摆动喷管水下工作过程流场及控制特性仿真研究

Simulation Study on Flow Field and Control Characteristics of Swing Nozzle During Underwater Operation

水下航行体垂直发射是一个非定常、高动态的过程,对基于摆动喷管控制的水下航行体,喷管摆角与动态摆动过程对流场演化、流体动力特性的影响不可忽略。本文采用流体体积多相流模型、动网格技术、叠加运动模型与动态流体相互作用模型,建立了流场与弹道耦合计算的三维仿真计算模型,研究航行体系留状态与航行状态两种工况下喷管摆动工作过程流场及流体动力非定常演化规律。仿真结果显示,在不发生流动分离的前提下,水下工作的发动机可以提供稳定、无延迟的控制力矩,但超声速射流方向的改变会引起流场的非对称脉动,即使航行体处于系留状态时,航行体仍然会受到流体干扰力矩的影响,导致水下推力矢量控制效率降低,当处于航行状态时,来流会产生诱导干扰力矩,航行体姿态的改变也会产生流体动力干扰力矩,在上述干扰力矩的影响下,控制效率进一步降低。

The vertical launch process of underwater vehicle is unsteady and highly dynamic.For the underwater vehicle based on swing nozzle control,the effects of swing angle and dynamic swing process on the evolution of flow field and hydrodynamic characteristics can not be ignored.A three-dimensional simulation model for the coupling calculation of flow field and trajectory was established based on volume of fluid(VOF)model,dynamic grid technology,superimposed motion model and dynamic fluid body interaction(DFBI)model.As a result,the unsteady evolution process of flow field and hydrodynamic force during nozzle swing under mooring and navigation conditions were studied.The simulation results show that the engine can provide stable and delay-free control force and moment if there is no flow separation on nozzle,and the change of the supersonic jet direction can cause asymmetrical pulsation of the flow field.Even if the vehicle is in mooring state,the vehicle will still be affected by the fluid disturbance moment,causing the reduction of the efficiency of underwater thrust vector control.When the vehicle is in navigation state,the incoming flow and the attitude change of vehicle will produce induced disturbance moment,which further reduces the control efficiency.