2013 1(12)

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Pages:

42 - 47

Language:

RU

Ref.:

4


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2013_1(12)_8.pdf

 

 

AN EXPERIMENTAL INVESTIGATION OF LONGITUDINAL STRUCTURES IN JETS

Litvinenko M.V., Litvinenko Y.A., Kozlov V.V., Grek G.R.

Khristianovich Institute Of Theoretical And Applied Mechanics SB RAS, Novosibirsk, Russia


Citation:

Litvinenko M.V. An experimental investigation of longitudinal structures in jets / M.V. Litvinenko, Y.A. Litvinenko, V.V. Kozlov, G.R. Grek // Modern Science: Researches, Ideas, Results, Technologies. - Dnepropetrovsk: SPIC "Triacon". - 2013. - Iss. #1(12). - PP. 42 - 47


Keywords:

round jet; plane jet; plane wall jet; laminar flow breakdown; longitudinal structures; Kelvin-Helmholtz instability; smoke visualization; hot wire measurements


Abstracts:

Results of experimental investigations of the mechanisms of formation and downstream development of longitudinal structures in round, plane and plane wall jets by visualization methods and hot wire measurements are presented. The investigations were carried out under “natural” and controlled conditions. Stationary longitudinal structures were artificially generated by roughness elements located at the orifice of the nozzle. The influence of the Reynolds number and acoustic forcing frequency on the generation and the characteristics of the longitudinal structures in jets was investigated. The mechanism of interaction between two-dimensional Kelvin-Helmholtz instability and longitudinal structures, which is a three-dimensional distortion of the two-dimensional disturbances on the local inhomogeneities of the flow, was determined. This process leads to an appearance of the azimuthal “beams”, which are Λ – like structures. The mixing process of jets and surrounding air takes place in the region of the azimuthal Λ– structures tips, which leads to an expansion of jets and their downstream turbulent destruction. An acoustic forcing resulted in change of two – dimensional Kelvin – Helmholz vortices periodicity, their scales and intensification of mixing process of jets and surrounding air.


References:

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