Begell House Inc.
TsAGI Science Journal
TSAGI
1948-2590
42
5
2011
ON REGIONS OF TURBULENCE IN SEPARATED FLOWS
555-563
10.1615/TsAGISciJ.2011004313
Victor Vladimirovich
Sychev
Central Aerohydrodynamic Institute, 1, Zhukvsky Str., Zhukovsky, 140180, Moscow Region, Russia
separation zone
mixing layer
turbulent stresses
A steady plane high Reynolds number uniform incompressible fluid flow around a symmetric body is considered. It is demonstrated that the flow in the closure region of the separation zone and further downstream in the wake is turbulent, while the flow everywhere outside these regions is weakly turbulent: the turbulent stresses and the corresponding changes in velocity are small.
LAMINAR-TURBULENT TRANSITION ON THE LV6 LAMINARIZED AIRFOIL: NATURAL TRANSITION
565-591
10.1615/TsAGISciJ.2011004354
Vadim Anatolyevich
Vlasov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky str., Zhukovsky, Moscow region, 140180 Russia
Sergey Vadimovich
Zhigulev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky str., Zhukovsky, Moscow region, 140180 Russia
Aleksandr Igorevich
Ivanov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky str., Zhukovsky, Moscow region, 140180 Russia
Andrey Filippovich
Kiselev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky str., Zhukovsky, Moscow region, 140180 Russia
Vladimir Aleksandrovich
Kuzminsky
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
Dmitry Sergeevich
Sboev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky str., Zhukovsky, Moscow region, 140180 Russia
Sergei Leonidovich
Chernyshev
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky, Moscow region, Russia
boundary layer
laminar-turbulent transition
Tollmien-Schlichting waves
separation bubble
The laminar-turbulent transition on a non-swept wing model with the LV6 laminarized airfoil is studied under natural conditions of a test section of the T-124 subsonic wind tunnel (TsAGI) at a Reynolds number of 5.5×106. It is shown that linear packets of Tollmien−Schlichting waves are formed and developed in the laminar boundary layer; the characteristics of these packets agree well with the results predicted by the linear theory of hydrodynamic stability performed for the test conditions. A comparison of the calculated and experimental data shows that, despite its long-term operation, the T-124 wind tunnel ensures a high quality of the flow and a low level of background perturbations (i.e., conditions necessary for studying the laminar-turbulent transition). The laminar-turbulent transition on the model occurs in the zone of the boundary layer separation with its subsequent turbulent reattachment. The experimental data are compared with semi-empirical models widely used in engineering practice. The data on the beginning and end of the transition zone in the separation region are found to be in good agreement.
INVESTIGATION OF SECONDARY DISTURBANCE DEVELOPMENT IN A BOUNDARY LAYER USING THE PARABOLIZED STABILITY EQUATIONS METHOD
593-612
10.1615/TsAGISciJ.2011004288
Maxim Vladimirovich
Ustinov
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
laminar-turbulent transition
secondary instability
boundary layer
streaky structure
parabolized stability equations
The effective numerical method intended for computation of the amplification factors of secondary disturbances in a boundary layer modulated by large-amplitude periodic primary perturbations is developed. It is based on the computation of perturbations induced by an ambient volumetric force in the form of a traveling wave using the modified parabolic stability equations (PSE) method. Computation starts from zero initial conditions unlike in the ordinary PSE-method, which requires accurate initial conditions found from the eigenfunction of the secondary instability mode. This makes the time-consuming two-dimensional eigenvalue problem solution unnecessary when starting the amplification curve computation. An elaborated technique was applied in the analysis of secondary instability of the streaky structure in a flat-plate boundary layer excited by streamwise vorticity in a free stream.
ON POSSIBLE WAYS OF DISTURBANCE PROPAGATION ALONG KARMAN VORTEX STREETS
613-635
10.1615/TsAGISciJ.2011004385
Viktor Fedorovich
Molchanov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
Karman vortex street
characteristic
fragment
Disturbances of the Karman vortex street have been found in the form of moving waves. This determines the condition at which the wake behind the body in the form of this street is possible.
STEADY AND PERIODIC REGIMES OF LAMINAR FLOW AROUND THE ROTATING CYLINDER
637-653
10.1615/TsAGISciJ.2011004380
Evgueniy Igorevich
Kalinin
Kazan Federal University, 18 Kremlyovskaya Street, Kazan 420008, Republic of Tatarstan, Russian Federation
Aleksandr Bentsianovich
Mazo
Kazan Federal University, 18 Kremlyovskaya Street, Kazan 420008, Republic of Tatarstan, Russian Federation
flow around the rotating cylinder
viscous fluid
vortex shedding
Magnus effect
periodic flows
numerical simulation
A numerical study of the problem of laminar infinite flow of viscous incompressible fluid around a rotating circular cylinder at Reynolds number 50 ≤ Re ≤ 500 and dimensionless rotation rate 0 ≤ α ≤ 7 has been carried out. The parametric map of flow regimes has been constructed, where two zones of steady and two zones of periodic solutions are singled out. The dependences of the drag and lift coefficients on the rotation rate for Re = 200 are studied in detail. Convergence of the numerical solution to the known asymptotic solution at large α is confirmed.
MATHEMATICAL SIMULATION OF DYNAMIC EFFECTS OF UNSTEADY AERODYNAMICS DUE TO CANARD FLOW SEPARATION DELAY
655-668
10.1615/TsAGISciJ.2011004364
Yuriy Alexandrovich
Vinogradov
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
Anatoliy Nicolaevich
Zhuk
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
Konstantin Anatolievich
Kolinko
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
Alexander Nikolaevich
Khrabrov
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
unsteady aerodynamic characteristics
wind tunnel experimental investigations
mathematical simulation
high angles of attack
aircraft with canard
Results of experimental investigation of unsteady aerodynamic characteristics for the model of a transonic airliner with canard surfaces and high-sweep wing during forced pitch oscillations with various amplitudes and frequencies are considered. Dynamic derivatives versus angle of attack at various oscillation frequencies are obtained using results of small-amplitude oscillations. For the canard configuration of the model a range of angles of attack was found where positive aerodynamic damping was observed. The positive damping value was varied with the frequency of oscillations. For large-amplitude pitch oscillations, nonlinear dynamic hysteresis loops of aerodynamic characteristics were investigated. The traditional linear approach to simulate the unsteady aerodynamic characteristics based on the aerodynamic derivatives concept fails to include the oscillation frequency influence on aerodynamic damping. The nonlinear hysteresis loops of the pitching moment coefficient obtained at large-amplitude oscillations cannot be described with the use of this approach. A new nonlinear state-space mathematical model of the pitch moment coefficient is proposed in the paper. This model is capable of describing all experimentally observed dynamic effects. In the proposed model an additional ordinary differential equation is introduced to simulate the dynamic effects of canard flow separation delay.
CONSTRUCTION OF SIMULATION MODEL FOR FLYING VEHICLE AERODYNAMIC CHARACTERISTICS UNDER RESTRICTED DATA CONDITIONS
669-682
10.1615/TsAGISciJ.2011004381
Andrey Valeryevich
Tarasenko
GosMKB "Raduga" Zhukovsky str. 2a, Dubna, Moscow Region, 141980 Russia
artificial neural network
approximation
simulation mathematical model
aerodynamic characteristics
A method of constructing a simulation model of flying vehicle aerodynamic characteristics by means of an artificial neural network is presented. The technique is shown to decrease the approximation error of the aerodynamic characteristics compared to the technique based on the expert fitting of the approximating function.
INTERSECTION OF AIRPLANE COMPONENT SURFACES FOR DESIGN OF AN AERODYNAMIC CONFIGURATION
683-700
10.1615/TsAGISciJ.2011004389
Andrey Vladimirovich
Vermel
Planit CAD/CAM software, Plc, Marksistskaya str. 22, Moscow, Russia
Vladimir Dmitrievich
Vermel
Central Aerohydrodynamic Institute (TsAGI) Zhukovsky str. 1, Zhukovsky, 140180 Russia
Evgueniy Ivanovich
Kalitin
Central Aerohydrodynamic Institute (TsAGI) Zhukovsky str. 1, Zhukovsky, 140180 Russia
parametric surface-surface intersection
singular points
tracing method
Numerical evaluation of an intersection curve of parametrically defined surfaces of different-purpose aircraft components is considered. Two methods complementing each other in practical use are presented. Iterative algorithms to search a point on an intersection curve are described in detail. Parametric singularities that require special handling during the iterations are analyzed. Methods are given to proceed with convergence to a curve point in the presence of singular points of various order, and to evaluate length and direction of a linearized step along the curve to serve as an initial guess for iteration toward the next curve point. The presented methods have been implemented in a CAD/CAM software system.