Alexander Fedorov - Profile on Academia.edu (original) (raw)

Papers by Alexander Fedorov

Numerical modelling of supersonic boundary-layer receptivity to solid particulates

Journal of Fluid Mechanics, 2018

Atmospheric particulates may be a major source of boundary-layer instabilities leading to laminar... more Atmospheric particulates may be a major source of boundary-layer instabilities leading to laminar–turbulent transition on aerodynamically smooth bodies flying at supersonic speeds. Particulates penetrating into the boundary-layer flow can excite wavepackets of the first- and/or second-mode instability. The packets grow downstream, reach the threshold amplitude and ultimately break down to turbulent spots. A numerical model is developed to simulate excitation of unstable wavepackets by spherical solid particulates. As an example, computations are carried out for a 14circ14^{\circ }14circ half-angle sharp wedge flying at an altitude of 20 km, Mach number 4 and zero angle of attack. The numerical results agree satisfactorily with the theory developed by Fedorov (J. Fluid Mech., vol. 737, 2013, pp. 105–131). The numerical model opens up an opportunity to investigate receptivity to particulates for practical supersonic and hypersonic configurations such as blunt bodies of revolution.

The results of experimental study of boundary layer laminar-turbulent transition on a blunted pla... more The results of experimental study of boundary layer laminar-turbulent transition on a blunted plate with leading edges of various shapes and thicknesses at free-stream Mach number M=5 and unit Reynolds numbers Re1 from 1.5x107 to 9x107 m-1 are presented. The Reynolds number Reb, calculated by leading edge thickness b, was varied from 0 to 2x106. The following leading edge shapes were studied: cylinder, flat face, ellipse, and \"smoothed cylinder\". They were chosen by the results of numerical study of a non-viscous gas flow around a blunted plate. It was shown that at Reb0.5x105, the shape of the leading edge practically does not affect the transition position. At the same time, the laminar flow segment is monotonously extended as b increases. For large Reb values the variation of leading edge shape significantly changes the transition position. A laminar - turbulent transition reversal was observed for all investigated shapes of leading edge. However, the Reynolds number ...

Numerical Simulation of Three-Dimensional Wave Packet in Supersonic Flow over a Compression Corner

45th AIAA Fluid Dynamics Conference, 2015

Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

Experimental study of the laminar-turbulent transition on a blunt cone

Journal of Applied Mechanics and Technical Physics

ABSTRACT Results of an experimental study of the laminar-turbulent transition in a hypersonic flo... more ABSTRACT Results of an experimental study of the laminar-turbulent transition in a hypersonic flow around cones with different bluntness radii at a zero angle of attack, free-stream Mach number M ∞ = 6, and unit Reynolds number in the interval Re ∞,1 = 5.79 · 106–5.66 · 107 m−1 are presented. Flow regimes in which a reverse of the laminar-turbulent transition (decrease in the length of the laminar segment with increasing bluntness radius) are studied. Heat flux distributions over the model surface are obtained with the use of temperature-sensitive paints. Lines of the beginning of the transition in the boundary layer are analyzed by using heat flux fields. The critical Reynolds number Re ∞,R ≈ 1.3 · 105 beginning from which the laminar-turbulent transition substantially depends on uncontrolled disturbances, such as the model tip roughness, is found. In supercritical regimes, the line of the transition beginning is shifted in most cases toward the model tip (reverse of the transition). The results obtained are compared with available experimental data.

The extended GrtlerHmmerlin model for linear instability of three-dimensional incompressible swept attachment-line boundary layer flow

J Fluid Mech, 2003

Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports,

Journal of Fluid Mechanics, 2003

Parametric Studies of Hypersonic Laminar Flow Control Using a Porous Coating of Regular Microstructure

46th AIAA Aerospace Sciences Meeting and Exhibit, 2008

Modeling of Forebody Nose Vortex Symmetry Breaking Using Conical Navier-Stokes Solutions

44th AIAA Aerospace Sciences Meeting and Exhibit, 2006

Progress in Flight Physics – Volume 7, 2015

A localized heating or cooling e¨ect on stability and transition of the boundary layer §ow on a s... more A localized heating or cooling e¨ect on stability and transition of the boundary layer §ow on a sharp cone is analyzed at the Mach number 6. The mean §ows are calculated using axisymmetric NavierStokes equations. The spatial linear stability analysis is performed for twodimensional (2D) disturbances related to the Mack second mode. The transition onset points are estimated using the e N method. In this framework, the heater or cooler may cause earlier or later transition depending on the choice of critical N-factor. Direct numerical simulations (DNS) of 2D wave propagating in the boundary layer are compared with stability results.

Modeling of Plasma Flow Control Over a High-Speed Delta Wing

47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009

Numerical modeling of vortex flow over a delta wing with sharp leading edges of 60ο sweep angle h... more Numerical modeling of vortex flow over a delta wing with sharp leading edges of 60ο sweep angle has been performed at free-stream Mach number 1.5 and angles of attack from 0ο to 30ο. The flow field contains two strong vortices generated by the rollup of the shear layer ...

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2011

Low-subsonic flow past a flat plate and its control by surface dielectric barrier discharge (SDBD... more Low-subsonic flow past a flat plate and its control by surface dielectric barrier discharge (SDBD) is studied. Navier-Stokes equations for two-dimensional unsteady compressible flow are solved numerically. SDBD effect is simulated by momentum and heat sources included into Navier-Stokes equations. These sources are modeled using analytical approximations predicted by a phenomenological SDBD model, which is based on available experimental data and recent knowledge of SDBD physics. If SDBD acts downstream, the actuator generates a streamwise near-wall jet. If SDBD acts upstream, actuator generates strong concentrated vortices. This demonstrates that it is feasible to achieve quite different aerodynamic effects on the near-wall flow.

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2011

Ultrasonically absorptive coatings (UAC) can stabilize the Mack second mode and thereby increase ... more Ultrasonically absorptive coatings (UAC) can stabilize the Mack second mode and thereby increase the laminar run on configurations where laminar-turbulent transition is second-mode dominated. Theory indicates that the stabilization effect can be essentially enhanced by increasing the UAC porosity. However, direct numerical simulations (DNS) showed that coatings having closely spaced grooves can trigger a new instability whose growth rate can be larger than that of Mack' second mode. The nature of the new instability is investigated theoretically and numerically. 2D linear DNS and stability analysis are performed for the temporally evolving boundary layer on a flat wall at the outer-flow Mach number 6. The wall is covered by UAC comprising equally-spaced spanwise grooves. It is shown that the new mode is associated with acoustic resonances in the grooves. Disturbance fields near mouths of resonating cavities are coupled such that the boundary-layer disturbance is decelerated and becomes unstable. To avoid this detrimental effect the coating should have sufficiently small porosity and/or narrow pores of sufficiently small aspect ratio. Restrictions on these parameters can be estimated using the linear stability theory with the impedance boundary conditions. Nomenclature

Susceptibility of a boundary layer to acoustic perturbations

Journal of Applied Mechanics and Technical Physics

A solution is presented to the problem of the excitation of Tollmien-Schlichting waves by externa... more A solution is presented to the problem of the excitation of Tollmien-Schlichting waves by external acoustic waves that are scattered by small local surface irregularities. The amplitudes of the generated instability waves in a boundary layer on a plane plate are calcuated for incoming flow Mach 0.2-0.8. The results are found to be in good agreement with the available experimental data. A comparison is made between the efficiencies of the excitation of Tollmien-Schlichting waves by sound at local irregularities and at distributed flow inhomogeneities due to the nonparallelism of the boundary layer.

Numerical Simulation of Stability of a Supersonic Near-Wall Flow Past Rounded Compression Corner

International Symposium on Advances in Computational Heat Transfer, 2008

ABSTRACT Two-dimensional direct numerical simulation of stability of a near-wall laminar flow ove... more ABSTRACT Two-dimensional direct numerical simulation of stability of a near-wall laminar flow over a shallow wavy surface is carried out for the freestream Mach = 6. Numerical experiments are conducted for propagation of disturbances generated by a suction-blowing actuator placed on the wall. It is shown that high-frequency forcing excites unstable disturbances in the flat-plate boundary layer relevant to the second mode instability. The amplitude of these disturbances decreases over the wavy wall compared with the flat plate case.

On Numerical Prediction of the Stability of Hypersonic Boundary-Layer Flow Over a Row of Microcavities

Volume 2: Symposia, Parts A, B, and C, 2003

Page 1. Proceedings of FEDSM'03 2003 ASME JSME Joint Fluids Engineering Conference July 6-10... more Page 1. Proceedings of FEDSM'03 2003 ASME JSME Joint Fluids Engineering Conference July 6-10, 2003, Honolulu, Hawaii USA FEDSM2003-45635 ON NUMERICAL PREDICTION OF THE STABILITY OF HYPERSONIC ...

This report results from a contract tasking Moscow Institute of Physics and Technology as follows... more This report results from a contract tasking Moscow Institute of Physics and Technology as follows. To predict boundary-layer transition in a rational way and capture its sensitivity to freestream noise, turbulence, surface roughness. steps/gaps/waviness. etc.. a toolbox combining receptivity theory with nonlinear Parabolized Stability Equations and Direct Navier-Stokes Simulation is needed. This project addresses this need with theoretical modeling of high speed boundary-layer receptivity to acoustic disturbances as they interact with 3D roughness elements and waviness. The effort is basic. theoretical research on receptivity. Using the multiple-modes method, a compact and computationally robust algorithm providing fast calculations of receptivity characteristics will be developed. This algorithm will be integrated into a computational module that can be linked with a standard stability solver. Receptivity calculations will be made for the conditions relevant to future experiments i...

Numerical modelling of supersonic boundary-layer receptivity to solid particulates

Journal of Fluid Mechanics, 2018

Atmospheric particulates may be a major source of boundary-layer instabilities leading to laminar... more Atmospheric particulates may be a major source of boundary-layer instabilities leading to laminar–turbulent transition on aerodynamically smooth bodies flying at supersonic speeds. Particulates penetrating into the boundary-layer flow can excite wavepackets of the first- and/or second-mode instability. The packets grow downstream, reach the threshold amplitude and ultimately break down to turbulent spots. A numerical model is developed to simulate excitation of unstable wavepackets by spherical solid particulates. As an example, computations are carried out for a 14circ14^{\circ }14circ half-angle sharp wedge flying at an altitude of 20 km, Mach number 4 and zero angle of attack. The numerical results agree satisfactorily with the theory developed by Fedorov (J. Fluid Mech., vol. 737, 2013, pp. 105–131). The numerical model opens up an opportunity to investigate receptivity to particulates for practical supersonic and hypersonic configurations such as blunt bodies of revolution.

The results of experimental study of boundary layer laminar-turbulent transition on a blunted pla... more The results of experimental study of boundary layer laminar-turbulent transition on a blunted plate with leading edges of various shapes and thicknesses at free-stream Mach number M=5 and unit Reynolds numbers Re1 from 1.5x107 to 9x107 m-1 are presented. The Reynolds number Reb, calculated by leading edge thickness b, was varied from 0 to 2x106. The following leading edge shapes were studied: cylinder, flat face, ellipse, and \"smoothed cylinder\". They were chosen by the results of numerical study of a non-viscous gas flow around a blunted plate. It was shown that at Reb0.5x105, the shape of the leading edge practically does not affect the transition position. At the same time, the laminar flow segment is monotonously extended as b increases. For large Reb values the variation of leading edge shape significantly changes the transition position. A laminar - turbulent transition reversal was observed for all investigated shapes of leading edge. However, the Reynolds number ...

Numerical Simulation of Three-Dimensional Wave Packet in Supersonic Flow over a Compression Corner

45th AIAA Fluid Dynamics Conference, 2015

Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

Experimental study of the laminar-turbulent transition on a blunt cone

Journal of Applied Mechanics and Technical Physics

ABSTRACT Results of an experimental study of the laminar-turbulent transition in a hypersonic flo... more ABSTRACT Results of an experimental study of the laminar-turbulent transition in a hypersonic flow around cones with different bluntness radii at a zero angle of attack, free-stream Mach number M ∞ = 6, and unit Reynolds number in the interval Re ∞,1 = 5.79 · 106–5.66 · 107 m−1 are presented. Flow regimes in which a reverse of the laminar-turbulent transition (decrease in the length of the laminar segment with increasing bluntness radius) are studied. Heat flux distributions over the model surface are obtained with the use of temperature-sensitive paints. Lines of the beginning of the transition in the boundary layer are analyzed by using heat flux fields. The critical Reynolds number Re ∞,R ≈ 1.3 · 105 beginning from which the laminar-turbulent transition substantially depends on uncontrolled disturbances, such as the model tip roughness, is found. In supercritical regimes, the line of the transition beginning is shifted in most cases toward the model tip (reverse of the transition). The results obtained are compared with available experimental data.

The extended GrtlerHmmerlin model for linear instability of three-dimensional incompressible swept attachment-line boundary layer flow

J Fluid Mech, 2003

Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports,

Journal of Fluid Mechanics, 2003

Parametric Studies of Hypersonic Laminar Flow Control Using a Porous Coating of Regular Microstructure

46th AIAA Aerospace Sciences Meeting and Exhibit, 2008

Modeling of Forebody Nose Vortex Symmetry Breaking Using Conical Navier-Stokes Solutions

44th AIAA Aerospace Sciences Meeting and Exhibit, 2006

Progress in Flight Physics – Volume 7, 2015

A localized heating or cooling e¨ect on stability and transition of the boundary layer §ow on a s... more A localized heating or cooling e¨ect on stability and transition of the boundary layer §ow on a sharp cone is analyzed at the Mach number 6. The mean §ows are calculated using axisymmetric NavierStokes equations. The spatial linear stability analysis is performed for twodimensional (2D) disturbances related to the Mack second mode. The transition onset points are estimated using the e N method. In this framework, the heater or cooler may cause earlier or later transition depending on the choice of critical N-factor. Direct numerical simulations (DNS) of 2D wave propagating in the boundary layer are compared with stability results.

Modeling of Plasma Flow Control Over a High-Speed Delta Wing

47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009

Numerical modeling of vortex flow over a delta wing with sharp leading edges of 60ο sweep angle h... more Numerical modeling of vortex flow over a delta wing with sharp leading edges of 60ο sweep angle has been performed at free-stream Mach number 1.5 and angles of attack from 0ο to 30ο. The flow field contains two strong vortices generated by the rollup of the shear layer ...

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2011

Low-subsonic flow past a flat plate and its control by surface dielectric barrier discharge (SDBD... more Low-subsonic flow past a flat plate and its control by surface dielectric barrier discharge (SDBD) is studied. Navier-Stokes equations for two-dimensional unsteady compressible flow are solved numerically. SDBD effect is simulated by momentum and heat sources included into Navier-Stokes equations. These sources are modeled using analytical approximations predicted by a phenomenological SDBD model, which is based on available experimental data and recent knowledge of SDBD physics. If SDBD acts downstream, the actuator generates a streamwise near-wall jet. If SDBD acts upstream, actuator generates strong concentrated vortices. This demonstrates that it is feasible to achieve quite different aerodynamic effects on the near-wall flow.

49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2011

Ultrasonically absorptive coatings (UAC) can stabilize the Mack second mode and thereby increase ... more Ultrasonically absorptive coatings (UAC) can stabilize the Mack second mode and thereby increase the laminar run on configurations where laminar-turbulent transition is second-mode dominated. Theory indicates that the stabilization effect can be essentially enhanced by increasing the UAC porosity. However, direct numerical simulations (DNS) showed that coatings having closely spaced grooves can trigger a new instability whose growth rate can be larger than that of Mack' second mode. The nature of the new instability is investigated theoretically and numerically. 2D linear DNS and stability analysis are performed for the temporally evolving boundary layer on a flat wall at the outer-flow Mach number 6. The wall is covered by UAC comprising equally-spaced spanwise grooves. It is shown that the new mode is associated with acoustic resonances in the grooves. Disturbance fields near mouths of resonating cavities are coupled such that the boundary-layer disturbance is decelerated and becomes unstable. To avoid this detrimental effect the coating should have sufficiently small porosity and/or narrow pores of sufficiently small aspect ratio. Restrictions on these parameters can be estimated using the linear stability theory with the impedance boundary conditions. Nomenclature

Susceptibility of a boundary layer to acoustic perturbations

Journal of Applied Mechanics and Technical Physics

A solution is presented to the problem of the excitation of Tollmien-Schlichting waves by externa... more A solution is presented to the problem of the excitation of Tollmien-Schlichting waves by external acoustic waves that are scattered by small local surface irregularities. The amplitudes of the generated instability waves in a boundary layer on a plane plate are calcuated for incoming flow Mach 0.2-0.8. The results are found to be in good agreement with the available experimental data. A comparison is made between the efficiencies of the excitation of Tollmien-Schlichting waves by sound at local irregularities and at distributed flow inhomogeneities due to the nonparallelism of the boundary layer.

Numerical Simulation of Stability of a Supersonic Near-Wall Flow Past Rounded Compression Corner

International Symposium on Advances in Computational Heat Transfer, 2008

ABSTRACT Two-dimensional direct numerical simulation of stability of a near-wall laminar flow ove... more ABSTRACT Two-dimensional direct numerical simulation of stability of a near-wall laminar flow over a shallow wavy surface is carried out for the freestream Mach = 6. Numerical experiments are conducted for propagation of disturbances generated by a suction-blowing actuator placed on the wall. It is shown that high-frequency forcing excites unstable disturbances in the flat-plate boundary layer relevant to the second mode instability. The amplitude of these disturbances decreases over the wavy wall compared with the flat plate case.

On Numerical Prediction of the Stability of Hypersonic Boundary-Layer Flow Over a Row of Microcavities

Volume 2: Symposia, Parts A, B, and C, 2003

Page 1. Proceedings of FEDSM'03 2003 ASME JSME Joint Fluids Engineering Conference July 6-10... more Page 1. Proceedings of FEDSM'03 2003 ASME JSME Joint Fluids Engineering Conference July 6-10, 2003, Honolulu, Hawaii USA FEDSM2003-45635 ON NUMERICAL PREDICTION OF THE STABILITY OF HYPERSONIC ...

This report results from a contract tasking Moscow Institute of Physics and Technology as follows... more This report results from a contract tasking Moscow Institute of Physics and Technology as follows. To predict boundary-layer transition in a rational way and capture its sensitivity to freestream noise, turbulence, surface roughness. steps/gaps/waviness. etc.. a toolbox combining receptivity theory with nonlinear Parabolized Stability Equations and Direct Navier-Stokes Simulation is needed. This project addresses this need with theoretical modeling of high speed boundary-layer receptivity to acoustic disturbances as they interact with 3D roughness elements and waviness. The effort is basic. theoretical research on receptivity. Using the multiple-modes method, a compact and computationally robust algorithm providing fast calculations of receptivity characteristics will be developed. This algorithm will be integrated into a computational module that can be linked with a standard stability solver. Receptivity calculations will be made for the conditions relevant to future experiments i...