Average windward area is an important index for calculating the trajectory, velocity attenuation and terminal effect of explosive fragments. In order to solve the problems that existing theoretical method cannot calculate windward area of irregular fragment and experiment method is not convenient for automatic calculation and has low accuracy, a Monte Carlo subdivision projection simulation algorithm is proposed. The average windward area of arbitrary shaped fragments can be obtained with coordinate translation, random rotation, plane projection, convex-hull triangulation, concave boundary searching and sorting with maximum edge length constraint, subdivision area calculation, and averaging by thousands of cycles. Results show that projection area obtained by the subdivision projection algorithm is basically the same as that obtained by software method of computer aided design. Moreover, the maximum calculation error of the algorithm is less than 7%, and its accuracy is much higher than that of the equivalent ellipsoid method. The average windward area calculated by the Monte Carlo subdivision projection simulation algorithm is consistent with theoretical formula for prefabricated fragments, and the error is less than 3%. The convergence and accuracy of the Monte Carlo subdivision projection algorithm are better than those of the icosahedral uniform orientation method.

平均迎风面积是计算爆炸破片弹道、速度衰减和末端效应的重要指标。针对现有理论方法无法计算不规则破片迎风面积以及实验方法不方便自动计算且精度较低的问题，提出一种蒙特卡罗细分投影模拟算法。通过坐标平移、随机旋转、平面投影、凸包三角剖分、最大边长约束的凹边界搜索与排序、细分面积计算、数千次循环平均等方法，可以得到任意形状破片的平均迎风面积。结果表明，细分投影算法得到的投影面积与计算机辅助设计软件方法得到的投影面积基本一致。而且该算法的最大计算误差小于7%，其精度远高于等效椭球法。蒙特卡罗细分投影模拟算法计算出的平均迎风面积与预制破片理论公式一致，误差小于3%。蒙特卡洛细分投影算法的收敛性和精度均优于二十面体均匀定向法。