Study of turbulent jets by means of PIV technique

Abstract

Turbulent jets have been always present in fluid-mechanic researches due to the large number of applications they have and to the presence of all the turbulence features on them. Thanks to the use of relative new non-intrusive techniques–such as PIV (Particle Image Velocimetry)-, the knowledge of turbulence in general, and turbulent jets in particular has increased. This work is focused on the assessment of both, the main characteristics of the turbulent jet and, at the same time, some significant PIV features. For that aim two experiments are proposed: -The first one, denominated “Spatial Resolution in PIV”, tries to determine the best position to place the digital camera that films the movement of the particles present in the jet, taking into account that we are interested on studying not only the microscales of the turbulent flow, but also the velocity field and the recovering of isotropy by evaluating the turbulent parameters (skewness, kurtosis, square mean derivative ratios,…). -In the second one, called “Effect of the Reynolds Number in Turbulence”, starting from the results of the first experiment, the behavior of the jet depending on the relationship between the inertia forces and the viscous ones is analyzed. To do this, three different zones along the jet and eight different Reynolds numbers are to be studied. This report is structured in four different chapters. The first one corresponds to a theoretical introduction to turbulence. In the second one the experimental setup is described after introducing the PIV measurement technique. The third one presents the results and carries out a deep analysis of them. Finally, in chapter four, the results are summarized obtaining some important conclusions and considering as well future challenges of the present work.