الفهرس | Only 14 pages are availabe for public view |
Abstract This research is to study the heat transfer characteristics of jet impinging hot circular cylinder. Cooling is designated to be under single and triple jets. The effects of initial specimen temperature, cooling water temperature, jet velocity, and jet diameter and jet height are examined. Experimental and numerical investigations have been conducted for quenching of a hot cylinder with initial temperature of 300 to 400 oC by a subcooled water jet. Water is injected perpendicularly on cylinder circumference via a round jet. Jet diameters of 3 and 4mm are examined. Injected water temperature is controlled to cover range of subcooling from 20oC to 60oC. An original experimental device allowing the measurements of metal temperature variation with time inside the specimen is used. The distance between the jet and outer cylinder surface is 5 and 10cm. The water velocities are 4 to 8m/s. A numerical model is used to verify the experiments results. Heat fluxes and surface heat transfer coefficients are represented. In reference to the results, the transition from film boiling to nucleate appears clearly, before reaching the forced convection stage. The present work is focused on studying the parameters that affect the cooling rate of cylindrical steel specimens, and thus affect the steel hardness. As coming in next chapters, the effect of initial surface temperature, water flow rate, number of jets and water temperature will be examined. The study quantifies the effect of changing |