Similarity scaling of the axisymmetric turbulent jet

TL;DR

This study demonstrates that an axisymmetric turbulent jet exhibits self-similarity in its fully developed region, with statistical functions collapsing onto a single scale based on downstream distance, supported by detailed laser Doppler measurements.

Contribution

The paper provides the first detailed measurements of multiple statistical functions in an axisymmetric turbulent jet and shows they can be scaled with a single geometrical factor.

Findings

Statistical functions collapse onto a single scale with downstream distance.

Laser Doppler measurements confirm self-similarity in the jet.

Comparison with a jet model supports the scaling behavior.

Abstract

In the current work, we find that a free axisymmetric jet in air displays self-similarity in the fully developed part of the jet. We report accurate measurements of first, second and third order, spatially averaged statistical functions of the axial velocity component performed with a laser Doppler anemometer, including in the outer (high intensity) regions of the jet. The measurements are compared to predictions derived from a simple jet model, described in a separate publication, and we discuss the implications for the further study of self-similarity in a free jet. It appears that all statistical functions included in this study can be scaled with a single geometrical scaling factor -- the downstream distance from a common virtual origin.