Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Numerical Multi-physics Investigation of Underwater Vehicle’s Mast and the Wake Produced by the Mast
Liang Dong, Jianwei Wu, Haixiong Zhu, Yun Wang*, Qingjie Meng, Weihua Shi
Wuhan Second Ship Design and Research Institute, Wuhan, Hubei, China*Corresponding author

ABSTRACT(2014) present an improved GRECO algorithm to calculate and analyze
the RCS distribution of a mast. Yuan (2014) proposes a hybridalgorithm based on MOM-PO-FMM to estimate the mast column’s
RCS. Fan (2016) choses the method of moments and physical optics
hybrid algorithm to calculate the multilayer dielectric mast column's
RCS.

In this paper, the wake characteristics of the underwater vehicle’s mast issimulated by using CFD method based on the RNG k-ε model and VOF
model. It can be seen that Kelvin wake is generated due to the moving
mast. Then the radar scattering characteristic of the mast along with theKelvin wake produced by the mast is investigated by using thecomputation electromagnetic method based on the shooting andbouncing rays algorithm. It is shown that the wave surrounding the mast
has an impact on the radar scattering feature of the mast. On one hand,
the wave plays a role as stealth design by shaping, which is beneficial forstealth. On the other hand, the wave occupies the area which should becoated with radar absorbing material, which is harmful to the stealthy
performance.

In this paper, the mathematical calculation model of the hydrodynamic
and electromagnetic characteristics of underwater vehicle’s mast isintroduced. Then the wake feature and radar scattering feature arenumerically simulated and analyzed. The influence of radar scatteringfeature which the wake puts on the mast is investigated.

MATHEMATICAL CALCULATION MODEL

KEY WORDS: Underwater vehicle; mast; multi-physics; Kelvin wake;

The wake feature is caused by the movement of the mast. In this paper,
the free surface waves are provided by solving the Reynolds Averaged
Navier Stokes (RANS) flow equations.

radar cross section (RCS); radar absorbing material (RAM).

INTRODUCTION

∂ui=0
∂xi

When underwater vehicle carries out a mission such as wirelesscommunication, electron reconnaissance or searching, the mast will belifted above the water, which will generate Kelvin wake behind the mast.
The mast along with the wake produced by the mast can be easily
detected by airborne radar from a great distance. Therefore thehydrodynamic and electromagnetic characteristics of underwater
vehicle’s mast draw more and more country’s attention in the last twodecades.

ρ
∂ui
∂ui
∂p∂  ∂ui′j  0+ ρu j =+− − ρ ui′u=ρ Fi −µ∂t∂x j∂xi ∂x j  ∂x j

(1)
(2)

Additionally, k-ε turbulence model is used to solve transport equations
and provide closure of RANS equations. The volume of fluid (VOF)
method is used to capture the profile of the hydrodynamic wake on theinterface between the air and the seawater.

Jiang (2017) makes a numerical study on the flow around the combined
column in the unbounded flow field and the free-surface flow field. Jia(2008) analyzes the instantaneous and time averaged flow field and theforce on circular cylinders based on the LES method of FLUENT. Cao(2018) investigates the flow around three dimensional circular cylinders
numerically under subcritical Reynolds number by using LES method.
Cui et al. (2019) carry out hydrodynamic tests and CFD simulation ondifferent angles and low-speed, medium-speed and high-speed
conditions of masts on the water surface and under water. Cui et al.

The radar scattering feature of the mast and the wake produced by themast can be obtained by solving of Maxwell equations. Because theKelvin wake behind the mast is electrical large-scale structure, thehigh-frequency techniques are more suitable in this case. One of thehigh-frequency techniques is the shooting and bouncing rays algorithm
which can be carried out in two part in Lin (2017). Firstly, Giving theincident electromagnetic wave, geometrical optics is used to find the raypaths by ray tracing and determine the field amplitude of the exit rays

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