80 ANNUAL LITERATURE SURVEY 1996

tions and displacement mechanisms reported by Oren et al. and which accounts for flow through both wetting and intermediate fluid films is shown to correctly predict all the important characteristics of three-phase flow observed in glass micromodel experiments.

Porosity variations in saline media caused by temperature gradients coupled to multiphase flow and dissolution/precipitation Olivella S., Carrera J., Gens A. & Alonso E.E., Transport in Porous Media, 1996, 25/1 (1-25). In English. This paper presents a theoretical-numerical investigation of porosity variations induced by temperature gra- dients in unsaturated saline media. It is known that temperature variations cause humidity variations which lead to liquid flow towards and vapour flow away from the hot source. When this phenomenon occurs in saline media, the liquid is salt saturated brine, so that evaporation causes salt precipitation and an ensuing porosity reduction. This process may be important in the case of heat generating waste because it suggests that selfsealing may take place near the waste.

Abrasion resistance of carbon cathode materials at room temperature Xianan Liao & Oye H.A., Tribologia: Finnish Journal of Tribology, 1996, 15/3 (3-34). In English. A test equipment similar to a slurry erosion pot tester was designed to study the abrasion of carbon cathode materials by alumina slurries at room temperature. The alumina was suspended in a heavy liquid-sodium polytungstate aqueous solution (SPT). Effects of test time, specimen velocity and solid concentration of the slurry were studied. The wear is mainly caused by sliding contact. This mechanism is different from that in an erosion test. The lower velocity range and higher concentration range employed in the present study are attrib- uted to the difference. Various carbon cathode materials were ranked against CS graphite which was used as the standard.

Effect of lubricant supply starvation on the thermohydrodynamic performance of a journal bearing Vijayaraghavan D., Keith T.G. Jr & Brewe D.E., Tribology Transactions, 1996, 39/3 (645-653). In English. With judicious selection of supply groove location for journal bearings, the lubricant supply rate and power loss can be considerably reduced without sacrificing the load-carrying capacity. In addition, the lubricant supply rate can further be reduced, either accidentally or deliberately, and the applied load may still be maintained. In this parametric study, the effects of reduced lubricant supply rate compared to the flooded inlet is studied for an axial-grooved journal bearing. Cavitation effects in the fluid film are taken into account and a full THD model, including heat conduction to the metal surfaces, is included in the analysis. Performance parameters at various load values due to reduced supply rate and typical temperature distributions are presented. It is found that, it may be possible to operate the bearing with as much as 70% reduction in lubricant supply rate.

Surface roughness effects in journal bearings with non-Newtonian lubricants Wang-Long Li, Cheng-I Weng & Jang-I Lue, Tribology Transactions, 1996, 39/4 (819-826). In English. The static performance of finite journal bearings lubricated with non-Newtonian power law fluids is analyzed by using a control volume method with an Elrod algorithm to solve the average Reynolds equation and deter- mine the cavitation region accurately. The results show that the flow behavior index of power law fluids has an insignificant effect on the load ratios, side flow ratios and cavitation regions, while it significantly affects load capacities and side flow rates. Furthermore, the effects of film thickness ratios, pressure flow factors, shear flow factors, slenderness ratios, eccentricities and inlet pressures on the variations of cavitation regions are also discussed.

Two-dimensional piston ring lubrication - part Ih elastic ring consideration Qingmin Yang & Keith T.G. Jr, Tribology Transactions, 1996, 39/4 (870-880). In English. A two-dimensional analysis for piston ring lubrication is presented by considering elastic deflection, EHL and cavitation effects. A numerical procedure is developed for solving hydro dynamic pressure and oil film thickness shape due to ring deflection and elastic deformation. An elliptic cylinder liner and elastic ring are considered to investigate the circumferential flow effect which has been ignored in previous studied. Results for a typical automotive engine demonstrates that the elastic deflection and deformation of the piston ring have a tendency to reduce the gap caused by the noncircular cylinder. The two-dimensional analysis presented also reveals a reduction of piston ring oil film thickness due to the circumferential flow compared to one-dimensional ana- lysis.

Two-dimensional piston ring lubrication - part I. rigid ring and liner solution Qingmin Yang & Keith T.G. Jr, Tribology Transactions, 1996, 39/4 (757-768). In English. A two-dimensional elastohydrodynamic cavitation algorithm is developed for piston ring lubrication. The nonlinear governing equation derived from the Reynolds equation to include cavitation and elastohydrody- namics is linearized for numerical efficiency. An elliptic cylinder liner and rigid ring are considered to inves- tigate circumferential flow effects which have been ignored in previous studies. The hydrodynamic pressure distribution and film thickness at various crank angles are determined. Results for a typical automotive engine show that the elliptic liner causes a dramatic drop in the hydrodynamic pressure and reduces the film thickness. It is found that the pressure reformation effect cannot be neglected when the piston ring moves away from the top dead center.

The turbulent flow of non-Newtonian slurries in pipes Slatter P.T., Vodohospodarsky Casopis/Journal of Hydrology and Hydromechanics, 1996, 44/1 (24-38). In English. Large quantities of solid material are transported hydraulically as non-Newtonian slurries in many industries. The theoretical models of Torrance and Wilson and Thomas for predicting the turbulent flow behaviour from