The effect of added mass on dynamic behavior in fluid-conveying pipes modeled by different theories

Globalization has been widespread in today's geography and herewith the importance of the transportation routes has increased. As well as being the safest way of delivering the energy from production sources to the desired location, the pipelines are the most efficient way. Dynamic analysis of fluid-conveying pipes is very important for design and project planning. In this study, the dynamic behavior of fluid conveying pipes in the presence of added mass has been investigated by using Rayleigh and Euler-Bernoulli theories. The devices used to measure the flow inside the pipes are also defined as the added mass. The fluid is accepted as an ideal fluid and the equation of motion is formed by Hamilton's principle. The behavior of the fluid in the pipes is modeled by the Euler principle. For the results to be independent of the structure and geometry of the material used, and simpler, the nondimensionalization process was performed. The natural frequency values of the first three mode values were obtained by using the finite difference method. The obtained data were analyzed in the Maple program. For both theories, the effect of the changes in various parameters such as mass position, occupancy rate, and mass ratio on the natural frequency has been recorded. The interaction of added mass and vibrational frequencies is shown in the form of graphs. As a result, the frequency value decreases as the mass ratio increases, in addition, as the occupancy rate increases, the frequency value also increases. It is observed that the difference between the results obtained in the first mode is less than the difference in the results obtained for the second and third modes.