Volume 96, №7
SENSORS FOR INDIRECT MEASUREMENT OF NONSTATIONARY HEAT FLUXES BASED ON THE METHODOLOGY OF INVERSE HEAT CONDUCTION PROBLEMS
Sensors for diagnosing thermal regimes of heat-loaded structures have been developed and tested. To process the
results of these tests, use was made of computational methods based on solving inverse problems of heat conduction.
Heat fl ux sensors made of high-temperature ceramics are considered.
Author:
O. M. Alifanov, S. A. Budnik, A. V. Nenarokomov, M. O. Salosina, D. M. Titov
Keywords:
heat fl ux sensors, thermal diagnostics, inverse problems of heat conduction, iterative regularization, processing of experimental measurements
Page:
1675
FORMATION OF REGULATIONAL THERMAL REGIMES IN AN INDUSTRIAL ROOM WITH A RADIANT HEATING SYSTEM AND AIR EXCHANGE
The results of experimental studies and of mathematical simulation of heat transfer processes in a room with an
air exchange system and an operating gas infrared radiator are presented. Temperatures were recorded in the
local working area, in which a horizontal panel simulating equipment is located. The regimes of mixed convection
for variants with diff erent emissivities were studied, and their infl uence on the formation temperature fi elds and
the creation of comfortable conditions was established. It was found that the regulational thermal regime can be
achieved by increasing the emissivity and reducing the thermal conductivity coeffi cient of the materials of the fl oor
surface sections situated in local working areas.
Author:
B. V. Borisov, A. V. Vyatkin, G. V. Kuznetsov, V. I. Maksimov, T. A. Nagornova
Keywords:
gas infrared radiator, heat transfer, temperature fi elds, thermal regime, numerical simulation, mixed convection
Page:
1687
ENGINEERING METHOD OF SOLVING NONSTATIONARY PROBLEM OF THE THERMAL CONDUCTIVITY OF A DEFORMABLE ELASTOMERIC PLATE
The article presents an approximate (semianalytical) solution of the one-dimensional nonstationary problem of
the thermal conductivity of a uniformly deforming plate (shell) under time-dependent boundary conditions of the
third kind, obtained using the proposed piecewise integral heat balance method. It is shown that a change in the
thickness of the plate (shell) on deformation aff ects not only the quantitative, but also the qualitative behavior
of temperature and heat fl ux at diff erent points of the plate. It has been established that with an increase in the
frequency of temperature fl uctuations on the inner surface of the plate, thermal disturbances penetrate into the plate
to a shorter distance
Author:
V. S. Korneev, S. A. Korneev, V. V. Shalai
Keywords:
one-dimensional nonstationary thermal conductivity, highly elastic plate, large deformations, integral heat balance method
Page:
1697
LOOP THERMOSYPHON FOR COOLING HEAT-LOADED ELECTRONICS COMPONENTS
The thermal properties of a loop thermosyphon made of copper with a horizontally located evaporator, covered by a porous coating, and a condenser intended for cooling powerful electronic devices and transferring heat fl uxes with a power of 1 kW and above have been studied. The characteristics of thermosyphon evaporators having capillary structures and liquid- and air-cooled condensers of various types were studied experimentally. It is shown that coating the capillary grooves by a thin layer of sintered powder makes it possible to more than halve the thermal resistance of the thermosyphon evaporator and that, with a condenser cooled by air, the total thermal resistance of the device does not exceed 0.1o
C/W.
Author:
L. L. Vasiliev, A. S. Zhuravlyov, M. A. Kuz'mich, V. K. Kulikovskii, V. A. Olekhnovich
Keywords:
heat pipe, thermosyphon, heat exchange, cooling, phase transition, porous wick
Page:
1708
TWO-PHASE DEVICE FOR COOLING POWERFUL ELECTRONIC SYSTEMS
The paper presents the results of experimental studies of the characteristics of a two-phase heat transmitting device
(thermosyphon) that includes a fl at copper evaporator with capillary grooves and a multipipe heat-exchanger–
condenser intended for ensuring the temperature regime of powerful electronic and electrical devices. The capillary
grooves of the evaporator can be coated with a layer of porous sintered copper powder. Heat removal from the
thermosyphon condenser can be carried out by liquid or air fl ow. When using water as a coolant, the heat fl ux
transmitted by the thermosyphon is more than 1 kW
Author:
M. I. Rabetskii, L. L. Vasiliev, L. P. Grakovich
Keywords:
evaporative thermosyphon, condenser, heat exchanger, cooling, electronic components
Page:
1716
APPROBATION OF THE GENERALIZED SOLUTION FOR A SWIRLING FLOW IN VORTEX CHAMBERS AND PIPES
The calculations of thermohydrodynamic parameters using a mathematical model of a plane swirling fl ow are
compared with experimental data obtained in a vortex chamber and a Ranque vortex tube. It is shown that the
proposed generalized solution is in good agreement with experiment and describes a stable fl ow core in the plane
of the vortex cross section. In terms of application, the proposed solution can serve as the basis for engineering
methods for the preliminary calculation of vortex apparatuses
Author:
G. V. Dashkov, A. D. Solodukhin, V. D. Tyutyuma
Keywords:
vortex chamber, Ranque vortex tube, model of plane swirling fl ow, generalized solution, velocity fi eld, distribution of thermodynamic parameters, comparison with experiment
Page:
1721
ANALYSIS OF THE THERMO-STRESSED STATE OF AN UNCOOLED DEFORMABLE LASER MIRROR
Analytical and fi nite-diff erence methods have been used to analyze the thermo-stressed state of an uncooled
deformable mirror. Assessments have been made of temperatures and movements of the optical surface of the mirror
both in assigning a uniform intensity of the heat fl ux and in the presence of global and local nonuniformities.
A conclusion has been drawn about the possibility of using simplifi ed analytical computational methods in design
analysis
Author:
Yu. I. Shanin, D. A. Yagnyatinskii
Keywords:
thermal deformation, deformable mirror, optical surface, heat flux
Page:
1731
FINITE ELEMENT ANALYSIS OF THERMO-STRESSED STATES OF THE TELESCOPE OBJECTIVE MODEL FOR THE LIRA-B SPACE EXPERIMENT
The thermostressed state of one of the proposed telescope designs was analyzed by means of a fi nite element model using the ANSYS software package. It is shown that under normal thermal conditions, small temperature variations (within ±1o
С) do not cause telescope malfunction. The range of possible temperature changes that result in the
maximum permissible focus shifts and tilts of the axis of the secondary mirror relative to the primary mirror was
determined.
Author:
Yu. I. Shanin, D. A. Yagnyatinskiy
Keywords:
telescope, primary mirror, secondary mirror, thermal conditions, deformation, stress
Page:
1742
HYDRODYNAMICS AND HEAT TRANSFER IN MINICHANNEL COOLING SYSTEMS OF LASER MIRRORS
Consideration has been given to some issues of application of multilayered cooling systems with minichannels in laser mirrors and chips. Generalized results are presented for experimental investigations of hydraulic resistance and heat transfer in minichannel cooling systems with rough walls in a broad range of variation of the Reynolds number (2·101
< Re < 4·104
). A comparison has been made of the obtained results with the existing relations, and
signifi cant deviations have been detected in the hydraulic resistance of rough channels from that of smooth ones in
a laminar fl ow regime
Author:
Yu. I. Shanin
Keywords:
laser mirror, cooling system, multilayered cooling system, minichannel, hydraulic resistance, heat transfer
Page:
1748
DETONATION COMBUSTION OF A HYDROGEN–AIR MIXTURE WITH ADDITIVES OF ARGON AND OZONE
Using a detailed kinetic mechanism of chemical interaction, the eff ect of adding argon and ozone to a stoichiometric
hydrogen–air mixture on the detonation wave parameters was studied numerically. It has been established that the
mole fractions of the used additions can be chosen so that the cell size of the detonation wave in the resulting mixture
will be close to the average cell size in a pure hydrogen–air mixture, with the wave velocity and temperature of the
detonation products being reduced signifi cantly. It has been found that the detonation wave in a mixture with additives
in selected concentrations is more stable against perturbations caused by multiple obstacles (barriers) located in the
channel than in the initial mixture. The found specifi c features make it possible to consider the introduction of the
indicated additives into the combustible mixture as a mechanism that lowers the temperature in the detonation wave
without a signifi cant increase in the detonation cell size and that prevents the extinction of detonation combustion in
a channel with a number of barriers
Author:
V. A. Levin, T. A. Zhuravskaya
Keywords:
detonation, stoichiometric hydrogen–air mixture, cellular detonation structure, argon, ozone, multiple obstacles
Page:
1759
ACCELERATION OF THE FLAME IN A SMOOTH CHANNEL AND DETONATION TRANSITION
In the work, the authors have presented a systematization of the data on acceleration of the fl ame in a smooth channel fi lled with gaseous fuel mixture. A mixture of acetylene and oxygen, for which novel experimental and calculation-theoretical investigations have been carried out, was selected as an example of the fuel mixture. On the basis of
comprehensive analysis, the authors have described in detail all stages of development of the process, including the
initial stage of exponential acceleration of the fl ame, the stage of restructuring of the fl ame front accompanied by
its retardation, the resumption of fl ame acceleration, and the creation of conditions for detonation transition. It has
been demonstrated that of paramount importance in the development of each stage are hydrodynamic processes determining, in particular, the behavior of the fl ame in the fl ow formed in the channel and its acceleration and the compression of the fuel mixture, which is coordinated with it. This leads to the creation of conditions for the formation
of detonation. Importantly, the carried-out calculations reproduce, at a qualitative level, all stages of development
of the fl ame, and a parametric analysis of conditions for the transition to detonation quantitatively predicts, with a
good degree of accuracy, the critical detonation-transition conditions determined experimentally
Author:
A. D. Kiverin, P. N. Krivosheyev, A. O. Novitskii, O. G. Penyazkov, I. S. Yakovenko, A. V. Yarkov
Keywords:
slow combustion, acceleration of the fl ame, development of memory, defl agration-to-detonation transition (DDT), high-speed visualization, mathematical analysis, numerical modeling, natural and computational experiment
Page:
1769
TECHNICAL AND ECONOMIC ASSESSMENT OF THE USE OF ALTERNATIVE FUELS FROM WASTE AT THERMAL ELECTRIC POWER PLANTS IN EXCHANGE FOR TRADITIONAL FUELS
A feasibility study was carried out for the transition of typical power engineering objects, diff ering in thermal
capacities and electric powers, from traditional fuel (coal, natural gas, fuel oil) to the combustion of biomass,
composite liquid fuel, and generator gas. Three options for producing generator gas during gasifi cation of biomass,
composite liquid fuel, and coal were studied cash fl ows were calculated for the transition of each of the power
plants under consideration to alternative fuel and the payback period for such a transition. Relative indicators
of the effi ciency of the generator gas were determined taking into account a set of signifi cant parameters: heat
of combustion, fuel consumption, anthropogenic emissions, ash residue, maximum combustion temperature,
minimum ignition temperature, combustion initiation delay time, cost, technical and economic indicators of storage,
transportation and fuel combustion, fi re and explosion safety.
Author:
O. V. Vysokomornaya, M. A. Kurgankina, A. S. Shvets
Keywords:
gasifi cation, generator gas, thermal power plants, boiler houses, economic profi t, biomass, composite liquid fuels
Page:
1782
INFLUENCE OF THE GRADUAL IGNITION OF A POWDER IN A GUN AND OF ITS NONSTATIONARY AND EROSION BURNING ON THE INTERNAL BALLISTICS OF A GUNSHOT
A mathematical simulation of the internal ballistics of a shot from a gun, depending on the design of the charge of
the gun, has been performed. A general system of equations defi ning the unsteady movement of a two-phase gas–
powder mixture in the channel of the barrel of a gun in the one-dimensional approximation is presented. Results of
simulation of a shot from a gun charged with tubular powder or chopped powder are presented. The infl uence of the
gradual ignition of a powder in a gun and of its nonstationary and erosion burning in it on the parameters of the
ballistic process in the gun and the infl uence of the mass and disposition of an igniter in the gun on the dynamics of
a shot from it were investigated
Author:
I. G. Rusyak, A. M. Lipanov
Keywords:
internal ballistics, chopped powder, tubular powder, mechanics of heterogeneous media, ignition, nonstationary erosion burning, gas dynamics, heat and mass transfer, mathematical simulation, computational experiment
Page:
1795
PROPAGATION OF COMBUSTION OVER COMPOSITES BASED ON POROUS SILICON AND SODIUM-PERCHLORATE MONOHYDRATE
Results of experiments with energy-saturated composites, including those based on fragmented nanostructured
silicon (FPS composites), have been presented. It has been established that the process of combustion of FPS
composites is multistage, the phase that follows develops irrespective of the preceding one with stepwise increase
in the released energy and growth in the velocity of propagation. It has been shown that despite the problems of
propagation of an aerosol regime with the defi ciency of free water (at the humidity W = 0.7%, the delay time is
75 μs), after the coalescence of the combustion front with the source of a burning aerosol (frontal aerosol regime of
combustion), this factor plays no role against the background of sharp increase in the energy release. A study has
been made of the combustion of FPS composites in inert media (He, Ar, and Kr). It has been established that the
durations of smoldering and frontal regimes (phases) of combustion in helium and argon are similar and in inert
gases, there is no phase of aerosol combustion observed in the atmosphere, which points to its dependence on the
oxygen of the external medium. Maximum rates of frontal-aerosol combustion are nearly the same in all the gases.
This demonstrates the weak infl uence of the medium′s physical parameters on the behavior of the composites in the
most energy-saturated phase of chemical transformation
Author:
V. N. Mironov, E. S. Golomako, P. N. Krivosheyev, O. G. Penyazkov, S. O. Shumlyaev
Keywords:
FPS composites, sodium-perchlorate monohydrate, induction period, combustion phases, frontal aerosol regime
Page:
1805
CATALYTIC HYDROLYSIS OF SODIUM BOROHYDRIDE
A study has been made of the infl uence of temperature, NaON, and concentrations of NaBH4 on the rate of catalytic hydrolysis under isothermal and adiabatic conditions. Finely divided Co/TiO2 powder was used as the model catalyst. The catalyst preserves its initial activity during 20 cycles, ensuring an NaBH4 conversion of 94–98%. Activation energies equal to 65.6 and 55 kJ/mole have been determined in the aqueous and aqueous-alkaline solution of NaBH4 respectively. It has been shown that the standard method of determining activation energy without account of sorption/desorption processes leads to its dependence on the composition of the solution
Author:
V. G. Minkina, S. I. Shabunya, V. I. Kalinin
Keywords:
sodium borohydride, heat-insulated reactor, hydrogen, catalytic hydrolysis
Page:
1820
STUDY OF RADIATION CHARACTERISTICS OF SHOCK-HEATED GASES
The paper presents the results of studies with the use of shock tubes at the Institute of Mechanics of the M. V. Lomonosov Moscow State University, in which measurements were made of the radiation of shock-heated gases simulating the conditions of the entry of spacecraft into the atmosphere of the Earth and other planets of the Solar system
with orbital and superorbital velocities. A description of the measuring equipment is given, as well as techniques of
diagnostics and processing of the obtained spectroscopic information. Numerous experimental data on the radiation
of shock-heated gases in a wide range of the radiation spectrum from vacuum ultraviolet to infrared have been analyzed, which serve as the basis for the development of various gas-dynamical models.
Author:
P. V. Kozlov, V. Yu. Levashov, G. Ya. Gerasimov, I. E. Zabelinskii, N. G. Bykova
Keywords:
shock wave, shock-heated gas, radiation characteristics, radiation spectrum, superorbital velocities
Page:
1828
BOILING OF HELIUM II ON CYLINDRICAL HEATERS: ANALYSIS OF EXPERIMENTAL OBSERVATIONS FROM THE END SURFACE
The authors have presented experimental data on the boiling of superfl uid helium (helium II) on the surface of a
cylindrical heater located in the volume of helium II. Observations of the process of heat and mass transfer in the
experimental helium volume were carried out from the end of the cylindrical heater. The formation of a vapor fi lm
of fi nite thickness on the surface of the heater on applying thermal load to it, the existence of a noiseless regime of
boiling of helium, and the development of oscillations of the phase boundary in its volume have been shown
Author:
Yu. Yu. Puzina, A. P. Kryukov
Keywords:
helium II, experiment, oscillations, interface, cylindrical heater, heat and mass transfer, vapor fi lm
Page:
1839
BOILING OF VARIOUS LIQUIDS IN A MICROCHANNEL
A study of heat emission during the boiling of distilled water and isopropyl alcohol in a microchannel with a size of 12.5 × 3× 0.2 mm3 has been carried out. To calculate heat emission during boiling in the microchannel, the
Kutateladze equation for a fl at slot with one-sided heating was used, as well as the Kutepov–Sterman dependences
for nucleate boiling under conditions of directional fl uid motion and the Danilova dependence for calculating heat
emission during boiling. It is established that the Kutepov–Sterman equation yields the minimum deviation from
experimental data (no more than 25%).
Author:
Yu. A. Kuzma-Kichta, S. A. Kovalev, A. S. Kiselev
Keywords:
microchannel, heat emission, isopropyl alcohol, distilled water, departure diameter of a vapor bubble
Page:
1845
MULTISCALE MATHEMATICAL MODEL OF HEAT AND MASS TRANSFER IN A THIN VAPOR CHAMBER
A mathematical model of a thin vapor chamber is proposed. The model describes the processes of two-phase heat and
mass transfer in this chamber on two spatial scales: the microscopic scale of a single cell of the capillary structure
of the wick and the macroscopic scale of vapor chamber as a whole. Using the micromodel, the relationships used in
a macromodel are obtained that link the local capillary pressure, wick permeability, and the evaporation fl ux density
with the values of temperature, pressure, and degree of fi lling the wick with the working fl uid. Such a multiscale
approach was used for numerical study and optimization of the vapor chamber with a wick consisting of micropillars
forming a regular hexagonal structure. A fundamental limitation on the width of the vapor core of the chamber
is established, which is associated with an increase in the pressure of vapor during its fl ow in a narrow gap. The
dependence of the thermal performance of the vapor chamber on the initial degree of fi lling the wick with the
working fl uid has been studied, and the importance of the precision fi lling of the chamber is shown. The proposed
model can be extended by developing and introducing micromodels of new types of wicks, including those with a
heterogeneous structure
Author:
I. A. Koznacheev, A. I. Malinovskii, M. Yu. Lyakh, O. S. Rabinovich, D. A. Ivanov
Keywords:
vapor chamber, cooling, microelectronic devices, simulation, two-phase heat and mass transfer, capillary structures, optimization
Page:
1852
SATURATION TEMPERATURE AND HEAT TRANSFER DURING NUCLEATE BOILING ON A SUBSTRATE
The physical parameters exerting an eff ect on the density of the heat fl ux transported by vapor bubbles during
nucleate boiling are considered. It is shown that this density depends on the radius of bubble departure from
the substrate, the rate of formation of departing bubbles per unit area of the substrate, the thermophysical
properties of the liquid, and the saturation temperature. It has been established that the density of the energy
fl ux transported by bubbles increases exponentially with the saturation temperature and depends strongly on
the bubble departure radius. It is shown that the thickness of the superheated liquid layer, inside which bubbles
grow, does not exceed several hundred microns and depends on the total energy fl ux. In this case, if the average
distance between the bubbles is comparable to the departure radius, bubble coagulation leads to a boiling
crisis
Author:
I. A. Koznacheev, A. I. Malinovskii, O. S. Rabinovich, S. P. Fisenko
Keywords:
bubbles, superheating, departure radius, coagulation, energy fl ux
Page:
1862
MICROPROFILED SURFACES FOR HYPERFINE EVAPORATIVE-CONDENSING UNITS
The infl uences of structural parameters (shape, dimensions, structure pitch) on the capillary-transport properties of the wick was studied, and the choice of microstructured wick elements for hyperfi ne evaporative-condensing devices is substantiated. It has been established that steam chambers with conical microstructures are characterized by minimal mass at a high effi ciency in removing thermal loads from hard-to-reach heat-stressed elements. Laboratory technologies for producing microprofi led structures by chemical and electrochemical milling have been developed. Experimental samples of microprofi led structures with a porosity of 65% and a permeability of 91 darcy were obtained. Based on the developed wick (70 × 70 × 0.05 mm3
), a steam chamber of size 75 × 75 × 0.81 mm3
(working fl uid — water, casing — copper) with a thermal resistance of 0.13 K/W and isothermicity of 1.4o
C was created
Author:
O. L. Voitik, K. I. Delendik, N. V. Kolyago, O. G. Penyazkov, L. Yu. Roshchin
Keywords:
microprofi led surface, evaporative-condensing devices, steam chamber, wick, porosity, permeability
Page:
1867
SPECIFIC FEATURES OF THE COMBUSTION PROCESS AND THERMAL CALCULATION OF TWO-CHAMBER CYCLONE-BED FURNACES
An experimental study of combustion processes in laboratory and pilot plants of various size equipped with cyclonebed furnaces with a fi xed and a fl uidized bed and a wide range of solid biofuels was carried out. Numerical simulation
of furnace processes in cyclone-bed furnaces was performed using the standard k–ε turbulence model and the
Magnussen combustion model. A semiempirical method for calculating cyclone-bed furnaces has been developed
Author:
E. A. Pitsukha, É. K. Buchilko, Yu. S. Teplitskii, V. A. Dubina
Keywords:
cyclone-bed furnace, fi xed bed, bubbling bed, solid biofuel, numerical simulation, thermal calculation
Page:
1875
HEAT AND MOISTURE TRANSFER IN A DENSE DISPERSED LAYER OF VEGETABLE MATERIALS WITH RADIATIVE-CONVECTIVE ENERGY SUPPLY
The results of an experimental study and numerical simulation of heat and moisture transfer in a blown dense and
a stirred layer of vegetable materials under convective and cyclic radiative-convective heat supply are considered.
Based on the analysis of the kinetic dependences of the dehydration of vegetable materials, the possibility of reducing
the duration of the process is shown. A comparison of the calculated and experimental data on the kinetics of the
process is made, indicating their satisfactory agreement and the adequacy of the model.
Author:
P. V. Akulich, D. S. Slizhuk
Keywords:
heat and mass transfer in a dispersed layer, radiative-convective drying, drying of vegetable materials
Page:
1884
A THROUGH METHOD FOR SOLVING PROBLEMS OF HEAT AND MASS TRANSFER IN VAPOR–LIQUID SYSTEMS THAT TAKES ACCOUNT OF MANY-PARTICLE INTERACTIONS
The paper demonstrates a further development of the approach, which makes it possible to take into account manyparticle interactions inside of the condensed phase. This method is applied to the study of the problem of heat
conduction for argon and xenon. The values of thermal conductivity coeffi cient for diff erent numbers of interacting
particles are obtained. Next, using the proposed approach, a one-dimensional problem of evaporation–condensation
of argon between two layers of liquid is solved. Distributions of macroparameters along the coordinate and their
evolution in time are presented
Author:
I. N. Shishkova, A. P. Kryukov
Keywords:
heat and mass transfer through the interphase surface, function of velocity distribution of molecules, Boltzmann kinetic equation, potential of intermolecular interaction, through solution for the liquid–vapor system
Page:
1891