缸盖冷却水腔内沸腾临界热流数值模型

Numerical Model of Boiling Critical Heat Flux in Cylinder-Head Water Jacket

为了提前预测发动机缸盖冷却水腔内沸腾临界热流点的位置,拓展沸腾换热使用范围,基于分区渐进沸腾传热模型并联立临界热流气泡聚集模型,建立一适用于分析判断冷却水腔内部复杂几何流道的沸腾临界热流数学模型,最后制定了一评估沸腾传热安全系数.将其应用于6缸车用天然气发动机缸盖冷却水腔内完成流固耦合沸腾传热数值计算,结果表明:使用该计算模型能够描述出水腔内的沸腾传热过程,其计算温度场与试验测量结果吻合较好;同时能够判断出冷却水腔内部各区域沸腾状态分布情况,提前预测沸腾传热恶化临界点位置,为缸盖冷却水腔内实现合理利用沸腾传热提供理论依据.

To forecast the position of boiling critical heat flux point in the cooling water jacket of engine cylinder head, and to expand the usable range of boiling heat transfer, a numerical mathematical model was established to analyze and evaluate the boiling critical heat flux of the complicated geometrical chan- nels in the cooling water jacket of cylinder head based on the partition and progressive boiling heat transfer model combining with bubbles aggregation model of critical heat flux. A safety coefficient was formulated to evaluate the boiling heat transfer. The model was applied to the cooling jacket of six-cylinder engine cylinder head and made the numerical calculation with fluid-solid conjugate boiling heat transfer method. Research result shows that calculation model can describe the boiling heat transfer process of water jacket. The calculated temperature field agrees well with experimental measurement. Meanwhile, distribution of boiling state in all areas of cooling jacket can be understood, through which the position of critical point of boiling heat transfer deterioration can be forecasted in advance. Theoretical study provides guidance to structural design of cooling water jacket of cylinder head.