污垢沉积影响叶片表面换热的研究

选用了两个实际透平叶片MARKⅡ静叶和某高压透平静叶,前者为光滑叶片,后者为表面覆盖有圆台的粗糙表面叶片.利用CFD数值模拟技术对叶栅流道特性和叶片表面换热分布进行数值模拟计算,数值计算结果与实验结果对比验证了数值方法的可靠性.研究表明,准确预测转捩位置和选取合适的y+值是计算叶片表面换热特性的关键,剪切应力输运(SST)转捩模型预测的结果最令人满意.在粗糙叶片表面数值计算中,对表面粗糙度模型进行验证,然后详细分析了污垢沉积对叶片表面换热的影响.结果表明:随着叶片表面粗糙度的增大,叶片近壁面湍流增强,叶片的表面传热系数增大. 

Research of fouling deposition influence on heat transfer of blade surface

Two turbine blades, the MARKⅡ vane and a high pressure turbine vane, were chosen in the study. The former blade surface was smooth and the latter was rough, covered with evenly spaced truncated cones. The CFD numerical simulation technique was used to calculate the cascade characteristics and blade surface heat transfer distribution. The reliability of the computational method was validated by comparing the calculated results with the experimental data. The results show that accurate prediction of the transition location and appropriate y+ value are key to calculate the heat transfer characteristics of the blade surfaces. The predicted results by using the shear stress transport(SST)transition model are most satisfactory. In the calculation of rough blade, the roughness model was verified and then fouling deposition effects on heat transfer characteristics were analyzed in detail. It is shown that the heat transfer coefficient on the rough blade surface is enlarged with the increase of surface roughness, due to the enhancement of near-wall turbulence.