الفهرس 
Introduction and Review LiteratureOnly 14 pages are availabe for public view
 |  | from | 51 |  |  |
| | | from | 51 | | |
Abstract
The present study is an experimental investigation of the effects of two kinds of drag reducing polymer additives on the energy losses (frictional and secondary losses) in pipes and pipe fittings, as well as on the performance of sprinkler irrigation system. The experiments were conducted with dilute solution of a sodium carboxymethylecellulose polymer (CMC), and a polyacrylamide polymer (PAM). Wind tunnel experiments were also carried out to investigate the effect of adding a CMC polymer, on the evaporation rate of water droplets.
For all experiments, the present study showed that PAM solution reveals better results than CMC solution. The reason is substantially due to that PAM polymer has molecular weight much greater than CMC, and hence, much drag reducing capability. At same concentration of each polymer, the reduction in secondary losses, in general, is lower than the reduction in frictional losses. This is mainly due to the complex flow pattern through pipe fittings. However, it is well known that the frictional drag reduction increases by increasing polymer concentration; increasing Reynolds number; and decreasing pipe diameter. These parameters are also found to affect the secondary drag reduction in the same way. Beside these affecting parameters, it is found that the type of joining (smoothed or screwed joining) of pipe fittings, again, affected the amount of drag reduction.