Abstract
A study of the mixing flows (Schmidt number = 103) in a cavitating Venturi tube that feature linear and swirling flows is presented in this paper. The Large Eddy Simulation (LES) turbulence model, the Schnerr–Sauer cavitation model, and the mixture multiphase model, as implemented in the commercial CFD ANSYS FLUENT 16.2, were employed. The main emphasis is spending on the influence of different inlet swirling ratios on the generation of cavitation and mixing behaviors in a Venturi tube. Four different inflow regimes were investigated for the Reynolds number Re = 19,044, 19,250, 19,622, 21,276: zero swirl, 15% swirl, 25% swirl and 50% swirl velocity relative to the transverse inflow velocity, respectively. The computed velocity and pressure profiles were shown in good agreement with the experiment data from the literature. The predicted results indicate that the imposed swirl flow moves the cavitation bubbles away from throat surfaces toward the throat axis. The rapid mixing between two volumetric components is promoted in the divergent section when the intense swirl is introduced. Additionally, the increase in the swirl ratio from 0.15 to 0.5 leads to a linear increase in the static pressure drop and a nonlinear increase in the vapor production. The reduction in the fluid viscosity ratio from μ2μ1=10 to μ2μ1=1 generates a high cavitation intensity in the throat of the Venturi tube. However, the changes in the pressure drop and vapor volume fraction are significantly small of pure water flow.
Highlights
A cavitating Venturi tube is a micro- and nano-sized bubble generator which consists of three sequential parts: a convergent section, a throat section, and a divergent section
We monitored the development of volume-averaged dimensionless velocity, , with the in dimensionless simulation time, tt∗, under different inlet swirling ratios and found a noticeable narrow peak in the profile within tt∗ = 0.08
An attempt is made for the first time to discuss the influence of different inlet swirling ratios (W/U = 0∼50) on the generation of cavitation and mixing behaviors in a Venturi tube
Summary
A cavitating Venturi tube is a micro- and nano-sized bubble generator which consists of three sequential parts: a convergent section, a throat section, and a divergent section. Due to their simple structure, the cavitating Venturi tubes have been widely used for industrial applications, such as wastewater treatment, oil and gas industrial, mineral processing, and mixing of fluids. The major advantages of using a Venturi mixer are the high level of mixing efficiency, low energy requirement and short mixing length [2]. Much attention has been paid to the Venturi tubes in the past decades and numerous investigations in predicting the cavitating and mixing processing have been conducted
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