Begell House Inc.
TsAGI Science Journal
TSAGI
1948-2590
46
7
2015
INFLUENCE OF HIGH-BYPASS-RATIO TURBOFAN JETS ON AERODYNAMIC CHARACTERISTICS OF HIGH-LIFT WING
619-629
10.1615/TsAGISciJ.v46.i7.10
Albert Vasilievich
Petrov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region
Vladimir Fedorovich
Tretyakov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky,
Moscow Region, 140180, Russian Federation
jet blowing
high-lift wing
aerodynamic performance
The results presented here describe experimental investigations of the jet blowing effect on the aerodynamic performance of a rectangular wing with aspect ratio AR = 4 (span l = 1200 mm, chord b = 300 mm) with a two-element slotted flap. The investigations were performed at the TsAGI T-106 wind tunnel at the Mach numbers M∞ = 0 and 0.15 and Reynolds number Re∞ = 0.94 × 106,for wing angles of attack α = 2−10° and flap deflection angles δf = 0°, 35°/40°, and 40°/70°. Jet modeling was conducted using cold compressed air, blown from a subsonic nozzle with relative diameters equal to DN = DN/b = 0.27, 0.33, and 0.42, and corresponding to turbofan engines of different bypass ratios (m Ø 5−15) at different nozzle positions relative to the wing and in the thrust coefficient range cT = 0−1.6.
OPTIMIZATION OF THE FOREBODY OF A SUPERSONIC FLYING VEHICLE CONFIGURATION WITH A WINDWARD INTAKE
631-646
10.1615/TsAGISciJ.v46.i7.20
Sergey Alexandrovich
Takovitskii
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovskystr., Zhukovsky, 140180, Moscow region, Russia
optimization
forebody
aerodynamic drag
pitching moment
The problem of constructing the forebody of a supersonic flying vehicle with the integrated intake of a jet engine is considered in a two-dimensional formulation. Multi-objective optimization is performed for the purpose of minimizing the aerodynamic drag and pitching moment under the constraint of a constant lift force. Based on the method of local linearization of the relationship between the gas-dynamic functions and the geometric parameters, an analytical solution to the problem is obtained. The aerodynamic characteristics of the forebodies are compared with the results of numerical simulations within the framework of the Euler equations.
PARAMETRIC DESCRIPTION OF THE AIRFOIL USING COMBINED POLYNOMIAL FUNCTIONS FOR OPTIMIZATION APPLICATIONS
647-656
10.1615/TsAGISciJ.v46.i7.30
Nikolay Vladimirovich
Nikolaev
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky St., Zhukovsky, 140180, Moscow Region, Russia
airfoil
parameterization
optimization
An approach for airfoil parameterization using geometric parameters is proposed. This approach is meant to be used for the analytical airfoil contours. A class of combined polynomial airfoil contours is considered. The approximation accuracy is tested using the example of certain airfoils. The pressure distributions for the original and approximated airfoils are compared. An example of the optimization of the airfoil aerodynamic characteristics is considered.
ONE SOLUTION OF THE NAVIER−STOKES EQUATIONS: SPHERICALLY SYMMETRIC POINT SOURCE IN A COMPRESSIBLE PERFECT GAS
657-670
10.1615/TsAGISciJ.v46.i7.40
Oleg Evguenievich
Kirillov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky, 140180, Moscow Region, Russia
bulk viscosity
irregular singularity
convolution
source
Navier-Stokes equations
The solution of the Navier−Stokes equations for a spherically symmetric flow source is considered. Only the second (bulk) viscosity, in the absence of the first (shear) viscosity and thermal conductivity, is taken into account. This allows obtaining a solution in the form of a series in which the coefficients are expressed in terms of previously recurring convolution coefficients. The solution has two irregular singular points−in the center and at infinity−resulting in significant non-uniqueness of the solution; that is, the equations have many solutions that are physically indistinguishable at infinity. When the second viscosity tends to zero, the solution describes the inviscid limit of compressible flows. It records the second viscosity, followed by its aspiration to zero, which quickly allows physically solving the Navier−Stokes equations correctly for a compressible inviscid gas flow point source. Therefore, this method is called the method of correct compressibility. The results of the calculations and solutions that have physical meaning are presented.
CRITERION TO SELECT OPTIMUM VALUES OF AIRCRAFT LATERAL STATIC STABILITY MARGIN IN LANDING APPROACH
671-686
10.1615/TsAGISciJ.v46.i7.50
Pavel Anatolievich
Desyatnik
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky str., Zhukovsky 140180, Moscow region, Russia
lateral static stability margin
transport aircraft
directional handling qualities criterion
flight simulator
The equation of aircraft lateral/directional motion is analyzed and modified to determine generalized parameters critical to developing the handling quality criterion in the directional control axis. An extensive experimental database is collected on the TsAGI PSPK-102 flight simulator to assess the effect of the generalized parameters on the optimum (pilot opinion) values of Lβ that determine the best interaction between directional and lateral motion while under pedal control. The derivation of the directional handling quality criterion is presented based on the collected experimental database. The effectiveness of the criterion is demonstrated by its coincidence with the experimental results.
INVESTIGATION OF CRACK PROPAGATION PROCESS BY MEASUREMENTS OF LOCAL DEFORMATION RESPONSE: I. ACTUAL STRESS FIELD
687-714
10.1615/TsAGISciJ.v46.i7.60
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
Andrei Vladimirovich
Chernov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
stress intensity factor
T-stresses
crack compliance method
electronic speckle interferometry
local displacement measurements
This work consists of two parts. The first part includes detailed consideration of theoretical foundations of a modified version of the crack compliance method. On this basis, a new experimental method of determining the fracture mechanics parameters is developed and verified. The proposed approach is based on the joint application of the crack compliance method and the optical interference measurements of a local deformation response to a small increment of the crack length. The experimental information represents the values of the in-plane displacement components, which are derived by electronic speckle interferometry at the crack tip vicinity. The mathematical relationships required for the transformation of the initial data to the sought values of the fracture mechanics parameters are presented. It is shown that the values of the stress intensity factor (SIF) and the so-called T-stress can be obtained by determining the first four coefficients of an asymptotic Williams' series. Measurement of the absolute values of the tangential displacement components at reference points located on the line of the crack length increment is the key element of the developed approach. In addition, the availability of high-quality interference fringe patterns that reflect only the deformation displacements without the influence of rigid displacements is a reliable indicator of the real stress state in the vicinity of the crack tip. These facts indicate that in order to interpret the initial experimental data it is not required to use complicated mathematical (numerical) models containing all of the geometrical parameters of the investigated object and the conditions of the external loading. The accuracy analysis of the proposed approach involves comparing the SIF and T-stress values for the edge and central crack in thin plates with similar results to finite-element modeling and analytical solutions, respectively.