Novel 2D CFD Model of an Orbital Hydraulic Motor—Development and Experimental Validation

This article presents a two-dimensional (2D) computational fluid dynamics (CFD) model of the operating processes in a spool-valve-type orbital hydraulic motor. The model is developed to predict the flow rate and torque characteristics of the hydraulic motor as functions of rotational speed and pressure drop. To reproduce the fluid commutation process in the simplified 2D domain, an equivalent kinematic representation with a rotating shaft-distributor is implemented. An original methodology for torque determination based on the hydrodynamic forces acting on the gerotor is also proposed. The numerical results are validated using both manufacturer catalog data and experimental measurements obtained on a laboratory test rig under identical operating conditions. Good agreement is achieved between the numerical, catalogue, and experimental results. For the experimental validation, the absolute value of the relative flow rate error is within 0.07–3.58%, while the corresponding torque error is within 0.08–13.32%. The results demonstrate that the proposed 2D CFD model can be used to predict the main hydraulic and mechanical characteristics of the investigated hydraulic motor with satisfactory accuracy.