Mechanism of periodical dryout under oscillatory flow condition

Critical Heat Flux (CHF) is a very important design factor of boiling systems. Many investigations have been conducted so far, but almost all these investigations were conducted under steady flow conditions. CHF was strongly influenced by flow condition, and the reduction of CHF under unsteady flow oscillation was more than 60% compared with the CHF value under steady flow condition. In this investigation the CHF experiment was conducted by using the boiling channel equipped with a mechanical flow oscillator. The experiment was conducted under upward, downward and horizontal flow conditions. The superimposed flow oscillation included the strong flow reversal condition at the tube inlet, and the oscillation period was 2--6s. The simulation based on the lumped-parameter model and the calculation using the Mini-TRAC code developed by JAERI was also conducted. These simulation methods interpreted the experimental results reasonably