the two-stage EHD pumps. Thereafter, the corresponding EHD pumps are fabricated and tested experimentally for comparing and analyzing the performance influences induced by asymmetric electrodes. For all EHD gas pumps tested, experimental result shows that electric force and EHD-induced flow rate enlarge as number of electrodes increases. However, the flow rate approaches to an asymptotic limit for the 7-electrode module, which the electric-field interaction happens between electrodes. Also, the EHD-induced flow can move to downstream location further for this high-density electrode module.
Regarding the velocity distribution, the maximum velocity is observed near the electrode-installed plate while the lowest velocity is founded near the opposite plate. Also, the single-stage EHD pump with 3 electrodes powered at 30kV delivers the highest flowrate (4.82 L/s) with an energy efficiency of 4.97 L/s/W. Similarly, at 30kV input, the largest flowrates of 6.19 L/s and 6.42 L/s are obtained for the two-stage EHD pumps with two 3-electrode modules installed on the same and opposite plates, respectively. Note that, for all cases with different power inputs on two electrode modules, their energy efficiencies do not significantly downgrade from the corresponding single-stage EHD pumps. For examples, for asymmetric power inputs of 26 kV and 30 kV in sequential stages, the good flowrates and fair efficiencies are recorded as (5.56 L/s, 4.12 L/s/W) and (5.93 L/s, 4.39 L/s/W) for installation of two 3-electrode modules on the same and opposite walls, respectively. In summary, it is concluded that asymmetric electrodes applied on the two-stage EHD gas pump can enhance its flow rate slightly and maintain the energy efficiency at a reasonable level.

[1] 謝維哲，"以EHD技術增強熱傳研究"，國立清華大學碩士論文，2008年。
[2] N. E. Jewell-Larsen, H. Ran, Y. Zhang, M. K. Schwiebert, and K. A. Honer, "Electrohydrodynamic (EHD) Cooled Laptop," Semiconductor Thermal Measurement and Management Symposium, pp. 261-266, 2009.
[3] F. F. Chen, "Industrial Applications of Low-Temperature Plasma Physics," Phys Plasmas, Vol. 2, No. 6, pp. 2164-2175, 1995.
[4] F. C. Lai and R. K. Sharma, "EHD-Enhanced Drying with Multiple Needle Electrode," Journal of Electrostatics, Vol. 63, No. 3-4, pp. 223-237, 2005.
[5] F. C. Lai and K. W. Lai "EHD-Enhnaced Drying with a Wire Electrode," Drying Technology, Vol. 20, No. 7, pp. 1393-1405, 2007.
[6] H. J. Yu, A. Z. Bai, and X. W. Yang "Electrohydrodynamic Drying of Potato and Process Optimization," Journal of Food Processing and Preservation, Vol. 42, No 2, 2018.
[7] K. Pirnazari, A. Esehaghbeygi, and M. Sadeghi "Modeling the Electrohydrodynamic(EHD) Drying of Banana Slices," Journal of Food Enginerring, Vol. 12, No 1, pp. 12-26, 2016.
[8] W. Cao, Y. Nishiyama, and S. Koide, "Electrohydrodynamic Drying Characteristics of Wheat Using High Voltage Electrostatic Field," Journal of Food Engineering, Vol. 62, No. 3, pp. 209-213, 2004.
[9] M. S. Yang and C. J. Ding, "Electrohydrodynamic (EHD) Drying of the Chinese Wolfberry Fruits," SpringerPlus, Vol. 5, 2016.
[10] L. Leger, E. Moreau, and G. G. Touchard, "Effect of a DC Corona Electrical Discharge on the Airflow along a Flat Plate," IEEE Transactions on Industry Applications, Vol. 38, No. 6, pp. 1478-1485, 2002.
[11] R. Futrzynski, "Drag Reduction Using Plasma Actuators," KTH Engineering Sciences, Stockholm, Sweden, 2015.
[12] A. D. Hosey, H. H. Jones, "Portable Electrostatic Precipitator Operating form 110 Volts AC or 6 Volts DC," Ama Archives of Industrial Hygiene and Occupational Medicine, Vol. 7, No. 1, pp. 49-57, 1953.
[13] Mounir. Laroussi, "Low-Temperature Plasmas for Medicine," IEEE, Vol. 37, No. 6, pp. 714-725, 2007.
[14] F. Hauksbee, Physico-Mechanical Experiments on Various Subjects. London: Oxford University Press, 1709.
[15] A. P. Chattock, "On the Velocity and Mass of Ions in the Electric Wind in Air," Phil. Mag., Vol 48, No. 294, pp. 401-420, 1899.
[16] J. R. McDonald, W. B. Smith, and H. W. Spencer, "A Mathematical Model for Calculating Electrical Conditions in Wire-Duct Electrostatic Precipitation Devices," Journal of Applied Physics, Vol. 48, N. 6, pp 2231-2243, 1977.
[17] L. Fouad, S. Elhazek, "Effect of Humidity on Positive Corona Discharge in a Three System," Journal of Electrostatics, Vol. 35, pp. 21-30, 1995.
[18] I. A. Metwally, "Factors Affecting Corona on Twin-Point Gaps under DC and AC HV," IEEE transactions on dielectrics and electrical insulation Vol. 3, No. 4, pp. 544-553, 1996.
[19] M. Rickard, D. Dunn-Rankin, F. Weinberg, and F. Carleton, "Characterization of Ionic Wind Velocity," Journal of Electrostatics, Vol. 63, No. 6-10, pp. 711-716, 2005.
[20] M. Rickard, D. Dunn-Rankina, F. Weinbergb, and F. Carletonb, "Maximizing Ion-Driven Gas Flows," Journal of Electrostatics, Vol. 64, No. 6, pp. 368-376, 2006.
[21] S. M. Marco and H. R. Velkoff, "Effect of Electrostatic Fields on Free Convection Heat Transfer from Flat Plate," ASME Paper, No. 63-HT-9, 1963.
[22] M. E. Franke and L. E. Hogue, "Electrostatic Cooling of a Horizontal Cylinder," ASME Journal of Heat and Transfer, Vol. 34, pp. 544-548, 1991.
[23] H. Y. Li, R. T. Huang, W. J. Sheu, and C. C. Wang, "EHD Enhanced Heat Transfer with Needle-Arrayed Electrodes," IEEE, pp. 149-154, 2007.
[24] J. Zhang and F. C Lai, "Effect of Emitting Electrode Number on the Performance of EHD Gas Pump in a Rectangular Channel," Journal of Electrostatics, Vol. 69, No. 6, pp. 486-493, 2011.
[25] A. K. M. M. H. Mazumder and F. C. Lai, "Two-Stage Electrohydrodynamic Gas Pump in a Square Channel," Proc. ESA Annual Meeting on Electrostatics, 2011.
[26] B. R. Maskell, "The Effect of Humidity on a Corona Discharge in Air," Royal Aircraft Establishment, Farnborough (UK), Technical Report 70106, 1970.
[27] J. S. Townsend, “The Conductivity Produced in Gases by the Motion of Negatively-Charged Ions," Nature. Vol. 62, pp. 340-341, 1900.
[28] J. S. Townsend, Electricity in Gases, Oxford: Clarendon Press, 1915.
[29] J. S. Chang, P. A. Lawlwss, and T. Yamamoto, "Corona Discharge Processes, " IEEE Transactions on Plasma Science, Vol. 19, No. 6, pp. 1152-1166, 1991.
[30] T. Zhang, Y. Zhang, Q. Ji, B. Li, and J. Ouyang, "Characteristics and underlying Physics of Ionic Wind in DC Corona Discharge under Different Polarities, " Chinese Physics B, Vol. 28, No. 7, 2001.
[31] A. Castellanos, Electrohydrodynamics, New York: SpringerWien, 1998.