Three-dimensional analysis of transient slosh within a partly-filled tank equipped with baffles

The directional dynamic analyses of partly-filled tank vehicles have been limited to quasi-static fluid motion due to computational complexities associated with dynamic fluid slosh analyses. The dynamic fluid slosh causes significantly higher magnitudes of slosh forces and moments in the transient state that cannot be characterized through quasi-static approach, which provides reasonably good estimates of the mean responses. In this study, a three-dimensional nonlinear model of a partly-filled cylindrical tank with and without baffles is developed to investigate the significance of resulting destabilizing forces and moments caused by the transient fluid slosh, and the effects of baffles. The baffles and the end caps are modeled with curved shapes. The analyses are performed under varying magnitudes of steady lateral, longitudinal and combinations of lateral and longitudinal accelerations of the tank, and two different fill volumes using the FLUENT software. The results of the study are presented in terms of mean and peak slosh forces and moments, and variations in the mass moments of inertia of the fluid cargo within a clean bore and a baffled tank, for two different fill volumes and different magnitudes of acceleration excitations. The ratios of transient responses to the mean responses, termed as amplification factors, are further described to emphasize the significance of dynamic fluid slosh on the forces and moments induced on the vehicle. The results in general suggest that the mean responses attained from dynamic fluid slosh analyses correlate well with those attained from the quasi-static analyses for a clean bore tank. The amplification ratios of the resulting forces and moments could approach as high as 2. The results clearly show that the presence of baffles helps to suppress the peak as well as mean slosh forces and moments significantly.     

试论单桨船制动机动中的偏向力

制动机动是船舶操纵运动中一个比较复杂而有重要实践意义的课题,舰船驾驶员必须充分掌握舰船的制动机动性能。但是,由于单螺旋桨舰船制动机动过程中的偏向力尚未得到充分的研究和论述,目前还不能完善地定性、定量分析单桨船制动机动中的复杂的偏转现象。本文在总结船模和实船试验的基础上,通过定性分析的方法,给出单桨船倒车偏向力的一般规律和水动力学解释,并给出几类单桨船制动机动偏向力的估算方法,有助于舰船驾驶员充分、快速地掌握本船的制动机动性能。     

基于灰色系统理论的炮兵跨区机动能力评估

着眼炮兵部队跨区机动的特点,建立评估指标体系,利用层次分析法确定各指标的权重以及准则层的权系数,结合灰色系统理论建立评估模型并结合实例求解,并对结果进行分析得出结论,为能力评估提供了一种新的定量和定性相结合的方法。     

联合机动编队兵力配置冲突消解

联合机动编队兵力配置是攻防作战的前提,众多兵力同时配置产生的冲突制约编队战斗力的发挥。着眼于联合机动编队整体作战效益,对联合机动编队兵力配置中的冲突消解问题展开研究。在分析联合机动编队兵力配置冲突产生原因的基础上,确定消解冲突的原则,针对联合机动编队兵力配置中的典型冲突问题提出消解方法,为解决联合机动编队兵力配置中的冲突问题提供思路。     

不均匀流中船舶操纵运动仿真模型及应用

本文给出不均匀流中船舶操纵运动数学模型，研究了在不均匀流中作用于船体上流体动力的估算及不均匀流场的生成，提出了不均匀流中船舶操纵运动的仿真方法。最后介绍了在港口引航实践中的两个仿真应用。     

Analysis on maneuvering motion characteristics of submarine under static moment in vertical plane北大核心CSCD

[Objectives]Aiming at the problem of poor depth-changing ability of the stern rudder of submarine at low speed, and the problem of reversing the movement trend is difficult when the stern rudder is stuck and encountering abrupt changes of seawater density in the vertical steering maneuver. This paper conducts the mechanism research of static moment maneuver. [Methods]First, it is proved through theoretical analysis that the static moment maneuver can eliminate the reversed velocity phenomenon of the stern rudder. Then, the surfacing process under the static moment maneuver and the rudder hydrodynamic control is numerically simulated. [Results]The simulation results show that the static moment maneuver can make the submarine maintain good vertical plane maneuverability at low speed, eliminate the reversed velocity phenomenon of the stern rudder, and avoid excessive trim angle of the submarine at high speed. At the same time, the recovery effect of the two emergency situations of rudder jamming and falling deep has been improved. [Conclusions]The static moment maneuver is beneficial to the maneuverability and safety of the submarine. The research in this article can provide a reference for the maneuverability design of submarine. © 2023 The Author(s).     

神经网络用于船舶操纵动态特性学习的研究

本文针对BP网络存在的一些问题，提出一种单层神经网络结构，通过大量的仿真试验，对两种网络在学习、预报和适应参数变化等方面的特性进行了对比。结果表明单层神经网络用于学习船舶操纵动态特性，具有收敛速度极快、预测误差较小、能快速跟踪参数变化等优点，可用于船舶操纵特性的实时学习。     

浅谈超大型集装箱船舶在港内的操纵

集装箱船的大型化,对驾引人员提出更高的安全要求和挑战。阐述了超大型集装箱船的操纵特点,分析了风和流对超大型集装箱船的影响。详细介绍了超大型集装箱船在港内的靠、离泊操作,尤其是急流和大风浪时的靠、离泊作业和操作体会。     

车辆转弯制动横向轨迹控制驾驶员模型研究

为了较为真实地反映车辆转弯制动工况,建立了含Pacejka"魔术公式"非线性联合工况轮胎模型的4轮8自由度车辆系统模型,并基于预瞄跟随理论、加速度反馈控制和模糊PID控制技术建立了车辆转弯制动横向轨迹控制驾驶员模型。针对不同初始速度和制动强度,利用MATLAB/Simulink进行了横向轨迹控制仿真分析。分析结果表明,驾驶员控制模型能很好地跟踪横向轨迹,模型的可行性和有效性得到验证,同时不同仿真条件下结果的一致性也说明该控制方法具有较强的自适应能力和鲁棒性,为进一步研究复杂工况下的驾驶员模型及横向轨迹控制提供了一条可行的途径。     

“跨越—2009”跨区机动暴露的问题与对策

分析了"跨越—2009"跨区基地实兵系列军事演习在跨区机动中存在着通信指挥手段少、伪装防护办法少,铁路、公路间转运速度慢的问题;提出了在复杂电磁环境下,灵活运用多种通信指挥手段、实施全程动态伪装防护、开展多部门参与的转运联合训练等应对措施,这些措施对我军快速、安全进行远程机动具有一定的参考价值。