衝突噴流冷却中の高温面の非定常冷却伝熱 : ウェッティング速度と表面熱流束・表面温度分布の測定 : 熱工学,内燃機関,動力など

概要

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An experimental study of transient heat transfer during cooling of a hot cylindrical block with an impinging water jet has been done at atmospheric pressure. The internal block temperatures and the radius of wetted region were measured for the following conditions : a fixed initial block temperature of 250℃, a degree of subcooling of 20-80 K, a jet velocity of 5=15 m/s, a fixed nozzle diameter of 2 mm and three block materials of copper, brass and carbon steel. Heat transfer on the surface consisted of single-phase convective heat transfer, annular nucleate boiling and film boiling. The radius of the wetting front, which bounds the nucleate boiling region and the dry region, was well correlated with a power function of time. The maximum heat flux along the radial direction occurred on the moving nucleate boiling region. It also compeared with the critical heat flux at steady state. In the case of a good heat conductor such as copper which is capable to supply enough large heat to the surface, the maximum heat flux was comparable with the CHF. Reversely that for a poor amount of conductor was significantly limited below the CHF.
2001-08-25