Detection method of the self-resonating waterjet characteristic based on the flow signal in a pipeline
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摘要: 提出基于管道流體信號的自振射流特性檢測方法, 將壓力傳感器從高壓罐內移至高壓罐外, 布置在高壓罐外的前端管路上, 從而避開高圍壓環境影響; 通過雙壓力傳感器拾取管道流體壓力脈動信號, 并運用信號處理技術有效抑制干擾噪聲, 提高有用信號強度, 準確獲取射流的壓力脈動信息.試驗表明, 管道流體壓力信號的頻譜特征與噴嘴腔內檢測法具有一致性, 且與理論計算較為吻合, 充分表征了射流的壓力振蕩特性; 其聲功率譜與高壓罐內水聽器檢測結果相一致, 較好地表述了射流的空化作用特性.由此認為基于管道流體信號的檢測法用于自振射流特性的檢測是完全可行的, 具有先進性, 為高圍壓下自振射流的研究提供了新手段.Abstract: The self-resonating waterjet has the characteristics of high-frequency pressure oscillation and strong cavitation. Accurately grasping the jet characteristics is a prerequisite for the application research of self-resonating waterjets. The characteristics of the self-resonating waterjet are typically acquired through a test. Traditional test methods primarily include the striking test and signal detection in the nozzle chamber. However, these methods both have the disadvantage of low detection accuracy and the inability to overcome the impact of high ambient pressure. In this article, a detection method for self-resonating waterjet characteristics based on the flow signal in a pipeline was proposed. The pressure sensors were transferred from within the high pressure tank to the outside of the tank and were arranged in the front pipeline outside the tank to avoid the influence of high ambient pressure. Dual-pressure sensors were used to acquire the flow pressure pulse signal, and signal-processing technology was used to effectively suppress noise interference for enhancing the intensity of useful signals and accurately obtaining the pressure fluctuation information of the self-resonating waterjet.The test results show that the spectral characteristics acquired from the flow pressure signal in the pipeline agree with the results obtained from the signal in the chamber and are also consistent with the theoretical calculations. Thus, the pressure oscillation characteristics of the waterjet are fully characterized. Moreover, the acoustic power spectrum obtained from the flow pressure signal in the pipeline is in accordance with the result obtained from the hydrophone in the high pressure tank. Consequently, the cavitation characteristic of the waterjet is well characterized. Therefore, the detection method based on the flow signal in the pipeline is entirely feasible and advanced and provides a new means for the study of the self-resonating waterjet under high ambient pressure.
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Key words:
- self-resonating waterjet /
- flow signal /
- pressure oscillation /
- cavitation /
- detection method
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表 1 噴嘴結構參數及固有頻率
Table 1. Organ-pipe nozzle structure and natural frequency
Ds/mm D/mm d/mm L/mm f/kHz 23 10 2 24 14.9 表 2 試驗參數及自激頻率
Table 2. Test parameters and self-resonating frequency
v/(m·s-1) a/(m·s-1) fp/Hz Sd fj/kHz 165 1450 6.98 0.12~0.2 9.9~16.5 259luxu-164 -
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