Research On The Influence Of Ground Vortex On Nacelle Inlet With Blades

In this paper,the formation and development of ground vortex have been studied by means of numerical simulation.And the necessity of adding fan blades in nacelle inlet have also been analyzed.The influence of the flow conditions and the height of the ground on the ground vortex of the nacelle inlet adding with fan blades were summarized.And the ground vortex boundary lines under different conditions were also concluded.Firstly,this paper did simulations on the models with no fans under the crosswind and headwind conditions.The ground vortex will gradually disappear and the inlet distortion will increase sharply with the wind velocity increasing under crosswind conditions.The lower the nacelle inlet,the more likely it is to form the ground vortex.While the strength of the ground vortex under headwind conditions was weaker than the crosswind conditions when the freesteam velocity was the same.Secondly,simulations on the models with propeller under different conditions were done.No matter what freestream conditions were,the strength of ground vortex with propellers was clearly lower than the strength of ground vortex with no propeller.Also,the ground vortex circulation will slightly increase with the addition of the number of propeller.While the intake out plane DC60 will decrease as the number of propeller increasing.Furtherly,simulations on the ground vortex with real blade GE90 under crosswind,takeoff and headwind conditions were done.the strength of ground vortex with the real blade was clearly lower than the strength of ground vortex with no blade,increasing with the rotation speed.While the inlet distortion index with fan blade will be grater than that with no fan blade only when the freestream velocity was larger under crosswind conditions.And the total pressure recovery coefficients of the inlet with fan blade were both higher than that with no blade under the same conditions.Meanwhile this paper did simulations on the take-off conditions and find out that the strength of ground vortex under crosswind was largest and strength of ground vortex under no wind take-off came to the lowest.Lastly,the near ground velocity components under the nacelle inlet lip was measured by means of experimental method at the typical height of the nacelle inlet.So the existence of the ground vortex was verified,and the validity of the simulation result was proved.