Environmental characteristics of underwater explosion source and application of PVDF pressure sensor

Based on the environmental characteristics near underwater explosion source, an underwater explosion pressure sensor with PVDF film as the sensitive unit is proposed in this paper. The effect of temperature on the sensitivity coefficient of the sensitive unit was tested with the SHPB test system. By combining with numerical simulation and experiment, the measurement accuracy and reliability of the sensor near the explosion source are verified. The results show that the peak pressure and temperature of a 1 kg emulsion explosive explosion at one times the charge diameter are approximately 1.753 GPa and 317 K. In the temperature range of 5∼50 °C, the temperature has little influence on the sensitivity coefficient (k = 84 pc/MPa). In the temperature range of 50∼80 °C, the sensitivity coefficient of PVDF film increases with the increase of temperature, and the relationship between temperature and sensitivity coefficient is obtained by fitting the exponential function. The time history curves of pressure obtained by the high-frequency pressure sensor and the self-made PVDF pressure sensor are basically consistent, and the pressure peak values are within a reasonable range. Meanwhile, the measurement error of the PVDF pressure sensor and the PCB pressure sensor is less than 1 MPa, which verifies the measurement reliability of the PVDF pressure sensor. The peak pressures of 2 kg of emulsion explosive at 0.2 m and 0.4 m are 323.42 MPa and 173.86 MPa, respectively, and the errors with the numerical simulation results are about 19 MPa and 9 MPa, respectively. Meanwhile, the time-history curves of the complete pressure of 10 kg of emulsion explosive at the position of 0.3 m and the energy of the specific shock wave of 0.7 MJ/kg have been obtained, which verifies the feasibility of measuring the sensor in the vicinity of the explosion source.