The Effectiveness of Drag Reducer Agents in Turbulent Two Phase Flow

إنجليزية
number: 
2115
Degree: 
Author: 
Naeem Abdulmohsin Ismael Alhilo
Supervisor: 
Prof. Dr. Jabber Shanshool
Asst. Prof. Dr. Adil A. Alwan
year: 
2008

It is well known that the addition of small amount of polymer to a turbulennewtonian fluid flow can result inreduction  of drag forces, which has received considerable attention in anumber of liquid flow fields. Althoughthe dragreduction effect of polymers have been well investigated in singleliquid turbulent flow, while little works are done concerning the reduction odrag forces in twophase liquidgas flows. The present work represents an experimental study odragreduction performance of thewater soluble XG as polysaccharidepolymer in both water as single phase as well as in twophase,waterair turbulent flows. The essection used consisted of a 1.2 m lengthperspex tube to visualize the type offlow. Various concentra ons of XGaddi ve up to 100 ppm, at 40 16L/min water and 1020 L/min air flowrates were considered,theinvestigation. The results show that the drag reduction with XG additive in twophase flow are significantly higher than in single phase in a whole liquid flow rates. Thus, dragreduction increases as air flow rate increase eaching a maximum value at 15 L/min air flow. While at 20 L/min air flow rate results a low dragreduction effectiveness. The dragreduction ability in  airwater, twophase turbulent flow was noticeable even though in sence of polymeric additive. The dragreduction attributed to the formation of microbubbles, which reduce significantly  the drag forces in turbulent flow. At 20 L/min air flow, the flow regime approaches bubbleplug flow by damping the formation of microbubbles as it was visible through the perspex tube. Experimental work was devoted to investigate the performance of XG as drag reducer agent in airwater flow with existence of small amounts, up to 2.0 wt % of sodium chloride in water.The presence of up to 2.0 wt % NaCl in two phase flow enhances the dragreduction behavior at low degree of turbulence, 40 80 L/min liquid flow rates, leading to an increase of percentage dragreduction. It was noticed that the presence of salt cause to high degree of foaming which was easy noted through the perspex tube.These micro foams enhance the dragreduction performance. While,at water flow rates above 100 L/min less foaming was noted. Thus, the dragreduction decreases gradually with increasing of the concentration of salt. XG additive  demonstrate desirably high dragreduction efficiency in airwater twophase turbulent  flow, while undesirable mechanical molecular degradation progressed occurs  as circulation time.
 




 

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