旋翼跨介质飞行气动特性与机理仿真分析  

Numerical analysis of aerodynamic characteristics and mechanisms of a rotor in cross-medium flight

作　　者：高世才 王潇[1] GAO Shicai;WANG Xiao(National Key Laboratory of Helicopter Aeromechanics,Nanjing University of Aeronautics and Astronautics,Nanjing 210016,China)

机构地区：[1]南京航空航天大学直升机动力学全国重点实验室,南京210016

出　　处：《空气动力学学报》2025年第3期87-97,I0002,共12页Acta Aerodynamica Sinica

基　　金：跨域飞行交叉技术重点实验室基金(2024-KF03001,2024-KF03003)。

摘　　要：跨介质水空旋翼飞行器可以同时在水和空气两种不同介质中航行,近年来逐渐成为研究焦点。水和空气两种流体介质的物理特性差异巨大,旋翼在跨介质过程中将经历复杂的两相流环境。基于格子玻尔兹曼方法(LBM)着重研究了旋翼逐渐靠近水面过程中的气动特性和流动机理,CFD计算结果表明,在距离水面0.8倍旋翼半径的高度附近,旋翼处于类似地面效应的状态。随着旋翼逐渐靠近水面,其下洗气流显著作用于水面,诱导形成明显的液冠结构,并伴随强烈的涡环效应,导致旋翼下方的气压降低,进而造成旋翼拉力在这一时间段内持续下降,拉力特性出现拐点,不升反降,产生明显的气液两相流干扰现象。液冠结构破碎后,旋翼拉力趋于稳定,相较于空中工况,在H/R=0.2时,旋翼拉力增长了约26%;在H/R>0.4时,旋翼拉力的增长逐渐减缓,增长率以2%~5%的幅度缓慢下降,直至最终拉力趋近于空中工况的水平。本文初步揭示了旋翼在近水面工况下拉力特性的初步规律及影响机理,为后续理论研究与实际应用提供了参考。Aerial-aquatic rotorcraft,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.

关 键 词：旋翼 LBM 跨介质飞行器 多相流 近水面效应 地面效应 

分 类 号：V211.3[航空宇航科学与技术—航空宇航推进理论与工程]