Vol 16, No 2 (2017)

Control of deploying an extended tether system into the vertical position is considered in the paper. It is assumed that in the initial state the system consisting of two space vehicles moves in a circular Earth orbit. We propose nominal control programs ensuring the deployment of the system to a predetermined length and taking into account the restrictions on the speed of tether and force in the control mechanism. To construct nominal deployment programs a mathematical model of the system’s motion in the orbital moving coordinate system is used. The model takes into account the peculiarities of the problem. We assess the operability of the proposed programs of deployment according to the mathematical model of controlled motion of the orbital tether system with distributed parameters recorded in the geocentric coordinate system. To perform test calculations a linear regulator that provides feedback on the length and speed of the tether deployment is used. 

The article presents solutions of problems of natural fluctuations of liquid in cylindrical, conical and spherical tanks, with boundary conditions on the free surface and the surface with resistance, i.e. the drain surface. Particular attention is paid to finding the eigenvalues and eigenfrequencies of equations of oscillations of perturbed motion of fluid with the presence of dissipation on the boundary surfaces. It is shown that low speed of lowering of the free surface and resistance conditions on the surface of the drain can affect both the oscillatory and the aperiodic parts of the solution of the fluid oscillation problem.

The paper shows the possibility of improving gas-dynamic characteristics of a submerged air intake and presents a technology of developing design solutions according to the principle of conformity to the flow lines. The gas-dynamic principle of shaping is provided by means of computer-aided integrated technologies of design and application of numerical visualization methods as design tools. The revealed regularity of the working process of the external streamline of the preceding airframe surfaces unambiguously defines the fundamental design distinctions of the conformal air intake in the form of the converging side edges on the stream and determines its advantages over the analogs.

Benches are widely used in the process of creating automatic control systems (ACS) for gas turbine engines (GTE). The engine work is simulated via mathematical models. The model is supposed to be highly accurate in conditions of quite rapid calculation of the engine main parameters in both steady-state conditions and transient processes. A simulation model of a micro gas turbine Jet Cat P-60 engine is presented in the article. The model is based on the data obtained from generalized engine performance. A simulation model of a small-sized gas turbine engine is developed by plotting the rotor acceleration against the rotor rotational speed and the combustion chamber fuel consumption at each moment of time. The results of simulating the engine operation are compared with the experimental data obtained with increasing the GTE operation mode. The average modeling error value is obtained: 1.04% (ambient temperature is 288 K), 2.58% (249 K). It is acceptable for an adequate simulation of the GTE bench performance.

The article presents theoretical and experimental bases for the creation of a driving gear with an actuating mechanism based on a planetary roller drive to improve the fidelity of the specified motion law and velocity performance of the support equipment actuators and engineering systems of missile and space-rocket complexes, as well as for integrated tests of heavy missiles. We present a mathematical model of a controlled electromechanical actuator for special assembly and coupling equipment. The results of the tests carried out lead to the conclusion that in order to create a high precision electromechanical drive, it is necessary to use transmission with a smaller gap between the mating elements, high accuracy and reliability of operation. A new design of a planetary roller drive and the advantages of using a stepper motor are described. Thus, mathematical modeling of an electromechanical actuator with a planetary roller drive with a mockup test on an assembly and coupling tilting device makes it possible to create an electromechanical actuator with improved technical and operational characteristics for a  tilting device of the space head of a super heavy launch vehicle. This reduces the probability of emergency situations during conducting government and commercial space programs.

The stage of qualification vibration tests of space rocketry products is one of the most important stages of their design. To carry out the tests it is necessary to know the levels of vibration loads as early as the system definition stage. It is necessary to use methods that were previously tried and found efficient when defining the modes of vibration and acoustic loading on the structural elements of advanced launch vehicles and the assembly and protective blocks. The results of calculations made according to efficient methods in most cases agree with the results of full-scale measurements. We propose a methodological complex that will help engineers to create necessary vibration dynamic impact on the structures of space-rocketry products. Equations of shell vibration dynamics and a way of solving them on the basis of Bubnov-Galerkin method is presented in the paper. A method of forming the right-hand sides of the equations is also presented. The equations under consideration are equivalent to the actual spectra of external acoustic loads determined at the stage of flight development tests. A way of forming frequency-dependent damping characteristics of the structure is described. Spectral characteristics of vibration dynamic impact on a launch vehicle of the “Soyuz” type obtained by the results of processing of telemetric information are given. The vibration dynamic impact on the structure of the launch vehicle compartments is calculated on the basis of the characteristics specified. The results of the probability analysis of the vibration loads obtained are presented.

Application of innovative methods of production such as additive technologies and use of composite materials in the engine primary structure is one of the promising directions of reducing the cost of production of liquid rocket engines. The purpose of the work is to assess an innovative engine concept   with the mixing head made by an additive technology and the cylinder and nozzle made of a composite material. To solve the main tasks of the investigation we analyzed the available experience in introducing innovation production methods into aerospace engineering. A feasibility study of configurations of separate components manufactured by method of additive and traditional technologies was performed. According to the results of the validation firing of the model the operability of the new configuration was confirmed and the main engineering problems to be solved were determined. The results of the analysis of the innovation engine concept show a 3- or 4-fold reduction of labor intensity in serial production, as well as 3-6-fold reduction of the components variety required for a single assembly. In addition, it is necessary to note the 25% reduction of the item mass. The design modification makes it possible to provide the augmentation of engine operation up to 30% of nominal thrust.

The article describes a new numerical method for determining the parameters of a creep model within the first two stages of creep. The numerical method is based on the transition from a nonlinear model of creep to a linear-parametric discrete model. The linear-parametric discrete model describes the sequence of experimental values of creep deformation. The formulas describing the relationship between the coefficients of the linear parametric discrete model and the parameters of the reference creep model are presented. We propose an iterative procedure of RMS estimation of the coefficients of the linear parametric discrete model. The developed numerical method was tested in the estimation of parameters of a creep model, and the validity of the relationships obtained was confirmed.

A two-phase liquid-gas ejector with a supersonic nozzle is described in the article. The results of numerical modeling of the processes occurring in it and forming a two-phase jet are presented. The structure of a two-phase flow formed by the ejector and the velocity field of the dispersed phase are experimentally investigated. The characteristic curves of the ejected gas flow for different values of the working fluid consumption are obtained and the rarefaction achieved by the ejector is measured. The ejector ensures the system’s operation that forms two-phase high-concentration gas-droplet jets at different flow rates and pressures of working bodies. It is established that, due to the presence of air in a two-phase working body, a two-phase jet at the exit from the ejector accelerates in the initial section and then is decelerated. The results of the numerical modeling of internal processes occurring in a two-phase liquid-gas ejector are presented in fluid and gas dynamics ANSYS software application packages on the basis of analyzing a small-scale model. The characteristics of the energy efficiency of a full-size jet device are given, as compared to production prototypes. The prospects of using liquid-gas jet devices for high-altitude testing of jet engines and their units are indicated.