Begell House Inc.
TsAGI Science Journal
TSAGI
1948-2590
46
8
2015
ELIMINATION OF THE CROSS-FLOW INSTABILITY ON THE SWEPT WING BOUNDARY LAYER BY MEANS OF DIELECTRIC BARRIER DISCHARGE
715-732
10.1615/TsAGISciJ.2016016392
Maxim Vladimirovich
Ustinov
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
laminar-turbulent transition
swept wing
dielectric barrier discharge
Control of the laminar-turbulent transition caused by the cross-flow instability of the boundary layer on a swept wing by means of a dielectric barrier discharge is investigated. The practically important case of discharge on a large number of closely located electrodes is considered. The distance between the electrodes is assumed to be comparable with the boundary layer thickness. Unlike previous studies based on the solution to boundary layer equations, Navier-Stokes equations are applied to describe the discharge effect on the flow.
ENERGY CHARACTERISTICS OF PLASMA ACTUATORS FOR BOUNDARY LAYER FLOW CONTROL
733-752
10.1615/TsAGISciJ.2016016364
Marat Dzhaudatovich
Gamirullin
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, Moscow Region, 140180 Russia
Alexander Petrovich
Kuryachii
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region
Vladimir Mikhailovich
Litvinov
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, Moscow Region, 140180 Russia
Aleksandr Aleksandrovich
Uspenskii
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, Moscow Region, 140180 Russia
Sergei Leonidovich
Chernyshev
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky, Moscow region, Russia
dielectric barrier discharge
actuator model
velocity profile
total pressure probe
static pressure
volumetric force
electrical power
The results of measurements of energy parameters of electrogasdynamic actuating elements, functioning based on near-surface dielectric barrier discharge (DBD) and intended for boundary layer flow control are presented. Five various models of DBD actuators were tested. These models differed in the number of external electrodes and their geometry. The discharge was excited by the generator, which formed electrical voltage pulses of alternating polarity with amplitudes of 1-5 kV, duration of 20 s, and frequencies of 5-8 kHz. The average electrical power consumption was measured by means of a simplified methodology. This power is assumed to be spent directly on the discharge generation and excitation of high-voltage pulses. The dependency of the consumed power as a function of the geometrical parameters of the DBD actuators is established. The specific power spent per 1 m of the length of the external electrodes is determined. Based on the measured air velocity profiles induced by the actuators and the integral momentum method, the volumetric force and the operating efficiency of the actuators were evaluated both at normal and low air pressures.
NONLINEAR DEPENDENCIES OF LIFT ON THE ANGLE-OF-ATTACK IN THE LIFTING-LINE THEORY
753-767
10.1615/TsAGISciJ.2016016416
Alexander Alexandrovich
Nikolsky
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
wing
airfoil
lifting-line
The direct problem of the determination of the lift coefficient dependence on the wing angle-of attack using the known nonlinear dependence for the airfoil is reduced to the classical lifting-line theory for an equivalent ideal nonlinear twist wing. The generalized integral equation is obtained, and based on it the method of successive approximations for solution of the direct problem is developed.
Based on the direct problem solution method, an approach for solution of the inverse problem of determination of nonlinear lift dependencies on the angle-of-attack for an airfoil using the known dependence for the wing is developed. The method of determination of drag and torque of an airfoil is proposed
EFFECTS OF TRANSITION PROCESSES ON SYSTEMATIC ERRORS OF HEAT MEASURING IN WIND TUNNELS
769-782
10.1615/TsAGISciJ.2016016389
Evgeniy Pavlovich
Stolyarov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str.,
Zhukovsky, 140180, Moscow Region, Russia
intermittent wind tunnel
transition process
impulse transfer function
two-layered environment
heat flux density
inverse heat transfer problem
similarity parameters
asymptotic behavior
A procedure to estimate the heat flux density is presented based on results of temperature measurements using an elementary thin-film sensor. It is shown that the heat flux density cannot be measured but can be determined by means of convolution of the corresponding impulse transfer function with the time derivative from the temperature measured inside the sensor. Well-behaved analytic expressions of the impulse transfer functions are obtained using the inverse Laplace transformation of the inverse heat transfer problem, and a numerical solution method for short time periods is presented, with a provision for transition processes. Systematic errors are estimated, which depend on the main similarity parameters and the number of experiments.
IMPROVEMENT IN MODELING QUALITY OF UNSTEADY PROCESSES WHEN USING AN EXPLICIT SCHEME WITH FRACTIONAL TIME STEPPING
783-806
10.1615/TsAGISciJ.2016016410
Sergey Sergeyevich
Molev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str.,
Zhukovsky, 140180, Moscow Region, Russia
unsteady process
explicit scheme
global time stepping
fractional time stepping
The results of studying the fractional time stepping method for the Godunov-Kolgan explicit scheme on a model equation are obtained. It is shown that violations of scheme conservatism and local stability conditions lead to deterioration of the conditions in comparison with the global time stepping method. A conservative algorithm is proposed as well as a stability loss recognition and correction mechanism. The method is extended to Euler and Reynolds equations. Examples are given that demonstrate the accuracy of the obtained numerical solutions and the increase in computational speed.
INVESTIGATION OF CRACK PROPAGATION PROCESS BY MEASUREMENTS OF LOCAL DEFORMATION RESPONSE: II. RESIDUAL STRESS FIELD
807-832
10.1615/TsAGISciJ.2016016417
Andrei Alexandrovich
Apalkov
Institute of Machines Sciences named after A. A. Blagonravov of the
Russian Academy of Sciences, 4 Maly Kharitonyevsky Pereulok, Moscow,
101990 Russian Federation
Svyatoslav Igorevich
Eleonskii
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, 140180, Moscow Region, Russia
Igor Nikolaevich
Odintsev
Mechanical Engineering Research Institute of the Russian Academy of Sciences
(IMASh RAN), 4 M. Kharitonyevskiy Pereulok, Moscow, 101990, Russian
Federation
Vladimir Sergeevich
Pisarev
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
residual stress
hole-drilling method
stress intensity factor
T-stresses
crack compliance method
reflection hologram interferometry
electronic speckle interferometry
welded joints
The principal questions in relation to determining the fracture mechanics parameters for cracks in a residual stress field are analyzed using a modified version of the crack compliance method. It is shown that this approach can be effectively used for non-symmetrical cracks, which appear near a welded seam. Detailed metrological verification of the process used to generate initial experimental data is presented. The procedure is based on comparing corresponding values measured by reflection hologram interferometry and electronic speckle interferometry. Special attention is paid to the measurements of the in-plane displacement components near the area of local material removal. Both residual stress determination and determination of the stress intensity factor (SIF) and T-stress values for a small crack length increment are considered for the same residual stress field. For this purpose, a scheme for a combined interferometer is developed and realized. This optical system is capable of simultaneous measurement of the local deformation response by two different interference techniques on opposite faces of a thin plate. The practical implementation of the developed technique is illustrated by constructing dependencies of the SIF and T-stress values from a crack length, which is located in the vicinity of the joint made by electronic beam welding.
INDEX, VOLUME 6, 2015
833-841
10.1615/TsAGISciJ.v46.i8.70