闭式蛙人目标强度预报及试验

Target strength of closed frogman: measurements and modeling

闭式蛙人穿戴潜水服、眼镜、头盔和脚蹼,同时携带水下闭路呼吸器等在水下工作。本文通过理论建模和试验,研究水下闭式蛙人回声特性。将非刚性表面高频条件下目标回声特性预报的板块元方法算法进行局部修正,以适应考虑遮挡情况下不同属性材料组合目标回声特性预报计算。建立闭式蛙人潜水装备的分层介质反射系数模型,结合其几何外形的三维精确建模,计算闭式蛙人回声特性。给出了游泳姿态的0°~360°目标强度、回波时域角度谱、蛙人表面亮点分布等细致的计算图像。开展了真实闭式蛙人的湖上试验,理论计算与试验测量进行了对比分析。研究表明,气瓶、潜水服是主要的回波贡献,闭式蛙人目标强度概率分布区间在频率为50、70 kHz时为-20~-13 dB,在频率为80 kHz时为-23~-17 dB。

Closed frogmen wear diving suits, glasses, helmets and flippers, while carrying underwater closed-circuit ventilators to work underwater. In this paper, the echo characteristics of closed frogman are studied through theoretical modeling and measurements. The planar elements method for predicting the echo characteristics of the target on non-rigid surfaces at high-frequencies is locally modified to adapt to the calculation of target echo characteristics of different material combinations under occlusion. A layered medium reflection coefficient model of diving equipment of closed frogman is established. By combining this model with the three-dimensional accurate modeling of frogman geometric shape, the echo characteristics of closed frogman are calculated. The detailed computational images of the 0°~360° target strength of swimming posture, the echo time-angle spectrum,and the distribution of bright spots on frogman surface are given. The lake experiment of a real closed frogman is carried out. Theoretical models and experimental measurements are compared and analyzed. The results show that the closed-circuit scuba bottle and diving suit are the main contributions to echo, and the probability distribution range of the target strength of a closed frogman is-20~-13 dB at 50 kHz and 70 kHz, and-23~-17 dB at 80 kHz.