In order to enhance the buoyancy performance of the floating labyrinth seal and its adaptability to the radial runout of the rotor,a groove was designed on the runway of the main shaft.The experimental equipment and CFD numerical analysis model of the floating labyrinth seal were established.The effects of different grooving modes(non-groove,straight groove and spiral groove) on the leakage characteristics and buoyancy performance of the floating labyrinth seal under pressure difference and rotational speed were studied.Results show that with the increase of pressure differential,the leakage approximate linearly increases,the numerical calculation values of leakage of the straight groove floating labyrinth and spiral groove floating labyrinth is increased by 161% and 187% in maximum,respectively,and the test values is increased by 145% and 151% in maximum,respectively.There is little difference between the influence of straight groove and spiral groove on the buoyancy of floating labyrinth seal,however,with the gradual increase of differential pressure,the influence of spiral groove on buoyancy will will be greater and greater than that of straight groove.With the increase of rotating speed,the leakage and buoyancy of the three sealing structures change little,and the leakage and buoyancy of the straight groove and spiral groove sealing structures are greater than that of the non-groove sealing structure.