MODELING OF CONVECTIVE STREAMS IN PNEUMOBASIC OBJECTS (Part 2)

The article presents modeling for investigation of aerodynamic processes on area sections (including a group of complex constructional works for different regimes of drop and wind streams  and  temperature  conditions)  and  in  complex  constructional  works  (for  different regimes of heating and ventilation). There were developed different programs for innovation problems solution in the field of heat and mass exchange in three-dimensional space of pres- sures-speeds-temperatures of оbjects.The field of uses of pneumobasic objects: construction and roof of tennis courts, hockey pitches, swimming pools , and also exhibitions’ buildings, circus buildings, cafes, aqua parks, studios, mobile objects of medical purposes, hangars, garages, construction sites, service sta- tions and etc. Advantages of such objects are the possibility and simplicity of multiple instal- lation and demolition works. Their large-scale implementation is determined by temperature- moisture conditions under the shells.Analytical and calculating researches, real researches of thermodynamic parameters of heat and mass exchange, multifactorial processes of air in pneumobasic objects, their shells in a wide range of climatic parameters of air (January – December) in the Republic of Belarus, in many geographical latitudes of many countries have shown that the limit of the possibility of optimizing wind loads, heat flow, acoustic effects is infinite (sports, residential, industrial, warehouse, the military-technical units (tanks, airplanes, etc.)). In modeling of convective flows in pneumobasic objects (part 1) there are processes with higher dynamic parameters of the air flow for the characteristic pneumobasic object, carried out the calculation of the velocity field, temperature, pressure at the speed of access of air through the inflow holes up to 5 m/sec at the moments of times (20, 100, 200, 400 sec). The calculation was performed using the developed mathematical model of convection processes, heat and mass exchange in unlimited space based on the laws of momentum conservation, continuity, thermal conduc- tivity and the boundary conditions for pneumobasic objects which allow analyze, calculate thermal, convection streams in three-dimensional space (part 1 (2014,No4))

NUMERICAL SIMULATION OF METAL FLOW IN THE FORMS AND CRITERIA FOR ANALYSIS OF LOSS TEMPERATURES IN THE CASTING GATING SYSTEM

The complex quantitative criterion for the analysis of temperatures loss in gate systems of casting is offered on the basis of data of numerical modeling of metal current. Dynamics of change of criterion for the analysis of temperatures loss in gate systems on the example of the gate system with casting “Case of conical pair” is presented

PARAMETERIZATION OF MICROSTRUCTURES IMAGES OF SPHEROIDAL GRAPHITE CAST IRON ON THE BASIS OF THE GRAPHITE DISTRIBUTION DENSITY FUNCTION OF THE INCLUSIONS SIZE

The possibilities of parameterization of microstructures such as SHG2, SHG4, SHG6, SHG10, SHG12, SHgd15, SHgd25, SHgd45, SHgd90, SHgd180, SHgd360 according to GOST (State All-union standard) 3443–87 based on the microstructures of cast iron with different diameter spheroidal graphite are shown. It is proposed to use the function of the density distribution of graphite inclusions in size for the classification of cast iron microstructures with spheroidal graphite. It is shown that density function of graphite inclusions can be used as a criterion of classification of microstructures of cast iron with spheroidal graphite, that offers new opportunities for the quantitative analysis of relations «microstructure-property» for cast iron with spheroidal graphite

COMPUTER MODELING OF THE SPATIAL DISTRIBUTION OF THE CRYSTALLIZING STEEL DENSITY IN THE SYSTEM «CASTING- DISCARD»

The modeling of the shrinkage processes in the steel casting with a head for the different modes of instant steel casting for isotropic heat dissipation with different initial temperature of the metal was held. The calculations of the statistical distribution of temperatures and densities for various moments of time in the crystallizing casting with a head and comparative analysis with the density distributions in the cast without a head for similar temperature conditions are made

COMPUTER PROCESSING OF MICROSTRUCTURES OF IRON WITH DIFFERENT INCLUSIONS AMOUNTS OF LAMELLAR AND SPHERICAL GRAPHITE

Based on cast iron microstructures with different amounts of impurities of plastic and nodular graphite given in CCITT 3443-87 “Cast iron with various forms of graphite. Methods for determining the structure “shows the possibilities of automated quantitative analysis of microstructures SG2, PG4, PG6, PG10, PG12 (Plastic Box) and SHG2, SHG4, SHG6, SHG10, SHG12 (spheroidal graphite), which allows the development of methods for the determination of impurities of plastic and spherical graphite according to the microstructures image under the light microscope

MODELING OF THE TEMPERATURE DISTRIBUTION DENSITY FUNCTION IN A DETAIL AT A CONSTANT HEATING TEMPERATURE

The functions of the temperature distribution density of the detail on the basis of the results of numerical simulation of the heating process are calculated. Characteristics of the temperature distribution function of the detail for analysis of the level of formation of thermal stresses are proposed. It was shown that the difference between the maximum and minimum temperatures of the detail varies nonlinearly with the time of heating the detail in the furnace. The method for formalizing numerical simulation data for selecting the best thermal modes for heating details is proposed

ABOUT THE WAYS OF THE SYSTEM ANALYSIS OF METAL MOVEMENT IN GATING SYSTEMS BASED ON THE NUMERICAL SOLUTIONS OF NAVIER-STOKES EQUATIONS

Numerical modeling of distribution of the fields of speeds projections on axes X, Y, Z in gating system with the casting “Case of conical pair” for various temporal values is carried out. Numerical criteria for assessment of metal movement through the feeders having various spatial location relative to the gating system are offered. Dynamics of change of the offered criteria on the basis of integral average value of the speed component on axes X, Y, Z in the gating systems at the outlet from feeder is calculated

MATHEMATICAL MODELING OF SHRINK PROCESSES OF STEEL ON THE BASIS OF THE NAVIER­STOKES AND FOURIER­KIRCHHOFF’S EQUATIONS

The mathematical model for simulation of process of the shrinkage porosity formation in castings, taking into account the flows convection in crystallizing metal, is offered. The numerical simulation of the temperatures fields and metal density in the process of its crystallization is carried out

SIMULATION OF THE STATISTICAL CHARACTERISTICS OF THE MOLTEN METAL FLOW FOR THE EXPAND

Based on the simulation results distributions of the statistical characteristics of the molten metal for Widening and Narrowing gating systems with high static pressure was calculated. A comparative analysis of Widening and Narrowing gating systems with high static pressure was held. Found that only at the time of 12 sec, number of cells with high speeds for Narrowing gating system is excessed

SIMULATIONS OF DISTRIBUTIONS OF SHRINKAGE DEFECTS IN THE CASTING WITH THE PROFITS BASED ON THE NAVIER-STOKES AND FOURIER-KIRCHHOFF EQUATIONS

Numerical simulations of the process of obtaining a cast steel of bearing cases were performed for two options of technical processing. Three-dimensional motion dynamics ofsteel was calculated in the gate-casting system, three-dimensional temperature fields and densities in the process of casting were calculated as well. The possibilities of computer simulation were shown in order to find the best technical processing in the foundry production