Begell House Inc.
TsAGI Science Journal
TSAGI
1948-2590
45
2
2014
NUMERICAL SIMULATION OF ACOUSTIC RADIATION OF A TWO-DIMENSIONAL CAVITY IN A SUBSONIC FLOW
89-114
10.1615/TsAGISciJ.2014011334
Alexander Dmitrievich
Savel'ev
Dorodnicyn Computing Centre of Russian Academy of Sciences (CC RAS) Vavilov St. 40, 119991, Moscow, Russia
numerical simulation
compact difference schemes
subsonic flow past a cavity
vortex generation
acoustic radiation
A turbulent viscous gas flow past a two-dimensional plane cavity is numerically simulated for Mach numbers varying from 0.1 to 0.6 and aspect ratios of the cavity (length to depth) varying from 1 to 4. The general gas-dynamic pattern of the resulting oscillating flow is analyzed and the characteristics of the acoustic radiation are obtained.
PARABOLIC PROFILE WATER ENTRY WITH HORIZONTAL COMPONENT OF IMMERSION VELOCITY
115-124
10.1615/TsAGISciJ.2014011254
Aleksey Ivanovich
Arzhanov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky 140180, Russia
ideal fluid
free surface
water entry
parabolic profile
The two-dimensional problem of the initial stage of parabolic profile water entry is solved on the basis of the Wagner theory. The liquid is assumed to be incompressible and the horizontal component of immersion velocity exists.
WALL PRESSURE FLUCTUATIONS OF GRADIENT BOUNDARY LAYER
125-149
10.1615/TsAGISciJ.2014011454
Aleksey Yuryevich
Golubev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, Moscow Region, 140180, Russia
Boris Maksimovich
Efimtsov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180 Moscow region
pressure fluctuations
mean pressure gradient
turbulent boundary layer
space correlation spectrum
Experimental investigations of the wall pressure fluctuation field of the turbulent boundary layer over a wide range of variations of the mean pressure dimensionless gradient (−70 ≤ dp/dx ≤ 50), which covers this range on the fuselage surface in the zone of the passenger cabin and cockpit, are carried out. It is shown that the gradient turbulent boundary layer local aerodynamical parameters in the gradient flow region should be used in determining its wall pressure fluctuation field characteristics. In this case, the effects of the mean pressure gradient in the range of its dimensionless value (− 70 ≤ dp/dx ≤ 10) variation can be neglected. The calculation model for evaluating the characteristics of the wall turbulent pressure fluctuation field is proposed for the range of the mean pressure gradients of 10 ≤ dp/dx ≤ 50, when the pressure gradient effects cannot be ignored.
CALCULATION OF THE AIRCRAFT DYNAMICS DURING TAKE-OFF BY RESULTS OF ONBOARD MEASUREMENTS IN ORDER TO DETECT EMERGENCY SITUATIONS
151-168
10.1615/TsAGISciJ.2014011352
Anatoliy Vladimirovich
Bobylev
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
Viktor Fedorovich
Bragazin
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, 140180 Russia
Vasiliy Aleksandrovich
Yaroshevsky
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
quasi-static model of the landing gear
shock strut compression
hydraulic drag
closure diagram
calculation of unknown dynamic parameters
emergency situation
discrete algorithm
root-mean-square minimum error
state vector
The possibility of calculating aircraft balance, as well as other dynamic parameters, based on the discrete algorithm resulting from the condition of the root-mean-square minimum error is considered. A simplified problem without taking into account the lateral dynamics is solved, and a quasi-static model is used to determine the loads on the nose and main landing gears. The impact air pressure, longitudinal acceleration, pitch angle, and radio-altimeter readings are the measured parameters considered.
FREQUENCY METHOD OF FLUTTER ANALYSIS AND ITS APPLICATION TO CALCULATED AND EXPERIMENTAL STUDY
169-177
10.1615/TsAGISciJ.2014011291
Stanislav Viktorovich
Morgunov
Raduga State Machine-Building Design Bureau, 2a, Zhukovsky str., Dubna, Moscow Region 141980, Russia
flutter
transfer function
transfer matrix
frequency response
experimental modal analysis
generalized coordinates
eigenvalues
eigenvectors
It is shown that the problem of flutter analysis is analogous to the classical problem of stability analysis of the multi-input/multi-output closed-loop control system with cross links. It is also shown that the multi-connected open-loop system corresponding to the closed-loop system can be reduced to a set of simply connected circuits, in which the role of transfer functions is played by the eigenvalues of the transfer matrix of the system. This enables the stability of each of the contours to be analyzed using conventional frequency methods. A computing example illustrating the equivalence of the conventional approach and the approach considered in the paper is shown. It is shown that the method of the computational/experimental investigation of flutter based directly on the experimentally determined frequency structural characteristics can be drawn from the developed assumptions. This method does not require preliminary determination of the frequencies and natural modes of vibration and can become a significant addition to conventional methods of computational/experimental investigations of flutter and aeroelastic stability.