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Computer Architecture, 2004. Proceedings. 31st Annual International Symposium on

Date 7-11 June 2004

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Displaying Results 1 - 25 of 54
  • Proceedings. Users Group Conference

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  • Table of contents

    Page(s): v - viii
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  • Editors Preface

    Page(s): ix - x
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  • First principles calculations of the chemisorption properties of nitro-containing molecules on the Al2O3(0001) surface

    Page(s): 2 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    First-principles calculations based on density functional theory (DFT) and the generalized gradient approximation (GGA) have been used to study the adsorption of nitromethane (NM) and 1,1-diamino-2,2-dinitroethylene (FOX7) molecules on the basal plane of α-Al2O3 crystal. The calculations employ a (2×2) supercell slab model and 3D periodic boundary conditions. Based on these calculations we have determined that both NM and FOX7 molecules can adsorb nondissociatively on the surface, with the most stable adsorption configurations parallel to the surface. The corresponding binding energies are found in the range 25.3-26.0 kcal/mol for NM and 35.6-48.3 kcal/mol for FOX7 depending on the relative molecular orientation and the corresponding surface sites. The minimum energy pathways for NM dissociation have been determined and a low energy pathway leading to H elimination with formation of adsorbed CH2NO2 and hydroxyl species has been identified. Additional calculations have focused on adsorption properties of aci-nitromethane tautomers and on description of the energetic pathways connecting adsorbed nitromethane molecule with these tautomers. View full abstract»

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  • Parallelizing the Keldysh formalism for strongly correlated electrons

    Page(s): 7 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    Nonequilibrium quantum mechanics can be solved with the Keldysh formalism, which evolves the quantum mechanical states forward in time in the presence of a time-dependent field, and then evolves them backward in time, undoing the effect of the time-dependent field. The Feynman path integral over the Keldysh contour is employed to calculate the strongly correlated Green's function. We examine the accuracy of this procedure for the simplest problem that requires a nonequilibrium formulation: the electron spectral function of the spinless Falicov-Kimball model. View full abstract»

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  • Large-scale atomistic simulations of nanoindentation and crack propagation under compression

    Page(s): 17 - 19
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB) |  | HTML iconHTML  

    Large-scale molecular dynamics (MD) simulations have been performed on parallel computers to study nanoindentation-induced amorphization in silicon carbide crystal. The load-displacement response exhibits an elastic shoulder followed by a plastic regime consisting of a series of load drops. Analyses of bond angles, local pressure and shear stress, and shortest-path rings show that these load drops are related to dislocation activities under the indenter. We have found that amorphization is driven by the coalescence of dislocation loops and that there is a strong correlation between load-displacement response and ring distribution. Current efforts focus on large-scale MD simulations of (a) nanoindentation in amorphous and nanophase SiC and (b) crack propagation in amorphous and nanostructured SiO2 under compression. View full abstract»

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  • Accelerated modeling and new ferroelectric materials for naval SONAR

    Page(s): 27 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (136 KB) |  | HTML iconHTML  

    We have computationally designed new materials for use in naval sound navigation ranging (SONAR). Our quantum-mechanical studies show that these lead-free, nontoxic oxides are high-performance piezoelectrics with promise for use in naval SONAR and communications applications. To enable this research, we also present techniques for greatly accelerated modeling of oxide materials. We show that a simple atomistic model accurately reproduces our quantum-mechanical results yet is thousands of times faster. We also report successful porting and performance tuning of our computer codes to the CRAY X1, resulting in a great speed-up over previous architectures. View full abstract»

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  • Large-scale quantum-mechanical simulations of nanoscale devices and new materials

    Page(s): 34 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Recent advances in theoretical methods and high performance computing allow for reliable first-principles investigations of nanoscale devices and complex materials. Using large scale O(N) real-space-based ab initio calculations, we carried out a theoretical study of carbon nanotube-cluster composites as prototype systems for molecular sensing at the nanoscale. Dramatic changes in the electrical conductance of the composite are predicted when gas molecules are adsorbed onto the metal clusters. The observed sensitivity and selectivity might suggest new avenues for the design and production of nanotube-based molecular sensors. The second part of this article focuses on calculating and predicting the properties of piezoelectrics, and on "designing" new materials with enhanced piezoelectric response. We consider polymers in the polyvinylidene fluoride (PVDF) family and show that our calculations not only reproduce well the existing experimental data, but also provide a much improved understanding of their polar properties, which leads to a "design" of novel polymers with a BN backbone. The new polymers are predicted to have up to 100% better piezoelectric response and an enhanced thermal stability with respect to their PVDF analogs. Since methods for their synthesis are readily available, they offer a promising avenue for improving ferro and piezoelectric devices. View full abstract»

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  • Large-Scale Quantum-Mechanical Simulations of Nanoscale Devices and New Materials

    Page(s): 41 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    Recent advances in theoretical methods and high performance computing allow for reliable first-principles investigations of nanoscale devices and complex materials. Using large scale O(N) real-space-based ab initio calculations, we carried out a theoretical study of carbon nanotube-cluster composites as prototype systems for molecular sensing at the nanoscale. Dramatic changes in the electrical conductance of the composite are predicted when gas molecules are adsorbed onto the metal clusters. The observed sensitivity and selectivity might suggest new avenues for the design and production of nanotube-based molecular sensors. The second part of this article focuses on calculating and predicting the properties of piezoelectrics, and on "designing" new materials with enhanced piezoelectric response. We consider polymers in the polyvinylidene fluoride (PVDF) family and show that our calculations not only reproduce well the existing experimental data, but also provide a much improved understanding of their polar properties, which leads to a "design" of novel polymers with a BN backbone. The new polymers are predicted to have up to 100% better piezoelectric response and an enhanced thermal stability with respect to their PVDF analogs. Since methods for their synthesis are readily available, they offer a promising avenue for improving ferro and piezoelectric devices. View full abstract»

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  • RCS analysis of the reinforced carbon-carbon Tee-seals as potential "Flight Day 2" candidates in support of the Columbia accident investigation

    Page(s): 40 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB) |  | HTML iconHTML  

    During the Columbia Shuttle investigation, AFRL tried to identify a piece of on-orbit debris that originated from the Orbiter during its second day in space. This "Flight Day Two (FD2)" object was detected by UHF radar and tracked for three days before falling out of orbit. Extensive RCS measurements performed by AFRL and corresponding ballistic analysis by USAF Space Command narrowed the potential candidates down to just two possible classes of objects; (1) a section of reinforced carbon-carbon (RCC) leading edge panel acreage, and (2) a section of RCC "Tee-seals". During the investigation, AFRL was asked to estimate the UHF RCS of various whole and fragmentary Tee-seals originating between panel segment #6 and #11 on the shuttle Orbiter left wing, in order to compare with the on-orbit UHF RCS observations. Since actual Orbiter Tee-seal hardware, either whole or fractured, from the left wing area were not available, we predicted UHF RCS on various virtual Tee-seal fragment geometries to confirm or eliminate the Tee-seal as a candidate for the FD2 object. In this paper, we summarize our RCS predictions which conclusively show that a whole or partial RCC Tee-seal could not be the FD2 object. This left the RCC panel acreage as the only known object that satisfies both the on-orbit observed ballistic and UHF RCS data, a confirming piece of evidence in the Columbia investigation. View full abstract»

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  • Potential discrepancies in radar signature predictions for ground vehicles

    Page(s): 45 - 51
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB) |  | HTML iconHTML  

    An investigation of modeling issues at Ka-band and above was conducted using Xpatch, a high-frequency radar signature prediction code based on the shooting and bouncing ray technique. The lessons learned apply to a large class of ground targets of interest for millimeter wave radar applications. We summarize the unclassified modeling results and computational requirements at Ka-band frequencies. The ground vehicle simulations indicate that accurate target representations are required to a resolution on the order of the wavelength. In many cases the available data corresponds to near-field measurements. In this case we use the Xpatch near-field simulations to better reproduce the measured radar signatures. View full abstract»

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  • Network simulation of the electronic battlefield

    Page(s): 52 - 55
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (79 KB) |  | HTML iconHTML  

    While many existing tools can simulate specific parts of wireless communication systems in detail, no single software tool, or integrated framework has been proposed to simulate the complete wireless systems including highly detailed RF propagation and radio and networking protocols. It has been shown that results from network simulation can be simply wrong and misleading when underlying devices and operating environments are not modeled appropriately. The primary reason for a lack of such integrated tools is the major computational challenge that is imposed by the combined model. This project proposes to build such an environment using HPC resources to overcome the computational challenge. View full abstract»

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  • Preliminary modeling of air breakdown with the ICEPIC code

    Page(s): 56 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Interest in air breakdown phenomena has recently been rekindled with the advent of advanced virtual prototyping of radio frequency (RF) sources for use in high power microwave (HPM) weapons technology. Air breakdown phenomena are of interest because the formation of a plasma layer at the aperture of an RF source decreases the transmitted power to the target, and in some cases can cause significant reflection of RF radiation. Understanding the mechanisms behind the formation of such plasma layers aid in the development of maximally effective sources. This paper begins with some of the basic theory behind air breakdown, and describes two independent approaches to modeling the formation of plasmas, the dielectric fluid model and the particle in cell (PIC) approach. Finally we present the results of preliminary studies in numerical modeling and simulation of breakdown. View full abstract»

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  • Seismic waves from light trucks moving over terrain

    Page(s): 65 - 70
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    Seismic sensing is one sensor mode employed in US unattended ground sensor systems (UGS). Seismic sensors possess the advantage of beyond-line-of-sight sensing. They can detect ground vibrations generated by moving vehicles or personnel and they can be used to cue other sensors or possibly to classify or even identify targets. As a complement to field trials, our work has produced a simulation capability to support seismic UGS developments. We model ground vibrations from moving vehicles and generate synthetic seismic wavefield data over terrain of interest to US forces. Using supercomputers to simulate seismic wave propagation in large finite-difference time-domain simulations, our objective is to generate high fidelity data sets that provide new opportunities for understanding and exploiting signal features that may be unrecognizable in limited field trials. The method utilizes a vehicle-dynamics model to calculate the vehicle response to vehicle acceleration and movement over bumpy roads or terrain. It calculates forces transmitted to the ground; distributes these forces to grid points of a finite difference model; and simulates seismic waves propagating away from the vehicle. The current work focuses on light trucks moving toward and through a mountain pass and signature features associated with suspension and wheelbase characteristics. The results from two analyses show seismic waves propagating away from one and two trucks, respectively. We conclude that the wavefield data is realistic and suitable for virtual trials of seismic UGS. View full abstract»

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  • Flow past a stationary and moving cylinder: DNS at Re=10,000

    Page(s): 72 - 79
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    We conduct direct numerical simulations with 300 million degrees of freedom of turbulent flows past a stationary and a forced oscillating rigid cylinder at the Reynolds number Re=10,000. This one-order of magnitude increase in Reynolds number (compared to previous DNS) is accomplished by employing a multilevel-type parallel algorithm within the spectral element framework. Comparisons with the available experimental data show that the simulation has captured the flow quantities, mean, and rms statistics of the cylinder wake correctly. We also examine the effect of the randomness in the inflow on the vortex formation at a lower Reynolds number. We demonstrate that noisy inflows cause a vortex shedding-mode switching in the cylinder wake. View full abstract»

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  • High-accuracy DNS of supersonic base flows and control of the near wake

    Page(s): 80 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    Large-scale numerical simulations of axisymmetric, supersonic base flows were conducted at various Reynolds numbers. Direct numerical simulations (DNS) were employed to investigate the hydrodynamic stability behavior of the near-wake region. As a consequence of physical flow instabilities, large coherent structures evolve that have a significant impact on the mean flow wand and are responsible for a considerable amount of base-drag. It is demonstrated that the deliberate exclusion or reinforcement of certain helical modes can lead to a rise in base-pressure and thus decrease the drag of a blunt body at supersonic speed. For these investigations, a high-order accurate compressible Navier-Stokes solver in cylindrical coordinates with high parallel efficiency was developed and employed on the SGI Origin 3900 shared memory complex at the ERDC MSRC. In addition to providing vital insight into the physical mechanisms in supersonic base flows, the DNS results are intended for use as benchmark data for the development of a flow simulation methodology (FSM) for high Reynolds number turbulent flows. View full abstract»

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  • Numerical simulation of Kelvin-Helmholtz instability via direct- and large-eddy simulation

    Page(s): 89 - 95
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    Kelvin-Helmholtz (K-H) instability in a stably stratified background is studied numerically in order to support the AirBorne Laser (ABL) project. The wind shear associated with K-H events produces irregularities in the air density which result in both refraction and scattering of laser beams used for communications and for anti-missile purposes. Optical distortion is measured from the simulations through analysis of the second order structure function of the potential temperature fluctuations. To date, direct numerical simulations (DNS) have been conducted at bulk Richardson numbers of 0.05-0.1 and Reynolds numbers of 2000-2500 using up to 1000×350×2000 Fourier modes, run on as many as 1000 processors of the Cray T3E at ERDC. The structure function coefficients, power law exponents, and turbulence inner scale from these simulations are in good agreement with both theoretical predictions and field measurements. An initial phase of a companion large-eddy simulation (LES) study has been completed where the existing DNS has been replicated at lower resolution using dynamic subgrid scale modeling ideas. The results of these simulations show that the first and second order statistics (including the structure function) can be reproduced with acceptable accurately using meshes that are coarser by factors of up to six in each spatial direction. When the effect of the increased time step is taken into account, the LES can be completed at computational cost that is 1/64 = 1/1296 of that required for the DNS. We also anticipate that it should be possible to produce high-fidelity simulation results at Reynolds numbers that are one to two orders of magnitude higher using LES, which places the simulations within the range of high-altitude wind shear events. View full abstract»

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  • Application of direct and large-eddy simulation methods to late wakes of submerged bodies

    Page(s): 96 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    Late wakes of submerged bodies are simulated in support of the ONR mechanics and energy conversion turbulence program. Direct numerical simulations (DNS) is used to examine the dynamics, energetics, and structure of wakes evolving to late times. Particular emphasis is placed on quantifying the structural differences between wakes of towed and self-propelled bodies and on quantifying the influences of environmental shear and stratification. The DNS results clearly show that wakes of towed bodies lead to larger-scale coherent structures at late times. Stratification tends to confine the wake in the vertical direction and provides a mechanism for the radiation of internal waves. Shear is found to interrupt the upscale cascade of vorticity. In addition to DNS, large-eddy simulation (LES) is considered as a means of accessing higher Reynolds numbers and of enabling broader parameter studies. As a first step in this direction, the LES approach is validated by repeating prior DNS on much coarser meshes. A parameter-free dynamic subgrid-scale model is used for this purpose and good results for low-order statistics are obtained on a mesh that is a factor of 4 coarser in each direction as compared with the DNS. When the effect of the increased time step is taken into account, this represents a factor of 44 = 256 reduction in computational expense. Thus LES can greatly reduce the computer time needed for wake studies and can allow significant increases in Reynolds number. View full abstract»

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  • Multidisciplinary applications of detached-eddy simulation to separated flows at high Reynolds numbers (challenge 92)

    Page(s): 103 - 111
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    The current effort develops and demonstrates the application of high resolution turbulence modeling to flight mechanics and aeroelasticity of air vehicles at flight conditions where the vehicle is experiencing massively separated flow fields. The effort has both a basic research component to aid in developing the method and an applied component where the method is used to demonstrate an ability to simulate current DoD aircraft issues in flight mechanics and aeroelasticity. The high resolution turbulence method is a hybrid Reynolds averaged Navier-Stokes (RANS)-large eddy-simulation (LES) method introduced by Spalart et al. in 1997 called detached-eddy simulation (DES) implemented in an unstructured Navier-Stokes solver, Cobalt. In the basic research component, DES has been applied to an Aerospatiale-A airfoil at an angle of attack of 13.3 degrees and a Reynolds number of 2 million. The project is called DESFOIL and simulates laminar-to-turbulent transition, adverse pressure gradients, streamline curvature, and boundary layer separation of a 3D airfoil strip. This study is in the early stages of developing a baseline for RANS and DES computations. DES has also been applied to flight mechanic and aeroelasticity problems of DoD air vehicles to demonstrate the utility of DES and also discover some of the nonlinear mechanisms causing these flight issues. The applications studied include the F/A-18E forced motion about the roll axis and one degree of freedom simulation of abrupt wing stall (AWS), the F/A-18C at conditions of tail buffet, and the ARGUS missile at conditions where it experiences coning motion. View full abstract»

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  • RANS and detached-eddy simulation of the NCCR airfoil

    Page(s): 112 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB) |  | HTML iconHTML  

    A circulation control foil is studied using incompressible Reynolds-averaged Navier Stokes and detached-eddy simulation CFD methods. It is shown that Reynolds-averaged Navier-Stokes simulations of large jet momentum coefficient cases with a linear Reynolds-stress closure and a blended k-ω = k-ε turbulence model is able to successfully predict the pressure-distribution trends in comparison to benchmark data. Details of the simulated flow are presented through analysis of the integral forces and moment, velocity field, and turbulent kinetic energy. However, given the lack of data and CFD grid studies these results lack validation. Detached-eddy simulation is undertaken for the unblown case, and demonstrates that the method is capable of resolving turbulent vortex shedding. Statistical and spectral analysis is used to explain the simulation results, however, as with the RANS simulations, lack of data precludes validation for this problem. Nonetheless, results are encouraging and suggest further application of DES to both circulation control studies as well as other trailing-edge applications. Finally, implications for cavitation-free operation of circulation-control devices are discussed. View full abstract»

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  • CFD in support of wind tunnel testing for aircraft/weapons integration

    Page(s): 123 - 131
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB) |  | HTML iconHTML  

    Integrating data and computations using AEDC semiempirical and CFD techniques has provided vital support for integrating weapons with the Joint Strike Fighter (JSF) and the Joint Unmanned Combat Air System (J-UCAS). The techniques and the processes used are described. Computational results were obtained using HPC assets, and when possible, the results were validated against wind tunnel data. The success of these validations has led to high confidence in the computational results and also to the use of computational results to provide data outside the tunnel operating envelope. This has led in turn to the elimination of tests and saved the two programs millions of dollars. In summary, the subject computations: 1) provided information for pretest planning; 2) corrected errors in wind tunnel data reduction and results; and 3) obtained results for configurations that could not be obtained in the wind tunnel because of physical limitations of the support systems as well as limitations of the tunnel operating envelope. Computations and analysis performed for the two programs have demonstrated that the integrated test and evaluation process does reduce cost and risk. View full abstract»

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  • Applied computational fluid dynamics in support of aircraft/store compatibility and weapons integration - 2004 edition

    Page(s): 132 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (448 KB) |  | HTML iconHTML  

    The Air Force SEEK EAGLE Office (AFSEO), Eglin Air Force Base (AFB), FL, is the United States Air Force (USAF) authority for weapons certification efforts. AFSEO performs test and evaluation for aircraft/store compatibility certification and uses computational fluid dynamics (CFD) to support this process. Determining the flow about an aircraft/store combination can be extremely difficult. Complicated geometry such as pylons, launchers, and internal weapons bays can create severe acoustic and aerothermodynamic environments, which are challenging to numerically simulate. The additional challenge of rapidly and accurately simulating the trajectory of a store separation in a high-volume simulation environment is beyond the capabilities of most CFD programs. The USAF requirement for numerous, simultaneous and quick-reaction solutions for a wide variety of stores and aircraft can only be accomplished through application of parallel high-performance computing resources that meet the significant computational and memory demands of the various cases. This project increases combat capability for the current USAF fleet of tactical and strategic aircraft with associated weapon systems. Before operational use, all aircraft/store configurations must be certified for safe loading, carriage and jettison/release. AFSEO provides flight certification recommendations, which are based on combinations of engineering analysis, ground, and flight testing. Engineering analyses come from disciplines in carriage loads, store separations, flutter, ballistics, stability and control, and electromagnetic compatibility and interference. The AFSEO CFD team provides time-critical support for engineering analyses - in the form of computed aircraft/store carriage aerodynamic loads, predicted store separation characteristics, and visualized flow field physics - used to optimize the application of ground and flight testing, reducing risk and lowering cost of fielding new weapons. This paper discusses four of the most recently applied AFSEO CFD tasks and code development, related to specific aircraft/store certifications. View full abstract»

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  • High fidelity methods and physics for UAV flow regimes

    Page(s): 138 - 143
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    Planned Air Force Unmanned Air Vehicles (UAVs) will be limited by highly nonlinear flow regimes, so an advanced simulation capability has been applied to this class of problems. The proposed paper will document several large-scale computational studies and efforts to validate and to extend the solver capability. View full abstract»

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  • Time-accurate aerodynamic modeling of synthetic jets for projectile control

    Page(s): 144 - 150
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB) |  | HTML iconHTML  

    This paper describes a computational study undertaken to determine the aerodynamic effect of tiny unsteady synthetic jets as a means to provide the control authority needed to maneuver a spinning projectile at low subsonic speeds. Advanced Navier-Stokes computational techniques have been developed and used to obtain numerical solutions for the unsteady jet-interaction flow field at subsonic speeds and small angles of attack. Unsteady numerical results show the effect of the jet on the flow field and on the aerodynamic coefficients. The unsteady jet is shown to substantially alter the flow field both near the jet and the base region of the projectile that in turn affects the forces and moments even at zero degree angle of attack. The results have shown the potential of computational fluid dynamics to provide insight into the jet interaction flow fields and provided guidance as to the locations and sizes of the jets to generate the maximum control authority to maneuver a projectile to hit its target with precision. View full abstract»

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  • Tilt rotor aeromechanics phenomena in low speed flight

    Page(s): 151 - 157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB) |  | HTML iconHTML  

    This work investigates important aeromechanics phenomena affecting the V-22 tilt rotor in low speed sideward flight or while hovering in quartering or crosswind conditions. These phenomena, such as pitch-up with sideslip and increased power required in sideward flight, were identified during V-22 critical azimuth flight testing and impacted handling qualities in this flight regime. High fidelity, dynamic, unsteady, Navier-Stokes computational fluid dynamics (CFD) calculations are presented and compared with flight test data. CFD predicts the flight test trends as a function of wind direction, in good agreement with data. Detailed investigation clearly shows the interaction of the rotor wake with the airframe as the major cause of the aeromechanics phenomena seen on the V-22. Identification of the underlying flowfield physics allows investigation of options for alleviation and prediction of future tilt rotor configurations. View full abstract»

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