Thermal-fluid-structure coupling analysis for valve plate friction pair of axial piston pump in electrohydrostatic actuator (EHA) of aircraft

This paper deals with thermal-fluid-structure coupling analysis for valve plate friction pair of axial piston pump in electrohydrostatic actuator (EHA) of aircraft. The axial piston pump with high pressure and high rotational speed to be widely applied in EHA of more electric aircraft can increase the power density, but it also deteriorates thermal-fluid-structure coupling of the friction pairs. In order to reveal its interior multiphysics field coupling mechanism, taking the valve plate friction pair in three key friction pairs for example, this study carries out the research on multiphysics field coupling. Firstly, Navier-Stokes equations and energy equation of the incompressible fluid considering the influence of temperature and pressure on the oil properties, heat conduction governing equation with many boundary conditions including heat flux, heat convection, heat radiation and considering the influence of the structure deformation on the temperature and the influence of the temperature on the material properties, the elastic mechanics model of the structure exerted together by temperature, fluid pressure and mechanical load, are established. On this basis, a complete set of fast and effective thermal-fluid-structure coupling method is originally presented, and the numerical analysis is conducted using it for the valve plate friction pair. By the calculation results, the evolution laws with time and space are revealed regarding to the pressure and temperature of the fluid in the chambers, and the temperature, stress and deformation of the valve plate friction pair, the wedge-shaped clearance forms between them, even mixed friction occurs, and the corresponding improving measures aimed at the discovered problems are discussed. These results can provide the theoretical evidence for the design and development of the pump of EHA.