| The Prandtl Plus Scaling Parameters and Velocity Profile Similarity |
Oct 2012 |
27 pages |
| Authors:
David Weyburne; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH SENSORS DIR
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 | Numerous experimental results have demonstrated similar behavior of the velocity profile in the near-wall region of the turbulent boundary layer using Prandtl's Plus scaling variables. However, the implications for similarity behavior of the near-wall turbulent boundary velocity profiles using Prandtl's Plus scaling variables have not been carefully explored. In the following report, we apply the momentum balance type approach to study velocity profile similarity using Prandtl's Plus scaling variables. It ... |
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| Effects of Front-Loading and Stagger Angle on Endwall Losses of High Lift Low Pressure Turbine Vanes |
Sep 2012 |
211 pages |
| Authors:
M E Lyall; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| Past efforts to reduce the airfoil count in low pressure turbines have produced high lift profiles with unacceptably high endwall loss. The purpose of the current work is to suggest alternative approaches for reducing endwall losses. The effects of the fluid mechanics and high lift profile geometry are considered. Mixing effects of the mean flow and turbulence fields are decoupled to show that mean flow shear in the endwall wake ... |
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| Linking Dynamics of the Near-surface Flow to Deeper Boundary Layer Forcing in the Nocturnal Boundary Layer |
01 Jun 2012 |
86 pages |
| Authors:
Alexander R Smoot; OREGON STATE UNIV CORVALLIS
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| Weak-wind flow in the nocturnal boundary is one of the most poorly understood problems in the field of meteorology. The understanding of weak-wind flows is essential for the improvement of regulatory dispersion models which are currently rendered invalid under weak-wind conditions and stable stratification. Recently there have been increased efforts directed towards improving the understanding nocturnal boundary layer dynamics. The results of these studies have shown that nocturnal boundary layer ... |
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| Analysis of Sub-Grid Boundary-Layer Processes Observed by the P-3 Doppler Wind Lidar in Support of the Western Pacific Tropical Cyclone Structure 2008 Experiment |
02 Feb 2012 |
27 pages |
| Authors:
Ralph Foster; G D Emmitt; WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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| A major field program to study tropical cyclones in the Western Pacific was conducted as part of the THORPEX Pacific-Asian Regional Campaign (T-PARC). The tropical cyclone portion of the experiment was called the Tropical Cyclone Structure 2008 (TCS-08) Experiment. The goals of TCS-08 were to study the mechanisms of genesis, development, and extra-tropical transition of Western Pacific tropical cyclones. A major goal of this research was to investigate how well ... |
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| Computational Study of the Effect of Slot Orientation on Synthetic Jet-Based Separation Control |
Jan 2012 |
25 pages |
| Authors:
Shawn Aram; Rajat Mittal; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING
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| A computational study is conducted to explore the effect of synthetic jet orientation on boundary layer separation control. A six-to-one aspect-ratio rectangular slot is chosen in the current study and streamwise and spanwise orientations of this slot are analyzed. In the first part of this study, the interaction of the jet with an attached laminar boundary layer for both slot configurations is examined. The dominant feature in the streamwise oriented ... |
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| Effects of Passive Porous Walls on the First Mode of Hypersonic Boundary Layers Over a Sharp Cone |
Dec 2011 |
54 pages |
| Authors:
Sharon O Stephen; BIRMINGHAM UNIV (UNITED KINGDOM)
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| A theoretical linear stability analysis is used to consider the effect of a porous wall on the first mode of a hypersonic boundary layer on a sharp slender cone. The effects of curvature and of the attached shock are included for axisymmetric and nonaxisymmetric disturbances. The flow in the hypersonic boundary layer is coupled to the flow in the porous layer. The linear results for neutral stability and spatial stability ... |
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| An Evaluation of Boundary Condition Specification for a Littoral Hydrodynamic Model |
Sep 2011 |
5 pages |
| Authors:
Kacey Edwards; Jay Veeramony; Tiffany Nguyen; David Sitton; NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| Littoral hydrodynamic models are valuable tools for characterizing near-shore waves and currents. There are a number of ways to prescribe boundary conditions for these models. A tide model is used to obtain astronomic boundary conditions, and a regional model can provide time-series boundary conditions. We investigate the differences imposed by these two types of boundary conditions for 4 model cases: a two-dimensional and a three-dimensional case at two locations. In ... |
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| Analysis of Low-Frequency Unsteadiness in Shock and Turbulent Boundary Layer Interactions Using Direct Numerical Simulation Data |
09 FEB 2011 |
46 pages |
| Authors:
M. P. Martin; MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING
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| The effort described here is the result of a one-year research program, providing statistical evidence of the upstream and downstream influence in shock unsteadiness in a fully separated configuration of boundary layer flow over a compression corner at Mach 2.9 and Re(theta) = 2900. Direct numerical simulation data was gathered over 1000 delta/U(infinity) (350 L(sep)/U(infinity)), making the analysis of the low-frequency unsteadiness possible. The dominant scales in the flow were ... |
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| A Novel Approach to Turbulence Stimulation for Ship-Model Testing |
11 May 2010 |
88 pages |
| Authors:
Jason C Murphy; NAVAL ACADEMY ANNAPOLIS MD
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| Ship-model testing is vital component of naval architecture, allowing testing and evaluation on a small scale. The goal of this project was to develop an approach for creating a boundary layer on a ship-model that more closely represents the actual boundary layer on the ship. Flow within a ship s boundary layer is turbulent for nearly the entire length of the ship. However, in the boundary layer on a model, ... |
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| A Spectral Element Solution of the Klein-Gordon Equation with High-Order Treatment of Time and Non-Reflecting Boundary |
Jan 2010 |
11 pages |
| Authors:
Joseph M Lindquist; Beny Neta; Francis X Giraldo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF APPLIED MATHEMATICS
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| A spectral element (SE) implementation of the Givoli?Neta non-reflecting boundary condition (NRBC) is considered for the solution of the Klein?Gordon equation. The infinite domain is truncated via an artificial boundary B, and a high-order NRBC is applied on B. Numerical examples, in various configurations, concerning the propagation of a pressure pulse are used to demonstrate the performance of the SE implementation. Effects of time integration techniques and long term results ... |
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| Klein-Gordon Equation with Advection on Unbounded Domains Using Spectral Elements and High-Order Non-Reflecting Boundary Conditions |
Jan 2010 |
15 pages |
| Authors:
Joseph M Lindquist; Francis X Giraldo; Beny Neta; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF APPLIED MATHEMATICS
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| A reduced shallow water model under constant, non-zero advection in the infinite channel is considered. High-order (Givoli-Neta) non-reflecting boundary conditions are introduced in various configurations to create a finite computational space and solved using a spectral element formulation with high-order time integration. Numerical examples are used to demonstrate the synergy of using high-order spatial, time, and boundary discretization. We show that by balancing all numerical errors involved, high-order accuracy can ... |
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| Global Flow Instability and Control IV Held in Crete, Greece on September 28-October 2, 2009: A Synthesis of Presentations and Discussions |
Sep 2009 |
27 pages |
| Authors:
V Theofilis; NU-MODELING INC MADRID (SPAIN)
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| The Final Proceedings for Fourth Symposium on Global Flow Instability and Control, Hersonissos, Crete, Greece, on 28 September 2009 - 2 October 2009. The series of symposia was established in 2001, having as its primary objective the creation of a forum for presentation and discussion of current research and open issues in global flow instability and control. This has been particularly interesting in recent years in view of the increasing ... |
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| In Situ Measurements of Coherent Structures and Turbulence |
07-Apr-2009 |
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| Authors:
John Trowbridge; W R Geyer; WOODS HOLE OCEANOGRAPHIC INSTITUTION MA DEPT OF APPLIED OCEAN PHYSICS AND ENGINEERING
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 | The long-term objective of our research is to quantify the structure of turbulence in fluvial and estuarine environments, in order to develop remote-sensing tools for environmental assessment as well as to improve numerical simulations. The objectives of this program were: (1) to quantify the turbulence length scale and turbulent dynamics in an estuary under varying stratification conditions and geometries, including relatively uniform boundary-layer flows and highly disrupted wake flow conditions; ... |
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| Continued Investigation of Small-Scale Air-Sea Coupled Dynamics using CBLAST Data |
30 SEP 2007 |
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| Authors:
Dick K. Yue; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| This study uses direct numerical simulation, large-eddy simulation, and large-wave simulation for both air and ocean turbulent flows with surface waves to investigate the dynamics of coupled air-sea boundary layers at relatively small spatial scales. With extensive simulation in collaboration with measurement, we identify and assess the key transport processes within the atmosphere-ocean wave boundary layer (WBL). This project obtains a physical foundation for the parameterization of the momentum, mass ... |
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| On the Design of Hypersonic Inward-Turning Inlets |
Jun-2007 |
13 pages |
| Authors:
Barry A Croker; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
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| A family of dual-axis compression, high-contraction-ratio, inward-turning inlets has been designed to achieve a desired shock structure and aerodynamic performance at Mach 6. Computational simulations of the internal inlet flowfield were performed using the research code FDL3DI. These solutions are an integrated part of the inlet design methodology and offer insight into the fundamental fluid phenomenology. The effects of viscous/inviscid interactions, namely swept-shock/turbulent boundary layer interactions are discussed. Additionally, the ... |
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| Validating a Physical Model With Real Data. Part 1. Verifying Wind Tunnel Flow Features in Equivalent Real-Sized Data |
Dec-2006 |
17 pages |
| Authors:
Ronald Cionco; Gail Vaucher; ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM COMPUTATIONAL AND INFORMATION SCIENCE DIRECTORATE
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| How much realism is enough? Airflow around a single building was simulated in the Environmental Protection Agency [EPA] Wind Tunnel by Snyder and Lawson, and their results were published in 1994. Other researchers have done subsequent simulations in the EPA Wind Tunnel; however, the Snyder and Lawson results were selected for calibration against real air flow measurements acquired around an equivalent single office building in New Mexico. This paper will ... |
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| Dynamic-Active Flow Control - Phase I |
18 OCT 2006 |
61 pages |
| Authors:
Julio Soria; MONASH UNIV CLAYTON (AUSTRALIA) DEPT OF MECHANICAL ENGINEERING
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| This is the report of an investigation of active flow control using a wall-normal, zero-net-mass-flux (ZNMF) jet located at the leading edge of an airfoil. |
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| Ultra High Work, High Efficiency Turbines For UAVs |
JUN 2006 |
29 pages |
| Authors:
Rolf Sondergaard; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH PROPULSION DIRECTORATE
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| The opportunity for the reattachment and control of separated flows occurs in inlets, compressors, transition ducts and turbines. Passive and active control of separated flows has been demonstrated successfully by a number of techniques which employ the introduction of longitudinal or streamwise vortices. The role of these vortices is initially to reenergize the wall boundary layer flow by entraining and redistributing momentum from the primary flow to the wall layer ... |
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| Macroscopic Computational Model of Dielectric Barrier Discharge Plasma Actuators |
FEB 2006 |
162 pages |
| Authors:
Timothy R. Klein; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT/DEPT OF ENGINEERING PHYSICS
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| Recent progress in the generation and sustainment of gas discharges at atmospheric pressure has energized research in the field of plasma-aerodynamics. Plasma actuators are promising devices that achieve flow control with no moving parts, do not alter the airfoil shape and place no parts in the flow. The operation of a plasma actuator is examined using a macroscopic (force and power addition) computational fluid dynamic model of a dielectric barrier ... |
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| A Guide for Using the Transient Ground-Water Flow Model of the Death Valley Regional Ground-Water Flow System, Nevada and California |
2006 |
34 pages |
| Authors:
Joan B. Blainey; Claudia C. Faunt; Mary C. Hill; DEPARTMENT OF THE INTERIOR WASHINGTON DC
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| This report is a guide for executing numerical simulations with the transient ground-water flow model of the Death Valley regional ground-water flow system, Nevada and California using the U.S. Geological Survey modular finite difference ground-water flow model, MODFLOW-2000. Model inputs, including observations of hydraulic head, discharge, and boundary flows, are summarized. Modification of the DVRFS transient ground-water model is discussed for two common uses of the Death Valley regional ground-water ... |
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| Disturbances from Shock/Boundary-Layer Interactions Affecting Upstream Hypersonic Flow |
DEC 2005 |
132 pages |
| Authors:
Craig R. Skoch; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
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| Large disturbances and decreased Mach number in the core flow were sometimes found in the downstream end of the nozzle of the Boeing/AFOSR Mach-6 Ludwieg Tube at Purdue University. The cause of the disturbances has been identified using Kulite pressure transducer, hot wire, and hot film measurements. These disturbances were found to be separations caused by shock/boundary-layer interactions in the diffuser, often originating from shocks generated at the sting support. ... |
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| Experimental and Computational Study of the Effect of MHD Forces on Stability and Separation of Nonequilibrium Ionized Supersonic Flow |
28 SEP 2005 |
50 pages |
| Authors:
Igor V. Adamovich; OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING
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| The results of the present work demonstrate the Lorentz force effect on the supersonic boundary layer in M = 3 flows of nitrogen ionized by a transverse RF discharge in the presence of the magnetic field. Boundary layer density fluctuation spectra are measured using the Laser Differential Interferometry (LDI) diagnostics. In particular, decelerating Lorentz force applied to the flow produces a well reproduced increase of the densify fluctuation intensity by ... |
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| Control of High-Speed Flows Using Helium Injection |
24 AUG 2005 |
17 pages |
| Authors:
Alexander J. Smits; Richard B. Miles; PRINCETON UNIV NJ
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| Here, we summarize the results of our investigation of means for controlling high-speed flows using helium injection, first demonstrated by Auvity et al., with particular emphasis on the wavefront distortion of light transmitted through the boundary layer. Quantitative estimates of wavefront distortion were obtained, with and without helium injection, and new diagnostic techniques were developed, including a MHz rate Hartmann wavefront sensor. In particular, we demonstrated the ability to capture ... |
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| Reduced Navier-Stokes Equations Near a Flow Boundary |
04 AUG 2005 |
31 pages |
| Authors:
M. S. Kilic; G. B. Jacobs; J. S> Hesthaven; G. Haller; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MATHEMATICS
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| We derive a hierarchy of PDEs for the leading-order evolution of wall-based quantities, such as the skin-friction and the wall-pressure gradient, in two-dimensional fluid flows. The resulting Reduced Navier-Stokes (RNS) equations are defined on the boundary of the flow, and hence have reduced spatial dimensionality compared to the Navier-Stokes equations. This spatial reduction speeds up numerical computations and makes the equations attractive candidates for flow-control design. We prove that members ... |
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| Studies on Impingement Effects of Low Density Jets on Surfaces - Determination of Shear Stress and Normal Pressure |
13 JUL 2005 |
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| Authors:
Sarith P. Sathian; Job Kurian; INDIAN INST OF TECH MADRAS DEPT OF AEROSPACE ENGINEERING
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| This paper presents the results of the Laser Reflection Method (LRM) for the determination of shear stress due to impingement of low-density free jets on flat plate. For thin oil film moving under the action of aerodynamic boundary layer the shear stress at the air-oil interface is equal to the shear stress between the surface and air. A direct and dynamic measurement of the oil film slope is measured using ... |
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| Large-Bandwidth Phase-Locked Measurements for High-Speed Flow Experiments with Controlled Disturbance Inputs |
JUL 2005 |
25 pages |
| Authors:
Ndaona Chokani; DUKE UNIV DURHAM NC OFFICE OF SPONSORED PROGRAMS
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| The purpose of the present work is to develop an experimental apparatus that will enable us to accurately detect, and then measure, the phase-locked interactions that occur in high-speed flows. In particular, we examine the structure of the shockwave/boundary layer interaction induced by an unswept compression ramp flow in the Supersonic Low Disturbance Wind Tunnel at the NASA Langley Research Center. SLDT has a unique capability for generating a very ... |
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| Transition in High-Speed Boundary Layers: Numerical Investigations Using DNS and LES |
22 FEB 2005 |
125 pages |
| Authors:
Hermann F. Fasel; ARIZONA UNIV TUCSON DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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| Direct Numerical Simulations (DNS) of supersonic flow over a flat- plate with and without adverse pressure-gradient at Mach 3 were carried out in close collaboration with the experimental effort at Princeton University by G. Brown and co-workers. To confirm that simulations and experiments were based on the same "baseflow," the experimental baseflow profiles were compared with our Navier-Stokes results. The downstream development and the spatial growth rates of the disturbances ... |
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| Design and Testing of a 30-Degree Sweep Laminar Flow Wing for a High-Altitude Long-Endurance Aircraft |
01 OCT 2004 |
41 pages |
| Authors:
William D. Solomon Jr; Aaron Drake; Helen L. Reed; William S. Saric; NORTHROP GRUMMAN CORP EL SEGUNDO CA INTEGRATED SYSTEMS
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| A laminar flow wing was designed for a high-altitude long-endurance flying-wing aircraft with a sweep angle of 30 degrees. The resulting wing design satisfied the lift and pitching moment requirements of the aircraft and had extensive runs of laminar flow on the upper and lower surface. A portion of the wing was tested in a low-speed wind tunnel at flight Reynolds number with an equivalent pressure distribution designed to reproduce ... |
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| A Rapid Method of Calculating N-Factors for Estimating Transition Position |
01 OCT 2004 |
13 pages |
| Authors:
M. Gaster; LONDON UNIV (UNITED KINGDOM) DEPT OF ENGINEERING
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| Transition estimation using the E-to-N approach involves evaluating large numbers of eigenvalues of the linear perturbation equations. These eigenvalues provide the amplification rates of the modes of various frequencies and angles of orientation. The number of evaluations required to determine the N-factors can be large, especially when cross-flow modes over a leading edge are important. But since the variation in the values of the amplification rates varies relatively slowly and ... |
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| Integrated Flow Control Devices for the Design of Enhanced Low Pressure Turbines |
26 AUG 2004 |
8 pages |
| Authors:
Jeffrey P. Bons; BRIGHAM YOUNG UNIV PROVO UT DEPT OF MECHANICAL ENGINEERING
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| Flow separation limits the efficiency of low-pressure turbines (LPTs) in aircraft engines. Recent experiments with vortex generator jets (VGJs), conducted in AFRL's low-speed cascade at Wright-Patterson AFB, have demonstrated dramatic reductions in separation losses. The critical science that wilt enable this design innovation to reach its potential is a comprehensive understanding of the effect of VGJs on a separating boundary layer. Experiments are underway at BYU to better understand the ... |
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| Wind Tunnel Simulations of the Mock Urban Setting Test - Experimental Procedures and Data Analysis |
JUL 2004 |
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| Authors:
Ralph Gailis; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
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| The MUST experiment was a large outdoor field study in atmospheric dispersion, attempting to simulate an urban boundary layer by the construction of a regular array of shipping containers. The current report gives details of a wind tunnel dispersion study of the MUST array, aimed at bridging some of the gaps between laboratory and full-scale outdoor trials. The experimental setup and wind tunnel instrumentation are discussed in detail, the measurements ... |
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| Flow Around an Object Projected from a Cavity into a Supersonic Freestream |
MAR 2004 |
90 pages |
| Authors:
Scott T. Bjorge; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| The pressure and flow field of a supersonic flow over a cavity, with and without a store, was the focus of this experiment. One cavity geometry (length to depth ratio 3.6) was studied; the freestream Mach number and the placement of the store relative to the cavity floor were varied. The pressure spectra on the cavity floor were markedly different between Mach numbers of 1.8 and 2.9. The Mach 1.8 ... |
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| Steady-State Evaluation of Two-Equation RANS (Reynolds-Averaged Navier- Stokes) Turbulence Models for High-Reynolds Number Hydrodynamic Flow Simulations |
MAR 2004 |
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| Authors:
Nicholas J. Mulvany; Li Chen; Jiyuan Y. Tu; Brendon Anderson; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
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| This report presents an evaluation of the steady-state capability of the turbulence models available in the commercial CFD code FLUENT 6.0, for their application to the simulation of hydrofoil turbulent boundary layer separation at high-Reynolds numbers. Four widely applied two-equation RANS turbulence models were qualitatively and quantitatively assessed through comparison with high-quality experimental data at Reynolds numbers of 8.284'106 and 1.657'107. The turbulence models evaluated were the Standard k-e model, ... |
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| Data Assimilation Modeling of the Barotropic Tides in the Korea/Tsushima Strait |
2004 |
18 pages |
| Authors:
Jeffrey W. Book; Pavel Pistek; Henry Perkins; Keith R. Thompson; William J. Teague; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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| During 1999-2000, 13 bottom-mounted acoustic Doppler current profilers (ADCPs) and 12 wave/tide gauges were deployed along two lines across the Korea/Tsushima Strait, providing long-term measurements of currents and bottom pressure. Tidally analyzed velocity and pressure data from the moorings are used in conjunction with other moored ADCPs, coastal tide gauge measurements, and altimeter measurements in a linear barotropic data assimilation model. The model fits the vertically averaged data to the ... |
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| Flow Over Difficult Bathymetry: Processes and Parameterizations |
14 OCT 2003 |
15 pages |
| Authors:
Michael C. Gregg; Jack Miller; UNIV OF WASHINGTON SEATTLE APPLIED PHYSICS LAB
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| The goals of this grant were to understand the physics of flows generated by currents passing over small topographic features and to quantify and parameterize, if possible, the mixing these flows produce. |
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| A Doppler Sensor Array for High-Resolution Measurements of the Wavenumber-Frequency Spectrum of the Turbulent Wall Pressure at High Reynold Numbers |
06 OCT 2003 |
46 pages |
| Authors:
Ahmed M. Naguib; MICHIGAN STATE UNIV EAST LANSING DEPT OF MECHANICAL ENGINEERING
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| The Doppler frequency shift is utilized as the basic sensing mechanism for a new unsteady-surface pressure measurement technique. The frequency shift is experienced by a focused laser beam reflected off the aluminized top of a flexible-polymer diaphragm subjected to the unsteady pressure. Prototypical sensors based on this concept, with different sizes and diaphragm material and thickness are constructed as well as evaluated. The results provide understanding of the limits of ... |
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| Simulation of Moving Boundary Flow Using Overset Adaptive Cartesian/ Prism Grids and DES |
SEP 2003 |
22 pages |
| Authors:
Z. J. Wang; Laiping Zhang; MICHIGAN STATE UNIV EAST LANSING DEPT OF MECHANICAL ENGINEERING
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| Development of improved weapon systems requires better understanding of the complex aerodynamics created by moving boundaries. Carriage and release of conventional weapons from aircraft and aerial refueling fall in this category. The flow problem involving moving boundaries are very challenging to compute because the resultant flow field is intrinsically unsteady. Modeling such flow problems is made even more difficult due to the complex geometries and the highly turbulent nature of ... |
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| On Modeling Structural Excitations by Low Speed Turbulent Boundary Layer Flows |
AUG 2003 |
60 pages |
| Authors:
Y. F. Hwang; W. K. Bonness; S. A. Hambric; APPLIED RESEARCH LABORATORY STATE COLLEGE PA
|
| This report documents the results of an investigation on the modeling of structural excitations by low speed turbulent boundary layer flows. This work critically examines various spectral models, both wave vector-frequency spectra and cross-spectra. Many of these models became available after the publication of the monograph by Blake (1986). These models are used to predict the pressure spectra measured by flush-mounted hydrophones of various size and location on buoyantly propelled ... |
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| Development of Turbulence Models for Free-Surface Flows |
JUL 2003 |
8 pages |
| Authors:
David T. Walker; MICHIGAN UNIV ANN ARBOR DEPT OF NAVAL ARCHITECTURE AND MARINE ENGINEERING
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| The goal of this effort was to improve the ability to predict the free-surface flow in the near field of surface ships. The specific objectives were: to develop modeling approaches appropriate to the near-surface region in turbulent free surface flows and to obtain data for validation of CFD predictions of free-surface turbulent flows. The main results of this study can be summarized as follows: (1) The framework outlined in Hong ... |
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| Experimental and Theoretical Studies of Hypersonic Laminar Flow Control Using Ultrasonically Absorptive Coatings (UAC) |
MAY 2003 |
105 pages |
| Authors:
Anatoly A. Maslov; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSK INST OF THEORETICAL AND APPLIED MECHANICS
|
| This report results from a contract tasking Institute of Theoretical and Applied Mechanics as follows: The project is focused on detail experimental and theoretical studies of hypersonic laminar flow control using ultrasonically absorptive coatings (UAC) of regular porosity. Parametrical calculations of boundary layer stability on porous and solid walls will be conducted and compared with the experimental data to be obtained using the artificial wave- packet method and hot-wire measurements. ... |
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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
|
| 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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| 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
|
| 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-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 Gortler vortices. DNS studies were also ... |
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| Blowing Effects on Heat and Mass Transfer for Different Geometrical Configurations |
MAR 2003 |
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| Authors:
F. Bataille; L. Mathelin; J. Bellettre; A. Lallemand; INSTITUT NATIONAL DES SCIENCES APPLIQUEES DE LYON VILLEURBANNE (FRANCE)
|
| In this paper, the blowing impact on the dynamical and thermal boundary layers is investigated through experiments and numerical simulations. Two different geometries (flat plate and circular cylinder) are separately studied. It is shown that blowing tends to thicken the boundary layers and to dramatically decrease the gradients in the immediate vicinity of the surface, leading to a strong decrease of the viscous stress and heat exchanges. Hence, the surface ... |
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| Cranked Arrow Wing (F-16XL-1) Flight Flow Physics with CFD Predictions at Subsonic and Transonic Speeds |
MAR 2003 |
21 pages |
| Authors:
John E. Lamar; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| The increasing capability of computational fluid dynamics (CFD) to simulate real airplane geometries and flow conditions is found in the literature for both fighter and transport airplanes. In the continuance of that trend, this report details the results of a comparative study of CFD and flight data for the F-16XL-1 airplane over a wide range of test conditions from transonic to subsonic speeds. Though this airplane is not new, its ... |
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| Airwake Simulation of Modified TTCP/SFS Ship |
MAR 2003 |
13 pages |
| Authors:
Tsze C. Tai; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| Recent work on airwake simulation based on the steady-state solution to Navier-Stokes equations provides reasonably accurate flow field results that are useful to supplement experimental measurements which otherwise would be more costly and time-consuming. Work on airwake of a special configuration, the Simplified Frigate Shape (SFS), as defined by The Technical Co-operative Program (TTCP) panel, is aimed at validating computational fluid dynamics (CFD) codes. Simulated airwake results based on steady-state ... |
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| Exploratory Experimental Study of Transitional Shock Wave Boundary Layer Interactions |
31 JAN 2003 |
11 pages |
| Authors:
D. S. Dolling; N. C. Clemens; E. Hood; TEXAS UNIV AT AUSTIN DEPT OF AEROSPACE ENGINEERING AND ENGINEERING MECHANICS
|
| An exploratory investigation has been made of transitional shock wave boundary layer interactions. In this case, the interaction is induced by a circular cylinder perpendicular to a flat plate. The tests were conducted in the Mach 5 blowdown tunnel of The University of Texas at Austin. The primary goal of this initial, exploratory study was to determine if repeatable transitional interactions could be generated. Measurements included surface flow visualization using ... |
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| Cavity Wall Measurement Apparatus and Method |
23 DEC 2002 |
25 pages |
| Authors:
Lynn T. Antonelli; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A method of measuring the vapor-liquid boundary surrounding a supercavitational, high-speed underwater vehicle includes the steps of arranging a sensor on a surface of the vehicle. The sensor has a transmit source for emitting an optical signal and a plurality of optical detectors for receiving a reflected optical signal. The reflected optical signal is detected with one of the optical detectors, and the duration of time between the emitting of ... |
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| Air Intakes for Subsonic UCAV Applications - Some Design Considerations |
25 OCT 2002 |
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| Authors:
Peter G. Martin; DEFENCE SCIENCE AND TECHNOLOGY LAB FARNBOROUGH (UNITED KINGDOM)
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| Briefing charts from presentation on the design considerations of air intakes for subsonic UCAV applications. |
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| Sensitivity Analysis of Limited Area Ocean Model |
AUG 2002 |
57 pages |
| Authors:
Dubar K. Kamara; JOHNS HOPKINS UNIV BALTIMORE MD
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| The boundary data for a data assimilation problem for a limited-area ocean model can either be supplied by its global model or from observations interpolated from a conventional observing network. In this study, the sensitivity of the ocean model to variations in the boundary data is investigated. Additionally, the authors look at how predictions of wave height are affected by variations in basin depth. Two models are used to carry ... |
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| Role of the Streaky Structures in a Transition Mechanism of the Boundary Layers and Jets |
JUL 2002 |
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| Authors:
M. V. Litvinenko; V. G. Chernorai; V. V. Kozlov; G. R. Grek; L. L. Lofdal; CHALMERS UNIV OF TECHNOLOGY GOETEBORG (SWEDEN)
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| The role of streamwise structures during transition to turbulence both in near-wall and in free shear flows in many eases is determinative. The purpose of present study is the analysis of results of experimental researches of mechanisms of origin development and transition to turbulent state of the various shear flows with the streamwise structures which have been carried out of late. |
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Reports by Keyword(s)
BOUNDARY LAYER FLOW
