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Heath B Johnson - One of the best experts on this subject based on the ideXlab platform.
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investigation of mach 10 Boundary Layer Stability of sharp cones at angle of attack part 1 experiments
53rd AIAA Aerospace Sciences Meeting 2015, 2015Co-Authors: Eric C Marineau, George C Moraru, Daniel R Lewis, Joseph D Norris, John Lafferty, Heath B JohnsonAbstract:The Boundary-Layer transition and Stability characteristics of sharp cones at angle-of-attack are investigated with measurements at Mach 10 in the Arnold Engineering Development Complex (AEDC) Hypervelocity Wind Tunnel 9 on a 1.5-m long, 7-deg cone at unit Reynolds numbers between 1.8 and 15 million per meter. The transition location is determined with coaxial thermocouples and temperature sensitive paint, and Stability measurements are obtained using high-frequency response pressure sensors. The measurements are used to validate the STABL-3D linear Stability theory (LST) code at angles-of-attack up to 6-deg. The computations are found to reproduce the experimental trends regarding the effect of angle-of-attack on the growth of 2 mode waves. The amplitude of the 2 mode waves near breakdown on the leeward and windward meridians scale linearly with edge Mach number. The initial amplitudes estimated using linear Stability computations are found to scale with Pitot noise in the unstable 2 mode frequency band. Linear Stability computations along with the ability to correlate initial 2 mode amplitudes to tunnel noise and to correlate maximum 2 mode amplitudes to edge Mach number enables the use of Mack’s amplitude method to predict 2 mode transition. This methodology is investigated to accurately predict sharp cone Boundary Layer transition at 0-deg AoA. Extension to sharp cones at angle-of-attack is expected to be straightforward.
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assessing hypersonic Boundary Layer Stability in the presence of structural deformation
AIAA Journal, 2014Co-Authors: Zachary B Riley, Jack J Mcnamara, Heath B JohnsonAbstract:This work investigates the effect of two-dimensional surface deformations on hypersonic Boundary-Layer Stability. The deformations are obtained from previous research and represent the characteristic response of integrated thermal protection system panels due to combined aerodynamic and thermal loading. Boundary-Layer Stability is assessed using linear Stability theory and the parabolized Stability equations for several different cases, such as deformation direction, deformation location, multiple deformations in series, structural Boundary condition, surface temperature, the combined effect of Mach number and altitude, and deformation-mode shape. The broad set of results provides important insight into the conditions where thermomechanical compliance can promote, or even possibly delay, hypersonic Boundary-Layer transition.
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reacting hypersonic Boundary Layer Stability with blowing and suction
47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009Co-Authors: Heath B Johnson, Joel E Gronvall, Graham V CandlerAbstract:The Stability of hypersonic Boundary Layers over flat plates and cones is analyzed using CFD simulations of the mean flows and linear Stability analysis of the Boundary Layer profiles. Blowing and suction effects on disturbance amplification rates and predicted transition locations are investigated. In the case of blowing gas into the flow over a cone, it is found that the computational results match the trends observed in the experiments of increasing inStability with increasing blowing rate. Next for the case of blowing, both reacting and non-reacting gases are considered, and the possible stabilizing effect of chemical reactions is investigated. Stability analyses are performed for small rates of CO2 injection into a low-enthalpy air flow, and the results show only slight disturbance amplification. Further analysis is required to see if CO2 injection into flows at higher enthalpies can have a more significant effect. I. Introduction Understanding the factors that affect Boundary Layer Stability and transition to turbulence is very important for a number of hypersonic vehicle applications. A number of studies have been performed looking at the effects of blowing or suction on Boundary Layer Stability. This can occur in the case of forced mass flow through a porous surface or in the case of an ablative surface material which releases gas into the Boundary Layer. Schneider 1 performed a review of published open literature experimental results relating to the effect of blowing on Boundary Layer Stability, with a focus on experimental data which may be suitable for comparison with the results of calculations. The results were summarized in the conclusions that blowing generally moves transition upstream with higher mass flow rates, lighter injection gases, and injection occurring farther upstream having greater effects. Using computational fluid dynamics and linear Stability analysis, we attempted to reproduce some of the results of the experiments which were reviewed. This effort was hindered in many cases by missing details of the model geometries or experimental conditions. One series of experiments by Pappas and Okuno 2 contained a sufficient amount of detail for us to attempt a computational analysis with a few assumptions, and the results of that analysis will be presented. We also have begun to investigate the effects of blowing or suction in high-enthalpy flows where, in the case of blowing, the injected gas will not only mix with the free-steam gas, but may also chemically react, and some preliminary results from that work will be presented. For all our simulations, we use the STABL 3 suite of tools. The laminar mean flow solutions for this analysis are generated using an optimized 2D/axisymmetric CFD solver based on the implicit Data-Parallel Line Relaxation (DPLR) method. 4 The DPLR CFD solver and the Stability analysis code, PSE-Chem, have been extensively tested and validated for linear Stability theory (LST) and parabolized Stability equations (PSE) calculations in the analysis of many different problems. 3, 5, 6 The ability to calculate laminar mean flows and Boundary Layer Stability properties for models with suction or gas injection is new to STABL and this capability will first be validated by comparison with other published results.
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Boundary Layer Stability calculations for the hifire 1 transition experiment
Journal of Spacecraft and Rockets, 2008Co-Authors: Christopher R Alba, Heath B Johnson, Graham V Candler, Matthew D Bartkowicz, Karen T BergerAbstract:Boundary-Layer Stability analysis is performed by computational fluid dynamic simulation of experiments conducted in the National Aeronautics and Space Administration Langley Research Center 20-in. Mach 6 Air Tunnelinsupportofthe first flightoftheHypersonicInternationalFlightResearchExperimentationprogram.From the laminar computational flow solutions, disturbances are calculated using the linear parabolized Stability equations to obtain integrated disturbance growth rates. Comparisons are made between the experimentally observed transition locations and the results of the Stability analysis. The Stability results from the NASA Langley Research Center Air Tunnel are combined with previous work done for the Calspan University at Buffalo Research Center Large-Energy National Shock Tunnel to show excellent correlation between predicted and observed Boundary-Layer transition locations. Roughness calculations are also performed and a Reynolds number based on trip height is tabulated with experimental results.
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Boundary Layer Stability analysis of the hypersonic international flight research transition experiments
Journal of Spacecraft and Rockets, 2008Co-Authors: Heath B Johnson, Graham V Candler, Christopher R Alba, Matthew Maclean, Timothy Wadhams, Michael HoldenAbstract:Boundary-Layer Stability analysis is performed by computational fluid dynamics simulation of experiments conducted in theCalspan–University at BuffaloResearchCenter Large EnergyNational ShockTunnel in support of the first flight of the Hypersonic International Flight Research Experimentation program. From the laminar flow solutions, disturbances are calculated using the linear parabolized Stability equations method and inStability is quantified by integrating the resulting disturbance growth rates. Comparisons aremade between the experimentally measured transition locations and the results of the parabolized Stability equations analysis. The results show that for the cases tested, the e transition correlation works better than the commonly usedRe =Me engineering criterion for predicting the onset of Boundary-Layer transition from laminar to turbulent flow.
Xiaolin Zhong - One of the best experts on this subject based on the ideXlab platform.
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receptivity of mach 6 flow over a flared cone to freestream disturbance
42nd AIAA Aerospace Sciences Meeting and Exhibit, 2004Co-Authors: Xiaolin ZhongAbstract:This paper presents a numerical simulation study of the receptivity to weak freestream acoustic waves for a Mach 5.941 axisymmetric flow over a flared cone with a 5' half-angle. The flow conditions and geometry are the same as those of the hypersonic Boundary Layer Stability experiments carried out in NASA Lan ley Hypersonic Quiet Tunnel by Lachowicz et al. &? and transition experiments by Horvath et al. [51. In hypersonic Boundary-Layer flow over a blunt cone, the process of receptivity to freestream disturbances is altered considerably by the presence of the bow shock followed by an entropy Layer. It is crucially important that the interaction of disturbance waves with the bow shock is accurately computed in numerical simulations. In the present study, both steady and unsteady flow solutions are obtained by computing the full Navier-Stokes equations with a fifth-order shock-fitting finite difference scheme, which is able to account for the effects of bow-shock/freestream-disturbance interaction accurately. Whenever possible, the current numerical results are compared with published experimental results. In addition, a normal-mode linear Stability analysis is used to study the receptivity properties of the hypersonic Boundary Layer with the effects of the adverse pressure gradient and surface curvature. The focus of the study is on the generation of the second Mack modes in the Boundary Layer due to freestream acoustic disturbances, and the effects of surface curvatures of the flared cone on the receptivity process.
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high order non uniform grid schemes for numerical simulation of hypersonic Boundary Layer Stability and transition
Journal of Computational Physics, 2003Co-Authors: Xiaolin Zhong, Mahidhar TatineniAbstract:The direct numerical simulation of receptivity, inStability and transition of hypersonic Boundary Layers requires high-order accurate schemes because lower-order schemes do not have an adequate accuracy level to compute the large range of time and length scales in such flow fields. The main limiting factor in the application of high-order schemes to practical Boundary-Layer flow problems is the numerical inStability of high-order Boundary closure schemes on the wall. This paper presents a family of high-order non-uniform grid finite difference schemes with stable Boundary closures for the direct numerical simulation of hypersonic Boundary-Layer transition. By using an appropriate grid stretching, and clustering grid points near the Boundary, high-order schemes with stable Boundary closures can be obtained. The order of the schemes ranges from first-order at the lowest, to the global spectral collocation method at the highest. The accuracy and Stability of the new high-order numerical schemes is tested by numerical simulations of the linear wave equation and two-dimensional incompressible flat plate Boundary Layer flows. The high-order non-uniform-grid schemes (up to the 11th-order) are subsequently applied for the simulation of the receptivity of a hypersonic Boundary Layer to free stream disturbances over a blunt leading edge. The steady and unsteady results show that the new high-order schemes are stable and are able to produce high accuracy for computations of the nonlinear two-dimensional Navier-Stokes equations for the wall bounded supersonic flow.
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receptivity of a supersonic Boundary Layer over a flat plate part 1 wave structures and interactions
Journal of Fluid Mechanics, 2003Co-Authors: Xiaolin ZhongAbstract:This paper is the first part of a two-part study on the mechanisms of the receptivity to disturbances of a Mach 4.5 flow over a flat plate by using both direct numerical simulations (DNS) and linear Stability theory (LST). The main objective of the current paper is to study the linear Stability characteristics of the Boundary-Layer wave modes and their mutual resonant interactions. The numerical solutions of both steady base flow and unsteady flow induced by forcing disturbances are obtained by using a fifth-order shock-fitting method. Meanwhile, the LST results are used to study the supersonic Boundary-Layer Stability characteristics relevant to the receptivity study. It is found that, in addition to the conventional first and second modes, there exist a family of stable wave modes in the supersonic Boundary Layer. These modes play a very important role in the receptivity process of excitation of the unstable Mack modes, especially the second mode. These stable modes are termed mode I, mode II, etc., in this paper. Though mode I and mode II waves are linearly stable, they can have resonant (synchronization) interactions with both acoustic waves and the Mack-mode waves. Therefore, the stable wave modes such as mode I and mode II are critical in transferring wave energy between the acoustic waves and the unstable second mode. The effects of frequencies and wall Boundary conditions for the temperature perturbations on the Boundary-Layer Stability and receptivity are also studied.
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stable high order schemes and dns of Boundary Layer Stability on a blunt cone at mach 8
39th Aerospace Sciences Meeting and Exhibit, 2001Co-Authors: Xiaolin Zhong, Mahidhar TatineniAbstract:The objectives of this paper are two fold: 1) to present new high-order (12th or higher order) explicit and compact finite difference schemes with stable Boundary closures for the DNS of transitional or turbulent flows; 2) to present results of numerical simulation of nonlinear Boundary Layer Stability of Mach 7.99 axisymmetric flow over a blunt cone. The first part of this paper presents a way to stabilize high-order finite difference schemes with Boundary closures. Current numerical methods used in most practical DNS studies of compressible flows are limited to 6th-order or lower in the interior and 4th-order or lower on the Boundary because of the numerical inStability of the Boundary closure schemes. This paper shows that this numerical inStability for high-order schemes based on uniform grids is due to the inStability of polynomial interpolation based on uniform grids (the Runge phenomena). It is shown that the inStability can be overcome for arbitrarily high-order finite difference schemes with stable Boundary closure schemes if the schemes are derived directly on a non-uniform stretched grid. Explicit formulas for computing the coefficients of high-order compact (and explicit) schemes on nonuniform grids are derived. The second part of the paper is motivated by a project of NATO RTO Working Group 10 on Boundary Layer Transition to conduct numerical simulation of nonlinear Boundary Layer Stability for blunt cone at Mach 7.99 corresponding to Stetson's experiment. The emphasis is on the nonlinear second mode inStability of the hypersonic Boundary Layer observed in the experiments. The initial results of the first test case under the isothermal wall condition are presented and compared with the experimental results.
Mahidhar Tatineni - One of the best experts on this subject based on the ideXlab platform.
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high order non uniform grid schemes for numerical simulation of hypersonic Boundary Layer Stability and transition
Journal of Computational Physics, 2003Co-Authors: Xiaolin Zhong, Mahidhar TatineniAbstract:The direct numerical simulation of receptivity, inStability and transition of hypersonic Boundary Layers requires high-order accurate schemes because lower-order schemes do not have an adequate accuracy level to compute the large range of time and length scales in such flow fields. The main limiting factor in the application of high-order schemes to practical Boundary-Layer flow problems is the numerical inStability of high-order Boundary closure schemes on the wall. This paper presents a family of high-order non-uniform grid finite difference schemes with stable Boundary closures for the direct numerical simulation of hypersonic Boundary-Layer transition. By using an appropriate grid stretching, and clustering grid points near the Boundary, high-order schemes with stable Boundary closures can be obtained. The order of the schemes ranges from first-order at the lowest, to the global spectral collocation method at the highest. The accuracy and Stability of the new high-order numerical schemes is tested by numerical simulations of the linear wave equation and two-dimensional incompressible flat plate Boundary Layer flows. The high-order non-uniform-grid schemes (up to the 11th-order) are subsequently applied for the simulation of the receptivity of a hypersonic Boundary Layer to free stream disturbances over a blunt leading edge. The steady and unsteady results show that the new high-order schemes are stable and are able to produce high accuracy for computations of the nonlinear two-dimensional Navier-Stokes equations for the wall bounded supersonic flow.
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stable high order schemes and dns of Boundary Layer Stability on a blunt cone at mach 8
39th Aerospace Sciences Meeting and Exhibit, 2001Co-Authors: Xiaolin Zhong, Mahidhar TatineniAbstract:The objectives of this paper are two fold: 1) to present new high-order (12th or higher order) explicit and compact finite difference schemes with stable Boundary closures for the DNS of transitional or turbulent flows; 2) to present results of numerical simulation of nonlinear Boundary Layer Stability of Mach 7.99 axisymmetric flow over a blunt cone. The first part of this paper presents a way to stabilize high-order finite difference schemes with Boundary closures. Current numerical methods used in most practical DNS studies of compressible flows are limited to 6th-order or lower in the interior and 4th-order or lower on the Boundary because of the numerical inStability of the Boundary closure schemes. This paper shows that this numerical inStability for high-order schemes based on uniform grids is due to the inStability of polynomial interpolation based on uniform grids (the Runge phenomena). It is shown that the inStability can be overcome for arbitrarily high-order finite difference schemes with stable Boundary closure schemes if the schemes are derived directly on a non-uniform stretched grid. Explicit formulas for computing the coefficients of high-order compact (and explicit) schemes on nonuniform grids are derived. The second part of the paper is motivated by a project of NATO RTO Working Group 10 on Boundary Layer Transition to conduct numerical simulation of nonlinear Boundary Layer Stability for blunt cone at Mach 7.99 corresponding to Stetson's experiment. The emphasis is on the nonlinear second mode inStability of the hypersonic Boundary Layer observed in the experiments. The initial results of the first test case under the isothermal wall condition are presented and compared with the experimental results.
Sanjiva K. Lele - One of the best experts on this subject based on the ideXlab platform.
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effect of adverse pressure gradient on high speed Boundary Layer transition
Physics of Fluids, 2014Co-Authors: Kenneth Franko, Sanjiva K. LeleAbstract:The effect of adverse pressure gradients (APG) on Boundary Layer Stability, breakdown, and heat-transfer overshoot is investigated. Flat plate isothermal Boundary Layers initially at Mach 6 with APG imposed through the freestream Boundary condition are simulated using suction and blowing to produce Boundary Layer instabilities. The three different transition mechanisms compared are first mode oblique breakdown, second mode oblique breakdown, and second mode fundamental resonance. For all of the transition mechanisms, an adverse pressure gradient increases the linear growth rates and quickens the transition to turbulence. However, the nonlinear breakdown for all three transition mechanisms is qualitatively the same as for a zero pressure gradient Boundary Layer. First mode oblique breakdown leads to the earliest transition location and an overshoot in heat transfer in the transitional region. Both types of Mack second mode forcing lead to a transitional Boundary Layer but even with the increased growth rat...
A A Maslov - One of the best experts on this subject based on the ideXlab platform.
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high speed Boundary Layer Stability on a cone with localized wall heating or cooling
AIAA Journal, 2015Co-Authors: Alexander Fedorov, D A Bountin, A A Sidorenko, Vitaly Soudakov, I V Egorov, Yury Gromyko, Pavel Polivanov, A A MaslovAbstract:A localized heating or cooling effect on Stability of the Boundary-Layer flow on a sharp cone at zero angle of attack and freestream Mach number 6 is analyzed. Experiments were carried out in the Transit-M wind tunnel of the Institute of Theoretical and Applied Mechanics (Novosibirsk, Russia) for different heating/cooling intensities and freestream Reynolds numbers. The mean flows with localized heating/cooling are calculated using axisymmetric Navier–Stokes equations. These solutions are used for the spatial linear Stability analysis to estimate the transition onset points using the eN method. Direct numerical simulations of two-dimensional disturbances propagating in the Boundary Layer through the cooled/heated region are performed. The experiment and computations showed similar qualitative trends. The localized cooling decreases the second-mode amplitude and delays transition. The heating produced an opposite effect, which is less pronounced.
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mach 6 Boundary Layer Stability experiments on sharp and blunted cones
Journal of Spacecraft and Rockets, 2006Co-Authors: A A Maslov, A N Shiplyuk, D A Bountin, A A SidorenkoAbstract:Recent studies of hypersonic Boundary-Layer Stability and transition on cones with sharp and blunted nosetips are presented. The experiments were carried out on a 7-deg half-angle cone at freestream Mach number 5.95. Laminar‐turbulent transition locations are measured for various flow parameters and model nose bluntness. Mean and fluctuation characteristics of the flow are obtained using constant-temperature hot-wire anemometry. The spectral content and amplification rates of natural disturbances are obtained. The method of artificial wave packets is applied to obtain detailed information on the disturbances. Data on development of both natural and artificial finite-amplitude disturbances are compared. It is experimentally shown that the wave vector of the most unstable waves of the first mode have an inclination angle of 40‐49 deg. In the frequency range of the second mode, plane waves appear to be dominant and have the highest amplification. The bluntness of the cone nosetip results in an increase of the disturbance amplification rate downstream of the entropy Layer swallowing point. At the same time, nose bluntness dramatically increases the transition Reynolds number because of the strong damping of initial disturbances.
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nonlinear aspects of hypersonic Boundary Layer Stability on a porous surface
AIAA Journal, 2005Co-Authors: Ndaona Chokani, A N Shiplyuk, Dimitry Bountin, A A MaslovAbstract:The nonlinear aspects of the stabilization of the second-mode disturbance using a passive, ultrasonically absorptive coating (UAC) of regular microstructure are studied using bispectral analysis. The experimental data consist of hot-wire measurements made in artificially excited wave packets that are introduced into the hypersonic Boundary Layer on both solid and porous surfaces. The bispectral measurements show that the subharmonic and harmonic resonances of the second mode are significantly modified. The harmonic resonance, which is quite pronounced in the latter stages of the hypersonic Boundary Layer on solid surfaces, is completely absent on the porous surface. The degree of nonlinear phase locking that is associated with the subharmonic resonance and identified on the solid surface is substantially weakened on the porous surface. This nonlinear interaction persists farther downstream on theporous surface than on the solid surface; however, unlike on the solid surface, there are no strongly preferred interaction modes. The spectral measurements, made in previous work, show that the first mode is moderately destabilized on the porous surface. The bispectral measurements presented here identify a nonlinear interaction that is associated with the destabilized first mode; however, this is observed to be a very weak nonlinear interaction that has no deleterious effect on the performance of the UAC.
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stabilization of a hypersonic Boundary Layer using an ultrasonically absorptive coating
Journal of Fluid Mechanics, 2003Co-Authors: Alexander Fedorov, A A Maslov, A N Shiplyuk, E Burov, N D MalmuthAbstract:Experimental and theoretical studies of the effect of an ultrasonically absorptive coating (UAC) on hypersonic Boundary-Layer Stability are described. A thin coating of fibrous absorbent material (felt metal) was selected as a prototype of a practical UAC. Experiments were performed in the Mach 6 wind tunnel on a $7^{\circ}$ half-angle sharp cone whose longitudinal half-surface was solid and other half-surface was covered by a porous coating. Hot-wire measurements of ‘natural’ disturbances and artificially excited wave packets were conducted on both solid and porous surfaces. Stability analysis of the UAC effect on two- and three-dimensional disturbances showed that the porous coating strongly stabilizes the second mode and marginally destabilizes the first mode. These results are in qualitative agreement with the experimental data for natural disturbances. The theoretical predictions are in good quantitative agreement with the Stability measurements for artificially excited wave packets associated with the second mode. Stability calculations for the cooled wall case showed the feasibility of achieving a dramatic increase of the laminar run using a thin porous coating of random microstructure.