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A summary of key discoveries regarding the industrial applications of impinging jets on a vertical plate. The summary explores the link between the dynamics and heat transmission on one hand and the relationship between heat exchange and acoustic coupling on the other hand. The objective of this research work is to investigate the vortex dynamics and heat transfer mechanisms in impinging jets. The jet impingement technique finds widespread use in the industry, it serves purposes such as drying, cooling, and heating. The impinging jet system involves directing a fluid jet with high-velocity onto a surface. The jet impingement results in high heat exchange rates and mass transfer rates, making it an attractive technique in various industrial processes. To investigate these mechanisms, a combination of experimental and computational methods was used, including flow visualization and numerical simulations. The study of vortex dynamics in impinging jets is crucial for understanding the heat transfer mechanisms involved. The flow characteristics of impinging jets, such as the Reynolds number (Re) of the jet, the distance from the blowing mouth to the impinged wall, and the geometry of the blowing mouth, significantly affect the vortex dynamics and heat transfer rates. Therefore, optimizing these parameters can result in significant improvements in heat transfer efficiency. Several methods were proposed to enhance heat transfer, these methods can affect the flow dynamic, the surface of impingement, the nozzle’s shape and size, and the impingement parameters such as the impact distance and the jet angle. For example, investigations have identified that optimal heat transfer took place at an inclination angle between 40 and 90 degrees. In addition, studies have reported enhancement in heat transfer with diamond orifices that reached up to 17%. The key findings of this paperwork include the identification of optimal impingement parameters that maximize heat transmission rates and the understanding of the significant relationship between the dynamics of the flow and the acoustic emissions. For instance, studies showed that synthetic jets can enhance convective heat transfer by 3 times compare to natural convection. The correlation between the flow dynamic and the heat transmission on one side, and the flow dynamics and acoustic emission on the other side, emphasizes the researcher to present acoustic-thermal coupled studies on the impinging jet; this topic needs more effort to understand the relation between the two phenomena. The conclusion highlights the significance of previous findings in industrial applications, suggesting control mechanisms capable of reducing noise and enhancing heat transmission.

Impinging jets are found in many industrial applications and specifically in ventilation systems. Mostly, these jets are turbulent and under certain conditions can be a source of discomfort in closed areas due to the high level of noise it can generates. Therefore, it is very important to understand the flow dynamics that is responsible of generating the acoustic field in order to control and reduce such phenomenon. In this paper, an experimental study of a rectangular impinging air jet on a slotted plate is considered for three different Reynolds numbers producing self-sustaining tones (Re = 4100, 5100, and 5900). The sound pressure and spatial velocity field are obtained simultaneously using four microphones located at different locations and SPIV technique. Results show that Re = 5100 correspond to a critical regime where there is a significant drop in the sound pressure level (SPL) that reached 5 dB when compared to a lower Reynolds number Re = 4100. The flow dynamic analysis suggests that this drop in SPL could be contributed to the path followed by the large coherent structure at Re = 5100, where they are deviated in the transverse direction along the wall leading to low energy transfer from the dynamic field to the acoustic one. However, at Re = 4100 and 5900 the peak in SPL could be contributed to the two paths followed by the large coherent structures and particularly to the path where vortices hit the slotted plate before escaping through it. This path is responsible for the optimization of energy transfer from the dynamic field to the acoustic field. Moreover, at Re = 5900 the spectrogram of the instantaneous frequency and instantaneous flow dynamics results show that the acoustic frequencies (160 Hz and 320 Hz) are generated by symmetric and anti-symmetric modes respectively. This unusual aspect is related to the sudden changes in vortex mode.