Research On Numerical Simulation Method Of The Critical Heat Flux Of Water-cooled W/Cu Divertor

One promising and key path to realize controlled nuclear fusion is through a magneticallyconfined device which is called tokomak. In tokomak there is a key part called divertor which caneffectively eliminate the impurities and output energy. To ensure the divertor work reliably,water-cooled system is used because its high thermal load which is more than5MW/m2. In suchcases, the critical heat flux of divertor is one of the key design parameters because of its importanceon the safety of tokomak. The now CHF prediction method through empirical formula has a limitapplicable range, and it is very complexity and expensive to perform a CHF experiment.With the rapid development of computer technology, study the CHF of divertor throughnumerical simulation is an efficient way. However, the simulation method is not matured yet. Inorder to solve this problem, this paper mainly carries out the following researches:First, theEuler homogeneous boiling model was analyzed and modified based on thecharacteristics of divertor. Hertz-Knudsenformula was used to improve the calculation of water andstem transformation efficiency. At the same time, temperature-dependentphysical properties wereused. The results of model simulation were compared with experiment data from Ronald. Thecomparison shows that the calculation result of uncorrectedEuler homogeneous boiling model has anerror of about180%, and the error of correctedEulerhomogeneous boiling model reduced to20%.The calculation results of correctedEulerhomogeneous boiling model were analyzed in detail and itshowed that correctedEulerhomogeneous boiling model has the ability of simulating CHF ofdivertor.Afterwards, theEuler two-fluid boiling model was analyzed and modified based on thecharacteristics of divertor.Distribution function was used to solve its problem of unable to simulatethe film boiling, which means different calculate methods were used based on the mass quality ofvapor.The results ofuncorrected and corrected model simulation were compared. The result showedthat the uncorrectedEuler two fluid boiling model cannot simulate the film boiling effectively whilethe film boiling was successfully simulated by the correctedEuler two fluid boiling model. The CHFcalculated from correctedmodel is40%higher compared with experiment data from Ronald.Thecalculation results of correctedEulermodel were analyzed in detail and it showed thatcorrectedEulerhomogeneous boiling model has the ability of simulating CHF of divertor.Finally, the calculation results of corrected Euler homogeneous boiling model and corrected Euler two fluid boiling model were compared. It can be found: In view of the research range andresearch object of this paper, the Euler homogeneous boiling model has an error less than20%,while the Euler two fluid boiling model’s error is10%at high pressure(Pin=4.2Mpa) and40%at lowpressure(Pin=0.2Mpa);The Euler two fluid model is better at calculating the vapor distribution in thecross section and the heat transfer at wall section. After the sub-model of Euler two-fluid model iscorrected according to different working conditions, it will be better at simulating the CHF ofdivertor.