Research On The Influence Of Ground Vortex On Nacelle Inlet

An aero-engine operating near the ground can form a vortex that extends from the ground to the engine fan face,known as the ground vortex.Ground vortices create considerable stagnation pressure losses and decrease the total pressure recovery coefficient,increase the flow field distortion.even it could have enough suction power to kick up sand and rocks from the ground that are then sucked into the engine.This phenomenon is called foreign object damage(FOD).The work presented here used numerical simulation method to investigate formation and development of the ground vortex.And this paper reached the conclusions that flow conditions and the height between the intake and the ground have influence on the ground vortex.The ground vortex boundary lines under different flow conditions were also established.Furthermore,preliminary study on cause of formation of the ground vortex was done.Firstly,this paper did simulations on the model which used by Murphy in his experiments and proved the numerical simulation method was reliable by doing comparison between the data from the experiments and the results from simulations.Secondly,simulations on the ground vortex under crosswind,headwind and tailwind conditions were done.This paper reached the conclusions that wind velocity and the height between intake and ground have influence on the ground vortex.The strength of ground vortex under headwind conditions was weaker than crosswind conditions when the incoming velocity was the same.The intake outlet plane DC60 was also smaller under headwind conditions than crosswind conditions.The ground vortex boundary lines under crosswind,headwind and tailwind conditions were established respectively and the lines could give the answer whether the ground vortex would form or not.Thirdly,this paper did simulations on the ground vortex under take-off conditions.Computing cases included take-off under calm wind,headwind and crosswind conditions.Furthermore,sideslip conditions were also considered.This paper reached the conclusions that the relative movement between the intake and the ground had influence on formation of the ground vortex and as the sideslip angle increased,the strength of the ground vortex increased.Fourthly,simulations on the ground vortex with the real blade model were done and the conclusion was that the blade had little influence on the ground vortex under crowind and headwind conditions.Finally,unsteady numerical simulations of typical cases were done under crosswind and headwind conditions,respectively.By doing comparison between the data from unsteady and steady numerical simulations,it proved that the steady numerical simulations were reliable.Furthermore,preliminary study on cause of formation of the ground vortex was done and it found that the cause of formation of the ground vortex was different under crosswind and headwind conditions.