General Equation Set Solver for Compressible and Incompressible Turbomachinery Flows (original) (raw)
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Development of a Segregated Compressible Flow Solver for Turbomachinery Simulations
A steady multiple reference frame segregated compressible solver and an unsteady sliding mesh one are developed using OpenFOAM® to simulate turbomachinery. For each of the two solvers, governing equations, numerical approach and solver structure are explained. Pressure and energy equation are implemented so as to obtain the best numerical properties, such as the ability to use large time-steps. Sod shock tube test case is used to assess the prediction of compressible phenomena by the transient scheme, which shows proper resolution of compressible waves. Both solvers are used to simulate a turbocharger turbine, comparing their solutions to corresponding ones using ANSYS ® Fluent ® as a means of validation. The multiple reference frame solver global results quantitatively differ from those computed using ANSYS Fluent, although predicted flow features match. The solution obtained by the sliding mesh solver presents better agreement compared to ANSYS Fluent one.
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1991
A new technique was developed for the solution of the incompressible Navier-Stokes equations. The numerical technique, derived from a pressure substitution method (PSM), overcomes many of the deficiencies of the pressure correction method. This technique allows for the direct solution of the actual pressure in the form of a Poisson equation which is derived from the pressure weighted substitution of the full momentum equations into the continuity equation. Two dimensional internal flows are computed with this method. The prediction of cascade performance is presented. The extention of the pressure correction method for the solution of three dimensional flows is also presented.
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A preconditioned solution scheme for the computation of compressible flow in turboma- chinery at arbitrary Mach numbers is presented. The preconditioning technique used is applied to a state-of-the-art explicit, time-marching Navier-Stokes code which originally was developed for compressible, high-speed turbomachinery applications. It combines the ideas of low Mach number preconditioning and artificial compressibility method into a unified approach where principally fluids with arbitrary equations of state can be simulated. As shown by the test cases presented, it allows the code to simulate flows eciently and accurately independent of the Mach number. A description of the Navier-Stokes equations for rotating coordinate systems, along with the solution scheme and the details of the preconditioning method is given. Since turbomachinery computations are often performed on truncated domains, the solution scheme should be used in conjunction with non-reflecting boundary conditions. A ch...
Solution of the turbocompressor boundary condition for one-dimensional gas-dynamic codes
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Nowadays, turbocharged engines are widely used in cars and trucks. Gas-dynamic codes are an important tool in design and optimization of these types of engines. These codes solve the one-dimensional governing equations in ducts for compressible, unsteady and non-homoentropic flow. The ducts are generally solved using finite difference schemes, the volumes are solved by means of filling and emptying models and the connections represent the boundary conditions of the ducts. One important boundary condition is the compressor which connects two ducts. In this junction an increment of momentum and energy is undergone by the flow but depending on its sense the behaviour is different. This paper presents the mathematical base of a compressor model which solves this complex boundary condition. The governing equations of the model have been presented in detail. The solution involves a non-linear equation system that has to be solved iteratively. The Newton–Raphson root-finding method has been chosen to get its solution. Finally, some results of the model have been compared to measurements focusing in surge prediction.
Development and Validation of a Massively Parallel Flow Solver for Turbomachinery Flows
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This paper presents the development and validation of the unsteady, three-dimensional, multiblock, parallel turbomachinery flow solver, TFLO. The Unsteady Reynolds Averaged Navier-Stokes (Unsteady RANS) equations are solved using a cell-centered discretization on arbitrary multiblock meshes. The solution procedure is based on efficient explicit Runge-Kutta methods with several convergence acceleration techniques such as multigrid, residual averaging, and local time-stepping. The algebraic Baldwin-Lomax, the one-equation Spalart-Allmaras, and the two-equation Wilcox k-w turbulence models are implemented. The solver is parallelized using domain decomposition, an SPMD (Single Program Multiple Data) strategy, and the Message Passing Interface (MPI) Standard. A mixing model and a sliding mesh interface approach have been implemented to exchange flow information between blade rows in both steady and unsteady rotor/stator interaction flows. The dual-time stepping technique is applied to advance unsteady computations in time. This paper focuses heavily on the initial validation of the flow solver, TFLO, with emphasis on steady-state calculation of multiple blade-row flows. For validation and verification purposes, results from TFLO are compared with both existing experimental data and computational results from other software used in industry. The large set of cases tested increases our confidence in the ability of TFLO to accurately predict flows inside typical turbomachinery geometries, and sets the stage for the large-scale computation of unsteady, multiple blade-row flows.
Application of a Real-Fluid Turbomachinery Analysis to Rocket Turbopump Geometries
43rd AIAA Aerospace Sciences Meeting and Exhibit, 2005
A threedimensional flow solver has been developed for turbomachinery components utilizing real fluid properties. The code is applicable to both incompressible and compressible flow fields. In this study, the code has been applied to the analysis of inducer and ~ ___ ____ * Aerospace Engineer, Associate Fellow AIAA.
Computational Models for Turbomachinery Flows
1984
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COMPRESSIBLE FLOW SOLVERS FOR LOW MACH NUMBER FLOWS - a review
The low Mach number setting is a singular limiting situation in compressible flows. As Mach number approaches zero, compressible (density-based) flow solvers suffer severe deficiencies, both in efficiency and accuracy. There are two main approaches advocated in the development of algorithms for the computation of low Mach number flows; first, There is the modification of compressible solvers (density-based) downward to low Mach numbers; second, extending incompressible solvers (pressurebased) towards this regime. Here, we present a brief review of the literature in this area. This addresses the modifications necessary to effectively apply density-based schemes and develop compressible pressure-based schemes to such low Mach number configurations.
Volume 2B: Turbomachinery, 2014
In this paper we present a fully coupled algorithm for the resolution of compressible flows at all speed. The pressure-velocity coupling at the heart of the Navier Stokes equations is accomplished by deriving a pressure equation in similar fashion to what is done in the segregated SIMPLE algorithm except that the influence of the velocity fields is treated implicitly. In a similar way, the assembly of the momentum equations is modified to treat the pressure gradient implicitly. The resulting extended system of equations, now formed of matrix coefficients that couples the momentum and pressure equations, is solved using an algebraic multigrid solver.