Enhancement of Gas Discharge from a Closed End Hole by Using Acoustic Wave Irradiation

Abstract

Filling holes with liquid, or discharging gas from holes, is a fundamental process in both cleaning and painting. Discharging gas from small holes with closed end and high aspect ratio is extremely difficult due to surface tension. In this study, we developed a new gas discharge process from a hole by using acoustic wave irradiation. We irradiated two types of acoustic waves: waves with constant frequencies and those with variable frequencies in time i.e. sweep wave for test samples in a water pool. In addition, we observed gas discharge using high-speed video camera. As a result, we succeeded in completely discharging gas by using sweep frequency of the acoustic waves. From the observation results, we confirmed that gas discharge consists of three stages. The gas was discharged from the hole mainly at the first and third stage. In these stages, the natural frequency of the gas column in the hole was essential. In the second stage, the gas column in the hole breaks into multiple gas columns; then, the gas was hardly discharged even with the acoustic wave irradiation.

Removing Gas from a Closed-End Small Hole by Irradiating Acoustic Waves with Two Frequencies

“…These results suggest that resonance by the second harmonic occurred at 1200 Hz. Note that the removal rate was greater for only 600, not 1200, Hz for speakers with different acoustic characteristics [12]. For these reasons, we observed two peaks in sample one.…”

“…The repeatedly generated droplet deposition split the gas in the hole. Furuya et al [12] proposed using acoustic wave irradiation in a liquid to remove gas. They showed that releasing part of the gas at specific frequencies (f = 600 Hz) when irradiating with a single-frequency sine wave achieved complete gas removal when the frequency increased monotonically with time.…”