Determination of an Optimal Oil Jet Nozzle Layout for Helical Gear Lubrication: Mathematical Modeling, Numerical Simulation, and Experimental Validation

Abstract

To provide a basic guidance for the selection of nozzle layout, a mathematical model of the impingement depth for helical gears under oil jet lubrication is established. Furthermore, computational fluid dynamics (CFD) methods are adopted to validate the effectiveness and accuracy of the derived impingement model. Firstly, the distribution characteristics of the oil volume fraction and oil-gas pressure in meshing area were obtained in flow field simulation. Meanwhile, the influence of spray angle, jet velocity, and gear ratio on lubrication effect was obtained. Then, the transient temperature field of the tooth surface was simulated by the method of thermal-fluid coupling analysis, and the lowest temperature distribution and the corresponding oil jet velocity were determined. Finally, experiments on the temperature characteristics measured by an infrared thermal imager of helical gears with different nozzle parameters were carried out in a gear test rig. The simulation results of transient temperature field are in good agreement with those obtained by experiments, and it indicates that the thermal-fluid coupling analysis method is correct and feasible to predict the temperature field of the helical gear pair under oil injection jet lubrication.

Numerical Analysis for Wetting Behaviors of an Oil Jet Lubricated Spur Gear

“…They also conducted experiments to validate the theoretical depth models and pointed out that an optimal oil nozzle layout can provide a maximum impingement depth, bringing better cooling effect. Similar studies were submitted by Dai et al; they investigated not only the penetrating depth on spur/helical gear pairs [16], but also spiral bevel gears [17] and face gears [18]. These scholars emphasized the relationship between the nozzle layout and the theoretical impingement, but neglected the resistance torque or the impulse power losses due to the action of oil flow impacting the gear surface.…”

CFD investigation of air-oil two-phase flow in oil jet nozzle

“…More recently, Massini et al 6 carried out experiments on a novel rotating test bench capable of reproducing real aero-engine working conditions for single spur gear, experimental findings showed that under high Reynold number oil jet breakup happens, is detrimental for the lubrication and cooling of the target gears due to part of the oil escaping and not reaching the gear, on the other hand, the impingement velocity of oil jet reduced. By analyzing the oil jet lubrication process and meshing theory of helical/face gear pair, Dai et al 7,8 and Ouyang et al 9 further developed novel mathematical models of impingement depth closely associated with nozzle arrangement, the relationship between the measured temperature by experiments and the corresponding theoretical impingement depth indicates that a lower temperature comes with a larger impingement depth. So far, experimental researches on the detail of the flow field from the nozzle to the target parts are relatively weak.…”

Application of the GRAMC mesh-handling strategy for the simulation of dip and injection lubrication in gearboxes

“…Tetrahedral meshes are characterized by higher generation times with respect to prismatic or hexahedral elements. Single rotating helical gears [11] and spiral bevel gears [12] have been already simulated by the authors, while the virtual modelling of mating gears has been approached with mesh [13][14][15][16][17][18][19][20] and meshless methods [21][22][23][24][25][26] in commercial software. Works based on a general procedure in open-source software are still lacking in the literature.…”