Thesis (M.S.)--Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.

This thesis is concerned with the development of a theoretical method for predicting the turbulent flow and heat transfer in the cavity between a rotating and a stationary cone. The motivation for the work stems from the need, in the design process for the gas turbine aero-engine, for a fast and reliable predictive method for such flows. The method developed here is the integral method, which reduces the governing partial differential equations to ordinary differential equations. A number of solution methods for these equations are described, and the optimum in terms of speed and accuracy is indicated. Predicted moment coefficients compare well with experimental data. For half-cone angles greater than approximately 60° but poorly for half cone angle less than approximately 45°. The poor agreement for small cone angles is thought to be due to the presence of Taylor-type vortices, which cannot be incorporated into the integral method. Heat transfer is incorporated into the method using the Reynolds analogy. Due to the lack of experimental data, heat transfer predictions are compared with those from a finite difference program and show encouraging agreement. A computer program which solves the full Reynolds-averaged Navier-Stokes and energy equations in steady and axisymmetric form, using a finite-difference method is modified for use in the conical geometry. Comparison of the predicted moment coefficients with experimental data shows no marked improvement over the integral method. Examination of the secondary flow predicted by the program shows it to be similar to that of the integral method. The failure of the program to predict Taylor-type vortices may be attributed to the fact that they are non-axisymmetric and/or unsteady. The assumptions underlying the Integral method are investigated via the finite difference program and it is concluded that they are valid for half cone angles as small as 15°. Based on the results of the finite difference program, the Integral method is modified to allow for a rectangular outer shroud, and a new model for the stator is described. It is concluded that both the integral method and the finite difference program can be used safely in rotor-stator systems where the half cone angle is greater than about 60°.

Simulations were performed to determine the effect of turbulence on protoplanets as they accrete inside of a planetary gas disk at the stage of planet formation that involves interactions between relatively large, similar sized bodies. The effect of turbulence was implemented into an existing N-Body code using a parameterization of magnetohydrodynamic (MHD) turbulence performed by Laughlin et. al. (2004). The investigation focussed on the effect of turbulent perturbations on planetary dynamics and accretion at various locations in the disk, particularly at large semimajor axis. At these distances, protoplanet collisions are generally less frequent due to the large induced eccentricities from close encounters and due to the trapping of protoplanets in mutual resonances. It is, however, essential that large protoplanets develop at these distances since some must eventually grow large enough to accrete the massive gas envelopes indicative of the giant planets. The interaction between a protoplanet and the surrounding gas disk creates a torque imbalance acting on the protoplanet, which is generally believed to result in the rapid inward spiraling of the protoplanet. In order to create a fixed region in the disk within which protoplanets may interact without migrating into the central star, two scenarios were considered that would inhibit the inward migration of the protoplanets. The first scenario involved a gas disk that had been truncated at the inner edge, referred to as a planet trap, and the second involved the existence of a stationary giant planet within a gap in the disk, referred to as a planet barrier. Each scenario was tested using different density profiles of the gas disk, different numbers and masses of initial protoplanets, various rates of gas disk decay and also four different levels of turbulence intensities. The results demonstrated that the addition of turbulence to the gas disk promotes planet mixing and results in an increased number of collisions between planets, even at large heliocentric distances. A turbulent disk has the tendency to create a final system where the planets are, on average, larger than those produced in a non-turbulent disk. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-17 14:41:52.607

In this thesis, large-eddy simulation has been performed to investigate a heated plane channel flow subjected to streamwise system rotations. A variety of rotation numbers ranging from Roτ = 0 to 15 have been tested in conjunction with two fixed low Reynolds numbers Reτ = 150 and 300. The fundamental characteristics of the resolved velocity and temperature fields in terms of their mean and root-mean-square (RMS) values are investigated. Advanced physical features in terms of the transport of turbulent stresses, turbulent kinetic energy (TKE), heat fluxes and forward and backward scatter of local kinetic energy (KE) fluxes between the resolved and subgrid scales are also studied. Numerical simulations were performed using the conventional dynamic model (DM) and an advanced dynamic nonlinear model (DNM) for closure of the filter momentum equation, and an advanced dynamic full linear tensor thermal diffusivity model (DFLTDM) for closure of the filtered thermal energy equation.

No description available.

In this thesis, large-eddy simulation has been performed to investigate a heated plane channel flow subjected to streamwise system rotations. A variety of rotation numbers ranging from Roτ = 0 to 15 have been tested in conjunction with two fixed low Reynolds numbers Reτ = 150 and 300. The fundamental characteristics of the resolved velocity and temperature fields in terms of their mean and root-mean-square (RMS) values are investigated. Advanced physical features in terms of the transport of turbulent stresses, turbulent kinetic energy (TKE), heat fluxes and forward and backward scatter of local kinetic energy (KE) fluxes between the resolved and subgrid scales are also studied. Numerical simulations were performed using the conventional dynamic model (DM) and an advanced dynamic nonlinear model (DNM) for closure of the filter momentum equation, and an advanced dynamic full linear tensor thermal diffusivity model (DFLTDM) for closure of the filtered thermal energy equation.

No description available.

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 60-61). Also available via the Internet.

Thesis (M.S.) in Mechanical Engineering--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 106-111).