Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 11, 2022 - September 14, 2022
In this study, in order to observe and investigate characteristics of heat transfer phenomena of round impinging turbulent jet in a finite circular vessel, DNS of turbulent heat transfer phenomena is conducted. Also, LES is carried out to evaluate predictions of LES in such heat transfer phenomena as compared with DNS result. As the result of evaluation, predictions of LES almost give good agreements with DNS results, but the slight differences in thermal field can be found near the stagnation point. On the other hand, to reveal an effect of impingement distance giving influence to heat transfer phenomena, turbulent statistics, structures and heat transfer mechanism in round impinging turbulent jet are investigated in detail, in which the effect for turbulent heat transfer on the impinging wall can be clearly found. However, similar local Nusselt numbers at the stagnation point are obtained in both the cases of H/D = 2 and H/D = 4. Concerning the reason for obtaining similar values, it is found that the distributions of temperature and the wall-normal turbulent heat flux near the impinging wall are related, in which the wall-normal turbulent heat flux remarkably affects in the case of H/D = 4. As for the efficiency of heat transfer, the wall friction coefficients in all cases are larger than the Nusselt numbers around the point taking the maximum value of friction coefficient. Thus, it is found that the effective heat transfer rate is mainly obtained around stagnation point.
