【摘要】：液體中脈沖大電流放電產(chǎn)生強有力的激波被廣泛應用于工業(yè)生產(chǎn)、生物醫(yī)療等領(lǐng)域,如何穩(wěn)定、高效地獲得高強度的激波是該技術(shù)的關(guān)鍵�；诖罱ǖ囊弘娒}沖激波實驗平臺,該文研究了正極性針 板放電模式對激波強度的影響。通過高速攝像機拍攝流注通道發(fā)展過程,發(fā)現(xiàn)流注可能呈現(xiàn)出兩種不同的發(fā)展模式:樹枝狀亞音速流注與絲帶狀超音速流注。試驗結(jié)果表明放電電壓對水中間隙擊穿放電模式及對應的激波強度有明顯影響。通過改變放電電壓,可以實現(xiàn)對水中間隙擊穿放電模式的調(diào)控。亞音速流柱的發(fā)展過程屬于電熱擊穿過程,陽極尖端首先出現(xiàn)可見的氣泡簇,在外部不均勻電場的作用下氣泡簇內(nèi)部明亮流注沿著尖端向陰極發(fā)展,形成樹枝狀的流注通道。此后,氣泡簇包裹的叢林狀流注通道不斷向陰極發(fā)展,當流注頭部發(fā)展到與陰極距離足夠小時,水中間隙擊穿并產(chǎn)生強烈的激波。超音速流注的出現(xiàn)可導致間隙的快速動態(tài)擊穿,電容器上的能量可實現(xiàn)快速釋放,形成更為強烈的激波。針對本試驗條件,充電電壓提升到22.5kV時,亞音速流注將向超音速流注轉(zhuǎn)化,預擊穿過程的擊穿時延及泄漏能量將迅速降低。研究表明超音速流柱模式的能量轉(zhuǎn)換效率更高,即使在相同的施加電壓下,超音速流柱對應激波強度可以達到亞音速流柱模式下的2~4倍。
[Abstract]:The powerful shock produced by pulsed high current discharge in liquid is widely used in industrial production, biomedicine and other fields. How to obtain high intensity shock wave stably and efficiently is the key of this technology. Based on the experimental platform of electro-hydraulic pulse shock, the effect of the discharge mode of the positive needle plate on the shock intensity is studied in this paper. By using high-speed camera to capture the development process of streamer channel, it is found that the streamer may present two different development modes: dendritic subsonic stream and filamentous supersonic stream. The experimental results show that the discharge voltage has a significant effect on the gap breakdown discharge mode and the corresponding shock intensity in water. By changing the discharge voltage, the gap breakdown discharge mode in water can be controlled. The development process of subsonic flow column belongs to electrothermal breakdown process. The visible bubble cluster appears first at the anode tip. Under the action of the external inhomogeneous electric field, the bright flow inside the bubble cluster develops to the cathode along the tip, forming a dendritic flow channel. Since then the Jungle flow channel wrapped in the bubble cluster develops to the cathode. When the flow head reaches enough distance from the cathode the gap in the water breaks down and produces a strong shock wave. The appearance of supersonic flow can lead to the fast dynamic breakdown of the gap, and the energy on the capacitor can be released rapidly, resulting in a stronger shock wave. According to the experimental conditions, when the charging voltage is raised to 22.5 kV, the subsonic flow will be converted to supersonic flow, and the breakdown delay and leakage energy of the pre-breakdown process will be reduced rapidly. The results show that the supersonic flow mode has a higher energy conversion efficiency, and even at the same applied voltage, the corresponding shock intensity of the supersonic flow column can reach 2 ~ 4 times that of the subsonic flow mode.
【作者單位】： 強電磁工程與新技術(shù)國家重點實驗室(華中科技大學);
【分類號】：O461.25

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