Abstract
An experimental investigation of a laminar-turbulent transition in a round jet flowing from a cylindrical tube with a diameter of 3.2 mm have been carried out. The range of Reynolds numbers in the experiments Re = Ud / v were of 700-12000. The measurements have been carried out via the PIV system. The profiles of average velocities and their pulsations in the laminar-turbulent transition zone have been obtained, as well as axial distributions of the longitudinal velocity and longitudinal velocity pulsations. Based on a comparison with the data of other authors, the effect of the initial conditions on the laminar-turbulent transition in a submerged jet has been shown.
Highlights
An experimental investigation of a laminar-turbulent transition in a round jet flowing from a cylindrical tube with a diameter of 3.2 mm have been carried out
The modern development of MEMS (Micro-Electro-Mechanical-Systems) technologies stimulated the study of microhydrodynamics of near-wall and jet streams
The flow regime in micro-devices is laminar or transient, which contributed to the revival of interest in currents at low Reynolds numbers
Summary
The modern development of MEMS (Micro-Electro-Mechanical-Systems) technologies stimulated the study of microhydrodynamics of near-wall and jet streams. The flow regime in micro-devices is laminar or transient, which contributed to the revival of interest in currents at low Reynolds numbers. It is known that jets are unstable at Reynolds numbers Re = 10-30 [1], the transition to turbulence occurs at significantly higher values of Re = 30-2000 [2, 3]. Gas jets that flow from profiled nozzles and at large Reynolds numbers Re> 104 are studied. It is known that the initial conditions significantly have a great influence on the dynamics of flow development in the jet. A laminar-turbulent transition occurs in the jet flowing from the nozzle and from the cylindrical channel. This is due to the difference in the initial velocity profiles. Works with investigation results of jets that flow from long channels is practically absent in the literature, such cases are often encountered in practice
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