Global ETD Search

1	Method development for investigation of real effects on flow around vanes Mårtensson, Jonathan January 2010 (has links) <p>In the development of turbo machinery components it's desirable to not spend more time than necessary when setting up aero-thermal calculations to investigate uncertainties in the design. This report aims to describe general thoughts used in the development of an ICEM-mesh script and the possible configurations in the script file which enables the user to build mesh-grids with/without clearance gap at the hub and/or shroud for different blade geometries. It also aims to illustrate the performance analysis made on the Vinci LH2 turbine, a next generation upper stage engine to the Ariane 5 rocket, in which the effect of the tip gap size on the efficiency has been studied.</p><p>The calculations made have shown good agreement with experimental data. The efficiency loss due to the mixing of fluid where leakage flow passes the tip gap, which results in growth of a strong vortex, and the fluid passing the blade tip, with almost no work extracted from it, has shown a quite linear efficiency dependence depending on the tip gap size.</p> Master's Thesis Method Development Real effects Turbomachinery Turbine Flow Secondary Flow ICEM Block Mesh Topology Tip Gap Fluid mechanics Strömningsmekanik
2	Method development for investigation of real effects on flow around vanes Mårtensson, Jonathan January 2010 (has links) In the development of turbo machinery components it's desirable to not spend more time than necessary when setting up aero-thermal calculations to investigate uncertainties in the design. This report aims to describe general thoughts used in the development of an ICEM-mesh script and the possible configurations in the script file which enables the user to build mesh-grids with/without clearance gap at the hub and/or shroud for different blade geometries. It also aims to illustrate the performance analysis made on the Vinci LH2 turbine, a next generation upper stage engine to the Ariane 5 rocket, in which the effect of the tip gap size on the efficiency has been studied. The calculations made have shown good agreement with experimental data. The efficiency loss due to the mixing of fluid where leakage flow passes the tip gap, which results in growth of a strong vortex, and the fluid passing the blade tip, with almost no work extracted from it, has shown a quite linear efficiency dependence depending on the tip gap size. Master's Thesis Method Development Real effects Turbomachinery Turbine Flow Secondary Flow ICEM Block Mesh Topology Tip Gap Fluid mechanics Strömningsmekanik
3	Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR) Ivan, Lucian 31 August 2011 (has links) A high-order central essentially non-oscillatory (CENO) finite-volume scheme in combination with a block-based adaptive mesh refinement (AMR) algorithm is proposed for solution of hyperbolic and elliptic systems of conservation laws on body- fitted multi-block mesh. The spatial discretization of the hyperbolic (inviscid) terms is based on a hybrid solution reconstruction procedure that combines an unlimited high-order k-exact least-squares reconstruction technique following from a fixed central stencil with a monotonicity preserving limited piecewise linear reconstruction algorithm. The limited reconstruction is applied to computational cells with under-resolved solution content and the unlimited k-exact reconstruction procedure is used for cells in which the solution is fully resolved. Switching in the hybrid procedure is determined by a solution smoothness indicator. The hybrid approach avoids the complexity associated with other ENO schemes that require reconstruction on multiple stencils and therefore, would seem very well suited for extension to unstructured meshes. The high-order elliptic (viscous) fluxes are computed based on a k-order accurate average gradient derived from a (k+1)-order accurate reconstruction. A novel h-refinement criterion based on the solution smoothness indicator is used to direct the steady and unsteady refinement of the AMR mesh. The predictive capabilities of the proposed high-order AMR scheme are demonstrated for the Euler and Navier-Stokes equations governing two-dimensional compressible gaseous flows as well as for advection-diffusion problems characterized by the full range of Peclet numbers, Pe. The ability of the scheme to accurately represent solutions with smooth extrema and yet robustly handle under-resolved and/or non-smooth solution content (i.e., shocks and other discontinuities) is shown for a range of problems. Moreover, the ability to perform mesh refinement in regions of smooth but under-resolved and/or non-smooth solution content to achieve the desired resolution is also demonstrated. computational fluid dynamics finite-volume method high-order scheme adaptive mesh refinement (AMR) ENO scheme essentially non-oscillatory CENO body-fitted multi-block mesh high-order spatial discretization numerical method hyperbolic and elliptic PDE fixed stencil reconstruction piecewise linear reconstruction smoothness indicator Euler and Navier-Stokes equations advection-diffusion equation smooth and non-smooth solution content k-exact least-squares reconstruction hybrid numerical scheme compressible gaseous flows refinement criteria high-performance parallel computing solution monotonicity enforcement large-eddy simulation (LES) interpolation technique structured grid inviscid and viscous flow TVD scheme h-p-adaptation high-order boundary conditions complex curved geometries 0538
4	Development of High-order CENO Finite-volume Schemes with Block-based Adaptive Mesh Refinement (AMR) Ivan, Lucian 31 August 2011 (has links) A high-order central essentially non-oscillatory (CENO) finite-volume scheme in combination with a block-based adaptive mesh refinement (AMR) algorithm is proposed for solution of hyperbolic and elliptic systems of conservation laws on body- fitted multi-block mesh. The spatial discretization of the hyperbolic (inviscid) terms is based on a hybrid solution reconstruction procedure that combines an unlimited high-order k-exact least-squares reconstruction technique following from a fixed central stencil with a monotonicity preserving limited piecewise linear reconstruction algorithm. The limited reconstruction is applied to computational cells with under-resolved solution content and the unlimited k-exact reconstruction procedure is used for cells in which the solution is fully resolved. Switching in the hybrid procedure is determined by a solution smoothness indicator. The hybrid approach avoids the complexity associated with other ENO schemes that require reconstruction on multiple stencils and therefore, would seem very well suited for extension to unstructured meshes. The high-order elliptic (viscous) fluxes are computed based on a k-order accurate average gradient derived from a (k+1)-order accurate reconstruction. A novel h-refinement criterion based on the solution smoothness indicator is used to direct the steady and unsteady refinement of the AMR mesh. The predictive capabilities of the proposed high-order AMR scheme are demonstrated for the Euler and Navier-Stokes equations governing two-dimensional compressible gaseous flows as well as for advection-diffusion problems characterized by the full range of Peclet numbers, Pe. The ability of the scheme to accurately represent solutions with smooth extrema and yet robustly handle under-resolved and/or non-smooth solution content (i.e., shocks and other discontinuities) is shown for a range of problems. Moreover, the ability to perform mesh refinement in regions of smooth but under-resolved and/or non-smooth solution content to achieve the desired resolution is also demonstrated. computational fluid dynamics finite-volume method high-order scheme adaptive mesh refinement (AMR) ENO scheme essentially non-oscillatory CENO body-fitted multi-block mesh high-order spatial discretization numerical method hyperbolic and elliptic PDE fixed stencil reconstruction piecewise linear reconstruction smoothness indicator Euler and Navier-Stokes equations advection-diffusion equation smooth and non-smooth solution content k-exact least-squares reconstruction hybrid numerical scheme compressible gaseous flows refinement criteria high-performance parallel computing solution monotonicity enforcement large-eddy simulation (LES) interpolation technique structured grid inviscid and viscous flow TVD scheme h-p-adaptation high-order boundary conditions complex curved geometries 0538

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