An experimental and theoretical study on erosion of a metallic plate by solid particles entrained in a liquid jet has been performed. The test section involved a two-phase flow jet of liquid water and silica-sand impinging on a metallic plate upon which erosion occurred. In combining the fluid mechanics of particle suspension in a liquid and a model of weight removal from the plate (by a single abrasive particle), an analytical approach is developed to determine the distribution and amount of erosion along a metallic plate. This model of erosion distribution along the metallic plate can be used as a tool to predict erosive damage in industrial equipment such as pipe bends, elbows, subsurface safety valves, and pipe contractions.
A linear model of lubricant-related engine friction was developed. Based on lubrication fundamentals, the technique is comprised of three simple bench tests that respectively operate under thick fluidfilm hydrodynamic lubrication, elastohydrodynamic lubrication, and boundary lubrication. With adequate configunztion and appropriate test conditions, these bench tests are seen to simulate major friction losses in a typical intern1 combustion engine. Lubricant characteristics obtained in the bench tests were combined using SAS linear regression and correlated to ASTM Five-Car and Sequence VI engine tests. The linear model gave an excellent prediction of engine data. It further showed that hydrodynamic friction losses dominate lubricant-related engine fiction, followed by boundary friction losses, and elastohydrodynamic or mixed friction losses. This simple, reliable, and inexpensive technique can be used as a research tool to study fiction characteristics of crankcase lubricants and to develop superior fuel-efficient engine oils. Major findings fron this study can be summarised as f i h w s : I . The linear &l predicts that 5 to 6% fuel economy improvement over the industry high reference oil HR-4 is achievable with today's motor oil technology. both 'thick' and 'thin' fluid-film lubrication account for 63% of total friction losses caused by the engine oil while boundary friction losses amount to 37%. 3. Friction losses in the elastohydrodynamic mHD) engine are significant, up to 22% of total friction losses. This, combined with the fact that EHD film thickness is the most significant parameter in the linear model, suggests that pressure effects (ie, high-temperature I high-shear I high-pressure viscosity, pressure-viscosity coefficients) are important. Hydrodynamic friction losses in 4.Increasing fuel economy improvement is in general in the order: SAE lOW-40 < SAE low40 < SAE 5W-30, providing that base stock and additive systems are unchanged.
A new liquid-solid chromatography method, using a two-stage silica gel, was upplied to the separation of nine paraffinic base stocks into hydrocarbon salurates and aromatics, and pohr fractions. The buse stocks of various crude origtn and refining process were tested fur their tribological performance i n the elastoI~ydrodynamic regime and in the boundary regime.Two existing methods of calculation of viscosity-pressure coefficientr, one bmed on chemical composition and the other on physical pro/)erlie.s, indiccite that the former compares better with experimental cluta. I n wear testing, urlformulated buse stocks behaved like their aromcitic fraction or saturate fraction depending upon cncde origin, processing, separation method, and test conditions. Solventextracted bu. se stocks of high polar content showed stable friction, whereus hydrotreated hue stocks with low polar content showed tm~uition to kigh friction within a typical temperature range. Most sciturnte fractions showed average wear rates and stable friction, wlzereu.~ the aromatic fractions separated from mild hydrotreated bme stocks showed higher wear rates and unstable friction.
Nine nominal 100 neutral base stocks, comprising a wide range of crude origzns and refining processes, were separated via silica gel chron~atograplty into aromatic, saturate, and polar fractions. These tiydrocarbon and polar fractions, along with their mixtures were evaluated for wear chumcteristics in steellsteel reciprocating point t?-ibocontact at 2 5 and I OO°C temperatures.Overcdl, the saturate fractions gzve lower wear rates than their parent bccse stocks and the aromatic fractions. Increased refining of brrse stocks, as measured by decreasing polar or sulfur contenb, i s seen to deteriorate the wear characteristics of the aromatic fractior~s, whereas the saturate fractions are not affected much. Aromaticlsaturate mixtures, especially tltose front some model compou?uLs, exhibit synergistic effects for wear. Polar compounds extracted from solvent extmcted stock.. increase wiur but decrease friction, especially at higlt concentration.All test clata are analyzed and discussed with emphasis on the injlueitce of base stock chemical composition and structure of compounuk on wear characteristics.
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