Precise measurements of underwater explosion phenomena by pressure sensor using fluoropolymer

Abstract

Abstract To study underwater explosion phenomena, it is necessary to precisely measure underwater shock wave and bubble pulse. Currently, underwater shock wave is measured by pressure sensor, using tourmaline. However, this method cannot sustain underwater shock pressure higher than 20 MPa. To realize a pressure sensor which can sustain underwater shock pressure higher than 100 MPa, we developed a pressure sensor using fluoropolymer as the sensing element. Measurements of underwater shock wave profiles were performed by pressure sensor using fluoropolymer and the results were compared with those obtained using tourmaline. The experimental results show that the sensor using fluoropolymer can precisely measure underwater shock wave profiles in pressure ranges above 100 MPa. To understand the destructive effects of underwater explosion phenomena, it is necessary to accurately measure bubble pulse, as well as underwater shock waves. Precise measurements of peak pressure and impulse of bubble pulse, as well as underwater shock waves, were performed by pressure sensor using fluoropolymer. The experimental results show that the peak pressure of bubble pulse is about 15–30% of the peak pressure of the shock wave, but the impulse of bubble pulse is about 1.5–2.5 times bigger than that of shock wave, within the measured scaled distance range. This is due to the fact that the duration of bubble pulse is about ten times longer than that of shock wave.