Infrared thermography and PIV have been used to investigate the flow and heat transfer of quasi-annular jets. The principal parameter studied is the blockage ratio corresponding to the ratio of the inner diameter over the outer D_int/D. The mass flow rate has been taken constant between the different configurations for comparison purpose and a circular jet have also been studied for reference purpose. Results show that the presence of inner diameter create inner shear layer structures that are bring below the jet main flow causing an increase in heat transfer rate. Moreover, higher blockage ratio also increase the ambient air entrainment into the jet before impingement. Finally, taking into account both heat transfer rate and pressure drop, an optimum blockage ratio has been determined.

红外热成像和 PIV 已被用于研究准环形射流的流动和传热。研究的主要参数是堵塞比，对应于内径与外径 D _int /D的比率。出于比较的目的，不同配置之间的质量流量已被视为恒定，并且还研究了圆形射流以供参考。结果表明，内径的存在产生了内部剪切层结构，该结构低于射流主流，从而导致传热速率增加。此外，较高的阻塞率还增加了在撞击之前进入射流的环境空气。最后，考虑到传热率和压降，确定了最佳堵塞比。