Periodic vortex shedding phenomenon for various separation distances between two plane turbulent parallel jets. (August 2016)

• Record Type: Journal Article
• Authors: Mondal, Tanmoy; Das, Manab Kumar; Guha, Abhijit
• Is Part Of: International journal of heat and mass transfer. Volume 99(2016:Aug.)
• Page Start: 576
• Page End: 588
• Publication Date: 2016-08
• Subjects: Two plane parallel jets -- Unsteady RANS -- Periodic vortex shedding -- Strouhal number; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.03.095
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Unsteady flow characteristics are investigated for various separation distances between two plane parallel jets. Near flow field demonstrates a von Kármán vortex street when the ratio of separation distance to the jet width lies in the range d / w = 0.6–1.4. When d / w = 0.5 and 1.5, the near flow field remains steady. Within the range 0.6 ⩽ d / w ⩽ 1.4, Strouhal number decreases with increasing d / w . Abstract: In the present study, two plane parallel jets with various separation distances between the two jets ( d ) are numerically simulated using two-dimensional unsteady RANS equations. The Reynolds number based on the jet width w is Re = 10, 000. The results reveal that when the separation distance between the two jets lies in the range 0.6 ⩽ d / w ⩽ 1.4, the flow field demonstrates a periodic vortex shedding phenomenon close to the nozzle plate similar to what would be expected in the near wake region for flow over a two-dimensional bluff body. On the contrary, for d / w = 0.5 and 1.5, the near flow field region remains to be steady with two counter rotating stable vortices in the recirculation zone. Within the range 0.6 ⩽ d / w ⩽ 1.4, the time series of streamwise and transverse velocity signals display a pure sinusoidal oscillation. In this range, for a given d / w, the fast Fourier transform of both the velocity signals exhibits a single dominant frequency peak at a same value of Strouhal number (non-dimensional vortex shedding frequency) that gradually decreases with the progressive increase in the separation distance between the two jets.