Vol 62, No 2 (2019)

The new empirical method was developed for estimating the relative contribution of the deterministic, chaotic and noise components in the time series of the accident rate of aircraft in the Armed Forces of the Russian Federation. The behavior analysis of the senior Lyapunov exponent dependencies on the parameter of “number of neighbors used” specified in the algorithm in the case of model series (deterministic, chaotic and colored noise series) enabled to estimate the boundaries of numerical values of the parameters typical for these types of series and then apply them to the noise percentage analysis in the real series of the aviation events number.

We consider the methods of mathematical modeling and calculation of main parameters of small-size magnetic induction ejectors (separation systems) for precision launch into orbit nano- and microsatellites. Examples of some technical solutions are presented.

For a shell with three sections, dependences of the critical frequency on the different thicknesses of these sections are obtained. The error of the assumptions accepted at constructing the mathematical model of a shell is evaluated.

The paper reviews the results of assessing the ultra-low risks based on empirical functions of the probability distribution of the automatic aircraft landing accuracy, approximated by a mixture of distributions. Based on the outcomes obtained, the resultant approach can be recommended for resolving a wide range of problems of the validation of safety requirements including the case to create the evidential base in certification of automatic landing.

The paper describes the methods of forming the training samples and constructing the neural network models of regulators by increasing the number of layers and neurons in the case of one-channel and two-channel control of a dynamic object with smooth monotonous behavior. The paper presents results of constructing the neural network model of a regulator for controlling the roll motion of an unmanned aerial vehicle with an autonomous roll channel. We consider an example of constructing the neural network models of regulators for two-channel control of lateral motion for unmanned aerial vehicles with a simplified model.

The possibility of obtaining the better flight dynamics model of the flight simulator, relative to the real flight characteristics of a helicopter, is investigated. The paper presents an operating methodology of the imitation model that corrects values of forces and moments acting on the helicopter during flight. We perform the approbation of the proposed method, which corrects characteristics of the base model to conditionally modified helicopter characteristics.

A conjugate problem statement of the computational experiment performing level is formulated. A complex of computer application programs was developed and tested for its implementation. The results of numerical study are given.

Experimental studies of the heat transfer of surfaces with split ribs under the natural convection were carried out. The effect of the casing shrinkage and the angle of rib lobes extension on the heat transfer intensity was shown. In order to analyze the data of test experiments, the calculations were performed using the M.A. Mikheev and V.P. Isachenko dependencies for a smooth rib. The optimal parameters of the casing height and the angle of rib edges extension corresponding to the best heat transfer were revealed. The heat transfer coefficients of the smooth and split ribs were compared, the efficiency of using split ribbing was evaluated.

The porous elastic damping metal mesh material (metal fiber) is considered as a joint seal. The features of this type of turbine seals and requirements to their application are presented. Data of the experimental studies and already created seal designs are given.

A mixing process is simulated and a calculation technique for determining the mixing ratio is created based on experimental studies. Influence of some factors on this ratio is determined in the recirculation mixing zone in the swirling flow behind the flame tube head.

The method and algorithm are considered that allow us to diagnose change of the system dynamic state on the basis of the analysis of evolution of the window indicator function of number of states in discrete phase space. The model of a two-dimensional phase space is constructed, in which discrete states are introduced, and it is shown that indicator function increases when changing the dynamic mode leading to change of the current number of system states. The method feature is the possibility to construct the taught system of dynamic mode diagnostics on its basis. As an example, on the basis of the acoustic signal analysis, a change of the dynamic behavior type of a system with the running shaft is analyzed, in which the resonant flexural fluctuations arise after attaining the critical speed.

The paper proposes a method of checking calculation of turbine cooled blades of gas turbine engines, which significantly reduces the execution time and complexity of calculation of their thermal state compared to direct numerical calculation in ANSYS CFX. The method is demonstrated by the example of calculation of a turbine nozzle blade with the impingement tube and the spot cooling of the leading edge. The module with a bank of generalized experimental data on heat transfer and resistance in the cooling channels is used for closure of calculation.

The problem is considered of measuring the air parameters and state of the atmosphere on board the helicopter under the aerodynamic disturbances of the main rotor vortex column. The functional scheme, design features of the air parameter sensor and algorithms of information processing at the parking, starting, takeoff and landing and other modes of helicopter of the onboard system with a fixed receiver, ion-mark and aerometric measurement channels are revealed.

In order to develop an optimal receiver for pseudorandom signals of nonlinear dynamic systems, the auto- and cross-correlation functions of pseudorandom signals are analyzed.

The design and main calculation relations are presented for the driving electric motor with magnetic gear box to drive the helicopter main rotor. The design advantages in terms of volume and reliability are noted.