Chapter 5. About mechanism of origin and evolution of the
coherent structures in the laminar and turbulent round jet
The results of researches presented in presentation are published in the following
main articles:
1.
Kozlov G.V., Litvinenko Yu.A., Grek G.R., Sorokin A.M. About mechanism of the coherent structures origin and
downstream evolution in the laminar and turbulent round jets // Vestn. NSU. Seria: Physics. 2008. Т. 3. Vip. 1.
pp. 12–22, in Russian.
2.
Kozlov V.V., Grek G.R., Kozlov G.V., Litvinenko Yu.A. Physical aspects of subsonic jet flows evolution // The collection of
proceedings «Successes of mechanics of continuum» to the 70-anniversary of academician V.A. Levin, 2009. Dalnauka,
Vladivostok, pp. 331-351, in Russian
Scheme of the coherent structures development at initial region of the turbulent round
Jet: Guinevskiy А.S., Vlasov E.V., Karavosov R.K. Acoustics control by the turbulent
jets // Moscow: Nauka, 2001. pp. 1–239, in Russian (see, page of notes)
Scheme of the jet set – up and measurement and visualization
technique
Jet set - up scheme: 1 – Vitoshinsky nozzle; 2 – honeycomb; 3 – set of grids; 4 – settling
chamber; 5 – extension pipe of 150 mm; 6 – turbulizator; 7 –micromanometer; 8 –
smoke generator; 9 – video camera; 10 – dynamic loudspeaker; 11 – hot – wire probe;
12 – hot – wire anemometer; 13 – ADC; 14 – computer; 15 – fan.
General view of the jet set - up with the long channel of 150 mm
length.
General view of round jet set – up for the laminar round jet realization
General view of round jet set – up for the turbulent round jet realization
Smoke visualization patterns of the laminar round jet: а – general view of the jet; b –
streaky structures in the jet; c – transverse sections of the jet at different distances
from the nozzle exit downstream, U0 = 4 m/s (Re  U0  d / ν = 5300)
Smoke visualization patterns of the turbulent round jet: а – general view of the jet; b –
streaky structures in the jet; c – transverse sections of the jet at different distances
from the nozzle exit downstream; d – longitudinal section of the jet near at the nozzle
exit, U0 = 4 m/s (Re  U0  d /ν = 5300)
Mean velocity profiles of the laminar 1 and turbulent 2 round jet measured in transverse
direction at different distances from the nozzle exit (a–d, at x = 1, 2, 5 and 20 mm,
respectively), U0 = 4 m/s (Re  U0  d /ν = 5300)
Fluctuation velocity distributions of the laminar 1 and turbulent 2 jets measured in
transverse direction at different distances from the nozzle exit (a–e, at x = 1, 2, 5 and 20
mm, respectively). Fluctuation velocity distribution in transverse direction of the laminar
round jet (d , at x = 60 mm), U0 = 4 m/s (Re  U0  d /ν = 5300)
Distributions of the velocity fluctuations in transverse direction of the turbulent 1 and
laminar 2 round jet at different distances downstream from the nozzle exit (a – c, at x =
2, 5 and 20 mm, respectively), U0 = 4 m/s (Re  U0  d /ν = 5300)
Key points:
 Main features of the laminar jet instability including generation of the ring
vortices and their interaction with the longitudinal structures of perturbations
apply to the turbulent jet, as well.
 Quantitatively, almost the same response of laminar and turbulent jets to
external acoustic forcing at generation of the ring vortices is found.