M.Sc. Tezi Görüntüleme

      In this study, incompressible, two-dimensional, axisymmetric, transient laminar and turbulent forced convection problems in pipes were solved numerically. The wall boundary conditions which are used to solve the energy equation are constant temperature, constant heat flux, step temperature, step heat flux, conjugated constant temperature and heat flux, triangular heat flux and sinusoidal heat flux. In this study, inlet temperature varying sinusoidally with time was also investigated. To verify the program, the laminar and turbulent pipe flows for constant temperature and constant heat flux boundary conditions were investigated and the steady-state Nusselt number values were obtained. The results of this study and the literature for the laminar pipe flow with constant temperature were also compared and a good agreement was obtained. In the present study, the relations between the time step, the iteration number and the relaxation factor were investigated. Thermal instabilities in the transitions between the steps were observed for the analysis of the step boundary conditions. Drops occurred in the local Nusselt numbers in the pipe exit region which the heat flux was minimum for the triangular heat flux boundary condition. When the heat flux is sinusoidal, the heat flux in the middle of the pipe is zero and thermal shocks are seen. The values of peak points are increased with time for the laminar and turbulent flows. It was determined that centerline temperature amplitudes decrease exponentially along the pipe in the sinusoidal inlet temperature boundary condition.