International Journal of Applied Mechanics and Engineering
Based upon Christensen's stochastic model, this paper studies the optimal stiffness of hydrostatic thrust bearings including the effects of surface roughness and rotational inertia. The mean film pressure for a capillary-compensated circular step bearing is solved from the stochastic Reynolds-type equation together with the stochastic recess flow continuity equation. By applying the maximum principle,...
A local non-linear stability analysis using the spectral method is made of the Rayleigh-Benard situation in a high-porosity porous medium. The series expansion solution so obtained is valid for a large range of imposed temperature differences and yields a quantitative estimate of the heat transport by convection. Streamline patterns and mean temperature distributions have been obtained. The temperature...
Using a laser Doppler anemometer, liquid velocity was measured in the tank in which liquid was mixed by a self-aspirating disk impeller. The energy spectrum was the basis to determine the energy dissipation rate. This rate determines the size of eddies that are formed in the vicinity of the impeller. Results obtained by sample and hold method were compared with those obtained by other methods. An...
Separation characteristics of fluid flow in a pipe with sinusoidal wavy surface are investigated numerically. The pipe waviness is characterized by a wavelength ('lambda') and an amplitude (a) of the wave. Steady laminar flow of a Newtonian fluid is considered. Governing equations are discretized using the control volume based Finite-Volume method with collocated variable arrangement. SIMPLE algorithm...
A refined thermal Reynolds equation considering conduction and convection modes of heat transfer across the film for inlet zone of the liquid lubricated strip rolling, developed by Bhatt and Sengupta, is applied in this analysis. It is known that inlet zone plays a dominant role in fixing the lubricant film thickness in the work zone. Hence, for the present analysis the effect of conduction and convection...
Magnetohydrodynamic fully developed mixed convection flow of a viscous incompressible electrically conducting fluid confined to a vertical channel with asymmetric heating of the wall, is studied. It has been shown that a reversed flow occurs due to asymmetric heating of the wall when the magnitude of the buoyancy parameter Gr exceeds a certain threshold value. The limiting cases of the MHD free and...
The present paper compares the aerodynamic loads predicted by a vortex model with wind tunnel measurements for a straight-bladed Darrieus rotor. A computation unsteady discrete-vortex method, based on lifting line theory and a free vortex wake model, is used. Thus the wake is composed of shedding spanwise discrete vortices, whose strengths are equal to the change in the bound vortex strength as dictated...
In this paper, the effect of a transverse magnetic field on the performance characteristics of finite slider bearings with an electrically conducting fluid is presented. To take account of the Lorentz force on the lubricant film, a generalized two-dimensional Reynolds-type equation is derived by using the MHD motion equations with Maxwell equations. This MHD Reynolds equation is applicable to the...
By using high strength steels wheel-flat tests and flat-induced shelling tests are performed. Test results are evaluated from the viewpoint of the occurrence of surface damages such as thermal cracks, fatigue cracks and wear. An austenitic steel with nearly the same hardness as that of the present wheel steel is estimated to be a better steel material from the viewpoint of the occurrence of these...
The effect of reinforcing 6061 Aluminum alloy with 10% sub-micron Al2O3 by volume on the wear properties was studied using a pin-on-disc type tribometer as well as Vickers micro-Hardness tester. The dry wear test, for the alloy and the composite, was performed at room temperature under different loads with a relative speed of 1 m/s. The pin was either made of the 6061 alloy or the composite. The counter...
A method of obtain of sintered intermetallic alloys by pressing under cyclic loading at elevated temperature has been presented in this paper. Investigated samples were prepared as results of four different value of cyclic loading frequency of manufacturing process. Results of structure and phase analysis, especially in range of a content and morphology of aluminium oxides have been discussed. Basic...
In the present operation the made attempt to estimate thermomechanical baing of a brake assembly of a drill winch in multiplis process of landing of tubes. The calculations have shown, that the considerable influencing on the basic indexs of quality of surface layer and mechanical performances of a material renders cycliness (heating and chilling) and velocity of calorific process.
In this paper is it given an example of the reliability of the tribo-mechanical components (the power system for eccentric press INN 1500, the cutting tools made of cubic boron nitride - CBN for turning of hardened steel 20CrMo5 and the multi-bladed indexable inserts made of multi-coatings hard metal for turning of steel 18CrNi6). Reliability of the tribo-mechanical systems components is determined...
The proposal of classification the tribocorrosion tests are described in this paper. The compare investigations of nitrided, chromized and thermal toughened steels was carried out. Tribological properties of such diffusion layers was estimated on the ground of results of the sliding friction ests by concentrated contact and at the presence of corroding medium. It has been stated the high tribocorrosion...
We proposed a new type hydrostatic journal bearing with a floating bush to decrease the frictional torque. The characteristics of proposed bearing are calculated and we found out the optimum design parameter. Moreover, we fabricated the test bearing and measured the characteristics of bearing. The calculated results and the measured results are relatively coincide with each other.
Microscopic observation by human unaided eyes has greatly contributed to identify and/or classify worn surfaces of tribomaterials. Words, codes, sketches and photographs used in expressing surface characteristics by all means qualitative and depend on human a sense, which inadequately varies from time to time and from person to person. It would be, therefore, beneficial to be able to translate these...
Influences of the surface finishes upon seizure are investigated experimentally by using hydro-static air bearings as an experimental apparatus. Bronze and steel bearings finished by lapping and turning are used under the combination with steel shafts finished by honing. It was clarified that bronze bearings finished by lapping came to seizure more easily than the one finished by turning and the wear...
In this report the kinetic model of diffuse-limited propagation of dislocation loops in conditions of periodical crystal compression is proposed. It is shown that vacancy satiety, which originates by crystal compression, results in creation of vacancy clusters and dislocation loops. Main factors were analyzed responsible for anomalous features of plastic tlow in the subsurface material layers from...
A laboratory study has been undertaken to elucidate the influence of structural parameters of polymer/electrolyte systems commonly used for the formulation of water-based drilling fluids on their performances as filtrate reducers or viscosifiers.High temperatures and salt conditions encountered in the well may modify the rheological properties and this makes the use of polymers necessary. High molecular...
In this paper the authors present a solution to the problem of an inertia effect of ferromagnetic lubricant flow in a multilobe conical bearing. The problem was solved by Galerkin's method after assuming that the bearing is lubricated with an incompressible Newtonian lubricant. The general form of solutions for pressure distribution and axial load for particular cases of the bearing geometry are given