Liquid slosh and its influence on braking and roll responses of partly filled tank vehicles

摘要

Liquid cargo contained in a partly-filled tank is known to experience the sloshing movement when subjected to manoeuvre-induced disturbances. Large amplitude slosh can be induced within a partly-filled road tank vehicle under mild to severe directional manoeuvres, which could severely degrade the vehicle stability and directional control limits. A three-dimensional computational fluid dynamics slosh model is implemented for the partly-filled cleanbore and baffled tanks on the basis of the Navier-Stokes equations incorporating the VOF technique. A comprehensive experimental study is conducted to analyze the fluid slosh within a scale model tank with and without the baffles under continuous as well as single-cycle sinusoidal lateral and longitudinal acceleration excitations. The three-dimensional fluid slosh responses are further investigated for full scale baffled and unbaffled vehicle tanks using the validated fluid slosh model. The fluid slosh characteristics are analyzed under different fill volumes corresponding to a constant load and subjected to excitations representing steady-turning, straight-line braking, braking-in-turn and path change maneuvers. The fluid slosh analyses are also carried out to explore the anti-slosh effectiveness of baffles and to evaluate the effects of baffle design factors, such as equalizer and the orifice size. The influences of transient fluid slosh on the tank vehicle stability and responses are studied by incorporating the fluid slosh model to in-plane vehicle models. The two-dimensional roll-plane slosh models of partly-filled tanks of different cross-sections are integrated with the roll moment equilibrium of an articulated vehicle to derive the vehicle roll stability limits. The roll stability analyses are performed for circular and "Reuleaux triangular" tanks under the conditions of constant and variable cargo loads. The results attained are compared with the quasi-static solutions to demonstrate the role of transient slosh loads on the roll stability limits. The three-dimensional slosh model of a partly-filled tank is also integrated into a 7-DOF pitch plane model of a tridem truck to analyze its straight-line braking characteristics in the presence of fluid slosh. The straight-line braking responses of the coupled tank-vehicle model with and without baffles are analyzed under different fill volumes but constant load for different magnitudes of braking treadle pressure and road surface adhesion limits