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采用竖直窄缝通道内功率阶跃分布下的临界试验结果对非均匀加热临界预测模型进行验证。模型所预测临界触发位置、临界热流密度(CHF)及临界对应平均热流密度与试验结果的偏差均在合理范围内。采用该非均匀加热临界预测模型开展功率阶跃下CHF的数值计算,分析阶跃功率比、阶跃长度以及阶跃位置对沸腾临界的影响:随阶跃功率比的增大,CHF基本呈线性增大,但临界触发时的平均热流密度逐渐降低;阶跃长度的增大使得CHF逐渐减小,同时触发时的平均热流密度逐渐逼近均匀加热下的CHF值;随临界触发区域向流道上游迁移,临界触发位置将脱离功率阶跃区域的后端迁移至流道出口,此时的CHF值及临界触发时的平均热流密度值均趋近于均匀加热下的CHF值。
The critical nonhomogeneous heating prediction model is verified by the critical test results under the step distribution of power in vertical narrow channel. The predicted critical trigger position, critical heat flux density (CHF) and the critical average heat flux density of the model are in reasonable agreement with the experimental results. Using this non-uniform heating critical prediction model, the numerical calculation of CHF under power step is carried out. The influence of step power ratio, step length and step position on boiling threshold is analyzed. As the step power ratio increases, CHF is almost linear , But the average heat flux decreases gradually when the critical trigger occurs. The increase of the step length makes the CHF decrease gradually, meanwhile the average heat flux density at the time of trigger gradually approaches the CHF value under uniform heating. Migration, the critical trigger position will move away from the back end of the power step region to the exit of the flow channel. At this moment, the CHF value and the average heat flux value at the time of critical triggering are close to those under uniform heating.