Effect Of Radar's Trailing Vortex On Aerodynamic Performance Of Vertical-fin

Although the installation of millimeter-wave radar over the rotor of the helicopter improves the level of integrated design of avionics and integrated level of information,the radar's trailing vortex causes the change of aerodynamic performance of vertical-fin and brings new aerodynamic problems.In order to study the influence mechanism of the effect of radar's trailing vortex on vertical-fin,Pointwise is used to generate the mesh for the computational domain of different models.,and FLUENT is used to simulate the flow field of flow around the cylinder,the radar and vertical-fin and variation of radar's geometry.In numerical method,the incompressible method of URANS and the turbulence model of SST ?-?is used,based on the method of finite volume,the equations are discretized and solved by the algorithm of PISO.During calculation,first a steady calculation is performed to get a better initial flow-field,and then it is converted to an unsteady calculation until the final result is statistically stationary.First of all,the validity of the method of numerical simulation is verified based on the model of flow around the cylinder,and the selected mesh provides a reference for the setting of grid parameters in the subsequent calculation.Then,the grid independence is verified based on the simplified model of radar and vertical-fin.The composition of the three-dimensional vortex is discussed based on based on the flow field of original radar;the influence of different installation angles of the radar on radar's trailing vortex is analyzed based on the aerodynamic parameters and spectrum characteristics of vertical-fin;the influence of the effect of radar's trailing vortex on vertical-fin is analyzed based on the analysis of force of vertical-fin.Finally,the geometry of the radar is changed form three aspects,and the effect of variation of geometry on radar's trailing vortex is analyzed.The results show that:When the diameter of radar in radial direction is lengthened,the strength of the upper-part vortex in the z direction will increase,so the effect of the radar's trailing vortex will enhance;In a certain range,the increase of the normal diameter of radar can weaken the three-dimensional characteristics of the crescentic three-dimensional vortex,but beyond this range,the increase of the normal diameter will strengthen the intensity of falling-off vortex of radar,so as to enhance the effect of radar's trailing vortex;The increase of the sloping angle of the generatrix on the side of radar will not weaken the effect of trailing vortex.