【作者】 张泽远；

【导师】 张靖周；

【作者基本信息】 南京航空航天大学 ， 热能工程， 2006， 硕士

【摘要】 射流冲击是一种极其有效的强化局部传热或传质的方法。对于冲击-逆向对流-气膜复合冷却的火焰筒结构而言,火焰筒壁面冷气侧的冲击冷却实质上是半封闭通道的冲击冷却,即冲击射流从冲击孔板喷出,冲击到换热靶面后形成壁面射流沿通道单方向流出。本文的主要研究内容和结果如下:首先,对半封闭通道内单、双排孔射流冲击冷却进行了热像显示试验,总结了各种流动参数和几何参数对局部换热特性的影响规律。对于单排垂直射流,冲击冷却效果随射流雷诺数的增加、孔间距与直径比的减小而得到提高,冲击间距比为2时换热效果最好;冲击孔中心线向通道封闭一侧倾斜后,射流冲击冷却的范围变窄,当冲击间距比大于2时驻点区的对流换热能力明显降低;对于双排冲击射流,孔排间距与直径比的增加使冲击冷却范围变大,但在两排孔之间区域的对流换热系数有所下降;在较小的冲击射流雷诺数和较大的冲击间距比下,后排射流的冲击换热效果要逊于前排射流。其次,对半封闭肋化通道双排孔射流冲击冷却进行了热像显示试验,总结了各种流动参数和几何参数对局部换热特性的影响规律。冲击间距比对通道肋化部分的换热效果影响最大,在本文研究范围内,冲击间距比为1时肋化部分换热最好。通过对大量实验数据的分析和整理,建立了换热准则关系式,与实验结果对比表明:该准则关系式与实验实测数据吻合较好。最后,对单排、双排冲击孔试验板在半封闭通道展开了流量系数的研究,在变化各种几何因素及流动因素的情况下由实验得出了冲击孔流量系数值,讨论并分析了各种因素对流量系数的影响程度,建立了冲击孔流量系数的准则关系式,与实验结果对比表明:该准则关系式与实验实测数据吻合较好,精度较高,有较高的工程应用价值。更多还原

【Abstract】 Jet impingement cooling is an advantage method in heat transfer enhancement owing to its extremely high local heat transfer coefficient and simple structure. As regard as the combustor flame tube cooling structure is concerned, the impingement-converse convection-film composite cooling is an effective method, in this composite cooling structure, the impingement cooling problem could be modeled as impingement inside semi-confined channel. The main research contents are the following.The thermal visualizations of jet impingement cooling with single or double row holes inside semi-enclosed channel are measured by using infrared camera and then the impingement cooling heat transfer coefficients are deduced. The effects of flow and geometry parameters on convective heat coefficients are obtained. The results show that: for a single row normal impingement, the impingement cooling effectiveness is enhanced with the increase of impinging Reynolds number or the decrease of hole space to diameter ratio, and the best effectiveness is achieved under the jet-to-surface spacing equals to 2; when the jet is oblique to the confined wall, the cooling effectiveness is weaken especially under the jet-to-surface spacing ratio is greater than 2; for double rows normal impingement cooling, the cooling effectiveness of rear row jet is weaker than the front row under lower impinging Reynolds number or bigger jet-to-surface spacing. Then the thermal visualizations of jet impingement cooling with single or double row holes inside semi-enclosed ribbed channel are measured by using infrared camera and the effects of flow and geometry parameters on convective heat coefficients are obtained. The results show that: the impingement cooling effectiveness of ribbed surface is affected greatly by the jet-to-surface spacing, and the best effectiveness is achieved under the jet-to-surface spacing equals to 1. The correlation formulas of impingement heat transfer characteristics to the parameters are finally concluded and in good agree with the experiment data.更多还原