Static and Dynamic Simulations of a Generic UCAV Geometry Using the Kestrel Flow Solver

Lofthouse, Andrew J.; Ghoreyshi, Mehdi; Jirasek, Adam; Cummings, Russell M.

doi:10.2514/6.2014-2264

Cited by 11 publications

(5 citation statements)

References 30 publications

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“…11 top right) covering most of the 'outer wing' geometry. The same difficulty to predict pitch moment coefficient is reported (75) even when expensive numerical solutions are applied. The correct prediction of vortex breakdown has been shown to be a very difficult task, and the deficiencies may be attributed to the lack of appropriate turbulence models (71, chap.34) .…”

Section: Extensive Validation Efforts Have Been Undertaken By Nato's supporting

confidence: 52%

Technology challenges of stealth unmanned combat aerial vehicles

Sepulveda

Smith

2017

Aeronaut. j.

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The ever-changing battlefield environment, as well as the emergence of global command and control architectures currently used by armed forces around the globe, requires the use of robust and adaptive technologies integrated into a reliable platform. Unmanned Combat Aerial Vehicles (UCAVs) aim to integrate such advanced technologies while also increasing the tactical capabilities of combat aircraft. This paper provides a summary of the technical and operational design challenges specific to UCAVs, focusing on high-performance, and stealth designs. After a brief historical overview, the main technology demonstrator programmes currently under development are presented. The key technologies affecting UCAV design are identified and discussed. Finally, this paper briefly presents the main issues related to airworthiness, navigation, and ethical concerns behind UAV/UCAV operations.

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Section: Extensive Validation Efforts Have Been Undertaken By Nato's supporting

confidence: 52%

Technology challenges of stealth unmanned combat aerial vehicles

Sepulveda

Smith

2017

Aeronaut. j.

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“…Some of the papers in the NATO STO Task Group AVT-201 Special Sessions present the CFD validation results of the DLR-F19 wind tunnel models with and without control surfaces. 17,18,19,20 A problem of using CFD to fill tables is the mesh generation and the computational cost: to build an aerodynamic model using CFD, a separate high quality grid needs to be generated around aircraft for each control surface deflection. An aerodynamic model for stability and control also requires a large number of coupled computations for different values of motion frequency and amplitude for each configuration which makes time-accurate CFD simulations a very expensive approach.…”

Section: Introductionmentioning

confidence: 99%

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Ghoreyshi

Jirasek

Cummings

et al. 2014

32nd AIAA Applied Aerodynamics Conference

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This work is part of the NATO STO Task Group AVT-201 Special Sessions being organized by the AIAA Applied Aerodynamics Technical Committee. Reduced-OrderModeling techniques based on response functions are presented and validated for unsteady aerodynamic prediction of a generic unmanned combat air vehicle with trailing edge flaps. The overset grid approach was used to move these control surfaces and simulate the flow fields around the vehicle in static and dynamic conditions and with different control surface deflections. Single meshes were also generated to study the effects of gaps present in the overset mesh and the sting geometry available in the experimental model. The Reynoldsaveraged Navier Stokes predictions were first validated by wind-tunnel static and dynamic case measurements. The flow topology over the configuration was then described for a range of angles of attack and control surface deflections. The response functions with respect to angle of attack and pitch rate were directly calculated from step motion simulations in CFD and a grid motion approach. An aerodynamic model was then created from these functions and used to predict the vehicle aerodynamic responses obtained from pitching oscillations at different amplitudes and frequencies. The results show that predictions from a linear model are only in good agreement with time-accurate simulations of small amplitude motions. A model that has response dependence on the angle of attack match quite well with CFD data of large amplitude motions within the range of data used for model generation, however, small discrepancies can also be seen in pitch moment plots. The results show that model predictions get worsen with including sting geometry in simulations because of the nonlinear hysteretic behavior of a wake formed behind the sting. Nomenclatureroll moment coefficient in wind axes Downloaded by CORNELL UNIVERSITY on July 30, 2015 | http://arc.aiaa.org |

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“…The results of the very comprehensive windtunnel investigations over a wide range of onflow conditions are documented by Huber et al [39], Vicroy et al [40] and Rein et al [41] the numerical work is ea. published by Frink [42], Hitzel and Zimper [43], Kennett et al [44], Lofthouse et al [45] and Jirasek et al [46]. The TAU results are summarized by the author in Schütte et al [47].…”

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confidence: 98%

Numerical Investigations of Vortical Flow on Swept Wings with Round Leading Edges

Schütte

2017

Journal of Aircraft

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The present work is investigating the vortex-dominated flow physics as well as the aerodynamic behavior of swept wing configurations with round leading edges. The research is based on numerical simulations using the computational fluid dynamics method DLR TAU. The target configurations are swept wings of constant aspect ratio, variable leading-edge contours, and leading-edge sweep angles. The work deals with the onset of the vortical flow at the leading edge for constant and variable leading-edge nose radii, the influence of the angle of attack, the leading-edge sweep, and the onflow Mach number. Furthermore, the aerodynamic behavior is analyzed and assessed, as well as the specific flow physics in the vicinity of the vortical flow separation at round leading edges. The objective of the present work is to provide a contribution for the design and assessment of the physical characteristics of swept wing configurations. Furthermore, sensitivities will be given for the design process. In addition, the current investigation provides a deeper understanding of the separation onset process and the flow physics of swept wing configurations with round leading edges. Nomenclaturewing reference length, depth of the wing, m M ∞ = onflow Mach number, equal to a∕U ∞ p = pressure, N∕m 2 q ∞ = onflow dynamic pressure, N∕m 2 Re ∞ = Reynolds number, equal to U ∞ · c ref ∕ν r = radius at nose of the profile, m r N = nondimensional leading-edge contour radius, equal to r∕c ref s = wing semispan, m T = temperature, K t = time, s U ∞ = onflow velocity, m∕s u = local velocity within the flowfield, m∕s x, y, z = Cartesian coordinates, m y W = initial wall distance, distance of first grid point from wing surface, m y = nondimensional value to assess resolution of boundary-layer wall unit, equal to τ W ∕ρ p · y W ∕ν α = angle of attack, deg β = angle of sideslip, deg γ = circulation Δt = discrete time step, s Δx = discrete step in space, m μ = dynamic viscosity, Ns∕m 2 ν = kinematic viscosity, m 2 ∕s ρ = density, kg∕m 3 τ W = wall friction, N∕m 2 φ = wing sweep, deg k∂ρ∕∂tk = density residual, kg∕m 3 s Subscripts le = leading edge r = root ref = reference parameter ∞ = onflow condition

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Static and Dynamic Simulations of a Generic UCAV Geometry Using the Kestrel Flow Solver

Cited by 11 publications

References 30 publications

Technology challenges of stealth unmanned combat aerial vehicles

Technology challenges of stealth unmanned combat aerial vehicles

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

Numerical Investigations of Vortical Flow on Swept Wings with Round Leading Edges

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