水下航行器扰动对海面辐射特性的影响机理研究

The detection technique based on the optical wake has become one of the crucial approaches for non-acoustic antisubmarine detection. The optical wake on the sea surface generated by the perturbation of submerged object exhibits a wide-spatial and long-temporal distribution, resulting by the variation of the sea surface's temperature field, roughness, salinity field, and bubble distribution. This project focuses on the wake especially generated by the underwater heat exhaust and heat water, the effects of the submerged object's perturbation on the sea surface's radiative signature are investigated. Firstly, to seek the interactions between bubbles, the bubble dynamics model in the underwater exhaust wake is established preferentially. The impact mechanisms of the bubble dynamic behavior, such as the bubble breakup, coalescence and morphological transformation, will be revealed. Thereafter, to establish the coupling model of the flow field, temperature field and composition field under the perturbation of submerged object, the interactions between two-phase flow and heat transfer in the underwater exhaust wake are investigated. It's expected that the propagation characteristic of the multi-wake and its impact factor can be illuminated. Finally, in order to investigate the sea surface's BRDF characteristic under the perturbation of submerged object, the radiative transmission approach in the heterogeneous water containing polymorphic bubbles is developed. Furthermore, the theoretical model for the radiation characteristics of the submerged object's wake is established to unravel the effects of the submerged object's perturbation on the sea surface's radiative signature. This research will be meaningful to enrich the contents of thermal radiation theory. It is also possible to provide valuable theoretical foundations for the detection, identification, tracking of the underwater targets.

光学尾迹探测技术已成为非声探潜的重要发展方向。潜艇海面光学尾迹具有空间尺度大、存留时间长的特点，其影响主要来源于海面温度场、粗糙度、盐度场、气泡分布的变化。本课题聚焦水下排气排水尾流，开展水下航行器扰动对海面辐射特征的影响机理研究。其具体研究内容包括：（1）构建水下排气尾流中气泡动力学模型，探究气泡间的相互作用机制，揭示气泡破碎聚并、形态变化、浮升发展等动力学行为的影响机理；（2）建立水下排气尾流中气液两相流动传热模型，阐明水下航行器流场、温度场、组分场与排气气泡动力学行为的耦合机制，研究多类尾迹的产生传播规律及其影响因素；（3）发展多形态气泡分布的多组分非均匀水体中热辐射传递理论方法，构建水下航行器尾迹光学辐射特性的精细表征模型，揭示水下航行器对海面辐射特性的综合扰动规律。本项目对于丰富热辐射理论和方法的研究内涵具有重要意义，同时为水下目标的探测、识别、追踪提供重要的理论基础支撑。

水下航行器扰动对水面辐射特性的影响机理研究，可丰富热辐射理论和方法的研究内涵，促进工程热物理学科与海洋动力学、气泡动力学等学科的交叉融合；同时为海洋侦察、水下目标探测提供理论基础，对提高水下目标的发现识别概率具有重要价值。结合研究计划，本项目主要开展并完成了以下4方面的研究：.1.基于VOF方法研究了单、双气泡在浮升过程中的动力学行为，揭示了气泡破碎聚并、形态变化、浮升发展等行为的相互作用机制；基于欧拉-欧拉双流体模型，采用适用于多尺度气泡流动的Tomiyama气液相间曳力系数、升力系数和传热系数模型，建立了水下排气两相流的流动传热耦合模型，探究排气温度和速度对两相流流动传热性质的影响。.2.考虑水下航行器排水排气、温盐分层等影响，建立了水下航行器扰动下流场、温度场、组分场耦合模型，探究了温盐分层环境中水下航行器热尾迹、盐度尾迹、开尔文尾迹等多类尾迹的产生传播规律，揭示了水下航行器航行深度、速度、排气排水温度、流量等因素对海面兴波、热尾迹温度分布的影响规律。.3.发展了具有多形态排气气泡流、水下气泡层和水面泡沫层的多组分非均匀水体中热辐射传递理论方法，探讨了气泡尺度、浓度、水体盐度、风速等因素对水面辐射特性参数的调制作用；建立了水下航行器综合扰动作用下海面辐射特性表征模型并分析了其红外辐射特征变化规律。.4.提出了基于烟火药的水下热排气尾流模拟方法，开展了小型水槽热排气实验研究，研究了排气气泡流浮升速度、温度分布的时空变化规律和气泡尾流浮升规律；开展了大型水槽水下航模排气排水尾流实验研究，研究了水下航模热尾流浮升发展规律，探究了水面红外特征随排气排水参数的变化规律；结合实验数据验证了理论计算和数值模拟工作的可靠性。