A computational procedure for supersonic flows governed by the parabolic Navier-Stokes equations

1980 ◽  
Vol 35 (3) ◽  
pp. 356-380 ◽  
Author(s):  
C.P Li
Keyword(s):  
Stokes Equations ◽  
Computational Procedure ◽  
Supersonic Flows ◽  
Navier Stokes ◽  
Navier Stokes Equations

Influences of lateral jet location and its number on the drag reduction of a blunted body in supersonic flows

2020 ◽  
Vol 124 (1277) ◽  
pp. 1055-1069 ◽  
Author(s):  
M. Dong ◽  
J. Liao ◽  
Z. Du ◽  
W. Huang
Keyword(s):  
Drag Reduction ◽  
Drag Force ◽  
Blunt Body ◽  
Stokes Equations ◽  
Supersonic Flows ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Reduction Strategies ◽  
Promising Application ◽  
Force Reduction

ABSTRACTThe analysis of the aerodynamic environment of the re-entry vehicle attaches great importance to the design of the novel drag reduction strategies, and the combinational spike and jet concept has shown promising application for the drag reduction in supersonic flows. In this paper, the drag force reduction mechanism induced by the combinational spike and lateral jet concept with the freestream Mach number being 5.9332 has been investigated numerically by means of the two-dimensional axisymmetric Navier-Stokes equations coupled with the shear stress transport (SST) k-ω turbulence model, and the effects of the lateral jet location and its number on the drag reduction of the blunt body have been evaluated. The obtained results show that the drag force of the blunt body can be reduced more profoundly when employing the dual lateral jets, and its maximum percentage is 38.81%, with the locations of the first and second lateral jets arranged suitably. The interaction between the leading shock wave and the first lateral jet has a great impact on the drag force reduction. The drag force reduction is more evident when the interaction is stronger. Due to the inclusion of the lateral jet, the pressure intensity at the reattachment point of the blunt body decreases sharply, as well as the temperature near the walls of the spike and the blunt body, and this implies that the multi-lateral jet is beneficial for the drag reduction.

Viscous Flow Computations for Compressor/Combustor Diffuser Design to Allow Air Extraction for IGCC Systems

1991 ◽  
Author(s):  
Ajay K. Agrawal ◽  
Tah-Teh Yang
Keyword(s):  
Coal Gasification ◽  
Stokes Equations ◽  
Outer Wall ◽  
Computational Procedure ◽  
Navier Stokes ◽  
Structural Constraints ◽  
Navier Stokes Equations ◽  
Annular Diffuser ◽  
High Reynolds ◽  
Suction Slot

A computational procedure based on the solution of fully elliptic Navier-Stokes equations on a body-fitted non-orthogonal grid was used to obtain flow fields in annular diffusers with a suction slot at the inner and outer walls. The turbulence effects were simulated by high Reynolds number form of the k-ε model. The calculation method was used to modify an industrial gas turbine (GE MS · 7001F) compressor/combustor annular diffuser to allow extraction of compressed airflow for coal gasification in simplified IGCC Systems. The air for gasification was extracted through a suction slot on the outer wall of the diffuser which was curved to improve the overall performance and to avoid flow separation; both of these insured by providing accelerated flow through the suction slot and nearly constant wall pressure downstream of the slot. Suction slot and outer wall geometries to result in the above conditions were determined by a trial and error procedure. The diffuser’s performance was further improved by extracting 6% of the compressed air through a slot at the inner wall, kept straight due to structural constraints. The resulting diffuser arrangement was relatively insensitive to the upstream disturbances.

Supercomputing of Supersonic Flows Using Upwind Relaxation and MacCormack Schemes

1988 ◽  
Vol 110 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Oktay Baysal
Keyword(s):  
Stokes Equations ◽  
Supersonic Flows ◽  
Navier Stokes ◽  
Computational Algorithms ◽  
Navier Stokes Equations ◽  
Relaxation Scheme ◽  
Finite Volume Discretization ◽  
Finite Difference Discretization ◽  
The Mathematical Model ◽  
Difference Discretization

The impetus of this paper is the comparative applications of two numerical schemes for supersonic flows using computational algorithms tailored for a supercomputer. The mathematical model is the conservation form of Navier-Stokes equations with the effect of turbulence being modeled algebraically. The first scheme is an implicit, unfactored, upwind-biased, line-Gauss-Seidel relaxation scheme based on finite-volume discretization. The second scheme is the explicit-implicit MacCormack scheme based on finite-difference discretization. The best overall efficiences are obtained using the upwind relaxation scheme. The integrity of the solutions obtained for the example cases is shown by comparisons with experimental and other computational results.

Mixing Flow Characteristics in a Vessel Agitated by the Screw Impeller With a Draught Tube

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yeng-Yung Tsui ◽  
Yu-Chang Hu
Keyword(s):  
Stokes Equations ◽  
Flow Characteristics ◽  
Computational Procedure ◽  
Navier Stokes ◽  
Complex Flow ◽  
Navier Stokes Equations ◽  
Mixing Energy ◽  
Draught Tube ◽  
Flow Mechanisms ◽  
Entire Flow

The circulating flow in a vessel induced by rotating impellers has drawn a lot of interests in industries for mixing different fluids. It used to rely on experiments to correlate the performance with system parameters because of the theoretical difficulty to analyze such a complex flow. The recent development of computational methods makes it possible to obtain the entire flow field via solving the Navier–Stokes equations. In this study, a computational procedure, based on multiple frames of reference and unstructured grid methodology, was used to investigate the flow in a vessel stirred by a screw impeller rotating in a draught tube. The performance of the mixer was characterized by circulation number, power number, and nondimensionalized mixing energy. The effects on these dimensionless parameters were examined by varying the settings of tank diameter, shaft diameter, screw pitch, and the clearance between the impeller and the draught tube. Also investigated was the flow system without the draught tube. The flow mechanisms to cause these effects were delineated in detail.

Fluid-Structure Interaction for Flutter Predictions in Transonic and Supersonic Flows

2011 ◽  
Author(s):  
Zhi Yang ◽  
Xiang Zhao ◽  
Sijun Zhang ◽  
Chien-Pin Chen
Keyword(s):  
Mach Number ◽  
Stokes Equations ◽  
Structural Response ◽  
Supersonic Flows ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Number Range ◽  
Flow Solver ◽  
Compressible Turbulent Flow ◽  
Transonic And Supersonic Flows

This paper describes a numerical methodology coupling Euler/Navier-Stokes equations and structural modal equations for predicting flutter in transonic and supersonic flows. This coupling between Computational Fluid Dynamics (CFD) and Computational Structural Dynamics (CSD) is achieved through a Multi-Disciplinary Computing Environment (MDICE), which allows several computer codes or ‘modules’ to communicate in a highly efficient fashion. The present approach offers the advantage of utilizing well-established single-disciplinary codes in a multi-disciplinary framework. The flow solver is density-based for modeling compressible, turbulent flow problems using structured and/or unstructured grids. A modal approach is employed for the structural response. Two benchmark cases are employed to validate the present method. Flutter predictions in subsonic flows for an AGARD 445.6 wing at different Mach numbers (0.499 to 1.141) are presented and compared with experimental data. Supersonic plate flutter with Mach number range between 1.8 and 3.2 is studied and the critical Mach number is computed, our results are in a good agreement with the analytical solutions.

Solutions of the Three-Dimensional Navier-Stokes Equations in Non-Orthogonal Coordinates to Calculate the Flow in a Log Spiral Impeller

1982 ◽  
Author(s):  
B. W. Swanson
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Computational Procedure ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Elliptic Solution ◽  
Navier Stokes Equations ◽  
Orthogonal Grid ◽  
Good Agreement ◽  
Orthogonal Coordinates

A modification of Moore’s (12) method has been developed for solving the three-dimensional Navier Stokes equations to calculate the flow in a log spiral impeller. A complete mathematical development of this method is presented. The parabolic finite-difference marching code used to make the calculations is an extensive revision of a CATHY3 code obtained from D. B. Spalding. Calculations are made for Vr, Vθ and Vz on a non-orthogonal grid that is ideally suited for impellers with back-swept blades. An inviscid solution is in good agreement with the elliptic solution and validates the computational procedure. The method is applied to calculate the viscous three-dimensional flow in a log spiral impeller.

Sign in / Sign up

Export Citation Format

Share Document