| The iced blade can seriously damage the aerodynamic characteristics of the rotor,reduce the maneuverability and stability of the helicopter,and destroy the flight safety of the helicopter.It is of great theoretical and practical significance to study the mechanism of rotor icing and the related issues of rotor anti-icing and de-icing.When the rotor is frozen,the blade surface accumulates ice layer continuously,because the ice particles are unevenly distributed,ice roughness is formed.This roughness can affect the aerodynamic characteristics of the rotor in a local area and the growth of ice.Therefore,studying the effects of icing phenomena and icing roughness on the aerodynamic characteristics of rotors are essential.Considering computer simulation of rotor icing and the influence of icing roughness,rotor icing analysis with icing roughness are carried out.The major constructions of the investigated paper are as follows:In Chapter 1,the research background of helicopter rotor icing and icing roughness is described.The helicopter CFD method and the research status of numerical simulation method of rotor icing at home and abroad is presented.The shortcomings of the current research are pointed out,and the research contents methods are put forward.In Chapter 2,in the aspect of grid generation,a nested grid system of structural motion is developed,which is suitable for numerical simulation of unsteady flow field of rotor.Aiming at the blade shape change caused by icing roughness,a blade mesh reconstruction method based on spring mesh is developed.A numerical s imulation method for unsteady airfoil/rotor flow field considering icing roughness is proposed based on the structural moving embedded nested grid.It provides high-accuracy flow field information for rotor icing prediction and the influence of icing roughness on rotor aerodynamic characteristics.In Chapter 3,numerical simulation methods of airfoil/rotor icing are investigated.The euler method is developed to solve the three-dimensional droplet impact characteristics on the icing surface of rotor blades.The thermodynamic model and ice prediction method of airfoil/rotor are established.Based on the CFD flow field calculation method of rotor,the icing calculation of airfoil and rotor hovering state under typical conditions is carried out.In Chapter 4,the icing characteristics of rotor are studied.Based on the established method for calculating the icing of rotor motion,the icing calculation of typical airfoil and blade are carried out.The effects of temperature and average droplet diameter on rotor icing are analyzed.In Chapter 5,the effects of icing roughness on aerodynamic characteristics of airfoil/rotor are studied.Under typical conditions,aerodynamic characteristics of airfoils with icing roughness are calculated.According to different parameters of icing roughness,the influence of aerodynamic characteristics of airfoil with roughness is analyzed.In hover,the aerodynamic characteristics of typical rotor with icing roughness are calculated and analyzed.On the bases of the work above,the calculation and analysis of the icing characteristics of airfoil with icing roughness under typical conditions are carried out.In Chapter 6,the summary of the research and further work are described.The innovative points and new conclusions are summarized,and the prospects for future research work are put forward. |
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