Churn turbulent flow

Churn turbulent flow refers to a type of flow in which large and small bubbles coexist with varying rise velocities, resulting in an unsteady and highly chaotic movement. This type of flow is commonly observed in industrial units and appears frothy, with the direction of movement being unpredictable and changing frequently.From: Chemical Reaction and Reactor Engineering [2020], A Multiscale Approach Simulating Boiling in a Heated Pipe Including Flow Pattern Transition [2019]

Gas-Liquid Reactors

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Published in James J. Carberry, Arvind Varma, Chemical Reaction and Reactor Engineering, 2020

Sergio Carrà, Massimo Morbidelli

These parameters are affected by the column regime, which changes by increasing the upflow gas velocity as follows: Bubble flow, characterized by uniform flow of equally sized bubbles; it occurs approximately at Ug < 0.05 m/s (Fair, 1967a).Churn turbulent flow, where large and small bubbles are present with different rise velocities leading to an unsteady flow; it is the most common in industrial units.Slug flow, where the bubble occupies the entire column cross section; it occurs at large upflow gas velocity, with columns diameter, dc≲0.15 m. The a priori definition of the flow regime is difficult, since it is affected by many parameters, such as sparger type, physical properties, and velocity of the liquid phase. An approximate map of flow regimes is shown in Fig. 8.

A Multiscale Approach Simulating Boiling in a Heated Pipe Including Flow Pattern Transition

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Published in Nuclear Technology, 2019

T. Höhne, E. Krepper, D. Lucas, G. Montoya

The tendency to annular flow can be clearly seen. The churn-turbulent flow appears to be highly chaotic and frothy and may seem to move upward in some instances and downward in other instances. Also, in the annular flow regime at the end of the pipe, one may notice the existence of a gas core and a relatively uniform annular liquid film on the pipe wall as well as liquid slugs. The annular film moves mostly upward but occasionally may seem to pause. This pause occurs when a liquid slug fills the local cross section of the pipe, thus blocking the flow of gas in the core. Shortly afterward, however, the liquid slug gets penetrated by gas, and the upward annular-type flow is resumed.

Churn turbulent flow

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A Multiscale Approach Simulating Boiling in a Heated Pipe Including Flow Pattern Transition