Pressure-time formula for underwater explosion based on pressure-impulse curve
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摘要: 根据材料受冲击载荷时的压力-冲量函数,推导得到了适用于水下爆炸冲击载荷的压力时程公式。通过水下爆炸实验方法测量不同药量、不同距离的压力时程曲线,使用MATLAB软件对实验数据进行拟合,由此计算冲击波冲量和能量参数,并与通用的Cole与Орленко理论计算结果进行对比,验证拟合曲线的准确性。相较于Cole和Орленко理论,新方法得到的压力衰减曲线更接近实验值。计算水下爆炸冲击波的比冲量和比冲击波能时,新模型具有较高的计算精度,其中:比冲量与实验值的误差不超过4%,与Орленко理论相比,精度提高了5%~10%;比冲击波能与实验值的误差不超过1%,计算精度与通用理论相当。Abstract: Theoretical study on the attenuation law of underwater explosion shock waves plays a crucial role in predicting the underwater explosion power. The attenuation law of underwater explosion shock waves could be analyzed from the shock waves pressure-time curve. The pressure-impulse (p-I) model has usually been used to assess damage on material and structure. In this paper, the pressure-time formula is analytically derived according to the p-I model. To verify the accuracy of the formula, the pressure-time relation curve was obtained by experiments with various explosive charges and distances. The experimental data was fitted in accordance with the theoretical equations of Cole and Орленко, and also with the developed pressure-time formula. The parameters of the formula are thus obtained. The accuracy could be described by the fitting coefficient R-squared (R2) value. The R-squared value of the developed pressure-time formula exceeds 0.988, which is greater than the R-squared values calculated by the equations of Cole and Орленко. In order to further validate the formula, the impulse and energy of underwater explosion shock waves are derived from the developed pressure-time formula, experimental data, and the equations of Cole and Орленко, respectively. Compared with the experimental results, the error of impulse derived from the developed pressure-time remains below 4%, which is 5%−10% lower than the errors of impulse between the experimental results and the equations of Cole and Орленко. The energy of the shock waves is similarly analyzed. Compared with the experimental results, the error of energy derived from the developed pressure-time remains below 1%, approximately the same as the errors of energy between the experimental results and the equations of Cole and Орленко. Compared with the calculation by equations of Cole and Орленко, it is seen that there is better correlation between the developed pressure-time formula and the experimental results. The developed pressure-time formula can be used to calculate the impulse and energy of underwater explosion shock waves.
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表 1 3种拟合方法的精度
Table 1. Accuracy of three fitting methods
炸药 组号 R2 a/kPa c/(kPa2·s) 新模型 Cole理论 Орленко理论 9 g RDX 1 0.9882 0.9282 0.9854 −0.097 0.053 2 0.9923 0.9363 0.9881 −0.089 0.043 12 g RDX 1 0.9936 0.9327 0.9861 −0.210 0.135 2 0.9963 0.9306 0.9861 −0.200 0.133 19 g RDX 1 0.9897 0.9274 0.9895 −0.180 0.131 2 0.9908 0.9286 0.9900 −0.160 0.094 表 2 冲量的理论值与实验值
Table 2. Theoretical and experimental values of impulse
炸药 组号 I/(Pa·s) δ1(I)/% δ2(I)/% 实验 新模型 Cole-Орленко模型 9 g RDX 1 325.862 320.943 325.575 −1.510 −0.088 2 282.572 279.108 325.575 −1.226 15.280 12 g RDX 1 376.875 375.155 326.037 −0.456 −13.490 2 349.426 348.407 326.037 −0.292 −6.694 19 g RDX 1 439.536 439.484 431.403 −0.012 −1.850 2 400.488 400.228 431.403 −0.065 7.719 表 3 比冲击波能的理论值与实验值
Table 3. Theoretical and experimental values of specific shock wave energy
炸药 组号 Es/(MJ·kg−1) δ1(Es)/% δ2(Es)/% 实验 新模型 Cole-Орленко模型 9 g RDX 1 1.057 1.051 0.929 −0.578 −12.110 2 0.902 0.899 0.929 −0.370 2.993 12 g RDX 1 1.171 1.168 1.106 −0.256 −5.551 2 1.087 1.082 1.106 −0.460 1.748 19 g RDX 1 0.840 0.836 0.772 −0.429 −8.095 2 0.757 0.754 0.772 −0.396 1.982 -
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