【摘要】 以乙醇为工作液体,对声空化作用下直径为20 mm的水平铜管的沸腾传热进行试验研究。试验中对空化强度及超声换能棒和试件间的距离进行测定。试验研究发现,声空化对过冷沸腾有显著强化作用;在核态沸腾区,声空化对沸腾起始区域的强化率最大,但是随热流密度的增加,强化率逐渐减小;当热流密度相等时,强化率随空化强度的增加而增大。声空化引起的液体的宏观湍动及由于声冲流的存在导致的边界层厚度的减薄,直接或间接地影响加热表面上气泡胚胎的生成、长大和脱离。更多还原

【Abstract】 A series of experiments are carried out to make clear the effects of acoustic cavitation on boiling heat transfer from a 20 mm diameter circular copper tube taking alcohol as working liquid.The cavitation intensity and the distance between the bottom of ultrasonic transducer and the test section are measured in experiments.The experimental research shows that sub-cooled boiling can be enhanced by acoustic cavitation.In the nucleate boiling region,maximum enhancement rate appears in the initiation region of boiling heat transfer,but the enhancement rate decreases with the increase of heat flux.The enhancement rate increases along with the increase of cavitation intensity when heat flux isn’t changed.Macroscopic turbulence of the liquid caused by ultrasonic cavitation and decrease of the thickness of boundary layer induced by acoustic shock wave can directly or indirectly influence bubble formation and growth and departure on the wall.更多还原