Temperature distribution in a subduction zone

A model of the thermal and hydrodynamic structure of the subduction zone is proposed. This model includes free convection flows in the asthenospheric layer and layer C (mantle transition zone). Temperature profiles in the subducting lithospheric plate, as well as in the continental limb of the subduction zone, are presented. The heat flux due to friction at the contact between the subducting plate and the continental limb significantly affects the heat transfer and, consequently, the temperature field formation in the subduction zone. The temperature level in the crustal layer of the submerging plate implies that there is no melting in the crustal layer.

Experimental study of the local structure of a bubble flow in a flat channel with sudden expansion

The hydrodynamic structure of the flow in a flat channel with sudden expansion was studied at constant flow rates of liquid and gas in the vertical flow at Re = 6600 and gas content β = 0.03. The measurements were carried out using the PLIF method; and with this view, fluorescent particles for PIV studies and the dye Rhodamine G were added to distilled water. An optical threshold filter was installed on the lens of the video camera. When processing images to obtain data on the local gas content, only bubbles falling into the plane of the laser beam were considered (the boundary glows, casting a shadow).

Improving the dimensioning of closed collecting and drainage network of drainage systems

Research relevance. Climatic changes determine the need to ensure a high productivity of drained lands through the use of appropriate adaptive measures for regulating and accumulating moisture in the soil. Therefore, the issue of changing approaches to the creation and operation of water reclamation facilities on drained lands gains relevance. Relevant are also changes in the methodology of projects for drainage systems construction and reconstruction and their optimal design solutions (type, design, systems parameters, and components of their technical elements) in the closed collecting and drainage network. In this case, the closed collecting and drainage network is a key element of the drainage system, which can operate in the drainage and soil moisture regime. Aim of the study is to reveal new approaches to improving the methods of dimensioning the closed collecting and drainage network of drainage systems operating in the regime of drainage and soil moisture, based on justifying the relationship and considering the impact of network efficiency on the efficiency of water regulation on drained lands. Research methods. The analysis and generalization of the existing researches and methods on justification of the type, design, and parameters of the closed collecting and drainage network in the regime of drainage and soil moisture of the drained lands is executed. Systems approach and systems analyses were used to determine the existence of a structural relationship between the operation regime of the closed collecting and drainage network and the water regime of the drained lands. In performing the theoretical research, methods of mathematical modeling of the hydrodynamic structure of turbulent flow in pressure pipes using Navier-Stokes differential equations were applied. To confirm the adequacy of the obtained analytical models, the methods of statistical processing of experimental research results by Nikuradze I., Shevelyov F.O., and Altshul A.D. were used. Research findings and main conclusions. Thus, based on the performed theoretical and experimental research, we have proposed relatively new scientific positions in contrast to the semi-empirical theories for determining the hydrodynamic structure of the flow in the pressure pipe. This allows for dimensioning the entire hydrodynamic structure for all areas of the turbulent flow based on the application of the obtained universal equations. That is, we can construct a distribution profile of the total turbulent kinematic viscosity, averaged velocity, tangential stresses, and angular velocities of fluid particles. Prospects. The presented approach will make it possible to determine the efficiency of flow in drainage pipes and in a closed collecting and drainage network. Also, this approach will further be helpful in improving the methods of designing and dimensioning technological and structural parameters of the network and ensuring the overall technical, technological, economic, and environmental efficiency of drainage systems.

Study of structure of flows of a technological apparatus using the theory of random functions

The object of research is the structure of flows in the absorber of hydrogen chloride. One of the most problematic areas in the study of flow hydrodynamics in chemical-technological devices are both technological and technical difficulties, when the device is exposed to random disturbances and/or the supply of a standard indicator is impossible due to a violation of the technological regulations. A method for studying the hydrodynamic structure of flows in a shelf absorber of hydrogen chloride of the «Korobon-KA» type (Germany) in the normal operation of a chemical apparatus using the theory of random functions is proposed. An industrial experiment was carried out on the operating equipment to determine the input and output concentrations of the components of the gas flow. The absorber of hydrogen chloride is considered as a one-dimensional object, at the input of which a random function acts – the concentration of hydrogen chloride in the input stream, and at the output there is a random variable – the concentration of hydrogen chloride in the output stream. The method for determining hydrogen chloride and chlorine in a gas stream is based on the absorption of chlorine by a solution of potassium iodide, followed by titration of the released iodine with sodium thiosulfate. In parallel, portions of acid were sampled at the inlet and outlet, and then the density and temperature of the hydrochloric acid solutions were determined. An algorithm for calculating the impulse function estimates is developed. The obtained experimental data are smoothed. As a result of processing the experimental data, autocorrelation and cross-correlation functions were obtained, the Wiener-Hopf equation was solved, and the impulse weight function was obtained. Having calculated the moments of the obtained impulse weight function, it was proved that the structure of flows in the «Korobon-KA» absorber can be satisfactorily described by the ideal displacement model. The calculations were carried out in software environments MathCAD, Matlab. According to the results obtained, the proposed method for determining the hydrodynamic structure of flows will find application in the study of chemical-technological devices, when the object is exposed to random disturbances and the supply of a standard indicator is impossible due to violation of technological regulations. This makes it possible to find the parameters of flow hydrodynamics in the apparatus in the mode of its normal operation.

Particle Image Velocimetry Method for Prediction Hydrodynamic Conditions during Leaching Process on the Basis of Sn–NaOH System

In leaching processes controlled by diffusion and convectional transport of mass, the hydrodynamic structure formed in the reactor’s working volume is an additional factor affecting the process. This research work presents results related to hydrodynamic structures developing in batch reactors, different in shape, recorded by means of the particle image velocimetry (PIV) method. The movement of the distilled water and leaching solution was analyzed during investigations. Next, the system hydrodynamics and the process of tin leaching were analyzed. Finally, the leaching is affected by the reactor geometry and the hydrodynamic structure developed in its working volume, especially when a convectional or diffusion mass transport decides the process efficiency.

The Effects of Curved Blade Turbine on the Hydrodynamic Structure of a Stirred Tank

This work is aimed at studying the hydrodynamic structure in a cylindrical stirred vessel equipped with an eight-curved blade turbine. Flow fields were measured by two-dimensional particle image velocimetry (PIV) to evaluate the effect of the curved blade turbine. Velocity field, axial and radial velocity distribution, root mean square (rms) of the velocity fluctuations, vorticity, and turbulent kinetic energy were presented. Therefore, two recirculation loops were formed close to the free surface and in the bottom of the tank. Moreover, the highest value area of the vorticity is localized in the upper region of the tank which follows the same direction of the first circulation loop. The turbulent kinetic energy is maximum at the blade tip following the trailing vortices.

Performance of a Generic 4-Step Global Reaction Mechanism With Equilibrium Effects for Detonation Applications

A reduced 4-species, 4-step Global Reaction Mechanism (GRM) [1], derived from detailed chemistry using a thermochemical approach, is investigated for three different reactive mixtures. The trade-off between preciseness of Elementary Reaction Mechanisms (ERMs), and low computational overhead requirements of GRMs remains a dilemma in the application of chemical kinetic models to detonation problems. Reducing a reaction mechanism often compromises the chemical details, and reduces the scope of applicability of the derived model. This is largely due to the mixture chemistry having a vital influence on several key aspects of the detonation phenomenon like initiation, quenching, and the dynamics of the wave front and hydrodynamic structure during propagation. For detonation problems in particular, there has been an insufficient replication of the complex reality of the phenomenon through numerical simulations which has lead to a constant demand for more accurate and affordable models. Three separate stoichiometric combustion mixtures are investigated, each involving acetylene, methane, or propane mixed with oxygen. Each mixture exhibits very different global activation energies, heat release, and ignition characteristics.