Computer Simulation of a Variable Fill Hydraulic Dynamometer: Part 2: Steady State and Dynamic Open-Loop Performance

Abstract

Part 1 of this paper presented a theoretical model for the torque absorption and energy dissipation processes in a variable fill Froude-type hydraulic dynamometer. Effects of working compartment geometry changes on steady state running full torque absorption performance were also shown. Part 2 presents both steady state and dynamic computer simulations of an engine-dynamometer system under open-loop control. Comparisons between model simulations and test bed data show that the dynamic model reproduces both the negative torque-speed dynamometer characteristics and other transient phenomena that occur under real open-loop partial fill conditions. Requirements of control systems to modify this behaviour and ensure stable set point holding are introduced. Part 3 of the paper will deal with the simulation of the engine-dynamometer system under closed-loop control.