# TsAGI Science Journal, Issue 3, Year 2013

**ABOUT INCREASE OF EFFICIENCY OF PLASMA MULTI-ACTUATOR SYSTEM FOR BOUNDARY LAYER CONTROL**

*A. P. Kuryachii,** D. A. Rusyanov, S. L. Chernyshev, & V. V. Skvortsov*

*The numerical simulation of spatial-periodic systems of electrogasdynamic actuators (plasma actuators), using the dielectric barrier discharge (DBD) for a volumetric force impact on a gas flow was carried out. Both the typically used design of actuators and the advanced design with an additional screening electrode are considered. The mathematical model of the dielectric barrier discharge in air was formulated in the drift-diffusion approximation without accounting for convective transfer of the charged particles. The following volumetric reactions are taken into consideration, namely, the ionization of nitrogen and oxygen by electron impacts, the attachment of electrons to oxygen, the detachment of electrons from negative ions, and the ion-ion and the electron-ion recombination. The two types of boundary conditions were considered at the open dielectric surface, namely, the model of instantaneous recombination and the model of finite rates of recombination and electron desorption. The numerical simulation both for the typical and for the advanced actuator systems was done with the same set of problem parameters. It was shown that the advanced scheme provides the better energy efficiency of the system of DBD actuators. It was also found that the main integral characteristics of the DBD actuator weakly depend on the type of boundary conditions used on the dielectric surface. The new simplified design of a system of DBD actuators was proposed.*

**KEY WORDS: ***dielectric barrier discharge, plasma actuator, energy efficiency of an actuator, numerical simulation*

**SELECTION OF VISCOUS TERMS APPROXIMATION IN DISCONTINUOUS GALERKIN METHOD**

*A. I. Troshin,** V. V. Vlasenko, & A. V. Wolkov*

*The implicit discontinuous Galerkin method is presented for solving the two-dimensional model scalar convection-diffusion equation. Three approximations of diffusion terms are considered, which have been named Bassi & Rebay 1, Cockburn & Shu, and Bassi & Rebay 2. The results of the test computations are reported and accuracy order estimates are found. The influence of point discontinuities in boundary conditions on convergence rate to the exact solution is analyzed. Recommendations on choice of diffusion terms approximation are given.*

**KEY WORDS: ***discontinuous Galerkin method, convection-diffusion equation, accuracy order*

**AERODYNAMIC LOADS MEASUREMENTS ON AN AIRFOIL USING PIV SYSTEM**

*V. A. Vlasov, G. G. Gadzhimagomedov,** V. M. Lutovinov, & D. S. Sboev*

*An assessment of applicability of using PIV-velocity data for the nonintrusive aerodynamic force characterization (lift and drag) of an airfoil is made. The method of the control volume based on integration of hydrodynamic variables along the closed contour around an airfoil was used for calculations. The results of these calculations were compared with results of standard pressure-based lift coefficient measurements (surface pressure distribution and wake rake).*

**KEY WORDS: ***wind tunnel, velocity field, laser sheet, nonintrusive measurements, PIV system, aerodynamic loads, lift coefficient, drag coefficient, airfoil*

**SOLUTION OF THE INVERSE PROBLEM FOR AN AIRFOIL WITHIN THE FRAMEWORK OF THE REYNOLDS AVERAGED NAVIER-STOKES EQUATIONS**

*A. L. Bolsunovsky, N. P. Buzoverya, I. A. Gubanova,** & M. A. Gubanova*

*A new iterative method for solution of the inverse airfoil problem in a compressible gas flow within the framework of RANS equations has been developed. The method belongs to the class of residual correction methods. An airfoil geometry correction, decreasing the residual between the computed and desired pressure distributions, is defined by means of a correction block based upon the previously developed domestic inverse full-potential code. Several examples of inverse problem solution showing high efficiency of the method are given.*

**KEY WORDS: ***inverse problem, Navier-Stokes equations, ANSYS CFX, airfoil, pressure distribution*

**ENGINEERING TECHNIQUE OF CORRECTING THE MAXIMAL LIFT COEFFICIENT OF MODELS FOR THE FULL-SCALE FLIGHT CONDITIONS**

*G. A. Fedorenko*

*Results of experimental research of models of lifting surfaces (airfoil sections, half-wings, aircraft configurations) in wind tunnels (WTs) are analyzed for influence of Reynolds number, initial degree of flow turbulence, and roughness of model surface on the maximal lift coefficient C _{La }*

_{max}

*. It is shown that, on one hand, the maximal lift coefficient of an aircraft in full-scale flight cannot exceed maximal threshold C*

_{La }_{max∞}

*obtained for an aerodynamically smooth model in WT, and, on the other hand, it cannot be lower than minimal threshold C*

_{La }_{max(min)∞ }

*obtained for a completely turbulent boundary layer over a model. The technique of correcting the maximal lift coefficient C*

_{La }_{max}

*of models for the full-scale flight conditions is presented in this work.*

**KEY WORDS: ***maximal lift coefficient, influence of Reynolds number, initial degree of free-stream turbulence, surface roughness, correcting for the full-scale flight conditions*

**THE METHOD OF OPTIMAL PROFILING OF FLYING VEHICLE FUSELAGE AND NOZZLE AT THE CRUISING SUPERSONIC FLIGHT**

*A. P. Mazurov** & S. A. Takovitskii*

*The method of profiling of elements of a high-speed flying vehicle airframe and power plant nozzle is presented. The lift at the cruising flight is chosen as the objective function, which is maximized under external dimensions constraints and isoperimetric condition on the pitch moment. The direct optimization method is used, which combines the flow modeling within the framework of the Euler equations and the Newton minimization algorithm. The results of elementwise optimization and complex optimization which strengthens the positive effects of integration are compared. Analysis of total aerodynamic loads on the optimal configurations is performed.*

**KEY WORDS: ***optimization, objective function, fuselage forebody, nozzle, lift, flying vehicle trim*

**GENERATION OF THE ALGORITHM OF SYNCHRONIZATION OF RELAY-HYSTERETIC ELEMENTS IN DIGITAL REDUNDANT CONTROL SYSTEM BY MEANS OF FINITE STATE AUTOMATION**

*S. G. Bazhenov*

*The present work proposes a method for synchronization of states of the control axes’ discrete elements and for control of the two-channel self-testing computer of the modern digital control system of the aircraft. The method is based on the theory of finite automation. The algorithms of synchronization of relay and hysteresis outputs are discussed.*

**KEY WORDS: ***digital system, redundancy, synchronization, control axes, relay, hysteresis, finite automation*

**NONCONTACT MEASUREMENTS OF NORMAL DEFORMATION FIELDS OF A CONSTRUCTION SURFACE BY VIDEOGRAMMETRY METHODS WHILE STRENGTH TESTING**

*V. P. Kulesh** & S. M. Naumov*

*A videogrammetry method using one digital camera for noncontact measurements of a distributed normal deformation of construction elements with a flat surface or having a small curvature is developed. Investigations of the surface buckling are performed at the local shell buckling of typical cylindrical fuselage panels of a passenger plane made of aluminum alloy and at the general buckling of a full-scale flat panel of a perspective aircraft wing box made of polymer composite material with a loading up to destruction. It is found that in both cases, the buckling deformation of the surface has two main modes with the opposite sign of normal deviations. The maximum deformation deviations of positive and negative modes of the panel made of aluminum alloy are +1.26 and —2.47 mm, and those of the positive and negative modes of the panel made of composite material are ±1.33 mm directly before the destruction.*

**KEY WORDS: ***strength testing, deformation fields, noncontact measurements, videogrammetry*

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