Churn Flow – Vertical Tubes
Churn flow, also referred to as froth flow is a highly disturbed flow of two-phase fluid flow. Increasing velocity of a slug flow causes that the structure of the flow becomes unstable. The churn flow is characterized by the presence of a very thick and unstable liquid film, with the liquid often oscillating up and down. Due to its nearly chaotic properties, it is one of the least understood of gas-liquid flow regimes.
A typical example of churn flow is boiling flow in nuclear reactors during accidents. Especially for many accident scenarios, boiling may lead to high void fraction including churn-turbulent flow. Its flow structure and induced pressure changes may have a strong impact on the safety.