Citation: Wei, J.; Sha, Y.-B.; Hu, X.-Y.;
Yao, J.-Y.; Chen, Y.-L. Aerodynamic
Numerical Simulation Analysis of
Water–Air Two-Phase Flow in
Trans-Medium Aircraft. Drones 2022,
6, 236. https://doi.org/10.3390/
drones6090236
Academic Editors: Andrzej
Łukaszewicz, Wojciech Giernacki,
Zbigniew Kulesza, Jaroslaw Pytka
and Andriy Holovatyy
Received: 13 August 2022
Accepted: 31 August 2022
Published: 3 September 2022
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Article
Aerodynamic Numerical Simulation Analysis of Water–Air
Two-Phase Flow in Trans-Medium Aircraft
Jun Wei, Yong-Bai Sha , Xin-Yu Hu , Jin-Yan Yao 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:
A trans-medium aircraft is a new concept aircraft that can both dive in the water and fly
in the air. In this paper, a new type of water–air multi-medium span vehicle is designed based on
the water entry and exit structure model of a multi-rotor UAV. Based on the designed structural
model of the cross-media aircraft, the OpenFOAM open source numerical platform is used to analyze
the single-medium aerodynamic characteristics and the multi-medium spanning flow analysis. The
rotating flow characteristics of single-medium air rotor and underwater propeller are calculated by
sliding mesh. In order to prevent the numerical divergence caused by the deformation of the grid
movement, the overset grid method and the multiphase flow technology are used for the numerical
simulation of the water entry and exit of the cross-medium aircraft. Through the above analysis, the
flow field characteristics of the trans-medium vehicle in different media are verified, and the changes
in the body load and attitude at different water entry angles are also obtained during the process of
medium crossing.
Keywords:
trans-media aircraft; multi-rotor drone; multimedia spanning; aerodynamics;
multiphase flow
1. Introduction
With the continuous exploration of natural space by human beings, both ship and
aviation technology have made great progress in their respective fields. Among them,
aircraft have been widely used due to their advantages of high speed and good maneuver-
ability, but they also have shortcomings such as short endurance and poor concealment,
which can be compensated by submersibles [
1
]. Trans-medium aircraft is a new conceptual
aircraft that can both sneak in water and fly in the air. Due to its concealment of flight and
diversity of functions, it can realize both aerial reconnaissance and underwater inspection,
which expands the spatial scope of navigation [
2
]. Therefore, it combines the advantages of
aerial drones and underwater submersibles, which have been favored by researchers from
various countries since the early 20th century [
3
]. However, due to the large difference in
the characteristics of the water–air medium, it is not a simple matter to cross the water–air
medium, which involves the complex model entering and exiting the water process [
4
].
The process of aircraft entering and leaving water has a strong slamming effect. Slamming
generally refers to the violent impact phenomenon between the object and the medium
during the process of entering and leaving the water at a certain speed, which has a strong
nonlinear and complex flow process. Violent slamming may cause damage to the airframe
structure; thus, accurately predicting the change of slamming pressure with time becomes
extremely critical [5].
The process of entering and leaving the water is an important subject in marine
engineering and naval engineering. Considerable work has been conducted by predecessors
on the problem of objects entering and leaving the water. Von Karman [
6
] is a pioneer in
the research on the slamming theory of structures entering water. He uses the momentum
Drones 2022, 6, 236. https://doi.org/10.3390/drones6090236 https://www.mdpi.com/journal/drones
