Том 61, № 3 (2018)
- Жылы: 2018
- Мақалалар: 27
- URL: https://journals.rcsi.science/1068-7998/issue/view/14275
Aircraft Equipment
Analysis of a Lubrication Fluid Flow in the Leak-Proof Pump Electric Motor
Аннотация
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.
Flight Vehicle Design
Reusable Space Transportation System
Аннотация
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.
Definition of Wingtip Devices Shape and Dimensions for a Subsonic Airliner
Аннотация
The results of flow field numerical simulation on the typical wing-body prototype of the modern DLR-F4 airliner under sub- and transonic compressible air flow are presented. Using the DLR-F4 CAD model, the effect of the wingtip end plate area and of the cant angle of a typical Whitcomb winglet is studied. The dependencies of the model lift-to-drag ratio increment on the flat wingtip end plate relative area and on the cant angle of an airfoil Whitcomb winglet are obtained. The concept of an elliptic winglet with a variable cant angle that similar to the winglet used on Airbus A350 is studied. A technique is developed for solving the multi-parameter design optimization task for the Whitcomb winglet, taking the maximum lift-to-drag ratio of the wing as a criterion for optimization.
Structural Mechanics and Strength of Flight Vehicles
Nonlinear Fracture Resistance Parameters for Elements of Aviation Structures under Biaxial Loading
Аннотация
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.
Flight Dynamics and Control of Flight Vehicles
Efficiency Estimation of Electrothermal Thrusters Use in the Control System of the Technological Spacecraft Motion
Аннотация
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.
On the Non-coplanar Transfer of Type II between Two Circular Orbits
Аннотация
The paper regards two-impulse transfer from a low parking orbit into a circular orbit with the altitude less than 36 000 km, while the inclination correction is carried out with each maneuver. An approximate formula is proposed capable of evaluating analytically the optimal value of the first correction of inclination; the corresponding accuracy data are given. Examples are provided to show the operational efficiency of an optimal non-coplanar transfer of the type II with injections of satellites into various target orbits from Russian launch sites with due account of the available launch azimuths.
Influence of Interference Effects of the Rotor on the Launch Dynamics of Gliding Unmanned Aerial Vehicle
Аннотация
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.
Aircraft Trajectory Control at the Motion on the Predetermined Route Based on the Global Navigation Satellite System
Аннотация
An algorithm to control the aircraft trajectory is proposed. This algorithm is based on the dynamic stochastic systems optimal control theory. The optimal control implementation is shown to reduce the deviation of the controlled trajectory from the predetermined one. The optimal control is based on estimating phase coordinates with the high accuracy by the global navigation satellite system.
Development of Algorithms for Integration and Reconfiguration of the Flight Control System and Interfaces
Аннотация
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.
Aero- and Gas-Dynamics of Flight Vehicles and Their Engines
Reliability Providing Approach for Structurally- Parametrical Optimization Results of an “Aggressive” Intermediate Duct of the Bypass Gas-Turbine Engine
Аннотация
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.
To the Problem of Friction Minimization on Permeable Surfaces at Supersonic Flow Rate
Аннотация
In this paper, we consider the variational problem of minimizing the Newtonian drag on an airfoil in a supersonic gas flow. A new condition for Lagrange multipliers on the streamlined airfoil was found that can be used to construct an optimal law for injection control in the analytical form. It is shown that for the flow around wedges, this control is finite at the stagnation point that is important in terms of practical realization of the optimal control.
Computational Research of the Main Rotor Hover and Vertical Descent States Based on the Nonlinear Blade Vortex Model
Аннотация
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.
Aerodynamic Characteristics of Thin Cylindrical and Conical Shells in the Incompressible Flow
Аннотация
The paper presents aerodynamic characteristics of thin cylindrical and conical shells in the incompressible flow. Experimental data and results of numerical simulation in the OpenFoam software are compared. It is shown that the aerodynamic characteristics of the thin shells differ from the aerodynamic characteristics of the corresponding solid bodies and depend on the shell geometry parameters.
Mathematical Model of the Flow of a Liquid Film of Variable Thickness on a Flat Surface in a Viscous Gas Flow
Аннотация
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.
Aircraft and Rocket Engine Design and Development
Estimation of the Combustion Chamber Shell Working Capacity for the Reusable Liquid-Propellant Rocket Engine
Аннотация
On the base of the simplified analytical model for the bimetallic shell of the combustion chamber of the reusable liquid-propellant rocket engine, the analysis of the loading of connectors between the shell walls and the accumulation of inelastic deformations in the inner wall material was carried out. The results obtained can be used for evaluation of the maximal number of engine operation cycles.
Aircraft and Rocket Engine Theory
Influence Analysis of the Second Bypass Air Bleed Parameters on the Engine Performance
Аннотация
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.
Advanced Pulsed Plasma Thrusters and Their Application as a Part of Small Spacecraft Propulsion Systems
Аннотация
The paper presents the research results of the effect of a capacitor energy storage device configuration on the specific characteristics of advanced modern propulsion systems based on the ablative pulsed plasma thrusters (APPT). These thrusters are designed to perform specific tasks within the small spacecrafts with the onboard power capacity up to 200 W.
Analysis of Gas Dynamics and Combustion in a Small Reverse-Flow Combustion Chamber
Аннотация
This paper presents the calculation results by a reactor model, numerical simulation in ANSYS Fluent CFD software, and the results of studying the flow structure and the burn-up fuel in the reverse-flow combustion chamber. These results are intended to create a methodology for further refinement of a combustion process in a combustion chamber.
Aircraft Instruments and Instrumentation Computer Complexes
Analyzing and Ensuring the Dynamic Accuracy of the Aircraft Air Data System with a Fixed Flush-Mounted Flow Receiver
Аннотация
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.
Aircraft Production Technology
Dynamic One-Sided Thermal Scanning of Aircraft Composite Fairings
Аннотация
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.
Radio Engeneering and Communication
Performance Analysis of the EM Algorithm in Conjunction with Algorithms for Determining an Optimal Number of Clusters and Their Centroids, Which Allows Estimating Parameters of Non-Gaussian Interference in Mobile Communication Systems
Аннотация
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.
Technical Notes Aircraft Equipment
Angle Sensor for a High-Speed Galvo Scanner
Аннотация
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.