To study the state and distribution of dust cloud in the hovering flow field of helicopter brownout, a numerical model based on Reynolds-averaged Navier-Stokes equations and Menter Shear Stress Transport (SST) k-ω turbulence model and a discrete element model based on Hertz-Mindlin (No Slip) contact model are coupled through the application programming interface. A more realistic model is constructed based on the multi-sphere method, and non-spherical dust particles are used to calculate the motion and distribution in the flow field. The effectiveness of the approach is verified by comparing the numerical results with the available experimental results. The drag coefficient of the rotor in the in-ground effect, the position of the tip vortices and the macroscopic outline of the dust cloud are calculated. By using the established method, the in-ground effect flow field of helicopters at different hovering altitudes is calculated. The vorticity and velocity contour of the flow field are obtained. The velocity and distribution of dust particles in dust clouds at different hovering altitudes are compared. The influence of ground effect flow field on the state of dust particles and the formation mechanism of dust clouds are analyzed. The macroscopic distribution of dust clouds are also obtained. The results show that most of the dust particles in the flow field can only diffuse with the flow field on the ground, but can not form dust clouds. The concentration of dust in outer space is higher than that in inner space. The dust particles located in the lower region of the rotor disk move mainly in the radial direction with smaller tangential velocity, while the velocity of the dust particles located in the upper region of the rotor disk are different in direction and close in magnitude.
HU Jianping
,
XU Guohua
,
SHI Yongjie
,
WU Linbo
. Formation mechanism of brownout in full-scale helicopter based on CFD-DEM couplings numerical simulation[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2020
, 41(3)
: 123363
-123363
.
DOI: 10.7527/S1000-6893.2019.23363
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