Download or read book Preconditioning for Numerical Simulation of Low Mach Number Three dimensional Viscous Turbomachinery Flows written by Daniel L. Tweedt and published by . This book was released on 1997 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Preconditioned Algorithm for Turbomachinery Viscous Flow Simulation written by Xiao Wang and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The MSU TURBO code, distributed to U.S. engine companies by NASA Glenn, is a heavily used parallel compressible Reynolds-averaged Navier-Stokes flow solver for multistage turbomachinery flows, primarily for compressible flows at subsonic and transonic speeds. Many low speed turbomachinery flows in aerial vehicles or marine propulsion systems can not be effectively addressed by compressible flow solvers. It is well known that compressible flow equations face difficulties at low Mach number due to the large disparity of the acoustic and convective wave speeds. The current study is to develop and implement the computational capability for flow simulations at low Mach number, or incompressible Mach regime, under the framework of the MSU TURBO code. This is accomplished by applying a global preconditioning scheme to the unsteady term of the compressible governing equations and solving the conservative Riemann flux based on primitive variables. The preconditioning scheme is a single parameter diagonal matrix depending on a reference Mach number which represents the global flow properties in the flow simulation. For flows in rotating machines where speed varies along the radial direction from the axis of the rotation, it is found that a modified preconditioning parameter is necessary to assure numerical stability in simulating low Mach number rotating flows. The effectiveness of the modified preconditioning scheme has been analyzed, under various flow conditions, through Fourier footprints and validated by numerical investigations. The development of a preconditioned structured turbomachinery flow solver was accomplished in this dissertation. The conservative form of the governing equations were cast in the non-inertial relative rotating frame in terms of primitive variables and absolute velocity vectors. Characteristic-based boundary conditions, with implicit treatment of the source term resulting from the rotating relative frame, are derived for internal and external flows. The implicit finite volume scheme is developed for the preconditioned scheme with the flux Jacobians evaluated by either a flux approximate method or flux-vector-splitting. The viscous flux is also treated implicitly, and an analytic form of viscous flux Jacobians was developed in the preconditioned flow solver to reduce numerical uncertainties, and computing time. A series of flow simulations have been carried out by this preconditioned unsteady turbomachinery flow solver. The simulations of viscous boundary layer development over flat plates at very low Mach numbers demonstrate the effectiveness of the preconditioning algorithm. Computations of compressor rotor, and rotor/stator at subsonic, and transonic flow regions with acceptable results indicate that the preconditioned TURBO solver is compatible with the compressible version of the TURBO solver for subsonic and transonic flows. Moderate improvement in numerical convergence for flows in a rotating frame with mixed flow speeds is observed in the case of a tiltrotor blade at hover. The marine propeller simulation demonstrates the accomplishment of the preconditioned TURBO solver for an incompressible flow simulation. In the simulation of a low speed centrifugal compressor, the preconditioned TURBO is able to predicate the wake locations accurately.

Download or read book Preconditioning Methods for Low speed Flows written by E. Turkel and published by . This book was released on 1996 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Complex Turbomachinery Flows written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: An unsteady, multiblock, Reynolds Averaged Navier Stokes solver based on Runge-Kutta scheme and Pseudo-time step for turbo-machinery applications was developed. The code was validated and assessed against analytical and experimental data. It was used to study a variety of physical mechanisms of unsteady, three-dimensional, turbulent, transitional, and cooling flows in compressors and turbines. Flow over a cylinder has been used to study effects of numerical aspects on accuracy of prediction of wake decay and transition, and to modify K-epsilon models. The following simulations have been performed: (a) Unsteady flow in a compressor cascade: Three low Reynolds number turbulence models have been assessed and data compared with Euler/boundary layer predictions. Major flow features associated with wake induced transition were predicted and studied; (b) Nozzle wake-rotor interaction in a turbine: Results compared to LDV data in design and off-design conditions, and cause and effect of unsteady flow in turbine rotors were analyzed; (c) Flow in the low-pressure turbine: Assessed capability of the code to predict transitional, attached and separated flows at a wide range of low Reynolds numbers and inlet freestream turbulence intensity. Several turbulence and transition models have been employed and comparisons made to experiments; (d) leading edge film cooling at compound angle: Comparisons were made with experiments, and the flow physics of the associated vortical structures were studied; and (e) Tip leakage flow in a turbine. The physics of the secondary flow in a rotor was studied and sources of loss identified. Chernobrovkin, A. A. and Lakshiminarayana, B. Glenn Research Center NAG3-1736; NAG3-2025; RTOP 523-26-33...

Download or read book 28th AIAA Fluid Dynamics Conference 4th AIAA Shear Flow Control Conference written by and published by . This book was released on 1997 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Monthly Catalog of United States Government Publications written by and published by . This book was released on 1999 with total page 1076 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Steady Three dimensional Flows in Axial Turbomachinery Bladerows written by Anton H. Basson and published by . This book was released on 1992 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 40th AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2002 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulations in Turbomachinery written by and published by . This book was released on 1995 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AIAA Aerospace Sciences Meeting and Exhibit 42nd written by and published by . This book was released on 2004 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Institute for Computational Mechanics in Propulsion ICOMP written by and published by . This book was released on 1998 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation of 3 D Viscous Compressible Flow in Multistage Turbomachinery by Finite Element Methods written by Mohamad Sleiman and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow in a multistage turbomachinery blade row is compressible, viscous, and unsteady. Complex flow features such as boundary layers, wake migration from upstream blade rows, shocks, tip leakage jets, and vortices interact together as the flow convects through the stages. These interactions contribute significantly to the aerodynamic losses of the system and degrade the performance of the machine. The unsteadiness also leads to blade vibration and a shortening of its life. It is therefore difficult to optimize the design of a blade row, whether aerodynamically or structurally, in isolation, without accounting for the effects of the upstream and downstream rows. The effects of axial spacing, blade count, clocking (relative position of follow-up rotors with respect to wakes shed by upstream ones), and levels of unsteadiness may have a significance on performance and durability. In this Thesis, finite element formulations for the simulation of multistage turbomachinery are presented in terms of the Reynolds-averaged Navier-Stokes equations for three-dimensional steady or unsteady, viscous, compressible, turbulent flows. Three methodologies are presented and compared. First, a steady multistage analysis using a a-mixing-plane model has been implemented and has been validated against engine data. For axial machines, it has been found that the mixing plane simulation methods match very well the experimental data. However, the results for a centrifugal stage, consisting of an impeller followed by a vane diffuser of equal pitch, show flagrant inconsistency with engine performance data, indicating that the mixing plane method has been found to be inappropriate for centrifugal machines. Following these findings, a more complete unsteady multistage model has been devised for a configuration with equal number of rotor and stator blades (equal pitches). Non-matching grids are used at the rotor-stator interface and an implicit interpolation procedure devised to ensure continuity of fluxes across. This permits the rotor and stator equations to be solved in a fully-coupled manner, allowing larger time steps in attaining a time-periodic solution. This equal pitch approach has been validated on the complex geometry of a centrifugal stage. Finally, for a stage configuration with unequal pitches, the time-inclined method, developed by Giles (1991) for 2-D viscous compressible flow, has been extended to 3-D and formulated in terms of the physical solution vector U, rather than Q, a non-physical one. The method has been evaluated for unsteady flow through a rotor blade passage of the power turbine of a turboprop.

Download or read book 4th European Conference on Turbomachinery written by Gerard Bois and published by S.G.E.. This book was released on 2001 with total page 1100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 34th AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit written by and published by . This book was released on 1998 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt: