Citation: Wei, J.; Sha, Y.-B.; Hu, X.-Y.;
Cao, Z.; Chen, D.-P.; Zhou, D.; Chen,
Y.-L. Research on Aerodynamic
Characteristics of Trans-Media
Vehicles Entering and Exiting the
Water in Still Water and Wave
Environments. Drones 2023, 7, 69.
https://doi.org/10.3390/
drones7020069
Academic Editors: Andrzej
Łukaszewicz, Wojciech Giernacki,
Zbigniew Kulesza, Jaroslaw Pytka
and Andriy Holovatyy
Received: 7 December 2022
Revised: 13 January 2023
Accepted: 13 January 2023
Published: 18 January 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
Article
Research on Aerodynamic Characteristics of Trans-Media
Vehicles Entering and Exiting the Water in Still Water and
Wave Environments
Jun Wei, Yong-Bai Sha , Xin-Yu Hu , Zhe Cao, De-Ping Chen, Da Zhou and Yan-Li Chen *
Key Laboratory of CNC Equipment Reliability, Ministry of Education, School of Mechanical and Aerospace
Engineering, Jilin University, Changchun 130022, China
* Correspondence: chenyanli@jlu.edu.cn
Abstract:
The problem of aircraft entering and exiting water is a complex, nonlinear, strongly
disturbed, and multi-coupled multiphase flow problem, which involves the precise capture of the
air/water interface and the multi-coupling interaction between aircraft, water, and air. Moreover, due
to the large difference in medium properties during the crossing, the load on the body will suddenly
change. In this paper, the VOF (volume of fluid) algorithm is used to capture the liquid surface
at the air/water interface, and since body movement is involved in this process, the overset grid
technology is used to avoid the traditional dynamic grid deformation problem. In the process of
this numerical simulation prediction, the effects of different water-entry angles and different water-
entry heights on the body load and attitude of the trans-medium aircraft, as well as the cavitation
evolution law of the body water entry are analyzed. On this basis, to simulate the authenticity and
complexity of the water-entry environment, numerical wave-making technology was introduced to
analyze the water-entry load, posture, and cavitation evolution law of the body under different wave
environments. The numerical parameters under the condition of wave and no wave are compared,
and the difference in water-entry performance under the condition of wave and no wave is analyzed.
Keywords:
transmedia aircraft; multiphase flow; overset grid; cavitation evolution; numerical
wave making
1. Introduction
With the rapid development of small aircraft, ships, underwater submersibles, and
other intelligent mobile platforms in search and rescue, detection, communications, combat
reconnaissance, combat, and other types of military activities [
1
], civilian fields are widely
used. However, the three-dimensional process of modern warfare is accelerating, and the
environment in which combat equipment is located is gradually changing from the original
single type to the multi-phase type [
2
]. To better adapt to the operational needs of modern
warfare, the study of trans-media vehicles has become crucial.
The dynamic model of the trans-medium aircraft [
3
] is the basis for analyzing its
motion characteristics and studying flight stability control. As the core key link of the
dynamic model, the numerical prediction of the outlet/inlet section plays a vital role in
the accurate response of the dynamic model. The water-entry process is a complex fluid
phenomenon with strong nonlinear and unsteady characteristics [
4
]. From a mechanical
point of view, the water-entry process of an object passing through the water surface at
a relative speed mainly includes three stages [
5
]: the slamming when it contacts the free
surface, the open cavity with large deformation of the free surface, and the underwater
movement after the open cavity closes [
6
]. The first slamming stage is mainly a matter of
impact dynamics, while the last two water-entry stages involve fluid–structure interaction
of hydrodynamics and structural dynamics coupling [
7
]. In the initial stage of water entry,
due to the large difference in the characteristics of the liquid and gas media, the slamming
Drones 2023, 7, 69. https://doi.org/10.3390/drones7020069 https://www.mdpi.com/journal/drones
