Superlaminar Regime Research Articles

The Steady-State Characteristics of a Hydrostatic Thrust Bearing With a Floating Disk

To reduce the frictional power loss of hydrostatic thrust bearings, the hydrostatic thrust bearing with a floating disk shaped in a simplified configuration is proposed. And the load capacity and the frictional torque are experimentally investigated in laminar and superlaminar regimes. Following results can be obtained: (1) The disk floats at a certain stable position for given shaft rotational speed and rotates at nearly half rotational speed of the shaft. (2) The frictional torque of this type of the bearing is less than half of a conventional hydrostatic thrust bearing with the same surface configuration as the floating disk.

Performance of finite journal bearings in non-laminar lubrication regime

Fluid dynamic lubrication of journal bearings in a superlaminar regime, ie a transition or turbulent regime, is the subject-matter of this study. Results obtained by solving an appropriately modified Reynolds bidimensional equation have been put in the form of operating diagrams which allow the correct design of journal bearings in real conditions of flow

Analysis by the finite element method of hydrodynamic bearings operating in the laminar and superlaminar regimes

By adopting the non-linear theory proposed by Elrod and Ng, the generalized Navier-Stokes equations were modified and solved numerically for the flow field in the clearance space of a journal bearing. The performance characteristics of a finite circular hydrodynamic bearing (aspect ratio L/ D = 1) were studied in terms of the Sommerfeld number, attitude angle, oil flow, friction coefficient and temperature rise parameter at various eccentricities for Reynolds' numbers up to 13 300.

The reynolds boundary conditions—should they be used during turbulent hydrodynamic lubrication?

The Reynolds boundary conditions are the most frequently used boundary conditions in the solution of the hydrodynamic lubrication equation in the laminar regime. However, their use in the analysis of hydrodynamic bearings during superlaminar (turbulent) operation has not been verified. The phenomena occurring in laminar and turbulent flow are different, and therefore the validity of the Reynolds boundary conditions in the superlaminar regime requires investigation. The problem was investigated and it was found that the Reynolds boundary conditions do hold approximately in the turbulent regime.

Friction Reduction in Turbulent Journal Bearings by Highpolymers

The friction reduction by dilute polymer solutions is investigated experimentally in turbulent journal bearings. The effects of polymer substances, polymer concentration, bearing clearance, and journal eccentricity on friction reduction are examined over the wide range of Reynolds number in the superlaminar regime. In the experiments, the friction of polymer solution is less than 40 percent of that of Newtonian turbulent flow under the best conditions. The calculated friction factor for the Couette flow is in good agreement with the corresponding measured one. Degradation of highpolymer is also investigated experimentally, and is found to be affected by polymer concentration.

Theoretical and Experimental Investigations of a Short 360° Journal Bearing in the Transition Superlaminar Regime

An empirical treatment is used to derive effective viscosity constants governing pressure-induced flows in Taylor Vortex regimes. The theory of static and linearized dynamic behaviour of a short journal is developed, including an approximate representation of fluid inertia effects. Theory is compared with experimental results of duty parameters, attitude loci and dynamic forcing due to rotation of an eccentric journal.

Empirical treatment of hydrodynamic journal bearing performance in the superlaminar regime

Empirical treatment of hydrodynamic journal bearing performance in the superlaminar regime

Empirical Treatment of Hydrodynamic Journal Bearing Performance in the Superlaminar Regime

The application of a perturbation in terms of simple correlations for friction in turbulent Couette and ‘screw’ flows, together with a further empirical assumption consonant with the experimental work of Smith and Fuller (1), leads to a pressure field equation identical in form with the Reynolds equation. The load capacity of journal bearings throughout most of the superlaminar range may be represented by a single curve, and existing laminar solutions may be applied with the parameters modified by Reynolds number. The theory is compared with published experimental results, and with the most successful theoretical treatment (4). The correlations obtained confirm the adequacy of the theory to predict performance in the superlaminar régime.

Taylor Vortices with Eccentric Rotating Cylinders

THE stability of circumferential laminar flow between rotating concentric cylinders has been extensively investigated, the classical work being that of Taylor1. The effect of eccentric positioning of the cylinders, however, has received relatively little attention, although this further complication is of technological interest in connexion with operating journal bearings at very high speed in the so-called superlaminar regime. I have carried out experiments with an eccentrically positioned rotor inside a stator, the axes being parallel, and I have already described2 how the Taylor vortex pattern still appears, but with the critical speed raised appreciably above Taylor's value for concentric cylinders.

Investigation of a Partial Arc Pad Bearing in the Superlaminar Flow Regime

This paper describes the apparatus and the experiments conducted with a 60 deg partial arc journal bearing in laminar and superlaminar regimes. The experiments were conducted with two clearance ratios and over a range of Reynolds numbers (based on mean clearance) up to approximately 12,000. The data on load capacity and attitude angle are compared with laminar theory and with the currently available turbulent bearing theory. Agreement with turbulent bearing theory is satisfactory in the range where the empirical factor (k) was previously determined from other work. Beyond this range, the degree of correlation becomes progressively poorer indicating that (k) continues to vary with Reynolds number even at relatively high values of the latter parameter. The experimentally determined speeds for transition of flow from laminar to superlaminar regime compare well with the criterion for transition in eccentric bearings developed by DiPrima.