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KMID : 0371819980300030181
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Nuclear Engineering and Technology
1998 Volume.30 No. 3 p.181 ~ p.193
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Improvement of Liquid Droplet Entrainment Model in the COBRA-TF Code
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Ha, Kwi-Seok
Jeong, Jae-Jun/Sim, Suk Ku
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Abstract
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The COBRA-TF liquid droplet entrainment models have been assessed and improved through various experiments. The COBRA-TF code uses the Wurtz entrainment model in the film mist flow regime and the mechanistic model based on the critical Weber number and critical vapor velocity in the hot wall flow regimes, respectively. The Wurtz model has been replaced with the modified Sugawara model. The assessment against the experiments by Hewitt, Keeys, Yanai, and Whalley showed the modified Sugawara model better predicts the steam-water as well as the air-water experiments for the film mist flow regime. For hot wall flow regime, the COBRATF entrainment model was modified using two methods, one with an increased critical Weber number and the other with the Yonomoto´ s critical vapor velocity model. The modified models were assessed using the FLECHT-SEASET bottom reflood tests. The results showed that the Yonomoto model best predicts the quenching time whereas the local maximum rod temperature was not affected much.
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KEYWORD
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