Begell House Inc.
TsAGI Science Journal
TSAGI
1948-2590
40
4
2009
SEVERAL ASPECTS OF GAS FLOW WITH PRESCRIBED DISTRIBUTION OF HEAT SOURCES
401-417
Arkadii Nikolaevich
Kucherov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
A brief review of papers which analyze gas flow with energy supply was carried out. Some physical-mathematical problem statements are considered, and experimental and theoretical results as well as analytical and numerical solutions are discussed. The source of heat can be presented as laser radiation, electric discharge, burning, and other chemical reactions.
MONOTONIZATION OF THE FINITE ELEMENT METHOD IN THE PROBLEMS OF GAS DYNAMICS
419-436
Andrey Viktorovich
Wolkov
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky,
Moscow Region, 140180, Russian Federation
Sergey Vladimirovich
Lyapunov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
The conservation law approximation method—the Galerkin finite element method with discontinuous basis functions (DG)—was modified by adding the λ parameter, which enables smooth control of the order of accuracy of the numerical scheme. Modification of the known finite element scheme allows for a smooth transition from a high-order-of-accuracy scheme to a monotonic scheme of the first order of accuracy in the areas of flow singularities. The original approach to the choice of the λ parameter is considered. The developed DG-λ scheme provides for the absence of nonphysical oscillations of the solution in the areas of flow singularities, which is shown by the solution of the model convection-diffusion problem and the calculation of flows described by Navier–Stokes equations. The possibility to obtain high-accuracy solutions on adapted unstructured grids is shown.
AERODYNAMIC CHARACTERISTICS OF MODELS OF VERTICAL TAKE-OFF AIRCRAFT (TILTROTOR) FOR A WIDE RANGE OF ANGLESOF ATTACK
437-452
N. N.
Tarasov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
Mikhail Alekseyevich
Golovkin
Central Aerohydrodynamic Institute (TsAGI), Zhukovsky St., 1, Zhukovsky,
Moscow Region, 140180, Russian Federation
Results of experimental research of the aerodynamic characteristics of models with comparatively low loaded propellers of a VTOA (tiltrotor) within the range of angles of attack, corresponding to a vertical takeoff, helicopter-type flight, and a transition to propeller operation mode, are shown. Models of propellers have been tested, the hubs of which, like those of a helicopter, have axial, horizontal, and vertical hinges. The flapping movement of the blades of these propellers was studied at various flapping governor coefficients. Tests of propeller models were carried out, the hubs of which, like those of plane propellers, have only axial hinges (with rigid fastening of the blades to the hub). Results of measurement of six components of forces and moments acting on the indicated propellers at flight speeds equal to one-fourth the tip speed of the ends of the blades are given. It is shown that on the propeller with rigid fastening of the blades at flight modes close to the propeller ones, with angles of attack or sideslip angles of the aircraft 10÷20°, a force is realized which coincides by its direction with the projection of the speed of the freestream on the plane of its disk, which can be 10÷30% of the thrust force of the propeller. The result of this paper can be used as a preliminary assessment of the aerodynamics and the dynamics of flight, the forces and the moments, acting on the elements of the aircraft with tiltrotors, of ordinary aircrafts with a propeller and of helicopters with additional propeller-engines.
THE DIFFUSION OF VORTICES ON A TWO-DIMENSIONAL SPHERE
453-457
Murad Abramovich
Brutyan
Central Aerohydrodynamic Institute (TsAGI), 1 Zhukovsky Str., Zhukovsky 140180, Russia
The exact analytical solution of the diffusion of two vortices, being situated in two diametrical opposite points of the sphere, was found within the framework of hydrodynamic equations for the two-dimensional sphere. It is shown that the obtained solution does not decay at t → ∞, like a classical Oseen solution of the problem of vortex filament diffusion on a plane E2, but it tends to the solid-body rotation.
ANALYSIS OF THE SONIC BOOM INTENSITY USING NEAR-FIELD PERTURBATION UNDER THE AIRCRAFT, CALCULATED BY MEANS OF THE NONLINEAR THEORY
459-473
Kyuchul
Cho
Institute of KDC
A procedure of sonic boom profile prediction is formed based on calculation of the disturbed flow fields in the aircraft near-field while numerically solving the complete Navier–Stokes equations. The sonic boom calculation technique, developed at TsAGI by Yu. L. Zhilin et al., is the basis for the algorithm. Application of nonlinear methods of disturbed flow-field calculation enables consideration, to one extent or another, such factors influencing the sonic boom intensity as the nose bluntness, viscosity, nozzle jets of propulsion system, etc. As an example, the influence of the nozzle jets of the Tu-144 aircraft on the sonic boom profile is shown, and the calculation results are compared with the experimental ones.
NUMERIC INVESTIGATION OF THE VENTILATION SYSTEM OF AN ADVANCED AIRCRAFT PASSENGER CABIN
475-483
This work contains results of investigations on development and application of the algorithm of numeric modeling of airflows in advanced aircrafts passenger cabins. A numeric algorithm was developed based on the method of control volume of solution of complete Navier-Stokes equations averaged in accordance with Reynolds (RANS — Reynolds-averaged Navier-Stokes) and completed with the help of the Menter modified k-w model of turbulence. In order to assess the efficiency of the developed algorithm, results of flow test calculations are listed as well as a comparison with the results of the experiment in the flat diffuser. Using the algorithm, calculations were performed for several patterns of ventilation system function in various cross sections of the passenger cabin at the preliminary design stage of short- and medium-range aircrafts (SMRA).
A METHOD FOR TAKING INTO ACCOUNT THE INFLUENCE OF THE MODEL AND DYNAMOMETER WEIGHTS ON THE STRAIN-GAUGE BALANCE READINGS
485-495
Anton Roaldovich
Gorbushin
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
This paper deals with the problem of the impact of the model and dynamometer weights on the readings of a strain-gauge balance in wind tunnel tests. An exact solution to the problems of the dynamometer weight determination of a six-component strain-gauge balance and determination of the model weight and the coordinates of its application point in the reference frame of the balance measuring system has been obtained. A method for taking into account the influence of the model and dynamometer weights on the readings of the strain-gauge balance in wind tunnel tests is proposed. Exemplary data of the dynamometer and model are presented.
APPLICATION OF SIMILARITY TRANSFORMATION UPON PARAMETRIC INVESTIGATIONS OF FLUTTER
497-506
Vyacheslav Vladimirovich
Lyschinsky
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
Anatoliy Alekseevich
Rybakov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
Transformation using the theory of similarity of the family of curves obtained upon parametric investigations of flutter is discussed. Transformed families are compared in order to reveal curves in them which are in line with the requirements of similarity. The possibility of simplification of experimental works, while investigating flutter, is justified in such cases.
AN ENGINEERING METHOD FOR DETERMINING CHARACTERISTICS OF A PROTECTIVE SCREEN AT IMPACT OF A NONLOCALIZED ENGINE FRAGMENT
507-516
Andrei Vladimirovich
Chernov
Central Aerohydrodynamic Institute (TsAGI) 1, Zhukovsky str., Zhukovsky, 140180, Moscow region, Russia
We consider a simple engineering method for calculating the protective properties of structures under the impact of an engine fragment based on estimated parametric studies.