Abstract In the present study, swirling coaxial confined impinging turbulent air jets issuing from a novel designed nozzle is studied experimentally. Heat transfer characteristics and pressure distribution on the impingement plate are analyzed. Experiments have been conducted at different dimensionless nozzle-to-plate distances (H/D = 0.5, 1.0, 1.5, 2.0 and 2.5) and dimensionless flow rates (Q∗ = 0.25, 0.50 and 0.75) for a constant total flowrate of 1.33 × 10−3 m3 s−1 (80 L/min). The results show that the flowrate ratio improves the uniformity of the heat transfer through the impingement surface and increases the average Nusselt number. Also, the intensity of convective heat transfer is shown to enhance significantly with decreasing nozzle-to-plate distance. With regards to the pressure distribution, subatmospheric regions occur on the impingement plate. Contribution of swirl is also compared against the pure circular impingement jet condition (Q∗ = 0.0).

中文翻译：

---

旋流同轴约束撞击空气射流传热特性及壁压分布的实验研究

摘要 在本研究中，实验研究了从新型设计的喷嘴发出的旋流同轴约束撞击湍流空气射流。分析了冲击板上的传热特性和压力分布。已在不同的无量纲喷嘴到板距离（H/D = 0.5、1.0、1.5、2.0 和 2.5）和无量纲流速（Q* = 0.25、0.50 和 0.75）下进行了实验，以获得 1.33 × 的恒定总流速10−3 m3 s−1（80 升/分钟）。结果表明，流量比提高了通过碰撞表面的传热均匀性并增加了平均努塞尔数。此外，对流热传递的强度显示出随着喷嘴到板距离的减小而显着增强。关于压力分布，亚大气压区域出现在撞击板上。漩涡的贡献也与纯圆形冲击射流条件（Q* = 0.0）进行了比较。