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<p>Supercritical carbon dioxide (SC-CO₂) jets show great potential in oil and gas exploration due to their low viscosity and high permeability. To enhance the erosion ability, a pulsed abrasive SC-CO<sub>2</sub> jet (PASJ) is generated using a self-excited oscillation Helmholtz nozzle. However, the pressure pulsation characteristics inside the nozzle remain unclear. This study experimentally investigated the effects of differential pressure and nozzle structure on pulsation amplitude, peak value, intensity, and spectral characteristics. Results indicate that the maximum pulsation amplitude and intensity occur at <i>L</i><sub><i>c</i></sub>/<i>d</i><sub>1</sub> = 4. Under supercritical ambient pressure, pulsation intensity first increases and then decreases with the diameter ratio, whereas under subcritical pressure, it decreases monotonically. Spectral analysis reveals significant variations with nozzle structure and differential pressure, with a high-frequency band around 2700&#xa0;Hz under supercritical pressure. In contrast, at subcritical pressure, pulsation amplitude is lower, and high-frequency components (&gt; 1000&#xa0;Hz) are weak.</p>

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Pressure pulsation characteristics in the oscillation chamber of Helmholtz nozzle generating pulsed abrasive SC-CO2 jet

  • 期刊论文

  • 发表日期：

    2025年5月10日

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  • Chenxing Fan,
  • Mengda Zhang,
  • Qi Liu,
  • Yong Kang,
  • Xiaochuan Wang,
  • Deng Li

摘要

Supercritical carbon dioxide (SC-CO₂) jets show great potential in oil and gas exploration due to their low viscosity and high permeability. To enhance the erosion ability, a pulsed abrasive SC-CO2 jet (PASJ) is generated using a self-excited oscillation Helmholtz nozzle. However, the pressure pulsation characteristics inside the nozzle remain unclear. This study experimentally investigated the effects of differential pressure and nozzle structure on pulsation amplitude, peak value, intensity, and spectral characteristics. Results indicate that the maximum pulsation amplitude and intensity occur at Lc/d1 = 4. Under supercritical ambient pressure, pulsation intensity first increases and then decreases with the diameter ratio, whereas under subcritical pressure, it decreases monotonically. Spectral analysis reveals significant variations with nozzle structure and differential pressure, with a high-frequency band around 2700 Hz under supercritical pressure. In contrast, at subcritical pressure, pulsation amplitude is lower, and high-frequency components (> 1000 Hz) are weak.