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、速度分佈和能源效率之影響，首先選用設計參數為1、3、7根電極模組，變動其模型之電極模組配置方式，以實驗方法進行完整的性能測試和討論分析；接著選定Zhang之單級EHD泵、Mazumder之雙級四面EHD泵及Tien之非對稱雙級單面EHD泵作為參考模型，將其與本雙面EHD模型之特性做比較。本EHD泵之電極模組為內嵌壁面式且配置於管內對稱壁面，而雙級EHD的上下級為雙面且安裝於交錯面。實驗結果彙整發現，隨著操作電壓及電極數的增加可使EHD泵之流量增加，雖然進一步增加放電電極可使體積流率再提升，但電極密度過高時使電場彼此互相影響，也導致體積流率之增幅受到限制，且不同根數之電極模組也會影響其風速分佈。
關於流場型態與流量現象部分，因本單級雙面EHD泵的電極模組安裝於對稱兩面，故兩側風速較高而接近管中央則會降低，其中1根電極模組之單級雙面EHD泵在30kV時產生最佳流量12.15 CFM；而於雙級交錯式雙面EHD泵方面，以7根電極模組於上、下級電壓皆是28kV時，有最佳流量18 CFM。至於能源效率表現部分，效率值與操作電壓之增加成反比，其中單級雙面EHD泵之單根電極模組，在電壓24kV之17.77 CFM/W表現最佳；而雙級EHD泵的1根電極模組，在上級26kV、下級24kV下之18.88 CFM/W表現最佳。綜合來說，雙面交錯式模型相較單面式雙級模型，可在能源效率接近下提升較多流量，且風速覆蓋範圍也較多；而與四面模型相比，流量稍微低於四面模型，但是能源效率卻能夠大幅提升，因此雙面交錯式電極配置在流量與效率可取得較佳的平衡，能強化增加未來EHD泵之應用可能。除此之外，交錯式與同面式之雙面雙級EHD泵的性能相似，電壓提高時能源效率降低，提高電極數則能提高流量；唯兩者之風速分佈有很大的差異，上下級不同面之交錯安裝方式能使空間均勻充滿電暈風，且搭配電極模組的優化選擇可令電暈風覆蓋範圍更增加。

The effect of electrode arrangement in the single/double stage electrohydrodynamic (EHD) gas pump is experimentally examined for its flow pattern, discharge flow rate, and energy efficiency factor, which is defined as the volume flow rate delivered by a unit power input. In this work, electrode modules of EHD gas pump are flush mounted on two parallel walls, and offset arrangement of electrodes is used in different stages for the double stage EHD pump. Also, the measured EHD characteristics are summarized and compared with other reference EHD pumps equipped with electrodes on one and four walls. According to experimental outcomes, the volume flow rate of the EHD pump can be enlarged with the increase of operating voltages and electrode numbers. However, for a high electrode numbers, the electric fields induced by neighboring electrodes may interfere and restrict the discharge flow rate. In addition, the electrode numbers have significant influence on the velocity pattern, which becomes uniformly distributed for an increasing electrode quantity. Regarding the delivered flow rate, the highest 12.15 CFM is recorded at 30 kV for the single-stage EHD pump with one-electrode module, while an 18.0 CFM is obtained at 28 kV applied on both stages for the two-stage EHD with 7-electrode module. Moreover, this flow rate is roughly the same as the ion stream delivered by the EHD with 4-wall electrodes, and significantly larger than that generated by the EHD with one-wall electrode module.
Regarding the energy efficiency, EHD pumps with the single-electrode module generate the best energy efficiency factors as 17.7 CFM/W and 18.88 CFM/W at 24 kV for the single stage and at 26 kV/24 kV for the two stages, respectively. As expected, the power efficiency factor for the two-wall EHD models is slightly small than that of the single-wall EHD, and is significantly higher than that of four-wall EHD gas pumps. Hence, two-stage design successfully enlarges the flow rate by a huge 48% enhancement under a similar power efficiency factor as the single-wall EHD. Concerning the flow pattern, the two-stage, two-wall EHD gas pump with offset electrodes yields a much uniform distribution with the highest velocity near the duct walls and the lowest value at the duct center, which is quite different from the uneven velocity pattern produced by the two-stage, one-wall EHD pump. Note that this even flow pattern can create more mixing of the flow inside the channel, which is critical and greatly favorable for the application in the thermal management. In conclusion, the present results confirm that a two-stage, two-wall EHD gas pump with offset electrodes can extend Corona wind over a longer channel length, increase the flow rate, and still have a good power efficiency. Also, EHD gas pump has a great potential on thermal management and can be more energy-efficient when operated with uneven applied voltages.

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