I. N. Kavun

Bio: I. N. Kavun is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Supersonic speed & Boundary layer. The author has an hindex of 7, co-authored 15 publications receiving 74 citations.

Modification of turbulent airfoil section flow using a combined control action

Abstract: Both numerically and experimentally, the possibility of using a combined method to control the incompressible turbulent boundary layer on a symmetric airfoil section of 12-% relative thickness implemented via the blowing/suction of air through a finely perforated section provided on the wing surface part was examined. The study was performed at Reynolds number Rec = 0.7·106 in the range of angles of attack α = −6 ÷ 6°. The mechanism of action of this flow control method on the aerodynamic characteristics of the wing was identified. An ambiguous pattern of the effect due to blowing/suction from the viewpoint of ensuring a maximum lift, a gain in wing lift-to-drag ratio, and a reduction of wing aerodynamic drag was revealed.

Flow structure at the initial section of a supersonic jet exhausting from a nozzle with chevrons

Abstract: The spatial structure of the flow in a supersonic underexpanded jet exhausting from a convergent nozzle with vortex generators (chevrons) at the exit is experimentally studied. Exhaustion of a supersonic underexpanded jet from a nozzle with chevrons at the nozzle exit is numerically simulated with the use of the Fluent commercial software package. The experimental and numerical data are demonstrated to be in reasonable agreement. The influence of chevrons on the process of gas mixing is estimated.

Flow structure formed due to interaction of a supersonic jet with a porous obstacle

Abstract: Results of studying impingement of a supersonic underexpanded air jet onto a finite-thickness porous metal obstacle whose frontal plane is normal to the jet axis and whose side surface is impermeable for the gas flow are reported. The case of a non-porous obstacle of the same diameter is considered for determining the effect of porosity on gas-dynamic characteristics of jet–obstacle interaction.

Effect of Small Bluntness on Formation of Görtler Vortices in a Supersonic Compression Corner Flow

Abstract: The influence of small cylindrical bluntness of the leading edge of a flat plate on formation of spatial structures in a nominally two-dimensional supersonic compression corner flow at the Mach number M∞ ≈ 8 and a laminar state of the undisturbed boundary layer is studied by the method of temperature-sensitive paints. Streamwise vortices are found in the region of reattachment of the separated flow in a wide range of Reynolds numbers (0.15 · 106–2.55 · 106) for various angles of flow deflection and plate lengths. It is demonstrated that the existence of these vortices induces spanwise oscillations of the heat transfer coefficient; the amplitude of these oscillations may reach 30%. The maximum deviations of the Stanton number reaching 80% are observed in the case with significant roughness of the leading edge of the flat plate. Both the maximum Stanton numbers in the reattachment region and the amplitude of spanwise oscillations of the Stanton number induced by streamwise vortices are found to decrease significantly in the case of small bluntness of the leading edge. Solutions of three-dimensional Navier–Stokes equations are obtained for some test conditions. The computed results are in good agreement with experimental data, which points to a significant stabilizing effect of small bluntness on the intensity of streamwise vortices.

Aerodynamic Effects of Uniform Blowing and Suction on a NACA4412 Airfoil

Abstract: We carried out high-fidelity large-eddy simulations to investigate the effects of uniform blowing and uniform suction on the aerodynamic efficiency of a NACA4412 airfoil at the moderate Reynolds nu ...

Flow Control in Wings and Discovery of Novel Approaches via Deep Reinforcement Learning

Abstract: In this review, we summarize existing trends of flow control used to improve the aerodynamic efficiency of wings. We first discuss active methods to control turbulence, starting with flat-plate geometries and building towards the more complicated flow around wings. Then, we discuss active approaches to control separation, a crucial aspect towards achieving a high aerodynamic efficiency. Furthermore, we highlight methods relying on turbulence simulation, and discuss various levels of modeling. Finally, we thoroughly revise data-driven methods and their application to flow control, and focus on deep reinforcement learning (DRL). We conclude that this methodology has the potential to discover novel control strategies in complex turbulent flows of aerodynamic relevance.

Investigation of Blowing and Suction for Turbulent Flow Control on Airfoils

Abstract: An extensive parametric study of turbulent boundary-layer control on airfoils via uniform blowing or suction is presented. The control is applied on either the suction or pressure side of several f...

Unsteady effects in a hypersonic compression ramp flow with laminar separation

Abstract: Direct numerical simulations (DNS) are performed to investigate a hypersonic flow over a compression ramp with a free stream Mach number of 7.7 and a free stream Reynolds number of based on the flat plate length. The DNS results are validated by comparison with experimental data and theoretical predictions. It is shown that even in the absence of external disturbances, streamwise heat flux streaks form on the ramp surface downstream of reattachment, and that they are non-uniformly distributed in the spanwise direction. The surface heat flux exhibits a low-frequency unsteadiness, which propagates in the streamwise direction. Additionally, the unsteadiness of the heat flux streaks downstream of reattachment is coupled with a pulsation of the reattachment position. By conducting a dynamic mode decomposition (DMD) analysis, several oscillatory modes, characterised by streamwise low-frequency periodicity, are revealed in the separation bubble flow. The DNS results are further explained by a global stability analysis (GSA). Particularly, the flow structure of the leading DMD modes is consistent with that of the oscillatory unstable modes identified by the GSA. It is therefore concluded that the global instabilities are responsible for the unsteadiness of the considered compression ramp flow.