Vol 19, No 1 (2018)

Point of view
Numerical modeling of a wing leading-edge thermal regimes for a reusable space vehicle
Bodnya I.S., Timoshenko V.P.
Abstract

Throughout the history of human exploration of outer space, work is underway to reduce the cost of bringing cargo into space. One of the technically feasible solutions to achieve this is the use of smallsized reusable aerospace vehicles. As the new thermal protection materials are developed, they are employed for the construction of the reusable aerospace vehicles (RSV). In this paper, the assessment is given of the possibility of making RSV wing leading edge from an Al2O3 fiber based heat-resistant porous ceramic. The main advantages of using such material are its relatively low values of thermal conductivity and density, which makes it possible to improve weight characteristics of the RSV. The material of the support structure is heat-resistant carbon fiber reinforced polymer (CFRP). Due to the porous nature of such thermal protection system (TPS), it is necessary to consider the effect of air pressure on the thermal conductivity of the material. Therefore, a computational mathematical model is proposed that allows one to take into account this dependence of thermal conductivity on temperature and pressure for the wing edge porous TPS of an aerospace vehicle, during its re-entry in the atmosphere. Based on the temperature field inside the leading edge, the minimum thickness of the thermal protection coating was determined so that the support structure temperature stays within its maximum permissible operating range. It is shown that the Al2O3 heat-resistant porous ceramic can provide the required thermal protection, so that the maximum temperature of the composite support structure does not exceed 250 °C on the entire re-entry flight path.

RUDN Journal of Engineering Researches. 2018;19(1):7-21
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Numerical simulation of aerodynamic interference between ejected payload and the parent aircraft
Bykov L.V., Pashkov O.A., Pravidlo M.N., Yanyshev D.S.
Abstract

The purpose of this paper is to develop reliable methodology for numerical modeling of the interference between parent aircraft and ejectable payload and to investigate the influence of the interference on aerodynamic characteristics of the payload. An appropriate algorithm for the said problem is proposed. A mathematical model for supersonic flow around a solid body as well as its finite volume discretization process is described. In the presented mathematical model, a turbulence model is added to the Navier-Stokes system of equations. Namely, Menter’s SST model was chosen. Coupled solver algorithm is reviewed. Implicit Euler scheme is used for time discretization and Newton’s method is implemented to linearize the system of equations. The specifics of determining the appropriate boundary conditions and nondimensionalization of the aerodynamic coefficients are described. The calculations for the isolated payload were performed on an unstructured grid with 9 million cells and for the payload interfered by the parent aircraft - on a 24 million grid. As a result, the summarized aerodynamic characteristics for the payload were obtained for the isolated payload as well as for the payload in presence of the parent aircraft. The characteristics of the isolated object are compared with the ones of the object in presence of the parent aircraft in two different positions - Y rel = 0 m and Y rel = 0.6 m. The developed method was verified using wind tunnel data. It was identified that in presence of the parent aircraft, the coefficients of normal and side force are not zero as opposed to the isolated payload. Moving away from the parent aircraft decreases the interference and thus the side force, as well as the pitch and yaw torques. The obtained results show that the proposed method could be used in other cases of aerodynamic interference between moving objects.

RUDN Journal of Engineering Researches. 2018;19(1):22-37
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Mechanical engineering and power-plant
Calculation of clamping error when mounting a workpiece on fixture supports
Belousov Y.V.
Abstract

This article examines the conditions for reliable clamping of workpieces in fixtures, which are one of the main elements in a technological system. In order to calculate clamping error of workpieces in fixtures empirical relationships of nonlinear character are currently used. Values of the coefficients included in these relationships are only specified for steel or cast iron workpieces. The paper presents the technique for calculating the clamping error of workpieces mounted on fixture supports with spherical heads, which allow to achieve the greatest locating precision. Practically, this technique allows to perform the calculation of the specified error for different fixturing conditions of workpieces. Mathematical relationships for calculation of the error for machining workpieces of any modern engineering materials are obtained. Comparative analysis of the obtained relationships for the standard conditions of force contact of the support elements with the workpiece showed that the clamping error calculated in accordance with the obtained relationships and taking into account friction forces in the contact area of the supports with the surface of steel workpiece almost coincides with the error determined by formulas given in the reference literuture. It is demonstrated that with the decrease in clamping force the elastic displacements at the interface are negligible and the clamping error can be calculated through a simplified relationship.

RUDN Journal of Engineering Researches. 2018;19(1):38-45
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Technique for conducting experimental studies on stress-strain state of P-3 profile interference fits
Rozhkova E.A., Chetverikov S.V.
Abstract

In mechanical engineering the following profile connections are applied most often: with three sides (P-3); with three cut off sides (PC-3); with four cut off sides (PC-4) and with five sides (P-5 and PC-5). Despite considerable results, in the field of studying of stresses and deformations at contact interaction of solid bodies of various forms there is an unresolved number of tasks, which are of scientific and practical value. As the analysis of theoretical and experimental studies of motionless detachable and non-detachable connections (cylindrical, profile) has shown, there are unresolved tasks, in particular regarding the choice of geometrical form of contour curves, the magnitude of interference fit of motionless, non-detachable profile connections with equiaxial contour. The working capacity and reliability polygon profile connections with interference fit is defined by their strength, that is ability of elements to resist strain when in use. For the purpose of determination of working capacity of polygon profile connections with interference fit with respect to strength, stresses and deformations arising in hub with polygon profile opening from the action of polygon profile shaft installed in a nave with interference fit. The article considers the technique of conducting experimental studies by strain-gauging method for the purpose of assessing the influence of structural parameters and external loadings on stress-strain state of parts of the connection. Based on the experimental results tables of comparative characteristics of the recommended types of interference fits for P-3 profile connections and also the recommended interference fits for the corresponding n values of P-3 profile shaft-nave connections applied for tooth gearings were composed.

RUDN Journal of Engineering Researches. 2018;19(1):46-58
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On hydraulic analysis of the main parameters of longitudinalcirculating flow
Ponomarev N.K., Schesnyak L.E.
Abstract

Recently in practice of engineering hydraulic structures spillways with a longitudinal-circulating flow are applied. The distinguished properties of longitudinal-circulating flows are a unique example of compatibility of flow type with technological purpose of a spillway structure. The hydraulic characteristics of flow (throughput capacity, velocity distribution, pressure distribution, cavitation analysis, etc.) are determined on the basis of the calculation methods developed in the above studies, namely for: longitudinal flow using the known standard calculation methods [1]; longitudinal-circulating flow interacting with solid boundaries of spillway [1-4]; longitudinal-circulating flow in the form of a swirling stream in the aquatic environment or in the air [2; 3]; the flow arising from the interaction of unidirectional longitudinal-circulating flows [4; 5]; the flow arising from the interaction of oppositely swirling coaxial flows [3]. In this paper, the authors consider the longitudinal-circulating flow of viscous incompressible fluid in a closed channel and in a jet using a velocity wurf linking the three components of velocity U , V and W .

RUDN Journal of Engineering Researches. 2018;19(1):59-66
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Optimal control problem and its solution by grey wolf optimizer algorithm
Diveev A.I., Konstantinov S.V.
Abstract

The paper is devoted to a numerical method for solving the optimal control problem. The main approach to the numerical solution of the optimal control problem is the reduction of the optimal control problem to the problem of nonlinear programming and its following solution by classical gradient optimization methods. For this purpose, optimal control problem, which is a problem of searching time-dependent function, is replaced by the problem of searching of control values at discrete instants of time. An increase in the number of sampling points increases the accuracy of function approximation, but at the same time increases the dimensionality of the search space in the non-linear programming problem. In complex problems of non-linear programming with an unknown topology of the objective function, the statement that using classical gradient methods ensures finding a solution is not justified. The optimal control problem after the discretization and other modifications is often transformed to a non-linear programming problem with a non-unimodal objective function for which gradient methods are not applicable. In this paper we propose to solve the optimal control problem by evolutionary algorithms that do not use gradients and are able to find solutions of problems with nonunimodal objective function. The paper presents the modern evolutionary algorithm Grey wolf optimizer. The problem of the optimal combat turn of the aircraft is considered. In this problem the mathematical model of the control object is described by a system of seven ordinary differential equations. Also constraints on the value and rate of change of control are given. It is experimentally shown that the evolutionary algorithm Grey wolf optimizer successfully solves this optimal control problem.

RUDN Journal of Engineering Researches. 2018;19(1):67-79
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Innovative use of mineral resources
Special features of constructing systems for underground leaching of metals
Golik V.I., Razoryonov Y.I., Lyashenko V.I.
Abstract

The relevance of the work is attributed to the possibility of engaging stocks of low-grade ores in mining, which is prevented by insufficient knowledge of the leaching process. Preparation of ores is carried out without accounting for all properties of minerals and modes of solution movement, which increases the cost of mining, increases the loss of useful components and degrades the technicaleconomic criteria. The aim of this work is to systematize the theory and practice of using leaching technology with optimization of the mineral resources utilization criterion, accumulated in the uranium-mining industry of the USSR. The article contains the description of the processes carried out in mining practice for the first time. Results. The fundamental distinction of the technology of leaching metals from ores as changing phase of metal explicitly in-situ is formulated. The features of layout design and the use of preparatory and development workings on the conditions of their reuse in the process, crushing by condition to ensure penetration of the reagent solution into the ore piece, irrigation as a process determining the economic purposefulness of the technology, collecting solutions and preventing leakage for industrial sanitation and human health are described. The features of intensification of the drill-and-blast leaching process by deformation of the volume of leachable ore with of explosive gases and stress waves are distinguished. Examples of accounting for special features of ore deposits leaching in the USSR are presented. The practice of monitoring the completeness of leaching by excavation workings on leached ore is described. A brief description of the benefits of leaching technology in cleaning up the stocks lost by the traditional technology is given. Conclusion. It is noted that underground leaching may take priority positions in mining, so development of scientific basics for its implementation is one of the most important tasks of mining production, accomplishing which affects the creation of highly productive and waste-free systems of extraction of useful minerals from the subsoil. The experience of the ISL allows to create a methodological basis for expanding the scope of metal leaching technologies. The article contains the description of the processes carried out for the first time in mining practice.

RUDN Journal of Engineering Researches. 2018;19(1):80-91
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A study on kinetics of roasting of ore from tomtor field
Malkova M.Y., Zadiranov A.N.
Abstract

Research on kinetics of change of phosphorus, niobium, vanadium and titanium content during high-temperature roasting of ore from Tomtor field mixed with active additives: bicarbonate (NaHCO3), sodium carbonate (Na2CO3), alkalis (КОН, NaOH) is conducted. An equation of ore roasting kinetics is proposed and values of constant rate of high-temperature ore roasting for phosphorus, niobium, vanadium and the titanium under various conditions are calculated. Relationships of constant rate of high-temperature ore roasting in the atmosphere of air oxygen, argon and molecular chlorine to the temperature of roasting and content of active additives are obtained. It is established that in the atmosphere of air oxygen, ore roasting is most effective with additions of NaHCO3, Na2CO3, NaOH, taken with the ratio (1:1). It is shown that roasting of ore in admixture with carbonates and alkalis can translate into a solution for subsequent leaching at minimum 95.0% of phosphorus and 44.0% of vanadium contained in the original ore. It is established that the greatest rate of roasting in the atmosphere of oxygen is characterized by ore roasting in a mixture of NaHCO3 and NaOH. The constant rates of that process for phosphorus and vanadium are calculated. It is established that filter cake forming after ore roasting requires further processing because it contains high concentrations of vanadium and other valuable metals.

RUDN Journal of Engineering Researches. 2018;19(1):92-101
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Optical and chromatographic methods for efficiency analysis of non-stationary production
Guskova I.A., Levanova E.V., Beloshapka I.E.
Abstract

The problem of cost-effective oil production from carbonate reservoirs becomes more and more important every year due to a decrease in oil reserves in terrigenous reservoirs. Oil extraction from carbonate reservoirs is always associated with the low filtration properties of the rock matrix and the dense fracture network presence. One of the most effective methods at this development stage for carbonate reservoirs is the non-stationary drainage technology. The development of non-stationary deposit drainage technology by determining the effective action time with different work periods and well accumulation, due to deformations in the fracture system, will allow reducing wells watering percentage. As a result of fluid flows redistribution in the formation, unprocessed areas are attracted by capillary impregnation. An important stage in the application of non-stationary action is the study of oil optical properties. To assess the quality of the reserves involved in the development, laboratory studies of the deposit non-stationary production efficiency of the Romashkinskoye oil field were carried out. The investigations were carried out using a spectrophotometer and a chromatograph. The influence of non-stationary selection on the wells operation dynamics and on the final ORC was determined.

RUDN Journal of Engineering Researches. 2018;19(1):102-111
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Paleostrukture of East Orenburg region
Diakonov V.V., Kotelnikov A.E., Zhorzh N.V.
Abstract

The article states new views on structural features of East Orenburg Oblast. Results of long-term research of geological party of Mineral Deposits and their Investigation Department in RUDN formed the basis of writing the article. Unlike the predecessors considering this territory as a fragment of a double-fold structure of Ural, the authors of the article realize the thought of paleovolcanic structure of the territory. Having carried out photointerpretation of multiband satellite images, the scheme of tectonic disturbances, which is a combination of ring and radial faults, has been received. These disturbances emphasize the large ring structure, the center of which settles down near the Zhetykol lake. The carried-out facies analysis of volcanogenic and sedimentary rocks showed that groups of rocks corresponding to the main facies of volcanic constructions - vent, slope and distal - are outstanding for the territory. Rocks of these facies were formed in two independent tectono-magmatic cycles: the Baikal - Ordovician-Silurian age, and Caledonian - Upper Devonian-Upper Carboniferous age. The magmatism sequence is homodromous in both cycles and particular intrusive facies correspond to each cycle. For the Baikal cycle the intrusions are presented by serpentinite and ultramafite. For the Caledonian cycle the intrusive rocks are presented by complex granitoid intrusions of three-facies composition (the initial stages of intrusion are presented by gabbro and gabbro-diorites, the second phase of intrusion - by diorites, syenites and granodiorites, the third phase - by various granites). Interaction of granitoids with serpentinite leads to remobilization of dunite from serpentinite and to formation of chromite industrial mineralization in the latter. The research results open new opportunities in the analysis of allocation and confinedness of the known endogenous ore objects and predicting the new.

RUDN Journal of Engineering Researches. 2018;19(1):112-118
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Microstructural analysis for predicting the morphology and spatial arrangement of chromite bodies
Markov V.E., Vasiliev N.P., Karepina K.V., Karelina E.V.
Abstract

Shortage of chromite raw materials in Russia at present time encouraged the use of methods, which have not been previously used in exploration and prediction of ore bodies. Chromite deposits of the Urals are characterized by a very complex structure. For prediction of the declination of ore bodies it is possible to use the observed relationship between the structural elements of ultrabasites and the preferential orientation of the axes of the optical indicatrix of olivine. In the majority of cases the Ngaxis of the indicatrix are parallel statistically to the linearity of chromespinelide. An important structural element is the linearity, which is presented by subparallel chains of isometric grains of chromespinelide or elongated grains of chromespinelide oriented in the same direction. The results of microstructural analysis of the enclosing rocks and measurements of the preferential orientation axes of the optical indicatrix of olivine on Yujnopogureyskoe deposit has allowed to predict the decline of the ore bodies. Information about the spatial position and morphology of the ore bodies allows effective planning of the exploration work.

RUDN Journal of Engineering Researches. 2018;19(1):119-126
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Research on the development of the Nankai gas hydrates field
Malukov V.P., Tokarev I.S.
Abstract

The analysis of the development of the world’s first shelf field of methane hydrates on the east coast of Japan was carried out. To develop the marine Nankai gas hydrate deposit, a highly concentrated hydrate deposit discovered in turbidite sediments in the Nankai East Trough area, seismic exploration and exploratory drilling were performed. After intensive study of core samples and geophysical logging data obtained in previous studies, as well as additional engineering and geological studies, a development site was selected on the northern slope of Daini Atsumi Knoll. There were a number of goals: 1) to determine the production rate in a short period (from one to several weeks), 2) to achieve stability, integrity of wells drilled in loose sediments, 3) to implement monitoring technology to collect information on the state of methane hydrate during development. During the experimental work on the development of the gas hydrate deposit, the deep-water drilling vessel Chikyu was used. The water management system on the ship processed water from the reservoir, the degasser had removed dissolved methane, which was burned in the installed burner on the stern of the ship. Filters with gravel packing reduced the concentration of suspended particles associated with sand ingress when affected by a productive formation. The results of the 6-day stable development proved that the dissociation of methane hydrate is possible in marine sediments.

RUDN Journal of Engineering Researches. 2018;19(1):127-136
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