| CFD Validation for Base Flows with and without Plume Interaction |
01 JAN 2006 |
17 pages |
| Authors:
P. G. Bakker; W. J. Bannink; P. Servel; P. Reijasse; DELFT UNIV OF TECHNOLOGY (NETHERLANDS)
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 | In the framework of the NATO-RTO-AVT-WG-10 entitled "Technologies for Propelled Hypersonic Flight," base flow test cases have been selected for code validation. Concerning the first data set devoted to base flow-plume interaction at moderate nozzle pressure ratios, the influence of numerical discretization technique and turbulence models are discussed. The multi-dimensional upwind (MDU) discretization technique on unstructured grids applied to the axisymmetric base flow model with an under-expanded jet predicts base ... |
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| Formation Criterion for Synthetic Jets |
OCT 2005 |
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| Authors:
Ryan Holman; Yogen Utturkar; Rajat Mittal; Barton L. Smith; Louis Cattafesta; FLORIDA UNIV GAINESVILLE
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 | A formation criterion for synthetic jets is proposed and validated. A synthetic jet actuator is a zero-net mass-flux device that imparts momentum to its surroundings. Jet formation is defined as the appearance of a time-averaged outward velocity along the jet axis and corresponds to the generation and subsequent convection or escape of a vortex ring. It is shown that over a wide range of operating conditions synthetic jet formation is ... |
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| Mixing Chemical Reactions and Combustion in High-Speed Turbulent Flows |
31 MAR 2004 |
37 pages |
| Authors:
Paul E. Dimotakis; CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS
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| Research conducted under the sponsorship of this grant focused on fundamental investigations of mixing, chemical-reaction and combustion processes; in turbulent, subsonic, and supersonic flows. Research on hydrocarbon-combustion was on methane and ethane flames. Flame extinction strain-rate measurements, flame speed, and detailed experiment-simulation comparisons indicate difficulties in modeling of fuel-rich flames. Direct Numerical Simulations (DNS) of axisymmetric unsteady flows in both cold and hot impinging jets were also performed. The research ... |
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| Cold Flow Drag Measurement and Numerical Performance Prediction of a Miniature Ramjet at Mach 4 |
DEC 2003 |
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| Authors:
Wee Teik Khoo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Experimentation was carried out in a supersonic wind tunnel to investigate the drag force on a miniature ramjet when subjected to Mach 4 flow. CFDRC-FASTRAN, a numerical flow solver developed for the analysis of high-speed flows was used to model the performance of the miniature ramjet. To reduce computational time, a 2D axisymmetric model of the ramjet was developed to investigate the shock angles over the intake and the results ... |
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| Numerical Methods for Granular Flows and Related Problems |
10 MAY 2003 |
7 pages |
| Authors:
Pierre A. Gremaud; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
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| This project has led to significant progress on several critical questions related to granular flows. First, a high order code based on Discontinuous Galerkin method has been produced to study granular in axisymmetric hoppers. Before that, only ad hoc discretization methods were used. This led to the discovery of several new phenomena (such as shock formation and propagation). Several weaknesses of established models were also brought to the fore. Second, ... |
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| DNS Studies of Transitional Hypersonic Reacting Flows Over 3-D hypersonic Vehicles |
05 MAR 2003 |
54 pages |
| Authors:
Xiaolin Zhong; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| The objectives of this research project are to develop CFD techniques and to conduct DNS studies of fundamental flow physics leading to boundary-layer instability and transition in hypersonic flows During the three-year period, we have conducted extensive DNS studies on the receptivity of a supersonic boundary layer over a blunt cone, and over both sharp and blunt leading edge; and on the receptivity of the Goertler vortices. DNS studies were ... |
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| Vortex Effects in the Dynamics of Underwater Weapons |
MAR 2003 |
13 pages |
| Authors:
P. A. Lyes; A. P. Steer; BAE SYSTEMS WATERLOOVILLE (UNITED KINGDOM) UNDERWATER WEAPONS DIV
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| As the control and mobility of submarines are improved to meet the challenges of the 21st-century security environment, so the capabilities of underwater weapons must keep pace with these developments. An underwater weapon is typically propelled by a pump-jet, controlled by an arrangement of movable lifting surfaces, and stabilized by fixed fins. The propulsor, fins, and control surfaces are situated close together at the tail, and close to the axis ... |
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| Simplified Turbulent Boundary Layer Computation of Some Divergent Internal Flows |
23 AUG 2002 |
7 pages |
| Authors:
R. Askovic; UNIVERSITE DE VALENCIENNES ET DU HAINAUT-CAMBRESIS (FRANCE) LAB MACS
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| To calculate the flows of this type we are going to develop herein a simplified method by using a new variant of the phenomenologic semi-empiric turbulent boundary-layer theory that is founded on the analogy with the rheologic power-laws largely utilized in foe study of non-Newtonian non-linear flows and on the use of foe Karman turbulence model. It is to note also that the viscous sublayer is neglected as well as ... |
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| Numerical Boundary Conditions Simulating the Interaction Between Upstream Disturbances and an Axial Compressor |
06 AUG 2002 |
128 pages |
| Authors:
Richard J. McMullan; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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| New small disturbance and area reduction compressor face boundary conditions that model the unsteady interactions of acoustic disturbances with an axial compressor are presented. The new small disturbance boundary condition is formulated to correct the deficiencies associated with the Paynter small disturbance model. The area reduction boundary condition provides a simple approach for the inlet outflow boundary. Both of these boundary conditions are implemented in one-dimensional and axisymmetric turbulent flow ... |
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| Passive and Active Control of Supersonic Axisymmetric Base Flows: Direct Numerical Simulations and Large-Eddy Simulations |
24 APR 2002 |
116 pages |
| Authors:
Hermann F. Fasel; ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| A new compressible Navier-Stokes code in cylindrical coordinates was developed for investigating axisymmetric wakes of bluff-based bodies in supersonic flows. In this code, high-order compact finite differences derived for non-equidistant grids are employed and a new stare-of-the-art axis treatment is incorporated. Additionally, the fully three-dimensional transport equations for turbulent kinetic energy and turbulent dissipation are implemented to enable (steady or unsteady) Reynolds Averaged Navier Stokes (RANS) simulations. Furthermore, a new ... |
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| Investigation of the Dynamics of the Jet Mixing Layer |
17 SEP 2001 |
7 pages |
| Authors:
William K. George; Stephan Gamard; STATE UNIV OF NEW YORK AT BUFFALO FLUIDAND THERMAL SCIENCES LAB
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| The objective of this investigation was to study the dynamics of the jet-mixing layer using a unique experimental apparatus in conjunction with Proper Orthogonal Decomposition (POD) techniques. The experiments utilize 138 hot-wires in the mixing layer of an axisymmetric jet to simultaneously resolve the instantaneous stream wise velocity field at all locations. The POD is then applied to a double Fourier transform in time and azimuthal direction of the two-point ... |
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| Interactive Visualization of Highly Time-Dependent Data from Numerical Simulations of Transitional and Turbulent Supersonic Flows |
19 JUL 2001 |
9 pages |
| Authors:
Hermann F. Fasel; ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| High-performance graphics processing equipment consisting of a Silicon Graphics Origin 3400, 2 Silicon Graphics Octane SSEs, and other peripherals was purchased with funding from DURIP Grant No. DAADl9-OO-1-O1 16. This equipment significantly enhanced our research projects funded by DOD. For these research projects, Direct Numerical Simulations and Large-Eddy Simulations were employed to investigate complex transitional and turbulent flows for a wide range of applications and flow speeds, both subsonic and ... |
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| Modeling Diesel Engine Injector Flows |
19 JUN 2001 |
4 pages |
| Authors:
Stephen D. Heister; Gregory A. Blaisdell; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
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| This project is focused on the study of flows inside diesel injector flow passages with emphasis on resolution of time-dependent cavitation regions within the device. During the past year, the turbulent axisymmetric model has undergone substantial validation. In addition, an improved inflow boundary condition has been developed to increase accuracy in predicting discharge characteristics of these devices. |
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| Integrated Lifting-Surface and Euler/Boundary-Layer Theory Analysis Method for Marine Propulsors |
FEB 2001 |
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| Authors:
Christopher J. Hanson; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF OCEAN ENGINEERING
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| A propeller lifting surface design and analysis program is automatically coupled with a Euler/integrated Boundary Layer Theory (IBLT) axisymmetric flow solver. The lifting surface method solves the localized propeller problem, while the Euler/IBLT solver handles the global flowfield, capturing the effective inflow problem. For viscous flows, the boundary layer is constructed based upon the parameters specified by the IBLT solution, and is merged with the inviscid Euler flowfield. The robust ... |
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| Investigative Research on the Effect of Zero-Mass Jets on the Base Drag of Axisymmatric Bodies at Sunersonic Speeds |
APR 2000 |
31 pages |
| Authors:
Hermann F. Fasel; ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| Preliminary investigations of wakes behind bodies with a blunt base have been carried out. For low subsonic Mach numbers, we have found that zero- mass jets that are generated by high-frequency forcing can have a significant effect on the flow structures that develop downstream of the base. These investigations were carried out using Direct Numerical Simulations (DNS) based on the complete Navier-Stokes equations for compressible ... |
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| Advanced Modeling of InP Crystal Growth by the MLEK Process |
APR 1998 |
34 pages |
| Authors:
S. A. Orszag; A. Tomboulides; I. Staroselsky; Y. Zhang; E. Barouch; CAMBRIDGE HYDRODYNAMICS INC PRINCETON NJ
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| Two and three dimensional flow of a low Prandtl number liquid metal is investigated including the effects of heating, crucible and crystal rotation, and axial magnetic fields. The crucible shape and aspect ratio are also varied to determine their effects. A specially designed spectral element method for axisymmetric geometries is used. Axisymmetric flows that are stabilized with the use of rotation may be unstable to three dimensional ... |
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| Time Accurate Computation of Unsteady Hypersonic Inlet Flows with a Dynamic Flow Adaptive Mesh |
13 JAN 1998 |
38 pages |
| Authors:
D. S. McRae; Michael Neaves; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| Completed research is reported for an dynamic numerical investigation of unsteady flow in supersonic and hypersonic aircraft inlets. An explicit dynamic solution adaptive mesh computational code was further developed and used to obtain dynamic solutions for an axisymmetric mixed compression inlet and a generic dual mode scramjet inlet isolator diffuser combination. To improve robustness, an existing implicit code was modified for time accuracy and the solution adaptive mesh algorithm was ... |
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| Pressure Sensor Arrays and Microactuators for Fluid Mechanics Research |
NOV 97 |
22 pages |
| Authors:
Khalil Najafi; C. Huang; MICHIGAN UNIV ANN ARBOR DEPT OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCE
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| A combined microactuator/microsensor system has been developed using silicon micromachining techniques for use in high speed jets and control of screech in these jets. The 14 microns-thick electrostatic microactuator was fabricated and tested at the exit of a supersonic axisymmetric jet for the introduction of perturbations into the convectively unstable supersonic shear layer. It can be forced into mechanical resonance at frequencies of 5/14 kHz at an amplitude of greater ... |
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| Towards Perfectly Absorbing Boundary Conditions for Euler Equations |
MAY 97 |
17 pages |
| Authors:
M. E. Hayder; Fang Q. Hu; M. Y. Hussaini; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
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| In this paper, we examine the effectiveness of absorbing layers as non-reflecting computational boundaries for the Euler equations. The absorbing- layer equations are simply obtained by splitting the governing equations in the coordinate directions and introducing absorption coefficients in each split equation. This methodology is similar to that used by Berenger for the numerical solutions of Maxwell's equations. Specifically, we apply this methodology to three physical problems - shock-vortex interactions, ... |
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| Numerical Simulation of Flow Induced by a Spinning Sphere Using Spectral Methods |
MAR 97 |
59 pages |
| Authors:
Birol Zeybek; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| A direct numerical simulation, based on spectral methods, has been used to investigate viscous, incompressible, steady, rotationally symmetric flow due to a sphere rotating with a constant angular velocity about a diameter. The equations of motion have been reduced to a set of three nonlinear second order partial differential equations in terms of the vorticity, the stream function and the azimuthal velocity. The calculations have been carried out for Reynolds ... |
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| Study of Constitutive Models for Concrete Penetration Analysis |
DEC 96 |
43 pages |
| Authors:
Vladimir M. Gold; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL N J
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| Three-dimensional axisymmetric calculation of penetration of concrete targets have been conducted with the CALE (Arbitrary Lagrangian Eulerian) code. All the constitutive models studied accounted for the compressibility of concrete and employed either solid or porous equation of state models; the influence of these models on the penetration calculations is studied and presented. This size of the plastic zone in front of the penetrator is estimated from the calculations for both ... |
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| Development and Testing of a New Optimum Design Code for Hypersonic Wind Tunnel Nozzles, Including Boundary Layer, Turbulence, and Real Gas Effects |
OCT 96 |
271 pages |
| Authors:
Ralph C. Tolle; WRIGHT LAB WRIGHT-PATTERSON AFB OH
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| A robust and efficient hypersonic nozzle optimization code is developed and validated. The code is used to redesign an existing axisymmetric Mach 12 wind tunnel nozzle and utilizes response surface methodology (RSM) techniques. In the nozzle optimization, only two variable design parameters are used, along with constraints of fixed nozzle length, throat radius, and exit radius. Explicit, globally second order, flux-difference-splitting algorithms are used to solve the 2-D/axisymmetric Navier-Stokes (NS) ... |
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| Circumferential Actuator for Piping System. |
18 JUN 1996 |
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| Authors:
Lisa L. Louie; David J. Fry; DEPARTMENT OF THE NAVY WASHINGTON DC
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| The invention is directed to a circumferential actuator for actively controlling and generating pressure waves in a piping system having a fluid or a fluid flow therein. The circumferential actuator includes a casing, a plurality of actuator units mounted in the casing for generating controlled pressure waves, a plurality of amplifiers for electronically conditioning the force generated by each of the plurality of actuator units, a controller for providing the ... |
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| ALLSPD-3D. Version 1.Oa |
APR 96 |
166 pages |
| Authors:
K. H. Chen; B. Duncan; D. Fricker; J. Lee; A. Quealy; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER
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| This report describes the ALLSPD-3D computer program for the calculation of thee-dimensional, chemically reacting flows with sprays. ALLSPD- 3D employs a coupled, strongly implicit solution procedure for turbulent spray combustion flows. ALLSPD-3D utilizes generalized curvilinear coordinates with both multi-block and flexible internal blockage capabilities to handle complex geometries. The ALLSPD-3D algorithm, which employs preconditioning and eigenvalue rescaling techniques, is capable of providing efficient solution of flows over a wide range ... |
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| An Evaluation of Architectural Platforms for Parallel Navier-Stokes Computations |
MAR 96 |
23 pages |
| Authors:
D. N. Jayasimha; M. E. Hayder; S. K. Pillay; INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA
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| We study the computational, communication, and scalability characteristics of a Computational Fluid Dynamics application, which solves the time accurate flow field of a jet using the compressible Navier-Stokes equations, on a variety of parallel architecture platforms. The platforms chosen for this study are a cluster of workstations (the LACE experimental testbed at NASA Lewis), a shared memory multiprocessor (the Cray YMP), and distributed memory multiprocessors with different topologies - the ... |
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| Tidally-Forced Vorticity, Diurnal Shear and Turbulence Atop Fieberling Seamount |
MAR 96 |
76 pages |
| Authors:
Eric Kunze; John M. Toole; UNIV OF WASHINGTON SEATTLE DEPT OF OCEANOGRAPHY
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| Fine- and microstructure profiles collected over Fieberling Seamount at 32 deg 26'N in the eastern North Pacific reveal three intensified phenomena co-existing in a 200-m thick layer atop the summit plain: (i) an anticyclonic vortex cap of core relative vorticity O.50f, (ii) diurnal shear of 15 cm s-1/40 m, and (iii) turbulence levels corresponding to an eddy diffusivity Kp is approx. 0.0001 m2 s-1. The vortex cannot be explained solely ... |
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| Spatial Direct Numerical Simulation of Transition in Hypersonic Flows |
JAN 96 |
109 pages |
| Authors:
C. D. Pruett; COLLEGE OF WILLIAM AND MARY WILLIAMSBURG VA
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| Specifically, progress to date has proceeded on three fronts, each of which expands existing DNS capabilities in the direction of 'configuration DNS' stated in general objective 1 above. Previous experimental and numerical work on the elliptic-cone problem by others has shown that crossflow instabilities, rather than first or second mode instabilities, are likely to dominate the transition process when the eccentricity of the cross-sectional ellipse is moderate to large. Thus, ... |
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| A Closed-Form Dynamic Elasticity Solution to the Fluid/Structure Interaction Problem of a Two-Layer Infinite Viscoelastic Cylinder with Inner and Outer Fluid Loading Subject to Forced Harmonic Excitation |
29 DEC 95 |
264 pages |
| Authors:
Mark S. Peloquin; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
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| This report documents an exact closed-form solution to the problem of a two-layer viscoelastic solid infinite cylinder that is immersed in an infinite ideal inviscid fluid and contains an infinite ideal inviscid fluid within its diameter. The viscoelasticity is modeled with structural damping, which is incorporated by the use of a complex modulus of elasticity. The composite system is subject to forced harmonic vibration at the outer solid/fluid interface. The ... |
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| Effects of Base Cavity Depth on a Free Spinning Wrap-Around Fin Missile Configuration |
DEC 95 |
158 pages |
| Authors:
Jon A. Struck; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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| This study investigated the role base cavity depth plays in altering the overall subsonic aerodynamic forces on a free spinning axisymmetric body with wrap around fins. Wind tunnel usage allowed the forces to be monitored for varying base cavity depths and angles of attack. A base cavity depth analysis was also performed on a non-spinning axisymmetric body for comparison. Oil visualizations were conducted on the non-spinning configuration to further describe ... |
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| FORTRAN Algorithms for the Three-Dimensional Solution of Two-Layer Solid and Hollow Cylinder Dynamic Elasticity Problems With and Without Fluids |
29 NOV 95 |
254 pages |
| Authors:
Mark S. Peloquin; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
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| This document contains FORTRAN algorithms for the numerical evaluation of exact closed form solutions to four fluid/structure interaction mathematical problems that are modeled as cylinders and fluids. The cylinders (infinitely long in the longitudinal x-direction) are modeled as three- dimensional linear viscoelastic solids, and the fluids are treated as inviscid. The outer fluid extends to infinity in the radial r-direction; the inner fluid (contained within the hollow cylinder) is bounded ... |
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| Flow Simulation and Drag Components for HEAT Projectiles with Spike and Cone Noses |
NOV 95 |
55 pages |
| Authors:
Ameer G. Mikhail; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Seven computations are reported for the two classes of projectile configurations of shaped charge antitank projectiles. The first class is of spiked nose with vortex generator ring, boattail, and tail fin boom. The second is of conical nose, boattail, and tail fin boom. Navier-Stokes equations are solved for the turbulent flow with dominant separation region, in an axisymmetric formulation and for zero angle of attack. Two cases at Mach numbers ... |
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| Symmetrization, Vortex Rossby Waves, and Hurricane Motion in an Asymmetric Balance Model |
10 SEP 95 |
87 pages |
| Authors:
Randall J. Kallenbach; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| The physical complexities of primitive equation (PE) models commonly used for forecasting hurricane track and structure changes can often make interpretation of their output difficult and speculative. A simplified balance formulation of these phenomena is desirable to further understand the physics of rapidly rotating storms. This thesis presents a shallow-water numerical model suitable for simulating hurricane track and evolution based on asymmetric balance (AB) theory. The model is a shallow-water ... |
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| Stability Transition of High-Speed Flows over Realistic Bodies |
06 SEP 95 |
26 pages |
| Authors:
T. Herbert; OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING
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| The thrust of this research program has been the improvement of our capabilities for analyzing stability and transition in high-speed flows over realistic bodies. Examples of such bodies are swept wings of high-speed airplanes or the blunt conical bodies for hypersonic flight. We have extended the parabolized stability equations (PSE) for these situations and developed methods for solving these equations in disturbance environments typical of atmospheric conditions. Formulation, numerical methods, ... |
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| Drop1et-Turbu1ence Interactions Over A Wide Spectra1 Range |
01 SEP 95 |
56 pages |
| Authors:
William A. Sirignano; Said E. Elghobashi; Inhul Kim; M. Masoudi; CALIFORNIA UNIV IRVINE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
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| In the last year, the unsteady, three-dimensional, incompressible, viscous flow interactions between a pair of vortex tubes advected by a uniform free stream and a spherical particle held fixed in space was investigated numerically for a range of particle Reynolds numbers between 20 and 100. Useful correlations of lift coefficient, moment coefficient, and drag coefficient with velocity fluctuation, Reynolds number, offset distance, and initial vortex size have been obtained and ... |
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| Thrust Vector Control of Rectangular Jets Using Counterflow |
31 AUG 95 |
141 pages |
| Authors:
Michael R. Van der Veer; Paul J. Strykowski; MINNESOTA UNIV MINNEAPOLIS OFFICE OF RESEARCH AND TECHNOLOGY TRANSFER ADMINIS TRATION
|
| Fluidic vectoring of a subsonic jet was examined using a curved countercurrent mixing layer. A rectangular jet having a 4:1 aspect ratio was studied at Mach numbers up to 0.5 at a stagnation temperature of 300 K. Several different curved control surfaces called "collars" were placed downstream of the nozzle exit over which the pressure forces could act to produce jet thrust vectoring. Results showed that by applying counterfiow over ... |
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| The Dependence of the Time-Asymptotic Structure of 3-D Vortex Breakdown on Boundary and Initial Conditions |
JUL 95 |
251 pages |
| Authors:
Jeffrey C. Tromp; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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| The three-dimensional, compressible Navier-Stokes equations are solved numerically to simulate vortex breakdown in tubes. Time integration is performed with an implicit Beam-Warming algorithm, which uses fourth-order compact operators to discretize spatial derivatives. Initial conditions are obtained by solving the steady, compressible, and axisymmetric form of the Navier-Stokes equations using Newton's method. Stability of the axisymmetric initial conditions is assessed through 3-D time integration. Unique axisymmetric solutions at a Reynolds number ... |
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| Structure-Based Turbulence Model |
24 MAY 95 |
8 pages |
| Authors:
W. C. Reynolds; STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
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| Models of turbulence for complex engineering flows need to be able to span the full range of deformation rates from slow, where eddy viscosity models (e.g.k-e) relating the turbulent stress to the mean strain rate are valid, to rapid deformations where the stresses are determined by the amount of strain. In order to build a one-point turbulence model that can match Rapid Distortion Theory (RDT) when appropriate, new concepts are ... |
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| A Study of Mixing and Combustion in the Presence of a Strong Streamwise Vorticity. (Dual Stream Axisymmetric Mixing in the Presence of Axial Vorticity) |
OCT 94 |
36 pages |
| Authors:
V. M. Belovich; M. Samimy; M. F. Reeder; OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING
|
| An experimental investigation was undertaken to study the mixing process in a coaxial jet with an inner lobed mixer nozzle. Seven different inner jet nozzle geometries and also three different velocity ratios were explored. Flow visualizations using a passive scalar were performed using a laser sheet from a Nd:YAG laser as the light source. The laser has a 9 nsec pulse duration which effectively freezes the flow. Instantaneous cross sectional ... |
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| ARCJET Plasma Modeling with Experimental Validation |
01 SEP 94 |
84 pages |
| Authors:
Herman Krier; Rodney L. Burton; Thomas W. Megli; Scott A. Bufton; Nicholas T. Tiliakos; ILLINOIS UNIV AT URBANA DEPT OF MECHANICAL AND INDUSTRIAL ENGINEERING
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| We report for the first time thermal non-equilibrium (separate electron and gas temperatures) numerical results for a hydrazine arcjet. All viscous flow properties are considered, assuming laminar axisymmetric flow. The model includes anode temperature distribution, and the electrical conductivity is coupled to the flow properties, allowing for a self-consistent current distribution. The numerical solution algorithm employs the compressible form of the PISO algorithm to solve the continuity and momentum equations. ... |
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| A Numerical Study of Droplet-Vortex Interactions in an Evaporating Spray |
JUN 94 |
10 pages |
| Authors:
T. W. Park; S. K. Aggarwal; V. R. Katta; ILLINOIS UNIV AT CHICAGO CIRCLE DEPT OF MECHANICAL ENGINEERING
|
| In this paper, we present the time-dependent axisymmetric numerical simulation of an unsteady n-heptane evaporating spray, and investigate the droplet-vortex interactions which determine the structural and dynamic characteristics of a spray jet flow. The spray is formed between a droplet-laden heated nitrogen jet and a coflowing air stream. A detailed, multidimensional, two-phase algorithm is developed for the simulation. A comprehensive vaporization model is employed to calculate the instantaneous droplet size ... |
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| Hartmann Sensor and Dynamic Tomographical Analysis of Organized Structure in Flow Fields |
JUN 94 |
17 pages |
| Authors:
L. McMackin; J. Wissler; N. Clark; E. Chen; K. Bishop; PHILLIPS LAB KIRTLAND AFB NM
|
| In the Aero-optics research program currently underway at the Phillips Laboratory, we are examining the relationship between the organized structure in the near field region of an axisymmetric jet and the degradation of an optical field that propagates through the jet shear layer. We are developing an experimental capability in which dynamic tomographical analysis enables us to reconstruct a time series of flow field images while simultaneously recording the optical ... |
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| Marangoni Convection in a Gravity-Free Silicon Float Zone |
APR 94 |
52 pages |
| Authors:
Hans J. Lugt; Samuel Ohring; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| The onset of Marangoni convection in the float zone of liquid silicon is studied from a state at rest in the absence of gravity. This time-dependent flow problem is solved numerically with the aid of the Navier-Stokes equations for an axisymmetric flow with nonlinear free surface conditions. On this free surface the temperature gradient is generated by heat transfer and radiation from a heater, which is symmetrically located between the ... |
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| Surface Boundary Conditions and Related Technical Issues Concerning Burnett Equations for 2-D Hypersonic Flow |
14 JAN 94 |
21 pages |
| Authors:
Xiaolin Zhong; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AEROSPACE AND NUCLEAR ENGINEER ING
|
| Research on studying steady and transient rarefied hypersonic flow by using the Burnett equations and developing accurate and efficient numerical methods for both the Navier-Stokes and Burnett equations were conducted in three aspects: (1) A new method of formulating the additional boundary conditions for the Burnett equations was presented. The 2-D Burnett equations with first order slip conditions seem to be able to improve the Navier-Stokes equations in two dimensions ... |
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| Analysis and Computation for Vortex Dynamics and Rarefied Gases |
29 NOV 93 |
4 pages |
| Authors:
Russel E. Caflisch; CALIFORNIA UNIV LOS ANGELES DEPT OF MATHEMATICS
|
| Through support of this grant, a number of research projects on vortex dynamics and rarefied gas dynamics were completed. A few of the most outstanding results were the following: An analytic theory for singularity formation on the fluid interface in the Rayleigh-Taylor problem was developed and shown to agree with numerical results. Singular solutions were found by direct computation for Moore's approximation of the 3D Euler equations for axi- symmetric ... |
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| Centerline Discrepancies in HULL Axisymmetric Calculations |
JUL 93 |
37 pages |
| Authors:
Amitabha Ghosh; ROCHESTER INST OF TECH NY
|
| Axisymmetric calculations using the HULL hydrocode exhibit peculiar jetlike artifacts near the axis of symmetry. A series of numerical experiments were performed to determine the cause of this behavior. Governing equations and boundary conditions in the HYDRO subroutine were modified and tested. Results show considerable improvements of the artifacts. Calculations were performed with an airblast model and compared with experimental data and previous calculations.... Airblast calculations, Axisymmetric flows Boundary conditions, ... |
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| An Incompressible Axisymmetric Through-Flow Calculation Procedure for Design and Off-Design Analysis of Turbomachinery |
MAY 93 |
187 pages |
| Authors:
B. W. Siebert; A. M. Yocum; PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
|
| A computational procedure has been developed which solves the steady- state incompressible Navier-Stokes (or Reynolds) equations for axisymmetric flows through turbomachinery. The solution of the Navier-Stokes equations allows for the prediction of recirculating flow regions that my be due to either through-flow geometry or off-design operating conditions. The effects of the blade rows are represented in an approximate manner by replacing the forces they impart to the fluid in the ... |
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| Numerical Simulation of the Flow in a 1:57-Scale Axisymmetric Model of a Large Blast Simulator |
APR 93 |
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| Authors:
Klaus O. Opalka; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| This report presents an assessment of the suitability of the USA-RG2 hydrocode for simulating the flow in a variable-area shock tunnel. A multi-zone gridding technique is used to model the 1:57-Scale LBS test facility at the U.S. Army Research Laboratory. Computations for various grid configurations employing inviscid and viscous solution algorithms and three turbulence models were executed and the results are compared to experimental data. The need for an adequate ... |
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| Numerical Simulation of the Flow in a 1:57-Scale Axisymmetric Model of a Large Blast Simulator |
APR 93 |
33 pages |
| Authors:
Klaus O. Opalka; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| This report presents an assessment of the suitability of the USA-RG2 hydrocode for simulating the flow in a variable-area shock tunnel. A multi-zone gridding technique is used to model the 1:57-Scale LBS test facility at the U.S. Army Research Laboratory. Computations for various grid configurations employing inviscid and viscous solution algorithm and the turbulence models were executed and the results are compared to experimental data. The need for an adequate ... |
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| A Computational Study of the Base Region Flow Field for the M865 Projectile |
APR 93 |
36 pages |
| Authors:
Jubaraj Sahu; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Recent firing tests for the M865 projectile have indicated that for reasons unknown, the tracer in the base cavity region does not remain visible during the entire flight. To assist in analyzing this problem, a computational study has begun to examine the base region flow field for this projectile including the base cavity. Flow computations for this projectile have been performed at various supersonic Mach numbers, 2 < M < ... |
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| Anti-Tank Spike-Nosed Projectiles With Vortex Rings: Steady and Non- Steady Flow Simulations |
MAR 1993 |
55 pages |
| Authors:
Ameer G. Mikhail; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Numerical computations are reported for a spike-nosed projectile configuration with a vortex generator ring. A new vortex-dominated flow field is computed at supersonic speeds of M - 3.5, 3.0, and 1.9. A time-dependent Navier- Stokes computational technique with a zonal gridding was used. The axial force at zero angle of attack was computed and found to be in good agreement with the wind tunnel data at Mach 3.0. The sting ... |
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Reports by Keyword(s)
AXISYMMETRIC FLOW
