SCIENCE & EDUCATION

In this article an oil jet cooling system for heavy-duty piston is presented. The influence of oil flux, nozzle diameter, number of injectors and its inclination on cooling efficiency was established by means of numerical simulation in ANSYS CFX. An optimal combination of parameters was chosen with a maximum heat transfer coefficient criterion. Transient thermal analysis of the piston was conducted. It was established that usage of oil cooling made it possible to reduce the maximum temperature in the piston by 73,7°C and 50,3°C in the first ring groove. Thus, prolonged service life of pistons could be obtained.

In this article oil jet piston cooling efficiency is investigated. By means of numerical simulation non-stationary hydrodynamics and heat transfer problem was solved. The analysis of oil film flow on piston surface showed the regions of film separation. Heat transfer coefficient was highly affected by the relative jet speed. To obtain better efficiency of the piston cooling system it was necessary to keep the initial jet speed higher than the maximum speed of the piston.

Basic positions of methodology of creation of high-effective technologies and research of new methods of treatment were considered. Systematization of ways to improve the machining, built on the basis of generalization of experience of the solutions of technological industrial problems and scientific achievements in the field of the cutting theory was brought. By the example of machining, the effectiveness of practical use of this methodology was shown.

The author shows comparability of dynamic characteristics of cutting processes and tests of materials in high dynamic pressures environment. Possibilities and advantages of using the cutting method as a new method of studying physical-mechanical properties of materials were considered at high-speed deformation and destruction.

The authors consider the problem which describes high-speed interaction of an inert compact striker with various kinds of obstacles, including combined type barriers. The purpose of the study is, with the aid of mathematical modeling, to find out, what types of obstacles are capable of withstanding high-speed blow. They can be used as armor elements in personal body armor. Mathematical modeling of the process was done in Ansys 12.1 IDE. During the modeling of a high-speed interaction process a continuum mechanics device in two-dimensional axisymmetric setting was used. The authors developed and tested the mathematical model and drew conclusions concerning applicability of the armor elements.

By the method of differential scanning calorimetry the authors studied phase transformations in the binary alloy Ni-Al (7%Al) formed at the disintegration of a supersaturated solid solution. It was shown that formation process of phase Ni3Al is connected with hidden crystallization heat release.

The article presents a method of generation of assembly variants for a multipart device. The model of the multipart device is based on oriented hypergraphs of constraints. The oriented hypergraph describes the impossibility of assembly when constructional, technological, economical causes are present. Visual interpretation of the hypergraph is proposed; examples of constructive and technological constraints for the shaped charge are described.

The authors study the influence of nitrogen on the form of primary carbides in charge intermediates of alloy GS 30-VI. Metallographic researches of the structure and forms of primary carbides were conducted in initial charge intermediates with various impurity content of nitrogen. It was established that with the increase of nitrogen content from 0,0004-0,0008% to 0,0015-0,0035% carbide morphology acquires a rounded or polyhedral form instead of laminar. The authors present the dependence between the impurity nitrogen content in the heat-resisting alloy and the quality of produced single-crystals. The authors propose a formation mechanism of primary carbides of various morphology during melt solidification.

This article deals with the prospective use of diagnostic ultra-fluid jet in order to ensure the safety of industrial plants. The basic approaches to implementation of this technology, its purpose, features, functionally - diagnostic capabilities and etc. were considered in this work. Some results of theoretical and experimental studies were included.

This work is dedicated to key specifications of laser emission and ways of their application for labeling transparent dielectrics. On the basis the analysis of literature data and studies of all possibilities of applying laser emission for labeling different materials, the authors propose to investigate the influence of emission wavelength on the size of the obtained defect inside the material, and also to conduct some studies regarding the possibility of applying the existing methods for concrete equipment.

Different methods of quality control of multicomponent mediums were reviewed in this article by the example of cow’s milk. Chemical, biological and instrumental methods were considered. Brief theoretical information, required equipment, achieved precision, advantages and disadvantages, ability of quantitative measurement of main components of the product were included. Particular attention was paid to optical – electronic methods as to the most promising for quality control both in laboratory and field conditions. Their application for determination of product’s components in various enterprises was considered. The development of new methods of analysis of the content of polydisperese mediums was planned on the basis of conducted survey.

When designing constructions it is important to control the internal forces in order to produce machines and constructions with a rational mass. Such control is possible with the help of tracking tightenings produced on the basis of almost instantly changeable systems. The article is dedicated to the analysis of deflected mode of a three-disk flat almost instantly changeable system for the purpose of its usage in tracking tightening. The change of forces which appeared in the rods was considered depending on the angle of inclination of one of the rods in the system and on the external force time variable.

Problems with precise estimation of volume and weight flows of compressed air, when investigating pneumatic automation elements’ and devices’ characteristics, are widely known. Precise compressor-doser was designed on the basis of pneumatic cylinder; it allowed to give objective estimation of weight flow of compressed air, when determining flow-drop characteristics of orifice meters. It was shown that flow gages had stable linear characteristics in the case when estimation of flow based on the measurement of the pressure at the entrance of the orifice meter at the stage of exhaustion.

The dynamic diagnostic model of the mount of the winding in slot of the stator core of a powerful turbo-generator is constructed. The range of possible values of parameters of model is defined. Dynamics of the symmetric distributed vibro-impact system "winding - core" for various values of system parameters and external exciting forces is studied. Tendencies of change of parameters of the signal of shocking forces with development of defect are defined. Calculation of the spectra of signals of shocking forces that excite the vibroacoustic vibrations of the stator design is carried out.

Practicable methods of fastening of the composite details with metal parts of designs were researched. The results of tests were presented; empirical dependence for the forecast of working efficiency of such joints was proposed. Regression and dispersion analyses of obtained test data were carried out. Future development of such joints was outlined.

The article depicts the origin of harmonic drive kinematic error. Basing on computer calculation, the author studied influence of the accumulated error of the flexible gear pitch on the drive kinematic error dependence. It is shown that at low loads side clearance may significantly increase kimematic error of the drive.

Linear calibration dependencies were obtained under static stress with pressures up to 100 MPa for the following resistor types: Xicon, SEI Electronics, Russian TBO resistors and reference Allen-Bradley resistors. Under dynamic loads with pressures up to 0.5 GPa, calibration dependency for a Xicon resistor (rated resistance 470 Ohm, dissipation power 0.25 Wt) is shown to nearly match that of an Allen-Bradley sensor. Feasibility of using Allen-Bradley carbonic sensor calibration dependencies for Xicon resistors is asserted for the pressure range of 5 to 7 GPa. Authentic oscilloscope records of various symmetry flows in homogeneous and heterogeneous mediums, including explosive ones, are provided in order to testify feasibility of using over-the-counter Xicon resistors instead of well-known Allen-Bradley sensors.

The authors proposed a simplified segment-model of spherical aerostatic bearings which allows to determine static and dynamic behaviour of bearings. The model is based on two physical assumptions: the number of estimated segments is considered large, and the speed of tangential bearing surfaces is considered negligibly small. Bearing reactions are estimated on the basis of a series of preliminary calculations of air pressure in a separate segment field. The pressure field estimation is performed with the finite-element method in MATLAB program in a nonlinear formulation. The proposed model was tested on spherical aerostatic bearings with porous boost limiters developed for the high-precision nonferrous metal-turning work spindle. The segments number influence on accuracy of load characteristics is estimated.

The main stages of studying modern high performance engine connecting rod strength and reliability are shown. The study includes combining and analysis of calculation and experimental results.  The hierarchical system of mathematical models for structural analysis and cyclic strength estimation of connecting rods has been considered. The rationality of combining macro-element method (used at the first stage) with three-dimensional finite-element analysis used at the final stage is shown.

Modification of classical method of solving the knapsack problem as the task of bivalent programming in the case of boundaries vector is proposed. Algorithm of knapsack acquisition problem solving in the case of one criteria and vector of boundaries is presented. Problems of solution existence and optimality solution check are considered. An example of the problem solving on the basis of proposed method is given.