In order to reveal the dynamic pressure sealing performance of the cylinder fluid under the complex two-phase lubrication formed by lubricating oil and pressurized airflow in the bearing chamber of an aeroengine,based on the two-phase flow mixture model,the steady-state performance of gas-liquid two-phase cylindrical spiral groove fluid dynamic pressure seal was studied,and the effects of operating parameters and structural parameters on the dynamic pressure seal performance were analyzed.The results show that under the same working conditions,the gas-liquid two-phase cylinder fluid dynamic pressure seal has a good dynamic pressure effect.The increase of rotating speed,pressure difference and liquid-gas ratio is beneficial to the improvement of the open force of the cylinder fluid dynamic pressure seal,while the open force decreases with the increase of spiral angle and groove depth,and increases first and then tends to be stable with the increase of groove number.The leakage rate increases with the increase of pressure difference and rotating speed,increases first and then tends to be stable with the increase of spiral angle,increases gradually with the increase of groove depth,and decreases gradually with the increase of groove number.