DNSを用いた壁面に衝突する開花噴流の流動・伝熱特性

抄録

Impinging jet is widely used for cooling industrial applications such as electric devices, blades of gas turbine, hot steal, etc. It is characterized by high performance of heat and mass transfer rate in stagnation region. Nevertheless, heat transfer rate drops sharply at the position distant from the stagnation point, thus it is required to lead the nonuniform distribution of heat transfer rate to be uniform. In the industry, multiplexing with many nozzles are used, however, nonuniformity of heat transfer still occurs. Therefore, the viewpoint of new jet control is required in order to further improvement of the uniformity of heat transfer. On the other hand, blooming jets occur with superimposition of axial and helical excitations on the inlet velocity profile. Blooming jets are characterized by vortex rings moving along branches of separate streams. In previous studies, it is observed that blooming jets change its flow pattern with different frequency ratio of axial to helical, and its mixing and diffusion characteristics. Thus, there are no studies that observe heat transfer performance of the blooming jet. In this study, we conduct a direct numerical simulation of blooming jet that impinges upon the wall, and investigate its flow characteristics and heat transfer performance. Compared to the uncontrolled jet, it is confirmed that the uniformity of heat transfer is improved, suggesting that the blooming jets can be expected to be useful for the improvement of uniform heat transfer performance of impinging jets.