From my experience flow regime maps can give only a rough idea; if you want to achieve a bubbly flow regime design your sparger cautiously. E.g. Harteveld from TU-Delft - his phd and papers are available in google scholar search - achieved bubbly flow regimes up to 50% gas void fraction with a sophisticated sparger, far off from any regime transition predicted by regime maps. Moreover, use coalescence inhibitors like NaCl if possible to avoid the formation of large bubbles that can initiate the regime transition.

Best wishes

Thomas

Dear sir, 

I think you are trying to achieve bubbly flow regime in two-phase flow.

In case of two-phase flow one can predict flow pattern with the help of 'Flow regime map' observed by different researcher, e.g.  Baker, Taitel & Dukler, Triplett  etc.

There are different flow regime map available based on channel diameter (micro,mini or conventional channel) its orientation & types of flowing fluids.

Flow regime purely govern by Gas & Liquid superficial velocity. Once you identify suitable flow regime map, you need to maintain particular combination of Gas-Liquid velocity range to achieve Bubbly flow.

May be above information helping you.

Dear friend, 

thank you for the reply. Ok,  i'am agree but the maps of  flow regimes can  change with operating conditions.

Dear Sir,

This is true that the flow regimes can change with operating or inlet flow conditions. But you can find the range of bubbly flow in terms of inlet flow conditions from developed flow regime map by various researchers. Within this range, you can keep bubbly flow constant. 

For example i attaching here one review paper. May be this will help to you a lot... 

From my experience flow regime maps can give only a rough idea; if you want to achieve a bubbly flow regime design your sparger cautiously. E.g. Harteveld from TU-Delft - his phd and papers are available in google scholar search - achieved bubbly flow regimes up to 50% gas void fraction with a sophisticated sparger, far off from any regime transition predicted by regime maps. Moreover, use coalescence inhibitors like NaCl if possible to avoid the formation of large bubbles that can initiate the regime transition.

Best wishes

Thomas

Dear sir,

I am agree with the above discussion. The following research paper may help you.

Regards

Article Dynamics of a Bubble Column: Influence of Gas Distribution o...

Ok, great thank to all my colleagues: Jignesh Thaker,  Thomas Ziegenhein, Giorgio Besagni, Muhammad Furqan Ali. I'am agree, but the bubble size depends on several parameters like: superfical tension, pressure, gas flow rate, diameter of tube, viscosity, etc. 

Dear Sir,

The above all discussions is true but for horizontal flow condition. In upward flow gravity also affects the flow which is also balance then you will get a constant flow regime. In this field many analytical articles are there which explains the effect of inclination angle (Taitel and Dukler (1976), K-H instability). As explain by Adel Queslati bubbly flow depends on several parameters. Shear stress and surface tension also affects the bubbly flow regimes. Due to gravity, the gravitational force (only for vertical or upward flow) affects the flow regime because heavier density fluid is flow against the gravitation (less density fluid is also flow against the gravitation but the gravitational force is more in heavy density fluid). Hence, surface tension, shear stress and pressure gradient affected the bubbly flow regime. Here, I have attached two paper one is for analytical method of vertical and horizontal flow and second for dynamics of flow-regime in bubbly flow.

Dear Dr. Sunny Sainy,

Thanks a lot for your detailed answer. With my best regards!

Adel

Agree with Thomas Ziegenhein