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1.
D. N. Gorelov 《Journal of Applied Mechanics and Technical Physics》2007,48(2):184-191
A general formulation of a nonlinear initial-boundary problem of an unsteady separated flow around an airfoil by an ideal
incompressible fluid is considered. The problem is formulated for a complex velocity. Conditions of shedding of vortex wakes
from the airfoil are analyzed in detail. The proposed system of functional relations allows constructing algorithms for solving
a wide class of problems of the wing theory.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 48–56, March–April, 2007. 相似文献
2.
O. Yu. Korotkov G. M. Shumskii 《Journal of Applied Mechanics and Technical Physics》2000,41(3):452-455
A mathematical model of an unsteady separated flow around an oscillating airfoil is considered. This model is based on a viscid-inviscid
approach. The points of separation and the intensity of vorticity displaced into the external flow are determined using boundary-layer
equations in an integral form. Dynamic stall on an oscillating airfoil is studied. The mechanism and nature of antidamping
are discovered.
Novosibirsk State Technical University, Novosibirsk 630092. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika,
Vol. 41, No. 3, pp. 81–85, May–June, 2000. 相似文献
3.
S. M. Aulchenko V. P. Zamuraev A. P. Kalinina 《Journal of Applied Mechanics and Technical Physics》2008,49(6):957-961
The possibility of controlling the aerodynamic characteristics of airfoils in transonic flight regimes by means of one-sided
pulsed-periodic energy supply is studied. Based on the numerical solution of two-dimensional unsteady gas-dynamic equations,
the change in the flow structure in the vicinity of a symmetric airfoil at different angles of attack and the aerodynamic
characteristics of the airfoil as functions of the amount of energy supplied asymmetrically (with respect to the airfoil)
are determined. The results obtained are compared with the data calculated for the flow past the airfoil at different angles
of attack without energy supply. It is found that a given lift force can be obtained with the use of energy supply at a much
better lift-to-drag ratio of the airfoil, as compared to the case of the flow past the airfoil at an angle of attack. The
moment characteristics of the airfoil are found.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 82–87, November–December, 2008. 相似文献
4.
S. M. Aulchenko V. P. Zamuraev A. P. Kalinina 《Journal of Applied Mechanics and Technical Physics》2007,48(6):834-839
The possibility of controlling the aerodynamic characteristics of airfoils in transonic flight regimes by means of local pulsed
periodic energy supply is considered. The numerical solution of two-dimensional unsteady equations of gas dynamics allowed
determining the changes in the flow structure near a symmetric airfoil and its aerodynamic characteristics depending on the
magnitude of energy in the case of its asymmetric (with respect to the airfoil) supply. The results obtained are compared
with the calculated data for the flow around the airfoil at different angles of attack without energy supply. With the use
of energy supply, a prescribed lift force can be obtained with a substantially lower wave drag of the airfoil, as compared
with the flow around the airfoil at an angle of attack.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 70–76, November–December, 2007. 相似文献
5.
D. N. Gorelov 《Journal of Applied Mechanics and Technical Physics》2006,47(1):61-67
Criteria for the separation of unsteady flow past a closed smooth airfoil are studied using the ideal fluid model and the
Brillouin-Villat criterion. The necessary separation conditions are formulated.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 1, pp. 74–81, January– February, 2006. 相似文献
6.
S. M. Aulchenko V. P. Zamuraev A. P. Kalinina 《Journal of Applied Mechanics and Technical Physics》2006,47(3):359-365
Changes in the structure of a transonic flow around a symmetric airfoil and a decrease in the wave drag of the latter, depending
on the energy-supply period and on localization and shape of the energy-supply zone, are considered by means of the numerical
solution of two-dimensional unsteady equations of gas dynamics. Energy addition to the gas ahead of the closing shock wave
in an immediate vicinity of the contour in zones extended along the contour is found to significantly reduce the wave drag
of the airfoil. The nature of this decrease in drag is clarified. The existence of a limiting frequency of energy supply is
found.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 64–71, May–June, 2006. 相似文献
7.
Design of a separation-free airfoil with outer-flow suction over a certain range of angles of attack
The problem of the design of an airfoil with slot air suction from the outer flow for a prescribed velocity distribution over
the airfoil contour that ensures the absence of flow separation over a given range of angles of attack is formulated and solved.
The proposed combined numerical and analytical method of airfoil design within the framework of the inviscid incompressible
fluid model is based on the theory of inverse problems of aerohydrodynamics. Separationless flow past the airfoil is achieved
by eliminating the falling velocity intervals from the specified velocity distribution in two given flow regimes. The flow
past an airfoil with outer-flow suction is determined not only by the angle of attack as for an impermeable airfoil but also
by the value of the suction mass flow. The slot is modeled by an annular channel with constant velocities on the walls. To
satisfy the problem solvability conditions, free parameters are introduced into the initial velocity distribution. Examples
of airfoil design are given.
Kazan, Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 185–191, July–August,
2000. 相似文献
8.
O. V. Ilyin 《Fluid Dynamics》1994,29(4):458-464
A general solution is obtained for the boundary value problem of designing a thin airfoil in a channel with permeable walls
from the given pressure distribution. A suitable choice of permeability coefficients makes it possible to construct a thin
airfoil in a channel with impermeable walls, in a jet, etc. The effect of the wall permeability on the shape of the airfoil
is studied.
Cheboksary. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 28–34, July–August,
1994. 相似文献
9.
V. B. Kurzin 《Journal of Applied Mechanics and Technical Physics》2006,47(3):346-358
A model for separated incompressible flow past thin airfoils in the neighborhood of the “shockless entrance” condition is
constructed based on the averaging of the vortex shedding flow past the airfoil edges. By approximation of the vortex shedding
by two vortex curves, determination of the average hydrodynamic parameters is reduced to a twofold solution of an integral
singular equation equivalent to the equation describing steady-state nonseparated airfoil flow. In this case, the calculation
time is two orders of magnitude smaller than the time required for the solution of the corresponding evolution problem. The
results of a test calculation using the proposed method are in fair agreement with available results of calculations and experiments.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 49–63, May–June, 2006. 相似文献
10.
D. F. Abzalilov 《Journal of Applied Mechanics and Technical Physics》2008,49(6):978-984
A numerical-analytical solution of an inverse boundary-value problem of aerohydrodynamics is obtained for a two-element airfoil
in the full formulation, based on the velocity distribution defined on the sought airfoil contours in a range of angles of
attack. It is demonstrated that flow separation does not occur in the entire range considered for a specified non-separated
velocity distribution on the upper surfaces at the maximum angle of attack and on the lower surface at the minimum angle of
attack. An example of constructing a sectional airfoil is given; verification of the results obtained is performed with the
use of the Fluent software package.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 107–114, November–December, 2008. 相似文献
11.
K. E. Afanas'ev S. V. Stukolov 《Journal of Applied Mechanics and Technical Physics》2000,41(3):470-478
Steady problems of a circulation flow around bodies by a flow of a heavy liquid bounded by a free surface and a straight bottom
are solved. The method of complex boundary elements is used, which is based on the integral Cauchy formula written for a complex-conjugate
velocity. Results of numerical calculations of the flow around a circular contour and the Joukowski airfoil are presented.
Shapes of the free surface and the most important hydrodynamic characteristics of the process (velocity circulation over the
airfoil and the lifting force and its moment relative to the sharp edge of the airfoil) are given.
Kemerovo State University, Kemerovo 650043. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 3,
pp. 101–110, May–June, 2000. 相似文献
12.
N. D. Dikovskaya B. Yu. Zanin 《Journal of Applied Mechanics and Technical Physics》1999,40(1):108-113
The problem of the origin and evolution of two-dimensional waves of unstable disturbances in the boundary layer on an airfoil
in the region of adverse pressure gradient in the preseparation flow region is solved numerically. The stability of the experimental
velocity profiles, including the inflected profiles, is studied. As a result of the calculations, the boundaries of the instability
region and the parameters of the maximally unstable disturbances (frequency, growth rate, wavelength, and propagation velocity)
are determined for each velocity profile. The characteristics obtained in the present work are in good agreement with the
real experimental parameters of instability waves.
Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090. Translated
from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 1, pp. 126–132, January–February, 1999. 相似文献
13.
A. I. Zobnin 《Journal of Applied Mechanics and Technical Physics》2009,50(2):270-277
An unsteady kinematic problem for arbitrary two-dimensional motion of an airfoil in an ideal incompressible fluid with formation
of one and two vortex wakes is solved. The problem is solved by the method of conformal mapping of the flow domain onto a
circle exterior; solution singularities in the vicinity of a sharp edge are analyzed, and the initial asymptotics of the solution
is taken into account. The calculated results are found to be in good agreement with available experimental data on visualization
of the flow pattern. The necessity of correct modeling of the initial stage of vortex-wake formation is demonstrated. A regular
flow pattern is found to form after three and more periods of oscillations.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 120–128, March-April, 2009. 相似文献
14.
The results of calculating the steady separated flow of a viscous incompressible fluid past a 12% sinusoidal airfoil with
and without a splitter plate are presented. The Navier—Stokes equations written in stream-function—vorticity variables are
approximated in accordance with a central difference scheme and solved simultaneously by means of the direct method. The results
obtained are analyzed from the standpoint of their consistency with the asymptotic theory based on the well-known three-deck
scheme.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 155–160, March–April, 1994. 相似文献
15.
V. D. Kotelkin 《Fluid Dynamics》1994,29(1):114-122
The gas-dynamic equations are written in Cartesian coordinates in the potential plane. This approach to the inverse problem
makes it possible to seek a quasisolution within a set of closed contours. To solve this problem an iterative procedure is
developed using successive approximations and taking into account the fact that aerodynamic airfoils are elongated in the
streamwise direction. In the case where an arbitrary pressure distribution is prescribed, the procedure determines the airfoil
providing the best approximation to the design data.
Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.1, pp. 147–157, January–February,
1994. 相似文献
16.
To comprehensively understand the effects of Kelvin–Helmholtz instabilities on a transitional separation bubble on the suction
side of an airfoil regarding as to flapping of the bubble and its impact on the airfoil performance, the temporal and spatial
structure of the vortices occurring at the downstream end of the separation bubble is investigated. Since the bubble variation
leads to a change of the pressure distribution, the investigation of the instantaneous velocity field is essential to understand
the details of the overall airfoil performance. This vortex formation in the reattachment region on the upper surface of an
SD7003 airfoil is analyzed in detail at different angles of attack. At a Reynolds number Re
c < 100,000 the laminar boundary layer separates at angles of attack >4°. Due to transition processes, turbulent reattachment
of the separated shear layer occurs enclosing a locally confined recirculation region. To identify the location of the separation
bubble and to describe the dynamics of the reattachment, a time-resolved PIV measurement in a single light-sheet is performed.
To elucidate the spatial structure of the flow patterns in the reattachment region in time and space, a stereo scanning PIV
set-up is applied. The flow field is recorded in at least ten successive light-sheet planes with two high-speed cameras enclosing
a viewing angle of 65° to detect all three velocity components within a light-sheet leading to a time-resolved volumetric
measurement due to a high scanning speed. The measurements evidence the development of quasi-periodic vortex structures. The
temporal dynamics of the vortex roll-up, initialized by the Kelvin–Helmholtz (KH) instability, is shown as well as the spatial
development of the vortex roll-up process. Based on these measurements a model for the evolving vortex structure consisting
of the formation of c-shape vortices and their transformation into screwdriver vortices is introduced. 相似文献
17.
18.
W. Yuan H. Xu M. Khalid R. Radespiel 《International Journal of Computational Fluid Dynamics》2013,27(1):45-54
Low-Reynolds-number aerodynamic performance of small-sized air vehicles is an area of increasing interest. In this study, low-Reynolds-number flows past an SD7003 airfoil are investigated to understand important viscous features of laminar separation and transitional flow followed by the complicated behavior of the flow reattachment process. In order to satisfy the three-dimensional (3D) requirement of the code, a simple “3D wing” is constructed from a two-dimensional (2D) airfoil. A parametric study of large eddy simulation (LES) on the airfoil flows at Re = 60,000 is performed. Effects of grid resolution and sub-grid scale (SGS) models are investigated. Although 3D effects cannot be accurately captured owing to the limitation of the grid resolution in the spanwise direction, the preliminary LES calculations do reveal some important flow characteristics such as leading-edge laminar separation and vortex shedding from the primary laminar separation bubble on the low-Reynolds-number airfoil. 相似文献
19.
A. N. Khrabrov 《Fluid Dynamics》2005,40(3):474-485
The linear problem of the time-dependent inviscid flow past a thin symmetric airfoil with a control on its trailing edge deflected in accordance with an arbitrary law is considered. The aerodynamic loads on the airfoil are calculated. The intensity of the vortex wake shed from the airfoil is determined by numerically solving a Volterra integral equation of the first kind. Questions of the mathematical modeling of the time-dependent aerodynamic loads in a form convenient for the joint solution of the problems of aerodynamics and flight dynamics are also considered. The results of the modeling are compared with the numerical solutions obtained.__________Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, 2005, pp. 157–169.Original Russian Text Copyright © 2005 by Khrabrov. 相似文献
20.
Homogeneous heavy fluid flows over an uneven bottom are studied in a long-wave approximation. A mathematical model is proposed
that takes into account both the dispersion effects and the formation of a turbulent upper layer due to the breaking of surface
gravity waves. The asymptotic behavior of nonlinear perturbations at the wave front is studied, and the conditions of transition
from smooth flows to breaking waves are obtained for steady-state supercritical flow over a local obstacle.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 3, pp. 3–11, May–June, 2006. 相似文献