Begell House Inc.
Nanoscience and Technology: An International Journal
NST
2572-4258
8
4
2017
NUMERICAL STUDY OF THE EFFECT OF A NANOFLUID WITH NANOPARTICLES OF NONUNIFORM SIZE ON NATURAL CONVECTION IN AN INCLINED ENCLOSURE
261-308
Sina
Niazi
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588-0526, USA
Mehrdad Naderi
Beni
Department of Mechanical Engineering Faculty of Engineering, University of Kashan Kashan, Iran
Heat transfer and fluid flow with natural convection in an inclined cavity with variable size Al2O3 nanoparticles are studied. Moreover, the influence of the nonuniform size of nanoparticles, inclination angle, nanoparticle volume fraction, Prandtl number, and of Grashof number on heat
transfer rates is examined. The angle of inclination of the cavity between 0° to 120° is considered.
Computations show that the average Nusselt number increases with the Rayleigh number and that the average Nusselt number decreases as the nanoparticle mean diameter increases at all
angles except 90°. The results show that the change in the nanoparticle size and angle of inclination affects the natural convection heat transfer in a rectangular cavity.
EXPERIMENTAL AND THEORETICAL STUDY OF THE PROCESSES OF COMBUSTION OF EMULSIONS AND SUSPENSIONS OF LIQUID AND SOLID HYDROCARBONS WITH WATER
309-322
Yu. P.
Rassadkin
Institute of Applied Mechanics, Russian Academy of Sciences,
7 Leningradskii Ave., Moscow, 125040, Russia
V. P.
Avanesyan
Institute of Applied Mechanics, Russian Academy of Sciences,
7 Leningradskii Ave., Moscow, 125040, Russia
Nikolay N.
Zakharov
Institute of Applied Mechanics, Russian Academy of Sciences,
7 Leningradskii Ave., Moscow, 125040, Russia
The water present in hydrocarbon fuels, as well as its vapor in air or other oxidants, have a significant impact on the behavior of various physical and chemical processes occurring in them, including the direct effects associated with combustion. Notably, this occurs both in the normal
combustion reactions of organic and inorganic substances, and in the case of mixing of solid and liquid hydrocarbon fuels with water. A lot of experimental evidence concerning the influence of water on the occurring processes have been accumulated, which have not yet found an explanation.
It turned out that in this case, the main influence is exerted by vibrational excitation of H2O molecules in the liquid and gaseous phases. This paper describes the physical and quantum-mechanical processes proceeding in the formation of emulsions and suspensions by mixing liquid and powdered solid hydrocarbon fuels with liquid water, and the phenomena of their combustion in the atmospheric air. Experimental data on successful creation of such mixtures and significant improvement of the hydrocarbon fuels combustion efficiency are described. An explanation is given for the basic phenomena occurring during the formation of emulsions and suspensions, as well as during the combustion processes.
STUDY OF THE STRUCTURE AND MECHANICAL CHARACTERISTICS OF SAMPLES OBTAINED BY SELECTIVE LASER MELTING TECHNOLOGY FROM VT6 ALLOY METAL POWDER
323-330
Anton V.
Agapovichev
Samara National Research University, 34 Moskovskoe Highway,
Samara, 443086, Russia
A. V.
Sotov
Samara National Research University, 34 Moskovskoe Highway, Samara, 443086, Russia; A.A. Blagonravov Mechanical Engineering Institute, Russian Academy of Sciences, 4 M. Khariton'evskii Lane, Moscow, 101990, Russia
V. V.
Kokareva
Samara National Research University, 34 Moskovskoe Highway, Samara, 443086, Russia
V. G.
Smelov
Samara National Research University, 34 Moskovskoe Highway, Samara, 443086, Russia; A.A. Blagonravov Mechanical Engineering Institute, Russian Academy of Sciences, 4 M. Khariton'evskii Lane, Moscow, 101990, Russia
R. R.
Kyarimov
Samara National Research University, 34 Moskovskoe Highway, Samara, 443086, Russia
The material structure obtained by selective laser melting technology from a VT6 alloy metal powder is studied. The chemical and grain-size analyses of initial metal powder of VT6 alloy are carried out. The chemical composition of the material obtained by the technology of selective laser
melting from a VT6 alloy metal powder is investigated. Static stretching tests of samples in various modes of laser emission for defining the influence of these modes on the mechanical characteristics of material are carried out. As the use of the technology of selective laser melting is
significantly limited by the large roughness of synthesized parts in comparison with the parts obtained by machining, the influence of the parameters of laser emission on the roughness of the obtained samples was studied.
NICKEL CHELATE COMPLEXES AS A SINGLE-SOURCE PRECURSOR OF NANOCOMPOSITES
331-346
G. I.
Dzhardimalieva
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
1 Academician Semenov Ave., Chernogolovka, Moscow Region, 142432,
Russian Federation
N. N.
Volkova
Institute of Problems of Chemical Physics, Russian Academy of Sciences, 1 Academician Semenov Ave., Chernogolovka, Moscow Region, 142432, Russian Federation
Vitaly A.
Shershnev
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
1 Academician Semenov Ave., Chernogolovka, Moscow Region, 142432,
Russian Federation
N. D.
Golubeva
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
1 Academician Semenov Ave., Chernogolovka, Moscow Region, 142432,
Russian Federation
A. S.
Burlov
Institute of Physical and Organic Chemistry at Southern Federal University,
194/2 Stachki Ave., Rostov-on-Don, 344090, Russian Federation
L. D.
Popov
Faculty of Chemistry, Southern Federal University, 7 Zorge Str.,
Rostov-on-Don, 344090, Russian Federation
The thermal behavior of Ni(II) chelates with bi-, tri-, and tetradentate azomethine ligands is examined by the methods of thermal analysis (DSC, TGA, and DTA) and kinetic analysis of weight loss. It is shown that the controlled isothermal thermolysis of azomethine complexes of Ni(II) in a
self-generated atmosphere is an efficient method for obtaining nickel-containing nanoparticles. Products of thermal conversions of chelate complexes are characterized by the x-ray phase analysis and SEM. The magnetic properties of the nanocomposites obtained are studied.
MECHANICAL PROPERTIES OF Si3N4-BASED COMPOSITE CERAMICS WITH NANOSIZED POROSITY
347-357
Sergey A.
Lurie
Institute of Applied Mechanics, Russian Academy of Sciences, 7 Leningradsky Ave., Moscow, 125040, Russia; Dorodnicyn Computing Centre FIC IU of the Russian Academy of Sciences, 40 Vavilov Str., Moscow, 119333, Russia
Lev N.
Rabinskiy
Moscow Aviation Institute (National Research University),
4 Volokolamskoe Highway, Moscow, 125993, Russia
P. O.
Polyakov
Moscow Aviation Institute, 4 Volokolamskoe Highway, Moscow, 125933, Russia
S. A.
Sitnikov
Moscow Aviation Institute, 4 Volokolamskoe Highway, Moscow, 125933, Russia
Yury
Solyaev
Institute of Applied Mechanics, Russian Academy of Sciences, 7 Leningradskii Ave., Moscow, 125040, Russia; Moscow Aviation Institute, 4 Volokolamskoe Highway, Moscow, 125933, Russia
The paper presents the results of experimental and theoretical investigation of the mechanical properties of composite ceramics based on silicon nitride, reinforced with silicon carbide fibers. Composite ceramics samples reinforced with unidirectional fibers with a volume content of 10% were obtained using the 3D printing technology and manual lay-up method. The ceramic matrix contains up to 30% of porosity, and the average pore size is less than 1 μ;m. Flexural strength and the Young modulus of the pure and reinforced ceramics were determined in three-point bending tests. The results of experimental studies are compared with those of modeling. FE simulation of a porous matrix is performed based on realistic representative fragments generated using an overlapped solid grains model. Evaluation of the influence of fibers on the properties of unidirectional samples is performed on the basis of a simple slab model with regard to the porous matrix effective properties found in numerical simulations. It is shown that the experimental results for the effective elastic modulus of the composites agree well with the calculation results, but the strength of the experimental samples is 30% lower than that calculated.
MECHANICAL PROPERTIES AND MICROSTRUCTURE OF STAINLESS STEEL MANUFACTURED BY SELECTIVE LASER SINTERING
359-366
A. V.
Babaytsev
Moscow Aviation Institute (State University of Aerospace Technologies), 4 Volokolamskoe Highway, Moscow, 125993, Russia
M. V.
Prokofiev
Moscow Aviation Institute, 4 Volokolamskoe Highway, Moscow, 125080, Russia
Lev N.
Rabinskiy
Moscow Aviation Institute (National Research University),
4 Volokolamskoe Highway, Moscow, 125993, Russia
The results of investigation of the microstructure and mechanical properties of stainless steel samples manufactured with selective laser sintering are presented. The mechanical performance of samples is determined by using tensile and three-point bending tests. The test results proved the stability of the mechanical properties of the manufactured material. The values obtained for the
ultimate strength and yield strength exceed the standard values for the considered steels, however, Young's modulus found in the tensile and bending tests is significantly less than the standard one. The microstructure of the fracture surfaces of samples is also studied. The microanalysis
indicates the brittle-ductile type of failure with significant prevalence of brittle failure in a sintered material. Based on energy-dispersive x-ray spectroscopy results the conformance of the sample composition to the standard typical of stainless steel 316L is shown.
AVERAGING EQUATIONS OF MATHEMATICAL PHYSICS WITH COEFFICIENTS DEPENDENT ON COORDINATES AND TIME
367-375
Vladimir I.
Gorbachev
Department of Composite Mechanics, Mechanics and Mathematics Faculty, M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Moscow,
119991, Russia
Differential equations with variable coefficients describe the processes proceeding in inhomogeneous materials in which mechanical characteristics change either abruptly or continuously in the boundary area between the phases. One of the general approaches to solving equations with variable
coefficients is the use of the averaging method, which implies some of the ways to represent the solution of the initial equation in terms of a solution of an equation with constant coefficients. In the present paper, an integral formula has been obtained which presents the solution of the
original linear differential equation of the second order with the coefficients depending on the coordinates
and time, through the solution of the same equation with constant coefficients (the concomitant equation). The kernel of the integral formula includes the Green function of the original equation and the difference of the coefficients of the original and concomitant equations. From the integral formula an equivalent representation of the solution of the initial equation in the form of a series of all possible derivatives of the solution of the concomitant equation is obtained. The coefficients of the series are called structure functions. They depend substantially on the form of the inhomogeneity and tend to zero as the coefficients of the original equation tend to the constant coefficients
of the concomitant equation. A system of recurrence equations satisfied by the structural functions is written. Examples of calculation of the structure functions are given.
Index, Volume 8, 2017
377-383