TsAGI Science Journal, Issue 4, Year 2013

IMPROVEMENT OF AERODYNAMICS OF CIVIL PLANE WING HIGH-LIFT DEVICES

N. N. Bragin, A. L. Bolsunovsky, N. P. Buzoverya, M. A. Gubanova, S. I. Skomorokhov, & G. V. Hozyainova

The results of experimental investigations of high-lift devices of a civil plane wing are presented. The analysis of flow features has been carried out by both force measurements for different Reynolds numbers and flow visualization using mini-tufts. The proposed improvements have allowed increasing the efficiency of high-lift system and providing the required level of lift.

KEY WORDS: civil plane, aerodynamics, lift, flap, slat

INFLUENCE OF A SURFACE FRACTAL MICROSTRUCTURE ON THE CHARACTERISTICS OF A TURBULENT BOUNDARY LAYER

M. A. Brutyan, V. P. Budaev, A. V.Wolkov, A. M. Zhitlukhin, A. V. Karpov, N. S. Klimov, I. S. Menshov, V. L. Podkovyrov, A. Yu. Urusov, A. A. Uspenskii, & M. V. Ustinov

The results of startup experimental investigations on the properties of a turbulent boundary layer over flat plates with a chaotic micro- and nanostructure possessing hierarchy of granularity (fractality) are given. Experimental investigations were carried out in the low-turbulent and low-speed aerodynamic T-36I wind tunnel at TsAGI. The samples in the experimental study were flat plates (160×160 mm²) with a fractal surface, which were obtained by high-temperature plasma processing in the fusion device, QSPA-T, of metallic plates that were originally smooth. The influence of the surface fractal microstructure on the velocity spectrum and the structure of the turbulent boundary layer were registered in both load and hot-wire experiments. Suppression of the low-frequency bandwidth of the velocity spectrum and the change in aerodynamic drag were observed, which indicates the possibility of turbulence control.

KEYWORDS: fractal roughness, turbulent boundary layer, drag reduction

CALCULATION OF ROTATIONAL DERIVATIVES OF ROLL AND YAW MOMENTS FOR HIGH-ASPECT-RATIO WINGS

M. A. Golovkin

Analytical expressions for rotational derivatives of roll and yaw moments with respect to angular velocity and its components are derived using vector formulas. The resulting expressions can be used to estimate these derivatives for a wing with a very high aspect ratio within any range of angle of attack, given the distribution of normal and longitudinal forces and the distribution of their derivatives with respect to the angle of attack in the wing cross sections and induced downwashes along the wing span in the case of stationary flow. Analytical expressions are given for the following wings: a swept wing, a wing with a constant chord, a wing with linear dependence of normal and longitudinal forces on the angle of attack, and a wing with the elliptic law of load distribution along the span.

KEY WORDS: wing, roll and yaw moments, rotational derivatives, angular velocity components

INVESTIGATION OF ROTARY AND UNSTEADY DERIVATIVES OF THE PITCHING MOMENT OF AN AIRPLANE MODEL USING A 2DOF FORCED OSCILLATION RIG

I. V. Kolin, K. F. Latsoev, V. G. Markov, V. K. Svyatodukh, T. I. Trifonova, & D. V. Shukhovtsov

A new, dynamic two degrees-of-freedom (2DOF) oscillation rig, SLUK, which implements joint heave and angular harmonious oscillations of an aircraft model, was developed at TsAGI. The rotary and unsteady derivatives of the pitching moment coefficient and their sum are obtained experimentally for a passenger aircraft in a wide range of angles of attack. The values of the unsteady derivative obtained experimentally are shown to be in good agreement with its evaluations determined as the difference between the experimentally obtained values of the sum of the rotary and unsteady derivatives and the rotary derivative of the pitch moment coefficient.

KEY WORDS: wind tunnel, angular oscillations, translational motion, amplitude, frequency, angle of attack, pitching angle, strain-gauge balance, Strouhal number

SPACECRAFT RECOVERY AFTER A PLANETARY MISSION WITH ASCENT TO THE PARKING ORBIT

A. V. Bobylev & V. A. Yaroshevsky

The possibility of spacecraft ascent to the intermediate parking earth orbit after a planetary mission to assure further landing in the intended area is considered. The principle of setting the parameters of a nominal trajectory according to the conditions of atmosphere reentry is used to increase the accuracy of the trajectory control.

KEY WORDS: planet, spacecraft, parking orbit, atmosphere reentry, guidance law, transient process, lift-to-drag ratio

NUMERICAL SIMULATION OF MECHANICAL SYSTEMS WITH AN AUTOMATIC CONTROL SYSTEM AT EARLY STAGES OF HELICOPTER DESIGN

E. V. Kasumov

A numerical simulation technique used in the early stages of helicopter design with an automatic control is considered. Using the simulation of a predetermined flight mode of a light helicopter, kinematic analysis and load design of its rotor system taking into account the simulation of its automatic control is considered.

KEY WORDS: deflected mode, fatigue strength, mathematical model, kinematic analysis, load design, design, mechanical system, automatic control

VIDEOGRAMMETRY METHOD OF NON-CONTACT MEASUREMENTS OF INSTANTANEOUS DEFORMATION OF ROTATING PROPELLERS BLADES

S. I. Inshakov, V. P. Kulesh, V. E. Mosharov, & V. N. Radchenko

A videogrammetry method and a system for non-contact measurements of the instantaneous deformation of bending and torsion of the blades of rotating propellers are developed. A procedure for auto-calibration of the measurement system is presented. This procedure is performed during each wind tunnel run at low speeds of the propeller rotation, which allows tracking the possible changes of the measurement system parameters during the tests. A procedure to eliminate the influence of blade slippage caused by delay in the synchronization pulse is developed. The method was used in the tests of a two-rotor coaxial ventilator propeller in the T-104 and T-107 wind tunnels at TsAGI. It is shown

that the instantaneous bending deformation reached a value in the range from —0.5 to —4.5 mm at the tip of the front blade and a value in the range from 0 to 3 mm at the tip of the rear blade. The torsion deformations were in the ranges from 0 to 3.3° and 1.3 to 0°.

KEY WORDS: wind tunnels, propeller blades, deformation, non-contact measurements, videogrammetry

STRENGTH RESEARCH ON MULTI-ROW METAL-COMPOSITE JOINTS

Ya. S. Borovskaya, V. I. Grishin, I. N. Kacharava, & S. M. Naumov

Experimental and computational research on the stress—strain state and strength of metal—composite joints is presented. It is found that three-dimensional joints can be modeled by membrane finite elements during the computations. The computation time decreases by an order in comparison with that of the modeling of structure by shell elements, and the difference of forces in fasteners does not exceed 1%.

KEY WORDS: joints, metal, composite, load in bolts, composite, finite-element method, test