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

CFD Modeling of Damping Plate and Body of Deep-sea Vehicles
for Estimation of Hydrodynamic Coefficients
Zhichao Zhao1,2,3, Haitao Gu1,2, Hao Gao1,2, Mengmeng Feng1,2 and Yuan Sun1,2
1. State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences
Shenyang, Liaoning, China
2. Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences
Shenyang, Liaoning, China
3. University of Chinese Academy of Sciences
Beijing, China

and so on. Lian, Wang and Sun (2019) established the mathematicalmodel of parachute deceleration and cabin separation landing motion for
the underwater safe landing of latent weapons with parachute, andstudied the influence of different opening angles of parachute on thelanding motion process and the law of submarine weapon separation
deceleration sitting bottom motion by numerical calculation method, but
the influence of the dynamic parachute opening process on the landing
movement is not considered. Sun and Huang (2020) analyzed three
deceleration schemes for installing ballast tanks, deceleration parachuteand deceleration wing in the large escape capsule for submarine, all ofwhich can control the safe water-exiting speed, and the deceleration
wing scheme is the best. Ren and Bian (2018) found that the existenceof the damping plate will increase the axial additional mass of theunderwater vehicle and reduce the tail flow velocity through thesimulation analysis of the flow field, and the deceleration effect isobvious. Bian, Zhao, Li and Zhu (2017) constructed a mathematicalmodel of the trajectory of a vehicle with reverse damping plate, and used
the orthogonal test method to optimize and analyze the three parametersof the number, size and expansion angle of the damping plate of theunderwater vehicle.

ABSTRACT
For the purpose of studying the feasibility of deep-sea vehicles with
damping plate deceleration mechanism achieving a safe water-exit
velocity, the hydrodynamic coefficients of body and mathematicalmodel of the damping plate deceleration mechanism are estimated byusing computational fluid dynamics (CFD). CFD model is performed tosimulate extensive captive model tests including axial drag tests andplanar motion mechanism (PMM) tests and explore the eﬀect ofoscillation frequency and amplitude on the hydrodynamic coeﬃcients.
The dynamic expansion process of the damping plate is discretized toanalyze its axial drag force in steady motion at different expansion
angles and velocities. The mathematical model of damping plates isestablished by fitting its axial drag force with least-squares method. The
deceleration motion of the vehicle with dynamic deployment of
damping plates is simulated based on Simulink model. The result
indicates the unpowered vehicle with damping plates can realize a safe
water-exit velocity uζ⩽1m/s. Relevant research provides a reference forthe hydrodynamic modelling of body and damping plate deceleration
mechanism.

The damping plate deceleration mechanism with active forward layout
has higher reliability. The deployment of the parachute due tounderwater pressure cannot be effectively guaranteed, and it is easy togenerate lateral tension on the hull, which affects the ascent stability.
The deceleration wing usually adopts a reverse layout, which is widelyused in the underwater deceleration of large escape capsule forsubmarine. It is quickly deployed by water resistance during operation,
while there is a large instantaneous resistance, and the unsynchronized
deployment of the wing plates can produce a yaw moment, which results
in insufficient stability of ascent motion (Sun and Huang, 2020). Thus,
damping plate deceleration mechanism studied in this paper adopts alayout of active forward mechanism, as shown in Fig. 1. The damping
plate is fully integrated with the main body shape of the vehicle in therapid ascent phase. It is deployed or closed at a certain rate when thevehicle decelerating or accelerating, which avoids the problem of
insufficient stability caused by the excessive instantaneous fluid
resistance and the asynchronous deployment of the damping plate.

KEY WORDS:

Deep-sea vehicle; Damping plate; Deceleration;
PMM; Hydrodynamic coefficients.

INTRODUCTION
The ascent process of the deep-sea unpowered vehicle is divided into
two stages: rapid ascent and deceleration motion before exiting the water.
The vehicle adopts vertical attitude to achieve a greater vertical velocity
during rapid ascent phase. It needs to decelerate before exiting the waterto ensure the safe water-exit velocity of the unpowered vehicle, which
reduces the impact load of the vehicle of re-entry water. Because of thevehicle without propeller, it is difficult to decelerate due to the added
mass force from fluid during deceleration process (Quan, 2020).
Therefore, it is necessary to design an effective deceleration device.
The deceleration mode of unpowered underwater vehicles has various
forms, such as deceleration parachute, deceleration wing, ballast tank1116