Ice Accretion on Helicopter Fuselage Considering Rotor-Wake Effects

摘要

To accurately predict the ice shape on the fuselage under rotor-wake effects, discrete modeling of individual tip vortices is essential to determine the local aerodynamic interactions between the vortex and the fuselage. To this end, the actuator surface model is developed and applied to the present study. Then, water-droplet-trajectory prediction, thermal analysis, and ice growth module are seamlessly integrated. This study aims to perform detailed analysis of the rotor downwash effects on ice that accretes on a helicopter fuselage and to determine the variation with respect to the forward flight speed. As a result of comprehensive numerical computations, the following conclusions are reached. First, the rotor inflow transforms the droplet trajectories, the location of ice accretion and the amount of ice are changed. Actually, 16.5% less ice is accumulated on the overall fuselage in the rotor-fuselage interaction case compared to the isolated fuselage case. Second, a clear-cut distinction of the icing locations on the fuselage is observed with various advance ratios. In hovering conditions, massive ice is accumulated on the tail-boom and fuselage nose region, where the tip vortices collide with fuselage. Due to the large collision area with high speed of droplets, 15.2 and 9.1% more ice is accumulated in hovering case than that of forward flight case with the advance ratio 0.075 and 0.15, respectively. However, as the forward speed grows from 0.15 to 0.2, the total mass of ice exponentially increases. In case of the advance ratio 0.2, 36% more ice is accumulated than that of the hovering case.