scientific edition of Bauman MSTU
SCIENCE & EDUCATION
Bauman Moscow State Technical University. El № FS 77 - 48211. ISSN 1994-0408
Investigation of interaction of deuterium plasma with tungsten targets
# 12, December 2013
Assessment of retention of hydrogen isotopes in co-deposited films is of great interest for the problem of selecting materials for plasma-facing components of International Thermonuclear Experimental Reactor. The purpose of this work was to study deposition peculiarities of tungsten-deuterium films formed on silicon substrates by sputtering tungsten targets in deuterium plasma of magnetron discharge. Deuterium content in films was determined by the Elastic Recoil Detection method; tungsten concentration was calculated from the measurements of the film’s weight; the film’s thickness was determined by a profilometer. It was established that deuterium content in co-deposited films is comparable with that of tungsten atoms. It was suggested that the retained deuterium is located in the pores formed during the film growth. Increase in the distance between the target and substrate leads to decrease in the deuterium content in the film and subsequently to reduction in film porosity and to growth of its density.
Quantitative estimation of fluorine’s toxic effects on human health when dealing with uranium hexafluoride
# 11, November 2013
In this paper the authors consider how the impact of work chamber atmosphere at a nuclear industry enterprise where uranium hexafluoride is used affects the human body. History of studies in this field was briefly described, and the place of current investigations in these studies was indicated. This work deals with a model for calculating deposition of fluorine in the human body. In this paper quantitative relationship between concentration of uranium hexafluoride molecules in the air of a factory shop and the mass of fluorine deposited in the human body was obtained on the basis of mathematical simulation methods. A technique for determining the specified relationship was presented. Calculations were performed within the framework of a model which describes pollution of a work chamber atmosphere and penetration of toxic substances into the human body. This paper presents results for two injection methods — percutaneous (through the skin) and inhalation (through the respiratory system), and for two modes of air pollution — emergency release and technological outputs under conditions of daily industrial activity. The calculated injections were compared with experimental data; such injections lead to irreversible changes in the human body. Conclusions on possible medical care for victims were drawn.
Ensuring safety in factory shops under conditions of technological emissions of uranium hexafluoride
# 12, December 2013
This paper presents a review of literature and original methods for solving tasks of ensuring safety in factory shops at factories of nuclear industry that use uranium hexafluoride. The authors consider theoretical models of air pollution in factory shops with gaseous uranium hexafluoride and its hydrolysis products, settling of these products on factory surfaces, inhalation and percutaneous penetration of these products into human body. Capabilities of these models and some results of the calculations were described. This article was intended for publication in the journal "Science and Education: Electronic Scientific and Technical Periodical”.
Excitement of turbulence fluctuations by a drift wave in plasma flows with non-uniform velocity
# 09, September 2013
In this work processes of formation of the drift turbulence in plasma with regard to existence condition of H‑mode were investigated for the first time. An effect of the drift wave of finite magnitude on plasma was considered. Influence of a poloidal plasma flow with linear velocity distribution vy(x) = Cx on a drift wave was also taken into account. A model was proposed and a program was developed for calculating the perturbations’ characteristics, which occur as a result of the specified influence. Dependencies of average values of plasma density fluctuations on the shear of velocity C and the growth rate of a drift wave γ were also obtained.
Calculation method for non-stationary heating of nano-structures
# 09, September 2013
A non-stationary process of heat transfer in an insulated ordered multilayer nanostructure with specified initial temperature distribution was considered in the article. The structure consists of 1000 alternating layers of AlAs and GaAs. A heat transfer process model based on heat balance of a single layer was described in this paper. This model was used for heat transfer computations in ordered binary multilayer nanostructures for the first time. A process of heat transfer was investigated at different time moments, with different thicknesses of layers and heat resistances of interfaces. A case of deviation of periodicity in the structure was considered.
Numerical and experimental study of a supersonic separated turbulent flow and local heat transfer in a flat channel with sudden expansion.
# 09, September 2013
In this paper the authors present results of their numerical and experimental study of a supersonic separated flow and heat transfer in a flat channel with a sudden one-sided expansion at Mach number М ≈ 3 and with the presence of a turbulent boundary layer before separation. The numerical model was based on RANS (Reynolds Average Navier – Stokes Equations) with k-ω, k-ε and Spalart – Allmaras turbulence models. Computational fields of main gas-dynamic parameters in a stepped channel were also given. Comparison of numerical distributions with experimental data for wall pressure and heat-transfer coefficient downstream of a bench was carried out. A correlation analysis of the obtained velocity fields, wall pressure and friction, heat transfer coefficient in the area of separation and reattachment of turbulent boundary layer was also conducted.
Arc-flash processes during single-phase faults in single-phase shielded cables
# 05, May 2013
The aim of this research is to enhance reliability of power grids with single-phase shielded cables by preventing transition from a single-phase fault to a line-to-line short circuit. Arc-flash processes during a single-phase fault and sheath failure were analyzed in this study. Maximum duration of single-phase faults and its dependence on the method of cable installation were determined. The results of the study are important for estimating failure effects of single-phase faults on cables, for reducing maintenance and restoration costs of cable network. A mathematical simulation of electromagnetic and heat transient processes in a single-phase fault point was carried out using ELCUT software. The accuracy of the model was proved by a number of laboratory experiments with arcing short circuits. It was established that a single-phase fault transforms into a line-to-line short circuit for several seconds in case of a triangle configuration of three single-phase shielded cables with no gap between them. In order to prevent this process it was recommended to apply single-phase shielded cables of 6 – 35 kV to grids with low-resistance neutral grounding and with fast single phase-to-earth faults.
Estimating the influence of current limiting coil’s properties on transient recovery voltages at contacts of a high-tension switch in case of fault currents’ cut-off
# 07, July 2013
One way to reduce fault currents in a high-voltage power network is application of current limiting coils. However, mounting of current limiting coils influences transient processes in case of short circuits. Rates of transient recovery voltage development at the contacts of a switch in case of commutation in circuits with current limiting coils exceed permissible values. In order to break a circuit successfully, it is required that the rate of recovery voltage in a switch circuit should not exceed the limiting normalized values permissible for the specified switch type. This paper considers the influence of current limiting coils’ properties, such as inductivity and natural resonance frequency, on transient recovery voltages.
Application of above-critical carbon-dioxide cycles in industrial heat recycling facilities
# 02, February 2013
The authors consider schemes of gas turbine power units with above-critical carbon dioxide parameters designed for industrial heat recycling at manufacturing enterprises or gas turbine electric power stations. An approach to selection of such schemes was formulated and justified. The authors propose multi-threaded variants of heat schemes for recycling facilities which allow to increase the coefficient of heat usage. Thermo dynamic cycles of carbon-dioxide above-critical gas turbine devices were investigated for the proposed schemes. Possibility of significant increase in the degree of utilized heat, up to 2/3 of the total amount of disposed heat, was demonstrated.
Experimental study of parameters of surfaces coated with regular relief
# 01, January 2013
This article presents an analysis of published data on numerical and physical (experimental) study of thermal-hydraulic characteristics of different methods of heat exchange vortical enhancement. It is shown that the most effective is the use of heat exchange surfaces coatedwith regular relief (holes) which have a simple production technology combined with high thermal-hydraulic characteristics. The authors present a modernized test bench that allows, in a single experiment, to determine resistance and heat exchange parameters for two plates which are parallel to each other (smooth plates and plates coated with regular relief). In this case, resistance is determined by "weighing" on tensometric scales, and parameters are determined by a time-dependent heat exchange method using thermal imaging equipment. The authors present data of an experimental study of two types of heating surfaces. It is shown that surfaces with oval holes have a large (20-35%) resistance than surfaces with hemispherical holes.
Comparative analysis of parameters and characteristics of different power plant schemes with an additional remote propfan
# 12, December 2012
The authors made an assessment of economic and mass-overall characteristics of a power plant in a long distance aircraft using cryogenic fuel. The scheme consists of two dual-flow turbojet engines and a remote propfan mounted in the rear fuselage the thrust of which compensates aerodynamic resistance of the fuselage. The authors examined five design maps of the remote propfan drive, including the schemes using a fuel cell power plant. They estimated characteristics of these schemes at different levels of power ratio of cruise engines and the external propfan. A comparative analysis of the mechanical, electrical and gas-dynamic drive of the remote propfan was made. The authors present conclusions on practical schemes of an integrated circuit power plant and their application.
Study of electromagnetic transients in circuits of small hydroelectric generator voltage
# 12, December 2012
Currently, operation experience of vacuum and gas-insulated circuit breakers substituting oil ones in the chain "generator - transformer" is not enough. Therefore, in each case, installation of switches of a new generation requires an analysis of the switching processes. For conducting a research, mathematical models of the block scheme for low power hydro-plants and switches of various types among EMTP-RV were created. The authors estimated the levels of overvoltage occurring in switching by power-producing switches for various combinations of parameters of the main equipment unit; they analyzed the influence of parameters and places of installation of overvoltage protection. The main provisions of the research can be used by design organizations for reconstruction of low-power hydro-plants; in preparation of instructions for use of overvoltage protection when overvoltage is caused by commutation of vacuum switches in circuits of power-producing stations.
Prospective solar power tower with gas turbine energy convertor
# 11, November 2012
This paper presents research results of schematics, design parameters of prototype combined solar power tower with a gas turbine energy convertor of the power level of 4 MW. Computations of the main components of the power plant (solar receivers, solar tracking system, field of heliostats etc.) which determine its appearance and output parameters were conducted. On this basis design drawings were made. The environmental effect of application of such plants is shown. Estimation of the prospects of using solar tower power plants in Russia is presented.
Alternative ideal cycle of internal-combustion engine
# 08, August 2012
Basing on the harmonic analysis of the indicator diagram, the author proposes a cycle in which pressure varies in a cosine curve. Due to the fact that the second harmonic also contributes to the mean indicated pressure, the author considered the ideal cycle option as the sum of two harmonics. In contrast to conventional cycles, the proposed cycle provides the smallest possible value of the maximum pressure at a given mean indicated pressure. The material of this paper can be used in development of advanced electronic fuel control systems in high-power marine diesel engines.
Simulation of transients and analysis of dynamic stability of synchronous generators under the influence of large perturbations
# 10, October 2012
To ensure reliable operation of electric power systems it’s necessary to analyze and evaluate the inventory of dynamic stability of synchronous generators under large perturbations. In this paper the authors consider a methodology for analysis and evaluation of dynamic stability a feature of which is sharing high quality (the method of Lyapunov functions) and numerical methods. The authors propose an approximation method with the use of the interpolation polynomial to reduce computational costs and to carry out more accurate calculation of the critical value of the Lyapunov function. This method can improve accuracy of results to assess dynamic stability and make a more grounded choice of states of power systems and configuration of emergency automation systems.
Suppression of turbulence with linear velocity profile in high-temperature plasma
# 09, September 2012
The experiment showed effects of growth and destruction of drift waves which are directly responsible for plasma turbulence. As at the linear approximation of such waves the oscillation amplitude in the plasma is assumed to be small; it is impossible to to assess its value. The paper takes into account the amplitude finiteness of the drift wave and considers qualitatively the drift wave instability dynamics at nonlinear approximation. On the basis of this analysis it is shown that the presence of a linear velocity profile leads to wave breaking and suppression of turbulence. The authors obtained different characteristics depending on the nonlinear factor, increment of growth, wavelength, and initial amplitude.
Study of possibility of creating a 10kW two-loop closed gas turbine power plant
# 07, July 2012
This paper presents the results of optimization of a closed Brayton cycle gas turbine power plant with capacity of 10 kW with an electric heater as a heat source. The authors present the results of calculations of assemblies and units included in the model sample of the closed two-loop gas turbine power plant. Analysis of design and arrangement solution required for optimal location of the model sample in the limited dimensions of the room was carried out. Various configuration solutions are also included in the article.
Experimental study of the characteristics of the small-scale centrifugal-flow compressor
# 08, August 2012
This work describes an experimental study of the stage of a small-scale centrifugal-flow compressor which is necessary for development and improvement of closed gas turbine trigeneration. This trigeneration implements a combination of direct and inverse Brayton cycles and can simultaneously generate electricity, heat and cold for air conditioning needs. The scheme of the stand, method of determination of key parameters and relations needed to assess the characteristics of the compressor were also described in this work. The comparison of calculated characteristics of the stage with experimental data was carried out.
Investigation of characteristics of high-compact plate-fin heat-exchange surfaces with shifted fin
# 06, June 2012
The article presents a research problem of heat and hydraulic characteristics of high-compact plate-fin heat-exchange surfaces. These heat-exchange surfaces are widely used in aerospace applications, space and renewable power generation. The experimental facility and measurement routine are described. The experimental facility has a closed loop, which allows to use it for different working mediums (air, mixtures of inert gases etc.). A transient method of heat research was used. The experimental data for BMSTU №9 surface in the range of Reynolds numbers from 100 to 700 for air is given in the article. Obtained experimental data was compared with the data of Kays and London for surface №104.
77-30569/381537 Preliminary research of characteristics of various implementations of hybrid turbofan engines for short- and medium-haul aircrafts
# 03, March 2012
Existent estimation procedure for tractive-economical and mass-dimensional characteristics of turbofan engines was improved. The authors consider two schemes of hybrid turbofan engines with additional power input to fan spindle from an electric motor supplied with accumulators or fuel elements. For the first time in Russia characteristics of these schemes were evaluated at different capacity ratios of the fan drive between a low-pressure turbine and an electric drive. The authors present the results of thermodynamic calculations, speed and throttle characteristics of hybrid turbofan engines of both schemes. Conclusions were made on reasonable ranges of capacity ratios between the low-pressure turbine and the electric drive which are used for the fan drive.