scholarly journals The Experience of Non-Stationary Flow Visualization Using the Hydrogen Bubble Method

2019 ◽  
pp. 60-70
Author(s):  
S.M. Krivel ◽  
I.O. Bobarika
Keyword(s):  
Research Methods ◽  
Gas Flow ◽  
Stationary Flow ◽  
Experimental Models ◽  
Experimental Equipment ◽  
Incident Flow ◽  
Kinematic Parameters ◽  
Physical Processes ◽  
Hydrogen Bubbles ◽  
Design Construction

The study of the spectra of flow is carried out by experimental methods. The paper summarizes the authors’ experience in the design, construction and use of hydrodynamic installations for the visualization of liquid or gas flow using hydrogen bubbles obtained by electrolysis of water. The design of a vertical hydrodynamic pipe, the technology of making experimental models, the design and purpose of the main equipment are considered. Research methods and procedures are described. The article presents the results of the studies that make it possible to evaluate the capabilities of the experimental equipment and picture physical processes around the bodies that change the kinematic parameters of motion in the incident flow according to a given law. The proposed research methods and experimental equipment are distinguished by originality. They can be used to study the features of macrostructures around bodies of complex geometric shapes and laws of motion.

Modeling and Calculation of Initial Ignition Gas Pressure Flow through the Rigid Porous Media in 100 mm Ignition Simulator

2012 ◽  
Vol 560-561 ◽  
pp. 1103-1113
Author(s):  
Zheng Gang Xiao ◽  
Wei Dong He ◽  
San Jiu Ying ◽  
Fu Ming Xu
Keyword(s):  
Porous Media ◽  
Gas Flow ◽  
Ceramic Composite ◽  
Peak Position ◽  
Chamber Pressure ◽  
Lateral Side ◽  
Physical Processes ◽  
Local Permeability ◽  
Pressure Peak ◽  
Flow Through

To acquire better understanding of the early ignition phenomena in 100mm ignition simulator loaded with packed propellant bed, a theoretical model of ignition gas flow through rigid porous media is developed. Three pressure gauges are installed in the lateral side of ignition simulator for chamber pressure measurements after ignition. The pseupropellant loaded in the chamber is similar to the standard 13/19 single-base cylindrical propellant in size. It is composed of rigid ceramic composite with low thermo conductivity. It is assumed that the pseupropellant bed is rigid in contrast to the previous elastic porous media assumption. The calculated pressure values can be verified by the experimental data well at the low loading density of pseupropellant bed of 0.18 g/cm3. However, there is still error between the experimental and calculated results in the early pressure peak position close to the ignition primer when the loading density of pseupropellant bed increases to 0.73 and 1.06g/cm3, due to the change of local permeability of pseupropellant bed at high loading density, which is assumed a constant in the model for the modeling easily. The calculations can enable better understanding of physical processes of ignition gas flow in the ignition simulator loaded with the pseupropellant bed.

scholarly journals Features of the device, the design and use of experimental equipment for the study of elements of brake systems, chassis timber

2017 ◽  
Author(s):  
А.С. Лоренц ◽  
Д.Г. Мясищев
Keyword(s):  
Traffic Safety ◽  
Frictional Contact ◽  
Experimental Equipment ◽  
Physical Processes ◽  
Performance Requirements ◽  
Power Loading ◽  
And Performance ◽  
Forced Cooling ◽  
Wheel Brake ◽  
Oscillatory Processes

Статья посвящена обзору конструкции экспериментального оборудования для исследования тормозных систем. С повышением интенсивности движения и общего веса лесотранспортных систем возрастают требования к эффективности и безопасности торможения. Тягово-скоростные и тормозные свойства лесотранспортных машин связаны между собой. Чем выше скорость движения машины, тем эффективнее должны быть ее тормозные свойства. Следовательно, безопасность движения и производительность в большей мере зависят от тормозных свойств лесотранспортной машины. Кроме того, существует целая гамма внутризаводского самоходного оборудования (погрузчики, штабелеры и т. п.), где вопросы безопасности маневрирования также непосредственно связаны с эффективностью действия компонентов тормозных систем и, в частности, колесных тормозных механизмов. Существующие тормозные механизмы имеют ряд недостатков, устранение которых приводит к повышению надежности и увеличению ресурса тормозных устройств, что, в свою очередь, определяет безопасность движения колесных транспортно-технологических машин. В решении этих задач большое значение имеют совершенствование и создание тормозных устройств и механизмов, исследование их тепловой и силовой нагруженности, колебательных процессов основных деталей, естественного и принудительного охлаждения фрикционных пар, а также исследования, направленные на повышение эффективности действия тормозов. Рассматривается экспериментальная установка, имитирующая работу тормозных механизмов с подводом сжатого воздуха в область их фрикционного контакта. Оборудование позволит более точно всесторонне исследовать и проанализировать физические процессы торможения колеса лесопромышленных самоходных шасси и лесовозных автомобилей. This article provides an overview of the structure of experimental equipment for the study of brake systems. With an increase in traffic and the total weight forest system performance requirements increase and the safety brake. Tow speed and braking properties forest machines linked. The higher the speed of movement of the machine, the more effective it must be inhibitory properties. Therefore, traffic safety and performance in more dependent on inhibitory properties forest machine. In addition, there is a whole range of in-plant mobile equipment (forklifts, stackers, etc.), where the maneuvering security is also directly related to the efficiency of the brake system components, and in particular the wheel brake. Existing brakes have a number of shortcomings, the removal of which leads to higher reliability and increased life of brake devices, which in turn determines the safety of movement of wheeled transport and technological machines. In solving these problems is very important improvement and the creation of braking devices and mechanisms, the study of their thermal and power loading, the basic details of oscillatory processes, natural and forced cooling friction couples, as well as research aimed at improving the effectiveness of the brakes. In this paper the experimental setup simulates the work of the brakes with a supply of compressed air into the region of the frictional contact. The equipment will allow more accurate comprehensive explore and analyze the physical processes of braking wheel self-propelled chassis and timber haulage vehicles.

scholarly journals Parallel implementation of multiscale approach to the numerical study of gas microflows

2016 ◽  
pp. 147-165
Author(s):  
В.О. Подрыга ◽  
С.В. Поляков
Keyword(s):  
Gas Flow ◽  
Parallel Implementation ◽  
Numerical Study ◽  
Domain Decomposition Method ◽  
Three Dimensional ◽  
Multiscale Approach ◽  
Gas Flows ◽  
Physical Processes ◽  
Gas Microflows ◽  
Complex Technical Systems

Статья посвящена параллельной реализации многомасштабного подхода для расчета течений газов в микроканалах сложных технических систем. Многомасштабный подход сочетает решения уравнений квазигазодинамики (КГД) и молекулярной динамики (МД). Представлена параллельная реализация подхода, основанная на методах расщепления по физическим процессам и разделения областей. Реализация ориентирована на использование вычислительных систем с центральной и гибридной архитектурами. Разработанные параллельные алгоритмы обладают хорошей масштабируемостью. Полученные результаты подтвердили эффективность разработанного подхода. С его помощью методами МД были получены основные коэффициентные зависимости для КГД-системы, произведен расчет трехмерного течения. This paper is devoted to a parallel implementation of multiscale approach to the numerical study of gas flows in microchannels of complex technical systems. The multiscale approach combines the solutions of quasigasdynamic (QGD) equations and molecular dynamics (MD) equations. The proposed parallel implementation of this approach is based on the method of splitting into physical processes and the domain decomposition method. The implementation is oriented for using computer systems with central and hybrid architectures. The developed parallel algorithms show a good scalability. The obtained results confirm the efficiency of the approach under consideration. This approach was used to find the basic coefficient dependences for the QGD system by MD methods and to study a three-dimensional gas flow numerically.

Computation of Decaying Wall-Stabilized Arcs

1973 ◽  
Vol 28 (3-4) ◽  
pp. 443-453 ◽  
Author(s):  
W. Hermann
Keyword(s):  
Constant Temperature ◽  
Level Scheme ◽  
Numerical Stability ◽  
Gas Flow ◽  
Free Variable ◽  
Electric Arc ◽  
Radial Coordinate ◽  
Physical Processes ◽  
Time Step ◽  
Insight Into

AbstractThe interaction between an electric arc and a gas flow is governed by the flow of mass relative to surfaces of constant temperature. This fact is used to introduce a new method for the computation of decaying wall-stabilized arcs in which the temperature is used as a free variable instead of the radial coordinate. The method is also applicable to more general cases and gives direct insight into the physical processes involved. An implicit two level scheme is described which guarantees numerical stability for any chosen time step. The method is applied to a decaying wall stabilized arc. The results agree quite well with published experimental curves.

scholarly journals Análise noturna dos mecanismos que controlam os gradientes de CO2 e H2O em uma região costeira

2020 ◽  
Vol 42 ◽  
pp. e22
Author(s):  
Maria Eduarda Oliveira Pinheiro ◽  
Otávio Costa Acevedo ◽  
Pablo Eli Soares de Oliveira
Keyword(s):  
Gas Flow ◽  
Thermal Power ◽  
Physical Processes ◽  
Eddy Covariance Method ◽  
Transfer Processes ◽  
The North ◽  
Carbon Transfer ◽  
Adequate Representation ◽  
Dew Deposition ◽  
Different Levels

Understanding the water and carbon exchange in the soil-atmosphere system and the mechanisms that control these exchanges are fundamental to have a real and adequate representation of the physical processes involved. Under stable night conditions, carbon transfer processes such as respiration and water transfer processes such as dew deposition are more difficult to study by the eddy covariance method. Thus, the aim of this study is to investigate the mechanisms that control the exchange of water and carbon dioxide near a thermal power plant and the ocean, through the gradients of concentration of these quantities at different levels in the atmosphere. Data from the experimental site located in Linhares - ES - Brazil (19° 31'53 "S, 39° 48'03" W), 4 km from the coast and about 250 m from Linhares Geração SA thermeletric, were used. The concentrations of CO2 and H2O are measured by the AP200-Campbell system, which consists of vertically arranged chambers that pull gas flow at the following levels 1, 2, 5, 9, 15 and 20 m. In this study, a total of 67 nights (from 9 pm to 5 am), from 2017, were selected. The wind direction was from the north so that there was no interference from the thermal plant's feathers in the data analysis.

Mathematical modelling of the agglomeration in a reactive porous medium with variable permeability

2020 ◽  
Author(s):  
И.Г. Донской
Keyword(s):  
Gas Flow ◽  
Fixed Bed ◽  
Three Dimensional ◽  
Waste Incineration ◽  
Stationary Flow ◽  
Melting Rate ◽  
Variable Permeability ◽  
Exponential Behaviour ◽  
Bed Agglomeration ◽  
Fuel Particles

При переработке низкосортных твердых топлив, таких как отходы и биомасса, часто возникают проблемы, связанные с агломерацией. В работе предложен один из вариантов модели спекания, в которой локальная проницаемость изменяется при нагреве из-за физико-химического процесса (плавления), а центры агломерации (частицы плавящегося материала) случайным образом распределяются в двумерной пористой среде. Относительно простая модель позволяет исследовать развитие термогидродинамических неоднородностей в участке пористой среды и оценивать его гидравлическое сопротивление при разной доле расплавленного материала. Thermal processing of waste is usually carried out in fixed-bed reactors. Complex thermochemical behavior of individual components can lead to a decrease in technical and environmental efficiency. One of the problems is the bed agglomeration and formation of zones with decreasing permeability. The paper proposes a method of numerical simulation of porous media with physicochemical processes, which change permeability. Initial formulation proposes this process to be considered as melting of distributed particles in a stochastic media. The melting rate is controlled by heating of the selected element, and its local permeability changes during a phase transition. To solve this problem, numerical algorithm is developed on the basis of splitting methods. This algorithm was used to find a solution for system of non-stationary partial differential equations in two-dimensional case. The data on multiple calculations for different configurations are averaged to compare modelling results. The simulation results show that increasing the fraction of particles of the melting component leads to the significant change of the dynamic and stationary filtration regimes. The reduction in stationary flow rate is exponential function of the fraction of the melting particles. The dynamics of gas flow is also sensitive to the melting particles fraction, within the range of 510 there is a rather sharp transition from a gradual (almost linear) decrease of flow in time to a sharp one, which is close to exponential behaviour. The resulting calculations for the critical fraction are compared with the measured data published for the case of combustion of mixtures with sintering fuel particles (polymers). Further work will address the modification of the model to describe waste incineration, namely, taking into account the pyrolysis and oxidation processes, three-dimensional formulation, etc.

scholarly journals Radio Astronomical and Radiophysical Studies in the Near-Earth Space in the Radiophysical Research Institute

2013 ◽  
Vol 22 (1) ◽  
Author(s):  
S. D. Snegirev ◽  
N. V. Bakhmetieva ◽  
N. A. Dugin ◽  
A. N. Karashtin ◽  
V. P. Uryadov
Keyword(s):  
Research Methods ◽  
Experimental Investigations ◽  
Experimental Equipment ◽  
Radiophysical Research Institute ◽  
Earth Space ◽  
Near Earth Space ◽  
Equipment Development ◽  
Research Institute

AbstractThe paper describes possibilities of the experimental investigations of the near-Earth space by the facilities of the Radiophysical Research Institute at Nizhny Novgorod. We describe the experimental equipment, development of the research methods and some recent results.

Plasma Spraying of Zirconia Coatings

1989 ◽  
Vol 155 ◽  
Author(s):  
D. J. Varacalle ◽  
G. R. Smolik ◽  
G. C. Wilson ◽  
G. Irons ◽  
J. A. Walter
Keyword(s):  
Gas Flow ◽  
Analytical Study ◽  
Numerical Models ◽  
Fractional Factorial ◽  
Spray Parameters ◽  
X Ray Diffraction ◽  
Physical Processes ◽  
Particle Injection ◽  
Carrier Gas Flow ◽  
Temperature And Flow Fields

ABSTRACTAs part of an investigation of the dynamics that occur in the plume of a thermal spray torch, an experimental and analytical study of the deposition of yttria-stabilized zirconia has been accomplished. Experiments were conducted using a Taguchi fractional factorial design. Nominal spray parameters were: 900 A, 36 kW, 100 scfh argon primary gas flow, 47 scfh helium secondary gas flow, 11.5 scfh argon powder carrier gas flow, 3.5 lb/h powder feed rate, 3 in. spray distance, and an automated traverse rate of 20 in./s. The coatings were characterized for thickness, hardness, and microstructural features with optical microscopy, scanning electron microscopy, and x-ray diffraction. Attempts are made to correlate the features of the coatings with the changes in operating parameters. Numerical models of the physical processes in the torch column and plume were used to determine the temperature and flow fields. Computer simulations of particle injection (10 to 75 μm zirconia particles) are presented.

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