Tezduyar, Tayfun E.2019-05-172019-05-172018-052018-04-20May 2018Fu, Mingyuan. "Computational Analysis of a Diesel Engine Exhaust Manifold and Turbocharger Turbine." (2018) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/105781">https://hdl.handle.net/1911/105781</a>.https://hdl.handle.net/1911/105781The unsteady nature of the flow in turbocharges makes computational flow analysis challenging. The unsteadiness comes from the engine cycle and the flow in the exhaust manifold and turbocharger turbine. An additional challenge is that the time scale of the engine cycle is much larger than that of the turbine because of high turbine rotation speeds. This requires long-duration computations in the turbine time scale. We provide computational analysis of the turbine with different inflow and turbine rotation rates and the combined system of the manifold, turbine and the gas purifier device with steady and unsteady inflow. The core computational method is the space--time (ST) variational multiscale (ST-VMS) method. The other key methods are the ST Slip Interface (ST-SI) method, ST/NURBS mesh update method (STNMUM), and the ST Isogeometric Analysis (ST-IGA). The ST framework provides higher-order accuracy. The VMS feature of the ST-VMS addresses the computational challenges associated with turbulent flows. With the ST-SI, the mesh covering the rotor spins with it, retaining the high-resolution representation of the boundary layers. The SI between the spinning mesh and the rest of the mesh accurately connects the two sides of the flow field. An SI also provides mesh generation flexibility in a general context by accurately connecting the two sides of the solution computed over nonmatching meshes, which is helpful in isogeometric discretization. The STNMUM enables accurate representation of the mesh rotation. The ST-IGA provides more accurate representation of the geometry and increased accuracy in the flow solution. Because the ST-IGA provides higher spatial accuracy with less number of control points, and consequently with larger effective element sizes, it also enables using larger time-step sizes while keeping the Courant number at a desirable level for good accuracy. The computations show that the ST methods we use here are very effective in turbocharger flow analysis.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Turbocharger turbineSpace-time methodThesis2019-05-17