Analysis of Nonlinear Cyclically Symmetric Isolation Sistem of a Cargo in a Container under Plane Harmonic Vibrations

The problem of calculating the system of a cylindrical shaped load transverse damping installed in a coaxial container is considered. This system has several annular belts of insulation with a cyclically symmetric arrangement of shock absorbers along the circumferential direction. A simple dynamic model of one insulation belt formed by polyurethane tunnel-type shock absorbers is investigated. Such shock absorbers have a high energy absorption coefficient and can operate at very high drafts comparable to their height, which is important when the space between the cargo and the container wall is limited. Within the proposed model framework, a harmonic nonlinear analysis of cargo plane oscillations under kinematic excitation coming from the container is considered. A method for reducing a nonlinear cyclically symmetric system with discrete elastic elements, which allows limiting the analysis to the calculation of a vibration isolation system with one degree of freedom, is proposed. Using the harmonic linearization procedure, the amplitude-frequency characteristics of oscillations and plots of vibration isolation coefficients of cargo at different values of excitation amplitude have been obtained. The results are verified by comparing the analytical solution with the results of numerical integration for a non-reduced nonlinear system with two degrees of freedom. The obtained solution allows choosing the vibration isolation belt parameters, in particular the number of shock absorbers and their stiffness, depending on the conditions of kinematic excitation and permissible overload

Development of Methods to Increase the Efficiency of Management of Research and Research Activities of a Research and Production Enterprise

The features of scientific activity of scientific and industrial enterprises are considered. The analysis of the functioning of a research and production enterprise in carrying out complex scientific research has been carried out. The contour of scientific research management is presented in the form of the main stages of the technological process of their implementation. The possibility of using the program-target approach as an effective strategy for managing research in solving complex and complex problems of a research and production enterprise is shown. An example of a matrix organizational structure of management is given as the most effective for the approach under consideration, with a description of the main stages. The use of automated information systems to improve the efficiency of research management is proposed. The diagram of the inclusion of an automated information system in the general structure of management of scientific research of the enterprise is shown. The described methods have been introduced in the NPO "Lakokraspokrytie" and are successfully used in the implementation of innovative projects for the development, design and commissioning of energy-saving painting lines, within the framework of one of which a painting line for freight cars was designed and put into operation JSC "SPC "Uralvagonzavod" in Nizhny Tagil city, which allows painting up to 16 thousand different modifications of freight cars per year

Development of Tools for Thermodynamic Calculation of Rocket Engine Characteristics using the Julia Programming Language

The experience in developing an algorithm and a program for the thermal-chemical calculation of the characteristics of a rocket engine is presented. The program is written in Julia. To calculate the equilibrium composition of combustion products the freely distributed library Ipopt is used. The program is interfaced to the database on thermodynamic properties of individual substances IVTANTERMO. For the convenience of processing, the information on thermodynamic properties is stored in two text files of a special form. The program has been developed using the simplest working process model according to which the flow is one-dimensional, the product flow is adiabatic, there are no friction losses, the product flow is equilibrium, and the speed of condensed particles is equal to the gas flow speed. Ratios for calculating the derivatives of composition, as well as equilibrium values of heat capacity and sound velocity are given. The text of the program can be used in the study process and can easily be adapted to more complex models of the rocket engine workflow. The calculation results obtained using the developed program are in good agreement with the results of TERRA calculations. The execution time of one calculation for a four-element fuel, which includes the determination of the combustion products characteristics in the chamber, the critical cross section and at the nozzle cross section, varies in the range of 3--5 s

Automatic Control and Regulation Systems for Heat and Power Plants

The modern stringent requirements for fuel efficiency, exhaust gases toxicity and dynamic performance can only be met by equipping thermal power plants with modern control and regulation systems. Thermal power plants based on internal combustion engines have found the greatest application. They are used in different fields --- automobile and railway transport, agricultural, road-building and forestry machines, in ship-building, aviation, stationary power plants. The analysis of the main directions for further improvement of thermal power plants with internal combustion engines and their automated control and regulation systems has been carried out. Among these directions are an expansion of functional capabilities in such systems, improvement of control and regulation processes quality and their use at adaptation of thermal power plants to work on alternative fuels. The important aspects for improvement of thermal power plants with internal combustion engines are the necessity of studying the working processes of engines and their systems in order to decrease the exhaust gases toxicity. The relevance of these systems research is shown and the evaluation of the current level in their development is made. A characteristic feature of modern control and regulation systems of thermal power plants is their widespread construction on modern microprocessor element base The paper was based on the materials of the reports of the all-Russian scientific and technical conference n.a. Professor V.I. Krutov (27.01.2021)

On the Development of Tolerant Fuel --- a New Generation Fuel

The concept of tolerant fuel is considered as applied to water-cooled power reactors. The concept is based on eliminating the steam-zirconium reaction. For this, two work areas, i.e., using the physical and the thermodynamic barriers, were considered. Physical barrier presupposes exclusion of contact between water and zirconium, and the thermodynamic barrier (the most radical method) envisages replacement of the alloy containing zirconium with other materials inert to water when exposed to high temperature in the reactor core (∼ 1200 °C). Consequences of the most devastating accidents at the nuclear power plants in the world were discussed: Three Mile Island, Chernobyl and Fukushima. The latest accident in Japan brought to the fore the concept of tolerant nuclear fuel, i.e., being resistant to accidents. Work orientation in creating the tolerant fuel is indicated. Main attention is paid to materials and technologies applied to tolerant fuel. General requirements to safety analysis of the reactor facility fuel system currently developed in the Russian Federation and abroad, as well as current safety criteria for fuel elements, under design-based accidents are presented. Procedure for calculating justification of the safety criteria fulfillment for fuel elements under design-basis accidents is briefly considered. Main characteristics of the new generation materials under development for reactor cores as applied to tolerant fuel are presented. Based on comparing the proposed materials as the tolerant fuel for the fuel element claddings, composite materials based on the heat-resistant SiC/SiC ceramic system could be recommended, and as far as fuel materials are concerned --- materials with increased density, uranium capacity and thermal conductivity values, i.e., nitride fuel and fuel made of uranium silicide

Use of Turboprop Fans with the Device for Intensification of Aeration of Open Pits for Ventilation of Mined-Out Space

The application of open-pit fans on the basis of turboprop aircraft engines, working in complex with the devices for intensification of aeration of worked-out space, for ventilation of open-pit mines is considered. The most effective for the open-pit mines ventilation is the use of isothermal jets created by the mine fans with gas-turbine aviation engines. The principle design of the device for intensification of open pits airing represents inclined profiled blades installed on supports. Such a design allows to direct the developed ventilation jet into the quarry, as well as to increase its velocity at the outlet into the mined-out space in the constructions of confusers (blades--top platform of leeward side). The application of the complex, consisting of the ventilation installation and the device of quarries aeration intensification, installed on the surface, allows to increase considerably the volume of the air, supplied to the worked-out space, in comparison with the location of the fan in the pit, to decrease the noise levels in the working zones. By means of modeling qualitative and quantitative aerodynamic characteristics of the offered ventilation scheme (location of the fan and aeration intensifier, pattern of air currents in the quarry, speeds distribution) are defined, its application efficiency and conditions are evaluated

Investigation of Cutting Forces for Thin Layers when Planing and Milling

The problem of machining structural elements with removal of metal layers with thickness less than 0.01 mm by carbide tools, when the conditional radius of the blade rounding is less than or equal to the thickness of the cut layer, is considered. These cutting conditions can be considered constricted which requires research into cutting forces and chip shape. The problem of recording and measuring small cutting forces arising during blade machining of small grooves that serve for gas drainage in the manufacture of rubber products is solved. To measure forces, a lever fixed in a universal dynamometer, which has a supporting support with small friction, is used. Value of force moment measured with dynamometer can be used for optimization of cutting conditions, selection of tool geometry when processing small relief elements. Dependences of lever system cutting forces and displacements on the use of lubricant-cooling liquids, values of front angles during planing and milling with small-size tools are investigated. Experimental discrepancies between theoretical calculations of cutting forces according to classical and modern reference data and fixed results with the use of cutting liquids during cutting with small values of feed for carbide tools are found

Heat Exchange and Friction Analysis in Noble Gas Mixtures for Closed Gas Turbines

The types of heat exchange surfaces used in closed gas turbines for space applications and their conversion version (ground application) as autonomous long-resource power plants of low power (less than 10 kW) are considered. The data of the works currently known in Russia and abroad on the developed turbulent flow in the tube when using gas mixtures with abnormally low Prandtl numbers (0.2) have been analyzed. Recommendations on the application of the analytical relations of Kays, Petukhov and Popov for the calculation of the Nusselt number in pipes are given. The influence of non-isothermal flow and initial pipe section on friction as well as the working body Prandtl number on heat exchange and friction for highly compact plate and fin heat exchange surfaces with staggered arrangement of ribs are analyzed. It is revealed that the relations obtained for the air model are inapplicable for working bodies with Prandtl numbers different from the air Prandtl number. The necessity of further experimental and analytical investigations of heat exchange and friction in tubes under transient flow regime and in highly compact finned surfaces with staggered ribs is confirmed

Soot Formation Numerical Simulation in Reducing Gas Generators of Oxygen-Methane Liquid Rocket Engines

A method for numerical simulation of operating processes in reducing gas generators with calculation of the condensed phase (soot) formation process detailed structure has been developed. It is assumed that soot is formed from gas-phase fuel in two stages. At the first stage, active radical nuclei are formed, and at the second stage, carbon black particles are formed from these nuclei. Numerical modeling of processes, fuel mixing and combustion, as well as soot formation in model reducing oxygen-methane gas generators with gas-liquid coaxial mixing elements of jet-jet type has been performed. Gas generators of this type can be used in promising oxygen-methane liquid rocket engines operating on open and closed circuits with reducing gas generators, as well as on the gas-gas circuit having reducing and oxidizing gas generators. A comparative analysis of soot formation features in gas generators with single- and multi-nozzle mixing heads has been performed. It is shown that a decrease in the pitch between the mixing elements leads to a significant change in the mixture formation processes, fuel combustion and the flow of combustion products (all other conditions being equal), which significantly reduces the intensity of condensed phase formation in reducing gas generators. The numerical simulation method will be used for studies of fuel combustion and condensed phase formation in regenerative gas generators of modern and advanced liquid rocket engines at the stages of development, design and improvement

Experimental Studies of Rocket Fuels Oxygen--Hydrogen, Oxygen--Methane Ignition by a Semiconductor Laser

The paper presents results of experimental studies aimed at introducing laser ignition of fuel mixtures into aero-space design practice. The source of ignition energy was a semiconductor laser featuring fibre radiation output, operating in a quasi-continuous wave mode. We carried out experiments for oxygen--hydrogen and oxygen--methane fuel types. The purpose of our research was to demonstrate the fundamental possibility of implementing fuel ignition by means of this type of laser, using a rocket engine igniter and a low-thrust rocket engine as examples. Employing semiconductor lasers directly as an ignition source for fuel mixtures in aerospace technology is attractive as it may feasibly reduce the requirements for thermal conditions during operation of the laser ignition system on board a rocket or spacecraft, as well as expand the range of permissible vibration and shock loads. The paper presents experimental results that delineate operating parameter ranges and operation cyclograms for the devices under consideration that ensured stable ignition of oxygen--hydrogen and oxygen--methane fuel mixtures; we also list the required power parameters for a semiconductor laser. The investigation revealed the specifics of using a semiconductor laser-based ignition system, which will be useful in developing laser rocket launching devices, ensuring reliable repeated on-off functionality