Abstract Experimental studies on control of turning-and-diverging flow have been carried out; detailed diagnostics of averaged and turbulent characteristics have been made. Numerical modeling and comparison with experimental data based on known up-to-date turbulence models have been performed; comparative analysis of models has been done. The findings may be useful for determination of applicability

Abstract The thermal conductivity and thermal diffusivity of europium (Eu) in the solid and liquid states, including the melting-crystallization region, have been measured for the first time by the laser flash method in the temperature range from 298 to 1625 K. The error of measurement of the heat transfer coefficients was 4–6%. The data for the temperature regions of 298–550 K and 965–1625 K were

Abstract The paper presents results of experimental study of an upward flow in a vertical rod bundle consisting of nine rods arranged in a square. Spacing grids were used to keep the bundle geometry. The experiments were performed in single-phase and bubbly flows using an electrochemical technique. A local wall shear stress probe was mounted in the central rod. The dependence of the local wall shear

Abstract The paper addresses a mixed convection boundary layer flowing on a horizontal surface embedded in porous medium with exponentially decaying internal heat generation (IHG) and internal mass generation (IMG) from a specific component with chemical reaction in order to investigate the heat and mass transfer characteristics. Corresponding similarity solutions are used to reduce the governing partial

Abstract In this study, the motion of three phases (gas, liquid, and solid) and characteristics of particle removal inside the liquid chamber of industrial scrubbing tower were studied through unsteady simulations using the VOF-DPM coupled model. The study focused on the motion of dust particles in a three-dimensional computational domain of \(4200\times 8400\) mm. After the system achieved stability

Abstract Methods for determination of thermal properties of various materials, including iron ore, are adequately covered in the relevant literature. They rely, as a rule, on certain solutions to the problem of heat conductivity without consideration of internal heat sources that occur in the body of sample under study if the heating (cooling) process is accompanied by various thermochemical and phase

Abstract The article presents the results of an experimental study of the turbulent structure of flow over a two-dimensional hydrofoil, which is a scaled-down model of guide vane of high-pressure hydraulic turbine. The study was carried out for four regimes of cavitating flow, covering the cases of cavitation-free flow, quasi-steady sheet-vortex cavity with detachments of small-scale cavitation clouds

Abstract An experimental investigation has been carried out regarding the effect of microstructural parameters of capillary porous coatings produced by directed plasma spraying on the heat transfer and critical heat fluxes during boiling of nitrogen at steady-state heat generation on horizontally-oriented tubular heaters of 3 and 16 mm in diameter. For both the tube diameters, the highest increase

Abstract The possibility of increasing the reactivity of low grade Kansk-Achinsk brown coal 2 BR from the Irsha-Borodino deposit due to mechanically activated micronizing by means of special mill disintegrators has been shown on the 5-MW experimental firing stand at the Institute of Thermophysics SB RAS (IT). This coal is used in the coal-fired PK-38 boiler of station 2B of the Krasnoyarsk State District

Abstract A hydrodynamic model of motion of compressible liquid in a complex profile pipeline has been built and the resulting coupled equations have been solved. The dynamics of the liquid flow rate was determined in dependence on parameters of the system and inlet and outlet pressure variation.

Abstract This paper presents the experimental and numerical results of modeling the local structure of gas-liquid downflow in a vertical pipe. The measurements were carried out using the PIV/PLIF system “Polis-PIV,” developed at the Institute of Thermophysics SB RAS. The numerical model is based on the use of a two-fluid Eulerian approach. The effect of changes in the diameter of air bubbles on the

Abstract Convection in a sessile droplet of water in a laminar air flow was studied. The experiments were conducted in the air velocity range \(U_{1}=2\)–5 m/s. The experimental data are compared with approximate numerical solutions and an approximate analytic solution made for small numbers Re for both the liquid and gas phase. It has been shown experimentally and theoretically that the maximum velocity

Abstract One of the key challenges to model condition monitoring is; how to suitable match the level of detail of the model description of the diagnostic requirements. To do so, a counter-current heat exchanger of the tire factory was investigated. Moreover, a two-stage grey-box modelling was deployed. The modelling is deployed in a discrete state space, relying on a combination of prior knowledge

Abstract Operating characteristics of aeronautic and marine vehicles, as well as hydraulic machines designed for various purposes are largely affected by flow separation. Therefore, control of separated flows is an extremely important problem for modern aviation and marine engineering. Based on dynamometric measurements of forces and torque acting on model hydrofoils and the ship rudder, jet control

AbstractThe coaxial cylinders method was used to measure the thermal conductivity of the R-125/R-134A (39/61) gas mixture. The experiments were carried out in the temperature range of 320–415 K and in the pressure range of 0.1–1.8 MPa. Coefficients were determined for an equation describing the thermal conductivity as a function of pressure and temperature. Thermal conductivity on the dew line and

AbstractGas hydrates are a special state of matter because of their properties to concentrate significant volumes of gas in themselves. Different hydrate forming gases have different thermobaric regions of existence. These properties of gas hydrates create a prospect for developing promising industrial technologies for their synthesis and dissociation. This paper reflects the effects of surface-active

AbstractThe article presents the results of comparative investigations of operation modes of the DKVR 10-13 steam boiler system. The investigations were performed in two different modes. In the first mode, the boiler worked only on the gas fuel, whereas in the second mode, the boiler worked on the gas fuel and mazout simultaneously. Each mode requires considering the economic and ecological conditions

AbstractWe present a numerical model suitable for simulation of shock or blast waves passing through a cloud of water droplets. The model takes into account the droplet breakup, radiation, and evaporation effects. The gas phase (a mixture of air and water vapor) is solved within an Eulerian framework with a set of compressible transport equations. The disperse phase (water droplets) is represented

AbstractThis work investigates the motion of the liquid metal on the surface of a heated cylindrical rod. Experiment data are presented, and computational models modified in accordance with the experimental results are described. Exploration of the motion of molten metal over the surface of fuel column simulator both in gravitational runoff and at gas blowoff involved high-speed recording. Formation

AbstractSeveral challenges coexist in the field of flow boiling in microchannels, ranging from high superheat required for boiling incipience to boiling instabilities and early dryouts. The aim of this study is to mitigate or solve some of the challenges and develop an image-processing algorithm for analysis of boiling oscillations in multiple parallel channels. The experimental results were acquired

AbstractThe paper analyzes steady laminar boundary layer flow of low-conductivity Casson fluid over a stretching/shrinking sheet subjected to a transverse magnetic field in the presence of suction/injection when the fluid far away from the surface is at rest. This flow problem is mathematically modelled and the non-Newtonian fluid under consideration obeys the rheological equation of state by the Casson

AbstractThe flow in swirling turbulent wakes with varying total excess momentum and angular momentum is described using two second-order mathematical models. The first one includes averaged equations of momenta, turbulence energy balance, and dissipation rate in the far-wake approximation. The closure of the mathematical model relies on Rodi’s algebraic model for Reynolds stresses. The second model

AbstractA triple diffusive convective flow (thermal diffusion and dual species diffusion) in a viscous fluid flowing within a vertical duct is investigated under the Robin boundary conditions at the duct walls. Viscous heating and homogenous chemical reaction effects are included. The mass transfer (solutal) buoyancy effects due to concentration gradients of the dispersed components are taken into

AbstractThe aim of the present investigation is framing the effect of thermal radiation and slip on a magnetohydrodynamic (MHD) Casson nanofluid flow over a stretching surface under the influence of variable viscosity and convective boundary condition. First, non-dimensionally developed boundary layer equations are deduced with suitable transformations. Then they are solved numerically by the Runge–Kutta–Fehlberg

AbstractExperimentally obtained ranges of decreasing of temperature of combustion products after pulsed injection of an aerosol consisting of fine water droplets and time intervals with reduced (as compared to the initial) temperature of gases are presented. Fast-response thermocouples and panoramic optical methods of tracer visualization are applied. To ensure the possibility of using the experimental

AbstractThe paper present experimental results for temperature fields in heterogeneous droplets of liquids, freely falling in a preheated gaseous medium, before their micro-explosive fragmentation. The optical technique of Planar Laser Induced Fluorescence was applied. Unlike the known results of other authors, such fields were obtained for the first time without using holders for droplets, the latter

AbstractIn plate fin heat exchangers, fins of special shapes on the plates generate high turbulent flow in the flow channels formed by the plates, which enables achievement of high heat transfer coefficients. The present work uses a conjugated heat transfer approach to evaluate numerically the heat transfer improvement and pressure drop in plate fin heat exchangers due to zigzag (type B) and inner

AbstractThis paper presents experimental results on occurrence of large-scale maldistribution of parameters of liquid and vapor flows in a regular-packing distillation column. Experiments on separation of mixtures of R114/R21 freons were conducted in a Mellapak 350.Y packing of 0.9 m in diameter. Temperature distributions across column cross sections at different heights were obtained. The experimental

AbstractThe presented mathematical model enables calculation of the wave surface profile, as well as the fields of velocity and temperature, in falling wavy liquid films. Numerical simulation of wave formation and heat transfer intensity was performed for falling films of liquid nitrogen. Different activation functions for input perturbations were checked for films with different parameters. The dependencies

AbstractThis experimental and numerical work explains why a vortex breakdown bubble first emerges and then disappears as the fluid rotation speeds up. To this end, we explore a flow in a sealed cylindrical container with one end disk rotating and all other walls stationary. The rotation drives the meridional circulation: the fluid filling the container moves away from the rotating disk along the sidewall

AbstractThis paper presents the results of measurement and calculation within an upgraded Zuber model of critical heat flux (CHF) during nucleate boiling in thin horizontal layers of liquid. The layer height was increased in regimes of developed nucleate boiling. The two-phase layer was foam with vapor columns ascending at the corners of a rectangular square lattice. In the calculations, the foam was

AbstractThe investigation is focused on the phenomenon of heat transfer deterioration (HTD), inhibiting the use of supercritical fluids in the processes in which high-power local heat release is possible. The ordinary discussion is based solely on the data of quasi-stationary measurements. In order to clarify the intrinsic nature of HTD as an essentially non-stationary phenomenon, it is worthwhile

AbstractThe title of this paper echoes the title of a paragraph in the famous book by Frisch on classical turbulence. In the relevant chapter, the author discusses the role of the statistical dynamics of vortex filaments in the fascinating problem of turbulence and the possibility of a breakthrough in constructing an advanced theory. This aspect arose due to the large amount of evidence, both experimental

AbstractThe thermal conductivity of cerium in the solid and liquid states, including the phase transition, in the temperature range of 293–1800 K was measured for the first time by the laser-pulse method with an accuracy of 2–5%. Comparison of the results with the available literature data was made. Data for the 293–400 K temperature range were obtained for the first time. Reference tables on the thermal

AbstractAspire of this study is to study the effect of heat source, suction/injection, and chemical reaction on dissipative and radiative MHD flow of a Casson fluid over an exponentially permeable stretching sheet. Series solutions are obtained for converted non-dimensional ordinary differential equations using an analytical technique known as the homotopy analysis method (HAM). A decisive approach

AbstractThe article presents the results of a comprehensive fundamental numerical study of the problem of conjugate mixed convection with surface radiation from a vertical electronic board with multiple different discrete heat sources. The governing equations for the fluid flow and heat transfer, which are considered in their full strength, are transformed from a primitive variable form to a strea

AbstractThe paper presents the results of investigation of the products of oxidation of sludge-lignin (waste from the Baikal pulp and paper mill) in H\(_{2}\)O/O\(_{2}\) mixture in the autoclave and semi-flow modes at uniform heating of the reactor up to 750 K. The time dependencies of the reactor wall temperature and the power of ohmic heaters imply that the oxidation starts at 440 K and the maximum

AbstractThe article presents an improved numerical method developed for calculating turbulent flows basing on the algorithm SIMPLE, Rhie–Chow interpolation on non-staggered grids, and monotonic second and third order accurate TDV schemes. The use of high-order difference schemes for calculation of viscous flows enables achievement of significantly better resolution of the algorithm on coarse grids

AbstractThis work presents a numerical study of incompressible, laminar, two-dimensional, mixed convection flows in horizontal channels with two rectangular alternated blocks mounted in the surfaces. The influence of the geometry and positioning of the blocks on the heat transfer rate is evaluated using Constructal Design. The problem is subjected to two geometric constraints associated with the areas

AbstractAt present, electronic systems are thermally designed on the basis of the assumption that all the parameters and factors that determine the thermal processes are fully known and unambiguously determined, id est, that they are determinate. However, the practice of creation and operation of real electronic systems shows that the real values of determining parameters and factors, as well as the

AbstractThe conjugated temperature distributions of a microchannel fluid flow between two semi-infinite parallel plates are obtained analytically. The variables separation and transformation techniques are implemented to introduce the degenerate hypergeometric differential equation, the solution of which is given in terms of Kummer’s functions. The eigenvalues of the corresponding transcendental characteristic

AbstractA new approach for modeling chemical processes in industrial column apparatuses is presented. An exact approach for solving the equations in the convective type models is used. The use of experimental data for the average concentration at the column end for a specific process and column makes it possible to find out model parameters related with radial non-uniformity of velocity. These parameters

The results of modeling of flow structure, air bubble distribution over the pipe cross section, and heat transfer in a vertical polydispersed gas-liquid flow are presented. Themathematical model is based on the Euler description with allowance for the back effect of bubbles on the averaged characteristics and turbulence of the carrier phase. The polydispersity of two-phase flow is described by the

The shape of the liquid-liquid coexistence line in the phase diagram of a lithium-sodium system is determined using the gamma-ray attenuation technique. The measured coordinates of the critical point of the coexistence curve (critical temperature TC = 576.8 ± 1.0 K; critical composition XC= 35.9 ± 0.4 at. % Na) are in good agreement with the data in the literature. The critical exponent β for the coexistence

The paper presents the results of experimental study on characteristics of non-boiling multi-jet water cooling. Experimental data on the characteristics of droplet jets including the distribution of droplets sizes and their velocity, as well as liquid irrigation patterns on a transparent heating surface, were obtained using high-speed visualization. The surface temperature field of the thin-film ITO

The solvent extraction technology is a promising method for recovery of unconventional oil resources because of its high efficiency, low energy consumption, and high compatibility. Solvent selection and solvent loss are the main limitations in terms of industrialization of the technology. To evaluate the solvent, efficient detection of the residual solvent content in the extracted-oil gangue is also

Gas turbines (GTs) are thermal machines used to transform the energy released in combustion with a hydrocarbon into mechanical power, in order to drive a machine or generate thrust in aircraft. The critical issue in the GT design are the parts exposed to extreme mechanical and thermal conditions, e.g., the first row of turbine blades. The GT thermal efficiency is limited by the maximum temperature

It is experimentally shown that diverging nozzles with a cone angle of 12o -14° and a length of 10-15 mm provide the finest atomization of metastable superheated liquid with a submicron droplet fraction at a level of 65-70%.

This article presents values of heat transfer coefficients at pool boiling of aqueous solution of lithium bromide on smooth and fin tubes. The experimental studies were performed under conditions typical of absorption chiller with single-stage desorption. More exactly, the condensation pressure was about 7.8–8.5 kPa, and the concentration of lithium bromide solution was 60–61 wt%. The outer diameter

The well-known description of hydrodynamic instability of planar interfacial boundary at liquid combustion is applied to analysis of stability of a stationary analytical solution for the shape of the phase interface during propagation of self-sustaining evaporation front along a flat heater in superheated liquid. The applicability of the criterion of hydrodynamic instability of planar interphacial

This investigation discusses the effects of first order chemical (generative/destructive) reaction on the transport in a species of variable mass conductance in a Williamson liquid of variable diffusion coefficient. The problem is modeled using conservation laws with temperature dependent variable diffusion coefficients models. Several numerical experiments are carried out to analyze the effects of

MHD flow of an electrically conducting Newtonian fluid over a super linear stretching sheet in the presence of suction/injection and Navier slip is studied using modified Adomain decomposition method (MADM) and Padé approximants. Governing nonlinear partial differential equations are transformed into nonlinear ordinary differential equations using an appropriate similarity transformation. The transformed

Methods of calculating the motion of melt over the surface of fuel element in accident conditions are presented. The calculation is performed using mathematical modeling methods. The results of calculating the melt motion and solidification on the fuel pin surface at various vapor flow velocities and for various types of fuel are shown.

Problem statementThis study investigates the relationship between heating and humidity of silica sand materials in vibrating drying machines. Hence, a prototype of drying plant for one-meter length is designed, including choosing the parameters of the drying machine and computing the factors that affect drying process in addition to studying materials’ characteristics and hot air flow effect. ApproachStudying

A practical approach is implemented for thermal stresses in an axisymmetric thin annular fin, made of functionally graded material. All material properties of the annular fin are assumed to be graded along the fin radius as a power-law function. A linear differential equation is derived to be the governing equation. Analytical solution of such equations except for simple grading functions is difficult

Generation of the power on low earth orbit satellites remains based particularly on photogeneration (solar cells), whereas other sources of energy, such as heat, remain unexploited. Indeed, exchange of heat is considered generally on board spacecraft as hostile, destructive and undesirable, thereby different means are used to reduce its effect on board spacecraft. Heat being an important source of

Although the unique liquid behavior renders structured corrugation SiC foam packing (SCFP-SiC) a great alternative in distillation, the separation efficiency depends heavily on capacity and liquid property. The aim of this work is to discuss the change of flow pattern with miscellaneous liquids at different flow rates in order to explain the performance of SCFP-SiC in a distillation column. The ultraviolet

The paper presents results of an experimental study of separation efficiency and distribution of flow parameters over the cross section of the distillation columns. The experiments were carried out on the large-scale research setup “Large Freon Column” with diameter of packing of 0.6 m and 0.9 m. The mixture of refrigerants R114 and R21 was used as the working liquid at a pressure of 3 bar in the column

In this research we experimentally investigated the process of liquid hydrocarbon combustion at spraying by a jet of superheated steam, using waste automobile transmission oil as an example. In the laboratory burner model (up to 20 kW) we studied the effect of mode parameters on the characteristics of the combustion process in the presence of superheated steam, namely, heat release and composition

In this paper, a detailed investigation on MHD flow over a porous stretching sheet was conducted by taking power-law heat flux and heat source into account. Series solutions are achieved for the reduced nondimensional ordinary differential equations by admitting an analytical technique known as a homotopy analysis method (HAM). A precise way of convergence of series solutions is also furnished. The