Numerical analysis of multi-scale pressure pulsation on the energy accumulation for submarine-based tracking and pointing systems

Liu Zongkai,Tang Zhaolie

doi:10.1177/0020294021989748

Abstract

One of the main goals of submarine designers and researchers is to estimate the influence of submarine fluid dynamics for submarine-based optical tracking and pointing systems. In this study, firstly, based on the basic flow governing equation and hierarchical grids, the numerical simulation method of DNS (direct numerical simulation) is adopted to simulate the seawater flow around the submarine at 6° yaw angle and 107 Reynolds number. Secondly, the transformation equations from the earth coordinate system to the optical axis system have been deduced and the ultimate influence of pressure torques on the tracking system is studied. Transfer functions of the coarse channel direct current (DC) torque motor and fine channel fast steering mirror (FSM) also have been modeled and deduced. On this basis, the time domain step responses of both subsystems are analyzed by MATLAB Simulink. Finally, performance analyses have been deduced by comparing the error variation and vortices evolution. It revealed that the frequency characteristics of multi-scale pressure pulsation mainly depended on the lengths of submarine hull or its appendage, as well as the fluid dissipation and random interaction. In general, the coarse channel appears a good compensation performance at low frequency and large amplitude error that caused by the middle-scale pressure pulsation. Contrarily, the FSM fine channel exerts an excellent control effect for higher frequency and small amplitude error caused by small-scale pressure pulsations.

Highlights

Different from conventional photoelectric tracking system, laser directed energy device needs to guide and keep the laser beam continuously and stably focused on the target.[1]
In the case of high Reynolds number, tip vortexes will be generated at the end edge of the hull or appendages of the submarine accompanied by large force and torque fluctuations
Large low pressure area will be formed in vortex cores, and cavitation pittings will be aroused once the pressure drops to a certain degree.[3]

Summary

Introduction

Different from conventional photoelectric tracking system, laser directed energy device needs to guide and keep the laser beam continuously and stably focused on the target.[1]. The torque’s influence on the photoelectric mast and tracking device will be reflected in azimuthal and pitch angles, whose strength are mainly related with the submarine mass and the reference coordinate system.

Results

Conclusion