卷 61, 编号 3 (2018)

Steady-state flow of viscous lubrication fluid in the nonsymmetrical clearance between two out-of-line cylinders of the bearing unit in the aircraft electric motor is discussed. An analytical solution of the task based on application of the perturbation theory is presented.

We present a design lay-out diagram of the reusable space transportation system that consists of an aerospace transformed vehicle that is injected into an orbit by means of the first and second stages. Some starting configurations of such system with the first and second stages are considered.

This study is concerned with practical application of nonlinear deformation and fracture resistance parameters for residual durability estimation of the fuselage elements with operation damage. By means of numerical calculations for the fragment of fuselage skin with central crack the governing parameters of the elastic-plastic crack-tip stress field are determined as a function of biaxial loading. Two variants of modeling of the crack-tip stress field were performed for the panel of homogeneous isotropic material and a set of the special cohesive elements. As a result the assessment of the biaxial loading influence of fracture damage zone state on crack tip stress field in fuselage panel is given.

The influence of various control systems of the orbital motion of a technological spacecraft on the level of microacceleration of its internal environment is simulated. Conclusions are drawn about the effectiveness of control systems with different actuators for realization of certain gravitationally sensitive processes onboard a spacecraft.

A mathematical model of the gliding unmanned aerial vehicle (UAV) motion is performed taking into account the interference effect of the main rotor on the UAV. Calculated values are presented for the interference addition to the aerodynamic coefficients of forces and moments on the UAV path section close to the carrier. The problems of stabilization and control are solved, providing stability of the UAV motion at the launch with due account of the aerodynamic interference and the effect of short-term upper stage engine operation, as well as a safe distance between the carrier and the UAV during their simultaneous motion.

The integration potentiality is considered for the flight control system and interface algorithms to provide the flight accuracy and safety of highly augmented aircraft in the case of low maximum elevator rate limit and in the case of failures causing its sharp decrease.

Limit assessment for the new optimization approach is carried out. This approach allows us to optimize the gas turbine duct elements by using the structural analysis and computational fluid dynamics methods, and to minimize the necessary number of CFD computations. Obtained results were verified and confirmed by experimental aerodynamic investigation.

The research is conducted of aerodynamic performance of the Mi-8 helicopter main rotor in the hover state and the vertical descent state, including vortex ring states (VRSs). Total and distributed aerodynamic performance, wake patterns, and main rotor flow patterns are calculated. The findings and results were compared with those provided by other researchers.

The paper presents a mathematical model of the film flow over a half-plane directed at an angle to the horizon. In the cross section of the film, a quadratic law for the longitudinal velocity distribution is adopted, taking into account friction on the film surface. An approximate solution of the problem is obtained in the form of a series in powers of the small parameter. The solution is presented in the form of graphs of the film thickness and the average longitudinal velocity along the length of the plate.

The bearing capacity of hybrid segmented bearings with different groove systems is compared. The research establishes that the system with a crescent groove has the best characteristics.

This paper studies the dynamic loads of bevel gears with circular and straight teeth with the overlap factors less than two (ε_α < 2) and more than two (ε_α > 2). The advantages of the gears with straight teeth with ε_α > 2 are shown.

This paper considers double bypass aircraft engine with controlled air bleed to the second bypass duct. Its performance is evaluated by mathematical modeling techniques. The second bypass air bleed amount is determined to provide the best engine efficiency at various operating modes.

3D ANSYS CFX conjugate calculation was carried out to compare cooling effectiveness of the high pressure turbine vane platforms with the film cooling and the convection-film cooling.

The functional diagram and algorithms for computing the altitude-speed parameters, the models of dynamic errors, and methods to ensure the accuracy of the system measuring channels based of the ion-mark sensor of primary information under deterministic and random influences are presented.

A theoretical and experimental analysis of the dynamic one-sided thermal scanning of aircraft composite fairings during short-time convective heating is carried out. The model of thermal contrast based on the concept of the mechanism of molecular heat conductivity with rationalization of reducing statement from 2D to 1D format is given and an “effective” heat transfer coefficient from the heated convective source to the fairing surface is introduced. The calculation results show the qualitative sufficiency of this approach, and the full-scale experiments for the nose fairing of the MIG-29 aircraft confirm its correctness quantitatively. The conclusions are drawn on the feasibility of the thermal scanning method of aircraft fairings for identifying delamination cavities.

A new method of electrochemical machining of compressor blades is presented. The paper describes the sequence diagrams of electrochemical machining that contain various methods to feed electrodes.

In this article, the “elbow method” and the “average silhouette” algorithms are used for determining an optimal number of clusters. A “shifted” EM algorithm adapted to the number of clusters is put forward, which allows increasing accuracy of the Gaussian mixture distribution approximation that determines the probabilistic structure of the interference distribution. Dependencies of an average number of cycles and the Kullback–Leibler divergence on a number of clusters in an initial mixture are obtained via mathematical modeling with a preset range of parameters. A comparative analysis of the EM algorithm results is carried out.

The capacitive angle sensor of the galvanometer scanner is designed. The task of developing a rotation angle sensor in the range of ±20 deg for scanning speeds of up to 20 kHz is being solved. The linear dependence of the change in capacitance on the angle in the considered range is achieved.