Combined effects of groups of vortices generated by a pulsating turbulent plane jet impinging on a semi-cylinder: Effects of the forcing frequency

• Published in: International journal of thermal sciences 2018-11, Vol.133, p.273-283
• Main Authors: Kharoua, Nabil, Nemouchi, Zoubir, Khezzar, Lyes, Alshehhi, Mohamed
• Format: Article
• Language: English
• Subjects: Forcing frequency; Impinging jet; Large Eddy Simulation; Pulsating jet; Steady jet
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2018.07.019

A submerged pulsating plane turbulent jet was simulated using Large Eddy Simulation at different forcing frequencies. Based on a previous work, interesting phenomena, related to the interaction of coherent primary vortices with the dynamical and thermal fields along the target curved wall, were elucidated for a forcing frequency equal to 600 Hz. As a systematic continuation, the present work extends the study to the effects of more forcing frequencies. The main objective remains the same which is investigating the time-dependent responses of Nusselt number, friction coefficient and pressure profiles to the passage of the coherent structures along the curved impingement wall. The distance s, along the target wall, is measured from the impact point and normalized by the jet exit width W. It was found that for a forcing frequency equal to 200 Hz, coherent forced primary vortices induced by the pulsations are separated by less organized vortices naturally induced as in the unforced jet. The results showed clearly that the natural vortices have moderate effects on the boundary layer development on the impingement surface starting at relatively short distances from the stagnation point, s/W