Which description best characterizes churn flow?

Which description best characterizes churn flow?

• A. Slug flow is formed when gas bubbles coalesce into large Taylor bubbles that fill the pipe cross section, with liquid slugs in between.
• B. Churn flow is characterized by oscillatory, up and down motions of the liquid and a highly turbulent mixture of both phases.
• C. Annular flow occurs when gas is continuous and liquid forms a film around the pipe wall.
• D. Beggs and Brill is a two-phase pressure gradient correlation used for any pipe inclination.

Answer: (B)

Churn flow is a highly disturbed two-phase flow regime where gas and liquid are intimately mixed and constantly breaking apart and rejoining, leading to chaotic, turbulent motion rather than neat, organized patterns. The defining picture is liquid moving up and down in an oscillatory, turbulent mix with gas present throughout the flow, so both phases are continually intermingling rather than forming distinct slugs or a smooth film. That makes the description describing oscillatory, up-and-down liquid motion and a highly turbulent mixture the best fit for churn flow. Slug flow, by contrast, features large gas pockets (Taylor bubbles) separated by liquid slugs. Annular flow has gas flowing mainly in the core with a liquid film along the pipe wall. Beggs and Brill is a correlation for pressure drop, not a qualitative description of the flow regime.

Churn flow is a highly disturbed two-phase flow regime where gas and liquid are intimately mixed and constantly breaking apart and rejoining, leading to chaotic, turbulent motion rather than neat, organized patterns. The defining picture is liquid moving up and down in an oscillatory, turbulent mix with gas present throughout the flow, so both phases are continually intermingling rather than forming distinct slugs or a smooth film.

That makes the description describing oscillatory, up-and-down liquid motion and a highly turbulent mixture the best fit for churn flow. Slug flow, by contrast, features large gas pockets (Taylor bubbles) separated by liquid slugs. Annular flow has gas flowing mainly in the core with a liquid film along the pipe wall. Beggs and Brill is a correlation for pressure drop, not a qualitative description of the flow regime.