Homogeneous flow regime

The initial steady state of flow is the homogeneous flow regime (i.e., the uniform bubbly flow regime) and is represented by the following equations At time 1 = 0 ... 

The homogeneous flow regime can be maintained as long as the LHS of Eq. (183) is less than the RHS. For the aspect ratio (h = H/D) > 1 the RHS is a constant quantity. The LHS depends on the design of the gas sparger and the physical properties of the liquid. The role of these parameters will now be discussed systematically. 

Bubble formation and orifice activity are two important factors determining stability. Synchronous bubble formation, where almost all holes are active instantaneously, tends to produce a uniform bubble and gas holdup distribution. The uniform bubble distribution leads to a more stable homogeneous flow regime, less liquid recirculation, and higher gas holdup and gas-liquid mass transfer. Asynchronous orifice operation is often accompanied by alternating or oscillating orifice activity, which leads to flow instability. The instability creates more bubble-bubble interaction and leads to lower gas holdup and gas-liquid mass transfer. Hence, the gas distributor affects the critical superficial gas velocity at which the transition regime is detected. 

Superficial gas velocity at which flow transitions out of the homogeneous flow regime into the transition flow regime... 

Krishna, R., van Baten, J.M., and Urseanu, M.I. (2001), Scale effects on the hydrodynamics of bubble columns operating in the homogeneous flow regime, Chemical Engineering Technology, 24(5) 451-458. 

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