Pressure loss and heat transfer characteristics experiment of swirling impinging jet with different shape nozzles
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摘要: 提出了一种旋流喷嘴,即圆孔内径设有四条螺旋槽道的类螺纹孔喷嘴。实验对比研究了同一螺旋角下三类旋流喷嘴(插件、内置扭转带、导叶片)与螺纹孔喷嘴在雷诺数为6000、12000下靶面传热特性。分析了各喷嘴对应的气源室压力与流量系数。实验结果表明,螺纹孔喷嘴在靶面的中心区保持了高的传热效率,驻点努塞尔数比其他三种喷嘴高出29.7%~43.3%,当射流空间受限时(半封闭空间)所有喷嘴的努塞尔数下降了40%~60%,内置插件喷嘴下降幅度最大;另外,四种旋流喷嘴中,内置插件喷嘴的气源腔室压力最大,比最小的螺纹孔喷嘴高出一个数量级还多,压力损失系数的分析表明螺纹孔喷嘴的压力损失系数最小,仅是内置插件喷嘴的1/4左右,且雷诺数增大一倍,内置插件喷嘴的压力损失系数平均下降14%,下降幅度最大。Abstract: A type of swirl nozzle, i.e., a threaded hole nozzle with four spiral grooves on the diameter of the hole was proposed. The heat transfer characteristics of the three kinds of swirl nozzles (insert, built-in torsion belt and guide vane) with the helical hole nozzle at the same helix angle when the Reynolds numbers were 6000,12000 were investigated. The pressure and flow coefficient of the air supply chamber corresponding to each nozzle were analyzed. The experimental results showed that the spiral hole nozzle had a high heat transfer efficiency in the central area of the target surface, and the stagnation Nusselt number was 29.7%-43.3% higher than the other three nozzles. When the jet space was limited (semi-enclosed space), the Nusselt number of dropped down by 40% to 60%, and the built-in plug nozzles had the largest drop. In addition, the four kinds of swirl nozzles had the largest air supply chamber pressure of the built-in plug nozzle, one order of magnitude higher than the smallest screw hole nozzle. The analysis of the pressure loss coefficient showed that the pressure loss coefficient of the nozzle hole was the smallest, only about 1/4 of the built-in plug nozzle, the Reynolds number was doubled, and the pressure loss coefficient of the built-in plug nozzle dropped by 14% on average.
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