Научная визуализация, 2021, том 13, номер 3, страницы 82 - 92, DOI: 10.26583/sv.13.3.09

Computer Visualization of Turbulent Parameter Fields in a Round Jet Based on Laser Doppler and Fiber Optics Measurements

Автор: V.I. Smirnov¹

National Research University "MPEI"

¹ ORCID: 0000-0002-3047-988X, smirnovvi-mpei@yandex.ru

 

Аннотация

Based on local laser Doppler and fiber-optic anemometric (LDA and FOA) measurements, a computer visualization of the fields of turbulence parameters in an axisymmetric submerged fluid jet flow at Reynolds number 15,000 was performed by the parametric identification method. The scheme of the FOA measurement, the instrument function of the FOA and the problem of its elimination are considered. Formulas for calculating the first four moments of the two-dimensional probability density of turbulent pulsations of the local velocity are given, taking into account instrument distortions. Simple parametric models are proposed to describe the fields of turbulence parameters in an axisymmetric jet flow. On this basis, the patterns of the average velocity field, the turbulence intensity field, and the shear stress field are reconstructed. Estimates of the coefficients of asymmetry and kurtosis of the probability density function of the local velocity are obtained based on calculations of the higher statistical moments of turbulent pulsations of the local velocity. The results of measurements of the coefficients of asymmetry and kurtosis indicate deviations of the velocity pulsation statistics from the normal law, even for axial regions at long distances from the nozzle. This may be due to the presence of coherent vortex structures in the flow and intermittency. In the peripheral areas, return flows can also affect, caused by the peculiarities of the geometry of the cuvette and its final dimensions. The presented results of quantitative visualization allow us to calculate the energy dissipation and other integral characteristics of the flow.

 

Ключевые слова: laser measurements, turbulent flow, round jet, computer visualization, fields of turbulence parameters.