本研究探討雙級電液動力泵(Electrohydrodynamic Pump) 配置不同電極模組及其排列方式，於單/雙級方管電液動泵的放電特性、流場型態和能源效率之影響，選定之EHD參考模型包括Zhang之單級EHD泵、Mazumder之雙級EHD泵及Tien之非對稱型單/雙級EHD泵；在維持與參考模型外部尺寸後，接著改變EHD之電極模組配置方式，藉實驗進行完整的性能測試和討論分析，並將其與參考模型之特性做比較。本研究改變電極安組方式使用雙面型電極配置，探討之設計參數為1、3、7根電極模組，而雙級EHD泵之電極模組排列方式採用同面式安裝方式。彙整分析實驗結果後發現，隨著操作電壓的增加電場作用力也提升，離子風速也提高進而提升流量，但是電壓越高所能提升的風速與流量越少最終趨緩於定值；另外，當放電電極為7根時電極彼此間距過近，過於密集的電極會使電場彼此互相影響導致體積流率降低，但是多根電極所產生的風速分佈較為平均，可藉著雙級模型的氣流延續、風速加速之特性以增加流量。
至於在速度場部分，單根電極所產生的風速區集中在電極正下方，其中1根電極模組之單級雙面EHD泵於電壓30kV產生最佳流量為12.15CFM；而3根電極所產生之風速區會如梯形般往外擴散，7根電極則會產生最寬廣之風速區，但因互相干擾而風速較低。至於雙級同面式EHD泵方面，電極同面配置使上級產生之氣流得以延續，在上級低風速時會有明顯的加成效果；最高流量出現在3根電極模組上下級電壓皆為28kV，時其流量為20.29CFM。至於效率表現部分，效率與操作電壓成反比，其中單級EHD泵以1根電極模組的效率最高，且1根電極模組在24kV時所產生之17.78CFM/W為最佳；而雙級EHD泵在低電壓下效率表現較好，在上下級電壓皆24kV時，效率甚至會高於單級模型，而雙級3根電極配置能夠產生所有實驗組合中之最佳效率(26.09CFM/W)。與雙級參考模型相比，同面式雙面模型能產生單面式模型之兩倍流量，且能源效率十分接近；而與四面模型相比，同面式雙面模型之流量僅略低於四面模型，但能源效率有較大增幅，因此同面式雙面設計能在流量和效率取得較佳的平衡，可增加EHD泵在散熱方面之實用性。

This experimental study investigates the discharge features of the square channel electrohydrodynamic (EHD) gas pump with different electrode modules and arrangements. In this EHD pump, the electrodes are flush mounted on two parallel walls and powered by DC voltages ranging from 24 kV to 30 kV. Also, the two-stage EHD model is designed with aligned electrodes to increase the flow rate and extend over a longer channel length. Besides, three electrode modules considered here are 1, 3, and 7 electrode modules. The measured EHD characteristics include flow pattern, discharge flow rate, and energy efficiency factor, which is defined as the volume flow rate delivered by a unit power input. After summing up the experimental results, it is found that the ion wind velocity increases to enlarge the flow rate as the operating voltage increase. However, the less growths on velocity and flow rate are induced by the higher voltage. But, the small electrode distance within the 7-electrode module results in the electric-field interference and reduction on the discharge airflow. As for the velocity pattern, the ion wind generated by the single electrode is concentrated directly below the emitting electrode, while the wider distributions are observed for the 3- and 7-electrode modules. Though, the velocity distribution generated by multiple electrodes are relatively uniform, which is favorable to promote flow mixing inside the channel.
Experimental outcomes also show that the highest flow rate (12.15 CFM) of a single-stage, double-sided EHD pump is recorded in the single electrode module operating at 30 kV. Also, the two-stage, two-wall EHD pump with aligned electrodes enables the airflow generated by the first stage moving to the upstream of the second-stage EHD. It follows that the discharge performance of this two-stage EHD gas pump is enhanced. And, the highest flow rate 20.29 CFM is found for EHD with the 3-electrode module operating at 28 kV in both stages. For all models tested here, the flow rate of the single-wall model is doubled by introducing the two-wall design on EHD pump. Moreover, the power efficiency is inversely proportional to the operating voltage. Among all tests, the single-stage EHD pump has the highest efficiency (17.78CFM/W) with the single-electrode module at 24kV. As the two-stage EHD pump, the test efficiency is even higher than the single-stage model. Two-stage EHD pump with the 3-electrode configuration has the highest efficiency of 26.09 CFM/W. In summary, the two-stage, two-wall model with aligned electrodes can generate twice the flow rate of the single-sided model under the similar power efficiency.
Regarding the electrode orientations, this work confirms that an EHD gas pump with aligned electrodes can produce a larger volume flow rate than that with offset electrodes. However, the offset arrangement can create more mixing of the flow inside the channel. Also, an EHD gas pump with aligned electrodes can operate at a higher power efficiency than that with offset electrodes. In conclusion, the present results reveal that EHD gas pump has a great potential for applications in the thermal management and can be more energy-efficient when operated with uneven applied voltages.

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