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The disk groove can greatly influence the hydrodynamic behaviors of the rotating film, especially on the cooling performance and the transmission efficiency. In the present work, the effects of groove orientation on the hydro-viscous transmission of the parallel-disk system are investigated. The Reynolds equation and thermal equation, considering tangential Coriolis effect and temperature–viscosity dependency, are derived and solved. The effects of the groove orientation on the shear stress, load-carrying capacity, viscous torque, and transmission efficiency are analyzed. The results reveal that the Coriolis resisting torque can be restrained but the load-carrying capacity declines if the groove orientation is consistent with the rotating direction, and the variation of the transmission efficiency can even be inverted at the turning point of the groove orientation. Therefore, the effects of groove orientation must be paid more attention in the hydro-viscous transmission.

The temperature rise of hydro-viscous film in rotating parallel disks is usually controlled by imposing throughflow for keeping high film viscosity, but the Coriolis effect induced by throughflow can resist hydro-viscous transmission in return. In this work, the combined effects of Coriolis force and temperature-viscosity dependency on the hydro-viscous transmission are investigated. Firstly, the momentum and energy equations are established and the temperature-viscosity relationship is given, meanwhile, the numerical method is introduced. Then the combined effects on temperature rise and viscous transmission are analyzed and partly validated in experiment. The results reveal that with throughflow rate increasing the resistant effect of Coriolis force can be more and more significant relatively to temperature-viscosity effect, so their balance should be highlighted.

The imposed throughflow into rotating parallel disk system is to decrease temperature rise of hydro-viscous film flow, but the induced Coriolis effects are usually underestimated on torque transmission. The analytical expressions of thin-film parameters are obtained based on Navier-Stokes equations with the method of approximate analytical iteration. The Coriolis force and the corresponding influence on torque transmission are analyzed by analytical calculation and experimental verification. The results show that the tangential Coriolis force serves as resistance to the viscous torque transmission and the Coriolis torque loss can lead to primary reduction of efficiency among all motion effects. Therefore, the Coriolis effects should be paid more attention for the practical designs and applications of rotating hydro-viscous parallel-disk systems with imposed throughflow.

This paper presents a new cutter-head driving system of tunnel boring machine (TBM) with hydro-viscous clutch (HVC) applied in order to improve the extricating performance, and a kind of theoretical methodology is proposed to analyze the extricating performance of HVC. Firstly, the Navier-Stokes equations are reduced upon the characteristics of oil film within HVC and the dynamical mathematical models of cutter-head system in the process of extrication are established. Then an approximate iteration algorithm is adopted to solve the NS equations and the analytical expression of the HVC output torque is obtained. Therefore the real-time simulation for the extricating process is performed. The theoretical results are validated in an experimental rig containing one friction pair. It is confirmed that the theoretical methodology is valid for the good agreement between the theoretical and experimental results. The results reveal that the HVC can indeed improve extricating performance of TBM cutter-head especially in relieving rigid impact. Furthermore, this also provides a design idea for the rotating speed regulating system especially in large mechatronics equipment when the hydro-viscous clutch is applied.