Aviation hydraulic actuator is widely used in many parts of an aircraft,such as aircraft wing, landing gear, hatch door. The typical seal form is reciprocating seal, and the failure of seal will seriously affect the execution of flight mission and even flight safety. The surface roughness of sealing pair as an important engineering controllable parameter is of great influence on the sealing performance. Therefore, it is of great theoretical and practical significance to analyze the influence of surface roughness on the sealing performance of actuator. A deterministic mixed lubrication numerical model for reciprocating combined seal is established, and the finite element method (FEM) is combined to calculate the film thickness. The effects of surface roughness and operating conditions on lubrication and sealing performance are analyzed. The results show that increase of roughness and wavelength of three-dimensional sinusoidal rough surface can contribute to the increase of fluctuation amplitude of film thickness and pressure, and the reduction of friction coefficient. Increase of amplitude of the sinusoidal rough surface is beneficial to the reduction of the minimum film thickness and leakage rate. However, the wavelength change has little effect on the minimum film thickness. The increase of viscosity of hydraulic fluid and kinematic velocity of piston is benefit to the increase of oil film thickness of sealing clearance, but is bad for leakage rate and friction coefficient.
