Abstract: In order to determine the outlet pressure of hydrodynamic retarder at the early design stage and shorten the design cycle, the internal flow field of hydrodynamic retarder was calculated in CFD numerical simulation software according to velocity-inlet boundary and outflow boundary condition. The outlet pressure distribution that was calculated from the flow field was solved by area-weighted average algorithm, then the outlet pressure values under different rotor speed and charging ratio were obtained. The results show that the outlet pressure of hydrodynamic retarder is a quadratic function of rotor speed and a linear function of charging ratio. The research obtained the mathematical expression that describes how the outlet pressure response to rotor speed and charging ratio’s variation, which provides the basis for control system design of hydrodynamic retarder.

Key words: fluid transmission and control, hydrodynamic retarder, computational fluid dynamics, outlet pressure