• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.1077-1085
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• 1997

The use of "clean fuels" such as butane, propane, and mixtures of these (LPG) is an attractive way to reduce exhaust emissions. In this study internal flow of the pintle type injector for LPG engine is studied. The breakup of liquid jet is the result of competing, unstable hydrodynamic forces acting on the liquid jet as it exits the nozzle. The nozzle geometry and up-stream injection conditions affect the characteristics of flow inside the nozzle, such as turbulence and cavitation bubbles. A set of calculations of the internal flow in a pintle type nozzle were performed using a two dimensional flow simulation under different nozzle geometry and upstream flow conditions. The calculation showed that the turbulent intensity and discharge coefficient are related to needle leading angle(.alpha.) and needle lift.edle lift.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.7-18
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• 2024

Because of their mineral composition, tire chips have very low thermal conductivity compared with natural geomaterials, leading to the use of sand-tire rubber mixtures in thermally insulating applications. However, systematic studies evaluating factors affecting the thermal conductivity of sand-tire rubber mixtures have been very limited. Thus, this study investigated the thermal conductivity of sand-tire rubber mixtures with varying size ratios and tire chip fractions according to the degree of saturation (S). Specimens were prepared in insulated cells, and thermal needle probe tests were performed. In addition, the contact angle and solid surface free energy of sand-tire rubber mixtures were investigated. The results of this study revealed that the thermal conductivity decreased with increasing tire chip fraction but increased with increasing water content (or S). However, the trend of increasing thermal conductivity with S varied with the tire chip fraction, and the specimens with tire chip fraction > 0.4 clearly showed a delayed increase in thermal conductivity with increasing S. This reflected that hydrophobic particles (tire chip) affected the dependency of thermal conductivity on S because of the delayed formation of capillary water bridges, which served as additional thermal conduction paths with increased moisture content.