Numerical Simulation of Flow and Heat Transfer in the Base Region of Martian Descent Vehicle

2010 ◽  
Author(s):  
Ivan Egorov
Keyword(s):  
Heat Flux ◽  
Reynolds Numbers ◽  
Base Flow ◽  
Navier Stokes ◽  
Back Surface ◽  
Near Wake ◽  
Flow And Heat Transfer ◽  
Turbulent Transition ◽  
Mach Numbers ◽  
Blunted Body

Numerical investigation of hypersonic flow and heating over two models of an interplanetary probe was carried out at Mach numbers from 6 to 20 and Reynolds numbers Re∞,D from 0.7×105 to 16×105. The models differ mainly by the shape of the back surface simulating the payload container. The Reynolds number, at which laminar-turbulent transition takes place in the near wake, was defined at Mach numbers M = 6–8. It was shown that at turbulent base flow, the heat flux to the back surface of a blunted body can be comparable with the heat flux at the forward stagnation point. The results of numerical flow within the framework of Navier-Stokes and Reynolds equations simulation were compared with the experimental data.

The Numerical Prediction of Viscous Flow and Heat Transfer in Tube Banks

1978 ◽  
Vol 100 (4) ◽  
pp. 565-571 ◽  
Author(s):  
B. E. Launder ◽  
T. H. Massey
Keyword(s):  
Heat Transfer ◽  
Viscous Flow ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Substantial Contribution ◽  
Navier Stokes Equations ◽  
Flow And Heat Transfer ◽  
Flow Domain ◽  
Tube Banks

A scheme for handling the numerical analysis of viscous flow and heat transfer in tube banks is presented. It involves the use of a cylindrical network of nodes in the vicinity of the tubes with a Cartesian mesh covering the remainder of the flow domain. The approach has been incorporated into the numerical solving algorithm for the Navier Stokes equations of Gasman, et al. [8]. A number of demonstration calculations is presented including a numerical simulation of the staggered square bank for which Bergelin and co-workers [4, 9] have reported experimental results for pressure drop and heat transfer rate. Agreement between predicted and measured characteristics is satisfactory when account is taken of end and entry effects that are present in the experiments but necessarily omitted from the calculations. Indeed the close agreement of the laminar predictions with measurements extends to Reynolds numbers in excess of 1000, a level at which it has hitherto been supposed that turbulent motion in the fluid made a substantial contribution to friction and heat transfer.

Axisymmetric Stagnation—Point Flow and Heat Transfer of a Viscous Fluid on a Rotating Cylinder With Time-Dependent Angular Velocity and Uniform Transpiration

2006 ◽  
Vol 129 (1) ◽  
pp. 106-115 ◽  
Author(s):  
A. B. Rahimi ◽  
R. Saleh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Angular Velocity ◽  
Stokes Equations ◽  
Time Dependent ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow And Heat Transfer ◽  
Self Similar

The unsteady viscous flow and heat transfer in the vicinity of an axisymmetric stagnation point of an infinite rotating circular cylinder with transpiration U0 are investigated when the angular velocity and wall temperature or wall heat flux all vary arbitrarily with time. The free stream is steady and with a strain rate of Γ. An exact solution of the Navier-Stokes equations and energy equation is derived in this problem. A reduction of these equations is obtained by the use of appropriate transformations for the most general case when the transpiration rate is also time-dependent but results are presented only for uniform values of this quantity. The general self-similar solution is obtained when the angular velocity of the cylinder and its wall temperature or its wall heat flux vary as specified time-dependent functions. In particular, the cylinder may rotate with constant speed, with exponentially increasing/decreasing angular velocity, with harmonically varying rotation speed, or with accelerating/decelerating oscillatory angular speed. For self-similar flow, the surface temperature or its surface heat flux must have the same types of behavior as the cylinder motion. For completeness, sample semi-similar solutions of the unsteady Navier-Stokes equations have been obtained numerically using a finite-difference scheme. Some of these solutions are presented for special cases when the time-dependent rotation velocity of the cylinder is, for example, a step-function. All the solutions above are presented for Reynolds numbers, Re=Γa2∕2υ, ranging from 0.1 to 1000 for different values of Prandtl number and for selected values of dimensionless transpiration rate, S=U0∕Γa, where a is cylinder radius and υ is kinematic viscosity of the fluid. Dimensionless shear stresses corresponding to all the cases increase with the increase of Reynolds number and suction rate. The maximum value of the shear stress increases with increasing oscillation frequency and amplitude. An interesting result is obtained in which a cylinder rotating with certain exponential angular velocity function and at particular value of Reynolds number is azimuthally stress-free. Heat transfer is independent of cylinder rotation and its coefficient increases with the increasing suction rate, Reynolds number, and Prandtl number. Interesting means of cooling and heating processes of cylinder surface are obtained using different rates of transpiration.

Conjugate Heat Transfer Analysis of Internally Cooled Configurations

2001 ◽  
Author(s):  
David L. Rigby ◽  
Jan Lepicovsky
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Energy Equation ◽  
Reynolds Numbers ◽  
Heat Transfer Analysis ◽  
Navier Stokes ◽  
The Past ◽  
Flow And Heat Transfer ◽  
Internally Cooled ◽  
Solid Region

This paper describes the addition of conjugate capability to an existing Navier-Stokes code. Also, results are presented for an internally cooled configuration. The code is currently referred to as the Glenn-HT code, because of its origin at the NASA Glenn Research center and its proven ability to predict flow and Heat Transfer. In the past, the code had been called traf3d.mb. The addition of the conjugate capability to the code was accomplished with a minimum amount of changes to the code, with the understanding that if more advanced techniques were required they could be added at a later date. In the solid region, the density is constant and the velocities are of course zero which leaves only a simplified form of the energy equation to be solved. This simplified energy equation is solved using the same method as in the gas regions with only minor changes to the numerical parameters. At the interface between the gas and solid the wall temperature is set so as to produce the same heat flux in each region. Results are presented for a pipe flow to validate the implementation. Numerical and experimental results are then presented for flow over a flat plate that is cooled internally. Flat plate Reynolds numbers in the range 180,000 to 950,000, and coolant channel Reynolds numbers in the range 30,000 to 60,000 are presented.

Time-dependent helical waves in rotating pipe flow

1990 ◽  
Vol 221 ◽  
pp. 289-310 ◽  
Author(s):  
Michael J. Landman
Keyword(s):  
Pipe Flow ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Reynolds Numbers ◽  
Linear Instability ◽  
Two Dimensions ◽  
Navier Stokes ◽  
Helical Symmetry ◽  
Navier Stokes Equations ◽  
Turbulent Transition

The Navier-Stokes equations for flow in a rotating circular pipe are solved numerically, subject to imposing helical symmetry on the velocity field v = v(r, θ + αz,t). The helical symmetry is exploited by writing the equations of motion in helical variables, reducing the problem to two dimensions. A limited study of the pipe flow is made in the parameter space of the wavenumber α, and the axial and azimuthal Reynolds numbers. The steadily rotating waves previously studied by Toplosky & Akylas (1988), which arise from the linear instability of the basic steady flow, are found to undergo a series of bifurcations, through periodic to aperiodic time dependence. The relevance of these results to the mechanism of laminar-turbulent transition in a stationary pipe is discussed.

Influencing Factors Analysis of the Shock-Induced Separation for Supercritical Airfoil

2013 ◽  
Vol 444-445 ◽  
pp. 221-226
Author(s):  
Xin Xu ◽  
Da Wei Liu ◽  
De Hua Chen ◽  
Yuan Jing Wang
Keyword(s):  
Mach Number ◽  
Influencing Factors ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Supercritical Airfoil ◽  
Factors Analysis ◽  
Mach Numbers

The shock-induced separation easily occurred on the upper surface of supercritical airfoil at transonic speeds, which would change the aerodynamic characteristics. The problem of the shock-induced separation was not solved completely for the complicated phenomena and flow mechanism. In this paper, the influencing factors of shock-induced separation for supercritical airfoil CH was analyzed at transonic speeds. The Navier-Stokes equations were solved, in order to investigate influence of different attack angles, Mach numbers and Reynolds numbers. The computation attack angles of CH airfoil varied from 0oto 7o, Reynolds numbers varied from 5×106to 50×106per airfoil chord while Mach number varied from 0.74 to 0.82. It was shown that the shock-induced separation was affected by attack angles, Mach numbers and Reynolds numbers, but the influence tendency and areas were quite different. The shock wave location and intensity were affected by the three factors, and the boundary layer thickness was mainly affected by Reynolds number, while the separation structure was mainly determined by the attack angle and Mach number.

scholarly journals Experimental and Computational Investigation of Flow Structure in Buoyancy Dominated Rotating Cavities

2020 ◽  
Author(s):  
Seyed Mostafa Fazeli ◽  
Vasudevan Kanjirakkad ◽  
Christopher Long
Keyword(s):  
Laser Doppler Anemometry ◽  
Numerical Study ◽  
Tangential Velocity ◽  
Reynolds Numbers ◽  
Convincing Evidence ◽  
Navier Stokes ◽  
Computational Investigation ◽  
Cfd Simulations ◽  
Flow And Heat Transfer ◽  
A Value

Abstract The flow and heat transfer inside HP compressor rotating cavities are buoyancy driven and are known to be extremely difficult to predict. The experimental data of Laser-Doppler Anemometry (LDA) measurements inside an engine representative cavity rig is presented in this paper. Traverses using a two component LDA system have been carried out in the shaft bore and the cavity regions in order to map the axial and tangential velocity components. The velocity data is collected for a range of Rossby, Rotational and Axial Reynolds numbers, Ro, Reθ and Rez: 0.08 < Ro < 0.64, 7 × 105 < Reθ < 2.83 × 106, 1.2 × 104 < Rez < 4.8 × 104 and for values of the buoyancy parameter βΔT, 0.284 < βΔT < 0.55. Numerical study using unsteady Reynolds Averaged Navier-Stokes (URANS) simulations have been carried out to elucidate flow details for a few selected cases. The experimental results revealed that the Swirl number (Xk) varies from a value < 1 near the bore to near solid body rotation at increased radii within the cavity. The analysis of frequency spectrum of the tangential velocity inside the cavities has also shown the existence of pairs of rotating and contra-rotating vortices. There is generally satisfactory agreement between measurements and CFD simulations. There is also convincing evidence of two or more separate regions in the flow dominated by the bore flow and rotation.

scholarly journals Three-dimensional numerical investigation of turbulent flow and heat transfer inside a horizontal semi-circular cross-sectioned duct

2014 ◽  
Vol 18 (4) ◽  
pp. 1145-1158 ◽  
Author(s):  
Kamil Arslan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Forced Flow ◽  
Flow And Heat Transfer ◽  
Darcy Friction Factor

In this study, steady-state turbulent forced flow and heat transfer in a horizontal smooth semi-circular cross-sectioned duct was numerically investigated. The study was carried out in the turbulent flow condition where Reynolds numbers range from 1?104 to 5.5?104. Flow is hydrodynamically and thermally developing (simultaneously developing flow) under uniform surface heat flux with uniform peripheral wall heat flux (H2) boundary condition on the duct?s wall. A commercial CFD program, Ansys Fluent 12.1, with different turbulent models was used to carry out the numerical study. Different suitable turbulence models for fully turbulent flow (k-? Standard, k-? Realizable, k-? RNG, k-? Standard and k-? SST) were used in this study. The results have shown that as the Reynolds number increases Nusselt number increases but Darcy friction factor decreases. Based on the present numerical solutions, new engineering correlations were presented for the average Nusselt number and average Darcy friction factor. The numerical results for different turbulence models were compared with each other and similar experimental investigations carried out in the literature. It is obtained that, k-? Standard, k-? Realizable and k-? RNG turbulence models are the most suitable turbulence models for this investigation. Isovel contours of velocity magnitude and temperature distribution for different Reynolds numbers, turbulence models and axial stations in the duct were presented graphically. Also, local heat transfer coefficient and local Darcy friction factor as function of dimensionless position along the duct were obtained in this investigation.

Base Pressure Measurements on Elliptic Cones in Supersonic Flow

1967 ◽  
Vol 18 (3) ◽  
pp. 298-307 ◽  
Author(s):  
W. Stahl ◽  
H. Grauer-Carstensen
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Reasonable Agreement ◽  
Flow Theory ◽  
Reynolds Numbers ◽  
Base Flow ◽  
Base Pressure ◽  
Pressure Measurements ◽  
Pressure Coefficients ◽  
Mach Numbers

SummaryAt the Aerodynamische Versuchsanstalt Gottingen (AVA), base pressure measurements were made on five elliptic cones. The ratios of the axes of the ellipses were: 1:12, 1:3, 1:1, 3:1, and 12:1. All the cones had the same volume and the same length. The investigations were carried out for Mach numbers M∞=1·50, 1·73, and 1·98 at angles of incidence between about —2 degrees and about 8 degrees. Reynolds numbers, based on a mean length, lm, varied from 2·5×106 to 3·0×106; the boundary layer approaching the base was turbulent. The base pressure coefficients are given as a function of geometry. Some of the results were compared with the base-flow theory of Korst and reasonable agreement was found.

On the Organization of Flow and Heat Transfer in the Near Wake of a Circular Cylinder in Steady and Pulsed Flow

1992 ◽  
Vol 114 (3) ◽  
pp. 348-355 ◽  
Author(s):  
D. P. Telionis ◽  
M. Gundappa ◽  
T. E. Diller
Keyword(s):  
Heat Transfer ◽  
Circular Cylinder ◽  
Skin Friction ◽  
Power Spectra ◽  
Reynolds Numbers ◽  
Driving Frequency ◽  
Near Wake ◽  
Flow And Heat Transfer ◽  
Pulsed Flow ◽  
Oncoming Stream

Skin friction, pressure, and heat transfer gages are employed to monitor the flow and heat transfer field along the periphery of a circular cylinder in steady and pulsed flow at Reynolds numbers, Re = 23,000 to 50,000. Averaged distributions, RMS, and power spectra of all measurements are displayed. Special attention is directed at the organization of the near wake, as detected by the three types of surface gages. The response of the wake to pulsing of the oncoming stream is also examined. It is found that when the wake is locked on the driving frequency, the basic character of the flow is not changed, but the organized motion stands out more clearly. Moreover, the signals become cleaner and background noise in the spectra is reduced. Skin friction and heat transfer gages are shown to respond to local variations of the corresponding quantities, whereas pressure gages respond to global characteristics of the flow.

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