本研究探討不同縮口比(DR = 1/2,1/3,1/4)的噴嘴電液動泵的放電特性、流體現象和效能影響，首先經實驗方法進行完整的性能測試和討論分析，並與圓管電液動泵之特性比較。實驗結果顯示，三種縮口比電液動泵分別在不同條件下有較佳表現，噴嘴縮口程度越高能夠產生更高流速，其電流值增加趨勢越平穩，相較之下，縮口程度低在流體速度分佈、軸向吹送距離和體積流率有更好的表現，與等面積之圓管電液動泵比較，因為截面積減少使放電電極尖端較靠近，使得操作電壓和電暈電流皆較低，即代表電能能耗較低。至於噴嘴管道出口處的雷諾數與體積流率關係，因低縮口程度的電液動泵之阻抗低，可以得到較高的雷諾數和體積流率。同時在低電壓下，縮口程度低的電液動泵無法發揮真正的性能，在高電壓下，整體速度分佈和流速皆為最佳；相較之下，縮口程度越高之電液動泵之整體表現，會隨著操作電壓的風速值皆較高且穩定。在效能(輸出的流體體積流率與輸入的消耗電能筆值)表現部分，其不隨電壓增加而上升，且在15kV時三個電液動泵皆有最佳效能，其中以1/2D電液動泵能產生3L/min/W為最佳。在文中所討論的噴嘴電液動泵，所產生的的體積流率皆因為出口面積小，故其性能皆不及圓管電液動泵。以最佳速度分佈、風速值、體積流率和效能的觀點來看，1/2D電液動泵在高電壓下為最佳選擇；若以低能耗、近距離產生最高風速值來看，1/4D在所有電壓下皆為最佳選擇。所以在設計噴嘴式電液動泵以及其最佳表現效能方面，除了考慮不同縮口比的特性之外，未來更可以進一步加入放電電極的數目和電極間距的考量。

In this study, an electrohydrodynamic (EHD) gas pump fitted within a linear nozzle with different diameter ratios (DR) has been tested for a wide range of applied voltages starting from the corona threshold voltage up to 17 kV for the further improvement in its performance. The EHD gas pump has been critically evaluated by experimental measurements to reveal the relation between pump performance and diameter ratio (DR) as well as the velocity profile at downstream of the pump exit. The result shows that three nozzle configurations have their own characteristics and performs differently under various conditions. A pump with a diameter ratio of 1/2 performs the best in maintaining a velocity profile that can extend the longest distance downstream of the pump while a pump with a diameter ratio of 1/4 can produce the highest velocity with the smallest increase in corona current. It is also worthwhile to note that the maximum velocity, volume flow rate, and performance produced by a pump with a diameter ratio of 1/3 are somewhat between the other two, but the current it required is the highest among all. For the present study, the best performance (in terms of the volume of air delivered by a unit energy input) of 3 L/min/W has been achieved by an EHD gas pump with a diameter ratio of 1/2 operated at 15 kV. Most important of all, it has been found that the flow and electric characteristic are not totally determined by the configuration of nozzle (i.e., the diameter ratio). As such, the design consideration of EHD gas pump fitted within a nozzle should include other parameters (such as the number of electrodes, electrode spacing, and nonlinear surface profile) for its best performance.

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