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scientific edition of Bauman MSTUSCIENCE & EDUCATIONBauman Moscow State Technical University. El № FS 77  48211. ISSN 19940408
Power Machine Building, Metallurgical Machine Building and Chemical Engineering
Influence of microarc oxidation on durability of ICengine’s piston
# 09, September 2013 DOI: 10.7463/0913.0606017 This paper presents results of an experimental investigation of a possibility of increasing durability of ICengine’s pistons by creating nanostructured coating at the surface of a piston skirt with the use of the microarc oxidation method (MAO). The authors describe a method for creating a hardened layer at the surface of a piston skirt with the use of MAO; they also give a description of experimental procedures for pistons under conditions of engine operation and results of those experiments. This work was carried out in order to increase durability of ICengine’s pistons made of aluminum alloys; the obtained results could be used for increasing durability and reliability of ICengines.
Selection of optimum parameters for the hydraulic drive of a fan of a vehicle’s engine cooling system
# 07, July 2013 DOI: 10.7463/0713.0590873 The authors consider a problem of choosing optimal parameters for a hydraulic drive with a discrete control output link by the example of a hydraulic fan of a heavyduty vehicle’s engine cooling system. The objective function was selected in accordance with the efficiency criterion of the hydrostatic power drive. Limits of variable parameters’ values were set to reflect the work of the hydraulic drive in the specified system. Results of the application of genetic and modified genetic algorithms for determining parameters of the hydraulic drive were described in this article. The obtained results were compared with the results based on the LPτ search of hydraulic parameters, optimal by two criteria. Academic novelty of this article consists in consideration of different approaches to the problem of interactive design of technical systems with discrete controls which is composed of commercially available standard hydraulic units.
Intensification of aeration of pits with the use of guiding devices
# 06, June 2013 DOI: 10.7463/0613.0577364 The design of the guiding device was developed for intensification of aeration of pits, which allows one to increase the speed of straight and inverse air streams in working zones of excavations during weakened natural air exchange, and improve working conditions. On the basis of modeling and analysing research results, optimum parameters of an aeration device were determined; aerodynamics of air streams in pits with various geometry of the developed space was investigated; calculated dependences for determination of speeds of air wind currents were obtained. Thus, use of a guiding device increases efficiency of aeration of the developed space of a pit at the expense of increase in speed of a wind stream on failure into a pit, reduction of volume of a circulation zone and reduction of speeds of air streams in it.
Experimental studies of degradation of ethylenediaminetetraacetic acid (EDTA) in aqueous solutions with high concentration of sodium nitrate under pulsed broadband ultraviolet radiation
# 06, June 2013 DOI: 10.7463/0613.0577231 Experimental results of degradation of ethylenediaminetetraacetic acid (EDTA) under pulsed broadband UV radiation in the presence of hydrogen peroxide are presented in this article. The object of research was an aqueous solution containing EDTA with the initial concentration of 15 to 100 mg/l and sodium nitrate (NaNO_{3}) with the initial concentration of 4 g/l. Energy consumption for degradation and complete mineralization of ethylenediaminetetraacetic acid degradation products was estimated depending on the initial concentration of the acid, presence or absence of sodium nitrate and hydrogen peroxide at the concentration of 3 g/l.
Identification of mathematical model parameters of an electrohydraulic drive
# 06, June 2013 DOI: 10.7463/0613.0574706 This paper presents a method of identifying parameters of a mathematical model of an electrohydraulic drive. The method is based on comparison of the characteristics obtained during an experiment, and of the characteristics obtained by simulation. A criterion of identity was formed for this case. A search algorithm was built with the use of the NelderMead method for numerical minimization. A mathematical model of an electrohydraulic drive was presented. The author considers influence of quality of manufacturing spool valves on characteristics of electrohydraulic drives. Conclusions on effectiveness of the proposed method were drawn.
Mathematical model of vacuum nitrocarburizing of the complexalloyed VKS10 steel
# 08, August 2013 DOI: 10.7463/0813.0569132 This paper presents a mathematical model of a cosaturating complex alloy steel with carbon and nitrogen in the low pressure atmosphere. They developed software that gave an opportunity to estimate concentration curves of carbon, nitrogen, and basic alloying elements for VKS10 steel, as well as the main characteristics of the phase composition in tabular and graphical forms on the basis of the parameters of vacuum nitrocarburizing. The effect of the complex chemical composition of the steel on formation of the diffusion layer was taken into account. Sufficient adequacy of the model within the temperature range from 880 to 940 ° C was demonstrated; these temperatures are the same as during hightemperature nitrocarburizing. With the help of this mathematical model patterns of formation of diffusion layers depending on technological factors of vacuum nitrocarburizing were investigated.
Concept of optimization of an electrohydraulic servo drive with throttle regulation
# 06, June 2013 DOI: 10.7463/0613.0569281 This paper presents a technique of sequential optimization of an electrohydraulic servo drive. The electrohydraulic servo drive was considered as a set of subsystems of level 1 (Lv. 1) and level 2 (Lv. 2). At level 1 the electrohydraulic servo drive was considered together with an electrohydraulic servo valve replaced with a proportional link. A twostage nozzleflapper servo valve with mechanical feedback from the spool to the flap was selected at level 2. Objective functions were proposed to estimate project variants of each subsystem. Optimization by investigation of parameter space using the method based on the LPsequences or genetic algorithms were presumed to be suitable. The concept described in the article is based on generalization of methods of electrohydraulic servo actuator optimization, which are known in the literature, and includes new proposals on the structure of the optimization algorithm.
Justification of groove dimensions for mounting a ring of contact sealing devices
# 06, June 2013 DOI: 10.7463/0613.0565120 This work is aimed at providing theoretical justification for selecting groove dimensions for mounting an elastic ring of the contact sealing device. Available information is not enough for reasonable selection of those dimensions. The crosssection of the groove corresponds to the rectangular one. Groove depth is determined by the elastic ring’s ratio of compression. Groove width is determined by the crosssectional area of the ring in the initial condition considering the changes in shape of the section during deformation and the compressive strain in the cross section of the ring along with the volume swelling of this elastic ring in the environment of process fluids. Theoretical calculations for determining the groove dimensions depending on various factors were presented in this article in order to justify the selection of those dimensions for mounting an elastic ring. These results would allow one to determine more precisely the size of grooves that provide airtightnes, subject to various factors.
Surface roughness and airtightness of contact sealing devices
# 05, May 2013 DOI: 10.7463/0513.0565094 The aim of this work is to determine the effect of the value of surface roughness of the contact body on airtightness of contact sealing devices with elastomeric (rubber) rings. Rough edges of two sealing surfaces in contact between two solid surfaces form a system of cavities and capillaries of an arbitrary shape. Assumed values of roughness are not sufficiently justified. Studies of airtightness considering complex structure of the elastomer Oring on the compositional level and variety of roughness of the sealing surface were carried out using the bubbling method. The obtained results of the experimental studies justify the values of contact surface roughness used in industry and allow to work out guidelines for choosing values of surface roughness of contact bodies and a compression ratio of elastic rings which provide airtightness.
Modeling and calculating processes of induction heating for press equipment during manufacture of rubber products
# 03, March 2013 DOI: 10.7463/0313.0541632 The authors consider mathematical models of induction heating of a single plate in a hydraulic vulcanizing press for the initial warmup period and the period of maintaining the operating temperature. They carry out a comparative analysis of an industrial experiment for studying the processes of heating and maintaining the temperature of the working surface of such a plate with the results obtained by solving models with the method of finite integral transformations and with the application of the finite element analysis. For the first time, the authors proposed a mathematical model of the "induction platemoldrubber product" system, a technique for approximate solving the model by the finite element method; the model is supposed to be used for solving the optimization problem of press design and molds design, molds positions between the heating plates. The results of solving this problem by the example of the industrial press are provided in this article.
Simulation of air pressure losses in the finned tube bundle of an air condenser
# 03, March 2013 DOI: 10.7463/0313.0544307 The authors describe an approach to numerical simulation of air flows in the box of an air condenser by replacing the tube bundle geometry with an anisotropic filter  that is, with a selected area in the computational model with the given hydraulic resistance. Hydraulic characteristic of the finned air condenser’s heatexchange surface was determined by using CFD (Computational Fluid Dynamics) along with FlowVision, Phoenics and OpenFoam software in order to set the properties of the anisotropic filter correctly. The obtained results allow to simulate a threedimensional air flow inside the box of an air condenser and determine parameter fields of the flow at the input and output of the tube bundle without direct numerical simulation of the air flow in the intertubular space.
Development of a lowpressure helium compression control system strategy
# 02, February 2013 DOI: 10.7463/0213.0539096 Cryogenics is now widely used in large accelerator projects using applied superconductivity. Economic considerations require an increase in performance of superconducting devices. One way to achieve this is by lowering their operating temperature and cooling with superfluid helium. For this reason, large cryogenic systems operating at 1.8 K and capable of producing refrigeration capacity in the kW range, have to be developed and implemented. These cryogenic systems require large pumping capacity at very low pressure using integral cold compression or mixed coldwarm compression. The author compares and describes different cooling methods using cold and hybrid cycles along with cycle operational capabilities, and reviews a developed lowpressure helium compression control strategy for these cycles.
Automatic pressure regulation at the input of the main line pump during emergency cutout of an electric motor
# 01, January 2013 DOI: 10.7463/0113.0518041 This article describes a method of mathematical modeling of systems with centrifugal pumps. A structure chart directed at interactive solution of an optimal control problem of controlling pumping units was created with the use of this mathematical model. In this article, along with the results of calculations, the authors provide an example of an emergency cutout of a pumping module subject to the inertia of the pumping unit rotor, rotating frequency of its spindle, the pump’s headcapacity curve and parameters which determine hydraulic wave processes in the pipelines connected with the pump. Controlled parameters in this case are the pump module’s shaft speed and pressure generated by irregular fluid motion on intake side of the pump. Transition processes were determined for these parameters in case of an emergency cutout of the main line pump’s electric drive. Schematic diagram of the proposed mathematical model for investigation of centrifugal pump’s emergency modes was published for the first time
Dynamic processes in an electrohydraulic pressure controller with electric pressure feedback
# 01, January 2013 DOI: 10.7463/0113.0517493 The article gives a description of dynamic processes in the electrohydraulic pressure controller with electric pressure feedback. Linear equations of the lumpedparameter mathematical model, allowing for inertia of fluid in the connecting pipeline in lumped parameters, were composed. The authors analyzed the effect of different factors on stability of the system. The conducted research showed that the electrohydraulic pressure regulator might experience sustained oscillations; their existence depends on parameters of hydraulic resistance of the connecting pipeline regulator. Special attention should be paid to the difference of natural frequencies of amplifier and electro hydraulic accumulators.
Correction of regulator's dynamic characterisitcs in axial piston pump with electric proportional control
# 12, December 2012 DOI: 10.7463/0113.0516044 The article gives a description of the operating principle of the regulator in an axial piston pump with electric proportional control; a linear mathematical model of the regulator is also provided. It was shown that introduction of internal speed feedback could improve the dynamics of the regulator. The authors propose a way to implement this type of correction by introducing a nonlinear electric position feedback.
Computer study and calculation of hydrodynamic loads on the valve
# 10, October 2012 DOI: 10.7463/1112.0491484 The authors provide results of computer studies and calculations of hydrodynamic forces influencing the valve. With the use of FEM they determined pressure distribution on the surface of the valve which had the diameter of 6 mm in cavities 1 and 2. Moreover, the authors obtained distribution of axial hydrodynamic forces influencing the valve in the cavity 1 and cavity 2 with the valve shift to a maximum value of 0.6 mm; and they build graphs to compare the values of the hydrodynamic forces calculated by FEM and analytical method. The calculation results are confirmed by experimental data previously published by other authors. With the help of the developed methods the authors determined the effect of changing the temperature of the working fluid (oil) in the range from 40 ° C to +50 ° C of hydrodynamic forces.
Balancing hydrodynamic forces by shaping valve’s surface
# 11, November 2012 DOI: 10.7463/1112.0491497 A method of reducing power required for electromechanical converter by balancing hydrodynamic forces acting on the control valve was considered. To calculate these forces, the finite element method was used; it allows one to determine the shape of the valve’s surface, which provides minimal values of hydrodynamic forces. In addition, graphs were plotted in order to compare the values of hydrodynamic forces obtained with the finite element method for unshaped and shaped spools, for two types of spooltype valve (supply of liquid in the center and along the edges of the valve). Using the finite element method, the distribution of pressure over the surface of the valve having the diameter of 6 mm, in the gap and the cavity of the spooltype valve was performed. Results of computer shaping of the valve and investigation of the influence of manufacturing precision of the valve on balancing hydrodynamic forces are given in the article.
Thermal anchoring of wires in installation for investigation of lowtemperature properties of materials
# 12, December 2012 DOI: 10.7463/1212.0486450 This author considers thermal anchoring of wires with the use of a prototype installation for investigation of lowtemperature properties of materials. A mathematical model of thermal processes is provided along with a numerical example according to the chosen mathematical model. The influence of selfheating of wires on the finite geometrical dimensions of the thermal anchor was determined.
Methods of effectiveness increase for regenerative chamber of the second stage of Gifford  Mcmahon cryocooler.
# 11, November 2012 DOI: 10.7463/1112.0469389 Basic methods of influence on cooling capacity of the twostage GiffordMacMahon cryocooler are presented in the article. The main properties of materials of the regenerative chamber are considered. Examples of multilayer regenerators and selection principles for materials for each layer are also presented. The main advantages and disadvantages of structures such as GOS, GAP and alloys of rare metals in comparison with traditional materials of regenerators are analyzed. The possibility of using doublelayer particles in the second stage regenerator is shown.
Working off the methodology of numerical simulation of threedimensional viscous flow in axially radial impeller of centrifugal compressor using ANSYS CFX
# 11, November 2012 DOI: 10.7463/1112.0465832 The article presents a methodology for numerical simulation of viscous flow in a centrifugal compressor wheel of axially radial type using the ANSYS CFX. It shows the influence of various factors, such as the size of the cells and the method of constructing the grid, the choice of turbulence model, on calculation results. The graphical comparison of calculation results for different variable parameters is also presented. Optimal values of mesh size and turbulence model for further verification of the numerical experiment were established.



