E102 加熱面の振動が冷却限界及び沸騰気泡挙動へ及ぼす影響に関する研究(OS9 熱流動)

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Critical heat flux -CHF- on subcooled flow boiling under vibration conditions, focusing on liquid velocity, acceleration and frequency of vibrations was investigated experimentally. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.3 to 3.9 m/s at O.lOMPa. The liquid subcooling was 20K. The acceleration was 0.4, 1.3 and 4.15 m/s^2, respectively; the frequency was 2, 4 and 20 Hz, respectively. The vibration directions were horizontal and vertical to orientation of the heater. The present experimental results showed that critical heat fluxes under the vibration conditions of both vibration directions, i.e., horizontal and vertical vibrations to the heater, were higher than those for steady flow. The CHF under the vibration condition was increased with an increasing of acceleration of vibration. According to present observations, coalesced bubble on the heater was frequently released by vibration of the test heater: the characteristic length of coalesced bubble decreased. This behavior caused the CHF to become higher under the vibration condition.
2009-06-28