Hydraulic design and dynamic analysis of diffusers

Marine outfall sytems are composed of submarine pipeline transmitting wastewater, diffusers and pomp system. Diffusers that are usually placed at the last parts of pipeline have exit canals that are discharging wastewater by dilution with specific spaces and diameters.Internal flow in each cross-section contraction and port exit are calculated by main fluid mechanics correlation. However in this calculation external pressure with effects of wave must be considered. Wave pressures and flow parameters change according to wave theories. In this study linear wave theory based on. External pressures in the exit of ports are formed with hydrodinamic pressure with effect of wave changing according to time and main hydrostatic pressure. In dynamic analysis hydrodinamic forces with internal flow changing according to time are used, in stability analysis maximum hydrodinamic forces equivalant to static forces are based on in calculations.Exit canals; that are placed above the diffuser with specific spaces and diameters and also composed of one way pipe bended vertical and horizontal. There are contractions on the exit canal edge. Contractions are identified with different effusion coefficients.Contractions of cross sections cause axial dynamic forces changing according to time that are calculated effect of impuls moment. These forces are also calculated for riser.Diffuser modal that is balanced according to stability calculations, lying on the ocean floor freely and braced with two detective masses added in this calculation.Simple beam formed cylindrical ruined pipe with the effects of internal flow changing according to time and external forces, calculated dynamicaly with Single Degree of Freedom System ( the SDFS) and Time History Analysis Method. Pipe?s vibration with the effects of internal and external pressure forces calculated and findings compared with analytical and numeric method.