Name: Kelvin Cristien de Oliveira Barbosa
Type: MSc dissertation
Publication date: 10/03/2017

Namesort descending Role
Edson Jose Soares Advisor *
Renato do Nascimento Siqueira Co-advisor *

Examining board:

Namesort descending Role
Edson Jose Soares Advisor *
Paulo Sérgio da Silva Porto External Examiner *
Rafael Sartim External Examiner *
Renato do Nascimento Siqueira Co advisor *

Summary: The drag reduction by addition of small amounts of additives into a turbulent flow has been studied since the 1940s, when it was reported by Toms (1948). Due to the importance and wide applicability, many researchers directed their studies to this phenomenon in the last decades. However, most of the drag reduction studies are carried out with synthetic polymers, which are less resistant to high shear rates and toxic, factors that limit their use in some applications, such as environment and human beings. Therefore, the search for natural drag reduction materials is growing, because this materials are more resistant, more biodegradable and non-toxic, making them a good alternative to replace the synthetic ones in some applications. This work proposes two new natural drag reduction agents, the mucilage and powder of the aloe vera peel, which were investigated to verify their capacity to reduce drag. The tests were carried out in an experimental apparatus composed of pipes in series, WHERE the main section of the test is made of stainless steel with burnishing treatment, in addition to a magnetic flowmeter and three pressure transducers to obtain the data during the experiments. Since the materials tested are not commercially available, it was necessary to develop methodologies to their production. Several analyses were carried out as the mucilage concentration is varied, like drag reduction behavior, flow rate, pressure drop and efficiency loss (relative drag reduction - 𝐷𝑅′). Since mucilage is a natural material, it was made an analysis about the biological degradation in the drag reduction capacity. In addition, some tests were carried out with the aloe vera peel and the drag reduction results of peel and mucilage were compared with others drag reduction materials already studied, such as the rigid natural Xantana Gum (XG) and a mixture of okra polymer and fiber, and the flexible synthetic Polyethylene Oxide (PEO). Finally, these materials are mixed with each other and also with the flexible polymer PEO to analyze the existence of synergistic effects between them. From this study, the results obtained by the new natural drag reduction materials were promising and satisfactory.

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