GAO Shicai, WANG Xiao. Numerical analysis of aerodynamic characteristics and mechanisms of a rotor in cross-medium flight[J]. 2025, 43(3): 87-97.DOI: 10.7638/kqdlxxb-2024.0153.
Numerical analysis of aerodynamic characteristics and mechanisms of a rotor in cross-medium flight
capable of navigating in both underwater and aerial environments
has gradually become a focus of research in recent years. The physical properties of water and air differ significantly
thus the rotor experiences a complex two-phase flow environment during the cross-medium process. Using the lattice Boltzmann method (LBM)
this study focuses on the aerodynamic characteristics and flow mechanisms of a rotor as it gradually approaches the water surface from the
air. Combined with corresponding CFD results
it is shown that at a height of approximately 0.8 times the rotor radius above the water surface
the rotor enters a flow state similar to ground effect. As the rotor continues to approach the water surface
its downwash significantly interacts with the water
inducing the formation of a distinct liquid crown structure accompanied by strong vortex ring effects. This leads to a decrease in air pressure beneath the rotor
causing a continuous decline in rotor lift during this period. The lift characteristics exhibit a turning point
where the lift decreases instead of increasing
indicating significant gas-liquid two-phase flow interference. After the liquid crown structure breaks up
the rotor lift stabilizes. At
H
/
R
= 0.2
the rotor lift increases by approximately 26% compared to its performance in the air. At
H
/
R
0.4
the growth rate in rotor lift gradually slows
decreasing at a rate of 2% to 5%
until it eventually converges to the lift level observed in the aerial condition. This paper preliminarily reveals the initial patterns of the thrust characteristics of rotors under near-water surface conditions and their influencing mechanisms
providing a reference basis for subsequent theoretical research and practical applications.
ZHANG C Y, YANG F, LIU K, et al . Development and key technology analysis of morphing trans-media aircraft[J ] . Astronautical Systems Engineering Technology, 2021 , 5 ( 6 ): 54 − 61,72 (in Chinese).
MI B G, ZHAN H . Numerical simulation of aircraft dynamic stability characteristics flying over ground and water surface[J ] . Journal of Ship Mechanics, 2017 , 21 ( 11 ): 1348 − 1355 (in Chinese).
XU R, JU S Q, ZHAN Q, et al . Design of aerial-aquatic rotor test system and experimental study of rotor performance[J ] . Flight Dynamics, 2024 , 42 ( 3 ): 89 − 94 (in Chinese).
BAI X Z, WU W H, LIN Z C, et al . The influence factors of near water effect of rotor[J ] . Acta Aerodynamica Sinica, 2024 , 42 ( 1 ): 86 − 99 (in Chinese).
ZHAO W P, ZHANG Y H, GAO T, et al . Analysis of aerodynamic characteristics of electric aircraft flying near sea surface[J ] . Journal of Ocean Technology, 2022 , 41 ( 6 ): 8 − 16 (in Chinese).
LV T, WEI Z K, LI S Y . Analysis of rotor aerodynamic characteristics based on lattice Boltzmann method[J ] . Navigation and Control, 2015 , 14 ( 5 ): 89 − 93 (in Chinese).
ROTHMAN D H, KELLER J M . Immiscible cellular-automaton fluids[J ] . Journal of Statistical Physics, 1988 , 52 ( 3 ): 1119 − 1127 .
SHAN X, CHEN H . Lattice Boltzmann model for simulating flows with multiple phases and components[J ] . Life (Basel, Switzerland), 1993 , 47 ( 3 ): 1815 − 1819 .
SHAN X W, DOOLEN G . Diffusion in a multicomponent lattice Boltzmann equation model[J ] . Physical Review E, 1996 , 54 ( 4 ): 3614 − 3620 .
SWIFT M R, ORLANDINI E, OSBORN W R, et al . Lattice Boltzmann simulations of liquid-gas and binary fluid systems[J ] . Physical Review E, 1996 , 54 ( 5 ): 5041 − 5052 .
MARQUARDT J E, RÖMER U J, NIRSCHL H, et al . A discrete contact model for complex arbitrary-shaped convex geometries[J ] . Particuology, 2023 , 80 : 180 − 191 .
CHEN S Y, DOOLEN G D . Lattice Boltzmann method for fluid flows[J ] . Annual Review of Fluid Mechanics, 1998 , 30 : 329 − 364 .
DU T Z, LI X Q, ZHANG X L, et al . Lattice Boltzmann method used for the aircraft characteristics computation at high angle of attack[J ] . Science China Technological Sciences, 2010 , 53 ( 8 ): 2068 − 2073 .
CARADONNA F X, TUNG C . Experimental and analytical studies of a model helicopter rotor in hover[J ] . Vertica, 1981 , 5 ( 2 ): 149 − 161 .
DOERFFER P, SZULC O . Numerical simulation of model helicopter rotor in hover[J ] . TASK Quarterly, 2008 , 12 ( 3-4 ): 227 − 236 .
GARY R B. On the motion of the helical vortex shed from a single bladed hovering model rotor and its application to the calculation of the spanwise aerodynamic loading [D]. Princeton, New Jersey, USA: Princeton University, 1955.
YANG F, ZHAO G Q, CHEN X, et al . Analysis of aerodynamic characteristics of rotor near water surface[J ] . Flight Dynamics, 2023 , 41 ( 3 ): 1 − 6 (in Chinese).
ZHANG Z D. Structural design and fluid-solid coupling simulation analysis of large and medium-sized bionic flapping-wing aircraft[D]. Beijing: Beijing Jiaotong University, 2022 (in Chinese).