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为了探讨精密铸造涡轮叶片内部表面粗糙度对冲击换热特性的影响,数值模拟研究了粗糙度分别为0μm,10μm,20μm,30μm,冲击雷诺数为1×10~4~5×10~4,大、小两种尺度的双层壁结构靶面换热系数。采用瞬态液晶技术测量了大尺度模型粗糙度为0μm时靶面换热系数。结果表明,大尺度光滑靶面换热系数数值模拟结果和实验数据吻合较好。两种尺度的光滑壁面换热系数经无量纲处理后基本相同。粗糙度增加使小尺度靶面换热系数增大,冲击雷诺数越大,粗糙度对换热系数影响越明显,冲击雷诺数从1×10~4增加到5×10~4,相比于光滑靶面,粗糙度为30μm时平均换热系数提高了6%~48%。粗糙度对大尺度靶面换热系数影响非常小。
In order to investigate the influence of internal surface roughness of precision casting turbine blade on impact heat transfer characteristics, the effects of roughness on the impact heat transfer characteristics were studied numerically. The roughness was 0μm, 10μm, 20μm and 30μm, the impact Reynolds number was 1 × 10 ~ 4 ~ 5 × 10 ~ 4, Large and small scale double-wall structure of the target surface heat transfer coefficient. Transient liquid crystal technology was used to measure the heat transfer coefficient of target surface when the roughness of large-scale model was 0μm. The results show that the numerical simulation results of large-scale smooth surface heat transfer coefficient are in good agreement with the experimental data. The two types of smooth surface heat transfer coefficient are basically the same after dimensionless treatment. Roughness increases the heat transfer coefficient of small target surface increased, the impact Reynolds number is larger, the roughness of the heat transfer coefficient more obvious impact Reynolds number from 1 × 10 ~ 4 to 5 × 10 ~ 4, compared to Smooth surface, the average roughness of 30μm heat transfer coefficient increased by 6% to 48%. Roughness has a very small effect on the heat transfer coefficient of a large scale target.