Churning losses of spiral bevel gears at high rotational speed

Abstract

In the present study, no-load losses of different splash lubricated spiral bevel gears were measured. The authors used a specific test rig, and a set of gears, to investigate churning losses at higher tangential speeds: up to 60 m/s. An uncommon behavior of the drag torque was highlighted: the torque increased with the rotational speed until a local maximum was reached; then the torque decreased and a local minimum was noticed; at higher rotational speed the torque increased. The torque decrease seems to be linked with a windage phenomenon, which becomes non-negligible at such speeds. In this work, efforts were made to characterize this reduction of gear immersion depth in order to be able to predict no-load losses. It was found that the evolution of oil immersion was linked to a Froude number. Finally a new analytical model of no-load losses was developed for churning losses combined with windage effects. This formulation takes into account several parameters such as rotational speed, gear immersion depth, oil properties, and gear geometrical parameters.

Power Losses of Spiral Bevel Gears: An Analysis Based on Computational Fluid Dynamics

“…In the middle range, the simulations predict an almost constant value of the losses rather than a decrease of it, as evidenced by experimental measurements (Quiban et al, 2019), but generally speaking the trend is captured by the numerical approach. Quiban et al (2019) noticed that the oil flow rate is almost constant with the velocity of the wheels. After an initial increment of the expelled flow rate until 2500 rpm, it tends to stabilize to a lower value which is dependent on the decrement of the wheel's immersion depth.…”

“…From literature, it is wellknown that these effects have a different impact on the power losses depending on the rotational speed of the wheel. In fact, at low-moderate velocities, churning is predominant and windage plays a marginal role, while at higher velocities the windage effects become preponderant (Quiban et al, 2019). In fact, the windage losses can be related to the rotational speed with a 3rd order exponent (P w ∝ ω 3 ), while the churning with a 1.65 exponent (P c ∝ ω 1.65 ) (Dawson, 1984;Diab et al, 2004;Johnson et al, 2007).…”

“…A torque sensor of accuracy of 0.002 Nm measures the resistant torque due to the interaction with the lubricant. The geometry as well the experimental data used to validate the simulation model are taken from the manuscript by Quiban et al (2019).…”

“…In this paper, the uncommon behavior of the losses in relation with rotational speed observed by Quiban et al (2019) was studied with the opensource software OpenFOAM R . In fact, the torque increased until a certain rotational speed, then it decreased to a local minimum, and at higher velocities it restarted to increase.…”

Application of an unstructured overset method for predicting the gear windage power losses

“…Zhu et al (2020b) developed a quasi-analytical model to predict the windage power losses of an isolated spiral bevel gear. Furthermore, considering the windage behavior, Quiban et al (2019) and Dai et al (2020) respectively set up an analytical model to estimate the churning losses of a bevel gear. These models show higher accuracy in the air under the medium and low speed conditions.…”