Begell House Inc.
TsAGI Science Journal
TSAGI
1948-2590
46
3
2015
SELF-SIMILAR AND LIMITING SOLUTIONS OF TURBULENT BOUNDARY LAYER EQUATIONS: CONDITIONS OF D'ALEMBERT'S PARADOX
193-207
10.1615/TsAGISciJ.2015014084
Vladimir Victorovich
Mikhailov
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
Nina Veniaminovna
Samoilova
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky str. 1, Zhukovsky, 140180, Russia
turbulent near-wall flow
skin friction coefficient
relaminarization
The mean flow equations in a plane turbulent boundary layer of an incompressible fluid are considered.
A self-similar solution to these equations is obtained, and the criterion of relaminarization of
the boundary layer (reverse transition) is refined. For the limit of high Reynolds numbers in the flow
around a hydraulically smooth body, the distribution of the Clauser parameter and the skin friction
coefficient over the body surface are obtained in quadratures. If there is no relaminarization of the
boundary layer and no effect of surface roughness, it is shown that flow separation is localized at the
rear stagnation point of the body, i.e., d'Alembert's paradox occurs in this case. The result obtained
is illustrated by the example of a limiting analytical solution for a symmetric flow around elliptical
cylinders. In this case, a sufficient condition of a non-separated flow is the inequality k < 4.78, where
k is the ratio of the vertical to the horizontal axis of the ellipse aligned in the streamwise direction.
EVOLUTION OF VORTICITY IN SWIRLING AXISYMMETRIC FLOWS OF A VISCOUS INCOMPRESSIBLE FLUID
209-217
10.1615/TsAGISciJ.2015014086
Grigorii Borisovich
Sizykh
Moscow Institute of Physics and Technology (MIPT), 9 Institutskiy Per.,
Dolgoprudny, 141700, Moscow Region, Russia
Navier-Stokes equations
swirling flow
method of discrete vortices
Friedman velocity
Swirling axisymmetric flows of a viscous incompressible fluid are considered. The concept of the
Friedman velocity is introduced to describe the evolution of vorticity. Expressions for the Friedman
velocities for the vorticity vector components are obtained.
DYNAMICS OF A VORTEX SPIRAL
219-229
10.1615/TsAGISciJ.2015014285
Viktor Fedorovich
Molchanov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
vortex filament
cylindrical spiral
conical spiral
A vortex filament with slowly varying thickness that simulates viscous diffusion at high Reynolds
numbers is considered. The equations determining the spiral shape in the uniform flow are obtained
for the case of a spiraled vortex. It is shown that these equations an be solved until the vortex thickness
reaches a certain critical value. It is assumed that further evolution of the spiral is associated with its
rotation.
NONUNIQUENESS OF THE SOLUTION IN THE VICINITY OF THE PLANE OF SYMMETRY OF A DELTA WING IN A HYPERSONIC FLOWWITH STRONG INTERACTION
231-245
10.1615/TsAGISciJ.2015014302
Georgiy Nikolaevich
Dudin
Central Aerohydrodynamic Institute (TsAGI), 1, Zhukovsky Str., Zhukovsky,
Moscow Region, 140180, Russian Federation
Phon Hai
Nguyen
Moscow Institute of Physics and Technology (MIPT), 9 Institutskiy Per., Dolgoprudny, Moscow Region, 141700, Russia
boundary layer
strong viscous-inviscid interaction
delta wing
The flow in a spatial boundary layer in the vicinity of the plane of symmetry of a semi-infinite flat
delta wing in the regime of a strong viscous-inviscid interaction is investigated. For the case of a
finite-span wing, the stream functions are expanded into a power series in the transverse coordinate.
A boundary-value problem for the principal terms of the expansion is studied, and the effects of the
temperature factor and the sweep angle of the leading edge on the solutions obtained are considered.
ACTIVE CANCELLATION OF THE CROSSFLOWIN A SUBSONIC BOUNDARY LAYER ON AN OBLIQUE WING
247-258
10.1615/TsAGISciJ.2015014303
Sergey Viktorovich
Manuilovich
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky St. 1, Zhukovsky 140180, Russia
incompressible fluid
boundary layer on an oblique wing
crossflow
volume force
Explicit expressions for the volume force completely canceling the crossflow of an incompressible fluid
in a three-dimensional boundary layer (BL) on an oblique wing are derived. An optimal distribution
of the canceling force is found. Mixed problems are formulated for calculating the shape of the distributed
force and the corresponding parameters of the BL flow. As an example, the volume force and
velocity profiles in the BL for a wing with an elliptical cross section are calculated.
DESIGN OF FLY-BY-WIRE CONTROL SYSTEM ALGORITHMS FOR ADVANCED HIGH-SPEED HELICOPTER
259-287
10.1615/TsAGISciJ.2015014083
Viktor Andreevich
Anikin
Kamov Design Bureau, 8a, 8 Marta St., Lyubertsy, Moscow region, 140007, Russia
Oleg Vladimirovich
Animitsa
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, Moscow region, 140180, Russia
Vladimir Mikhailovich
Kuvshinov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, Moscow region, 140180, Russia
Veniamin Aleksandrovich
Leontiev
Central Aerohydrodynamic Institute, 1, Zhukvsky Str., Zhukovsky, 140180, Moscow Region, Russia
high-speed helicopter
stability and controllability
control system
Design of fly-by-wire control system (FBW) algorithms for an advanced high-speed helicopter (rotor-craft)
is considered in order to provide acceptable stability and controllability characteristics for all
flight regimes, including the high-speed flight. The algorithm and procedure for the parameter determination
of the FBW control system stability and controllability augmentation loop are developed for
the high-speed helicopter with coaxial rotors in case of the longitudinal and lateral motions. The algorithms
use different sensors and control elements including aerodynamic control surfacesâelevator
and rudder.
SOME ASPECTS OF MODELING A HIGH-ASPECT-RATIO COMPOSITE WING-BOX BY AN ANISOTROPIC BEAM
289-305
10.1615/TsAGISciJ.2015014306
Sergei Aleksandrovich
Tuktarov
Central Aerohydrodynamic Institute (TsAGI), 1, Zhukovsky Str., Zhukovsky, Moscow Region, 140180, Russia
Vasilii Vasil'evich
Chedrik
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky St. 1, Zhukovsky 140180, Russia
structural modeling
composite material
finite-element method
high-aspect-ratio wing
plate-beam analogy
Two analytical approaches to modeling a high-aspect-ratio composite wing-box by an anisotropic
beam with and without the restraint of strains in the cross section are presented. Finite-element
models corresponding to these methods are constructed. The results of the analytical and numerical
models for a test example of a wing-box are compared. The influence of anisotropy on the stiffness
characteristics of the wing-box structure under bending and torsion is studied. The stressâstrain
state and the strength of the wing panel under tensile and compressive loading are investigated.