The flows structure in unsteady gas flow in pipes with different cross-sections

The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle) in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration. © The authors, published by EDP Sciences, 2017.Thus, in this study it was found that the cross-sectional shape of the pipe has a significant impact on the structure of the gas flow. The secondary flows (steady vortex structures) are formed in pipes with cross sections in the form of a square and an equilateral triangle. Secondary flows (steady vortex structures) in the pipe can stabilize the pulsing flows. This phenomenon can be used in the design of the intake and exhaust systems of energy machines and plants with a view to their gas-dynamic improvement. The work has been supported by the Russian Science Foundation (grant No. 17 -69-00002)

Preparatory stage in the solution of the optimization problem of heat exchange intensification in a tube beam

The influence of the model parameters on the heat transfer processes in transverse flow past a single pipe in convection types is analyzed. Based on the results of the experiments, the optimal mesh model was chosen.В работе исследуется влияние параметров модели на процесс теплообмена при поперечном обтекании одиночной трубы в условиях свободной конвекции. По результатам расчетов была выбрана оптимальная сеточная модель

Simulation of heat transfer under conditions of free motion around a horizontal tube

В работе рассматриваются вопросы численного моделирования теплоотдачи от поверхности горизонтальной трубы в условиях свободной конвекции в неограниченном объеме. Результаты моделирования представлены в сопоставлении с данными теоретического расчета.The paper deals with the issues of numerical simulation of heat transfer from the surface of the horizontal tube under conditions of free convection in the unbounded space. The simulation results are presented in comparison with the theoretical calculations

Weak Wave Turbulence Scaling Theory for Diffusion and Relative Diffusion in Turbulent Surface Waves

We examine the applicability of the weak wave turbulence theory in explaining experimental scaling results obtained for the diffusion and relative diffusion of particles moving on turbulent surface waves. For capillary waves our theoretical results are shown to be in good agreement with experimental results, where a distinct crossover in diffusive behavior is observed at the driving frequency. For gravity waves our results are discussed in the light of ocean wave studies.Comment: 5 pages; for related work visit http://www.imedea.uib.es/~victo

The flows structure in unsteady gas flow in pipes with different cross-sections

The results of numerical simulation and experimental study of the structure of unsteady flows in pipes with different cross sections are presented in the article. It is shown that the unsteady gas flow in a circular pipe is axisymmetric without secondary currents. Steady vortex structures (secondary flows) are observed in pipes with cross sections in the form of a square and an equilateral triangle. It was found that these secondary flows have a significant impact on gas flows in pipes of complex configuration. On the basis of experimental researches it is established that the strong oscillatory phenomena exist in the inlet pipe of the piston engine arising after the closing of the intake valve. The placement of the profiled plots (with a cross section of a square or an equilateral triangle) in the intake pipe leads to the damping of the oscillatory phenomena and a more rapid stabilization of pulsating flow. This is due to the stabilizing effect of the vortex structures formed in the corners of this configuration

Influence of gas flow turbulence scale on heat exchange intensity in a long smooth pipe

It is known that the initial level of gas flow turbulence has a noticeable effect on the development and structure of the boundary layer and on the intensity of heat transfer, respectively. Many scientists have evaluated the influence of the flow turbulence number on the level of heat transfer for various applications, among them Dyban E.P., Kestin J., Simonich JC, Isomoto K., Dreitser G.A., Terekhov V.I., MacMullin R. and etc. In all cases, the turbulence of the flow led to the intensification of heat transfer. However, insufficient attention is paid to studies of the effect of turbulence on the heat transfer of flows in pipes. The studies were carried out on the basis of numerical modeling of gas dynamics and heat transfer of stationary flows based on the CFD method. The results of numerical modeling to assess the influence of the turbulence scale of gas flows on heat transfer in a long smooth pipe are presented in the article. It has been established that a growth in the heat transfer coefficient by about 3% occurs with an increase in the turbulence scale from 10 to 30% with a Reynolds number equal to 250,000. © Published under licence by IOP Publishing Ltd.The work has been supported by the Russian Science Foundation (grant No. 18-79-10003)

Pathomorphological talc-containing of change in the internal at intravenous drugs

The results of the study materials autopsy in 3 comparison groups and the control group. In individuals who died from morphine poisoning, talc-containing anisotropic crystals were found in 97.1%, while the second group (young people who have died from infectious diseases, mainly HIV) infection in 92,7%. In group 3 (young men who died mainly from trauma) and in the control group (children aged under 5 years), these changes were not identified. The features of histotopographic distribution and size of crystals in various organs during chronic intravenous drug abuse. It is noted that the identification of anisotropic crystals in the internal organs, primarily in the lungs, liver and spleen is an affordable and reliable method postmortem morphological diagnosis of chronic intravenous drug abuse. Talc-containing crystals were detected more often than giant cell granuloma at them, subject to the adequate application of polarization microscopy.В работе приведены результаты исследования материалов аутопсий в 3 группах сравнения и в контрольной группе. У лиц, умерших от отравления морфином, тальк-содержащие анизотропные кристаллы выявлены в 97,1%, а во второй группе (молодые люди, умершие от инфекционных заболеваний, преимущественно ВИЧ-инфекция) в 92,7%. В группе 3 (молодые люди, погибшие преимущественно от травм) и в контрольной группе (дети в возрасте до 5 лет) указанные изменения не выявлены. Показаны особенности гистотопографического распределения и размеров кристаллов в различных органах при хронической интравенозной наркомании. Констатируется, что выявление анизотропных кристаллов во внутренних органах, прежде всего, в легких, печени и селезенке является доступным и достоверным методом посмертной морфологической диагностики хронической интравенозной наркомании. Тальк-содержащие кристаллы выявляются гораздо чаще, нежели гигантоклеточные гранулемы на них, при условии адекватного применения поляризационной микроскопии

Cell block method in morphologic diagnostics of tumorous pleura lesions studied on the material of pleural fluid

In the article there have been estimated the resources of cell block method by having conducted an immunocytochemical research for further morphologic diagnostics of tumorous pleura lesions studied on the material of pleural fluid. During the research pleural fluid of patients with unilateral tumorous pleura lesions was studied with cell block method. Cell blocks were studied with immunocytochemical method and there were verified metastases of lung adenocarcinoma in pleura and mesothelioma. The results of the research have proved diagnostic significance of cell block method that improves quality of morphologic diagnostics of tumours of various localizations and provides conducting a valuable immunocytochemical research without using methods of “explosive” fixation that is especially valued when it is impossible to get histological material.В статье оценены возможности метода цитоблока с проведением иммуноцитохимического исследования для морфологической диагностики опухолевого поражения плевры на материале плевральной жидкости. В ходе работы методом цитоблока исследована плевральная жидкость больных с односторонним опухолевым поражением плевры. На материале цитологических блоков выполнено иммуноцитохимическое исследование и диагностированы метастазы аденокарциномы легкого в плевре и мезотелиома. В результате проведенного исследования доказана диагностическая значимость метода цитоблока, повышающего качество морфологической диагностики опухолей различных локализаций с возможностью проведения полноценного иммуноцитохимического исследования, не прибегая к методам «взрывной» фиксации, что особенно ценно при невозможности получения гистологического материала

Morphological diagnosis of intravenous addicts autopsy dead patients with HIV infection

The pathological examination materials 89 autopsies TSPAO Sverdlovsk regional traffic for 2015. Along with the standard procedures used microscopy studies of drugs in polarized light. The frequency of detection of morphological signs of chronic intravenous drug-addiction - CIA (angiogenic talcosis) in the formulations was 39.3% (35 cases). Target organs for angiogenic talcosis are the lungs, liver and spleen. The features of the location and the size of the anisotropic crystals in the tissues of these organs. Method for detection of anisotropic crystals of talc in the tissues and organs of deceased patients with HIV infection should be recommended for the diagnosis of morphological objectification CIA in these cases.Проведено патоморфологическое исследование материалов 89 аутопсий ЦПАО Свердловского областного ПТД за 2015 год. Наряду со стандартными методиками исследования использовали микроскопию препаратов в поляризованном свете. Частота морфологического выявления признаков хронической интравенозной наркомании (ХИН) в виде ангиогенного талькоза в препаратах составила 39,3% (35 случаев). Органами-мишенями для ангиогенного талькоза являются легкие, печень и селезенка. Описаны особенности локализации и размеры анизотропных кристаллов в тканях указанных органов. Метод выявления анизотропных кристаллов талька в тканях и органах умерших больных ВИЧ-инфекцией следует рекомендовать для морфологической объективизации диагноза ХИН в этих случаях

HIV and tuberculosis by data gained from pathologic anatomy autopsy

The study based on results of retrospective analysis ot autopsies of 264 HIV cases. The increasing amount of autopsies in HIV cases combinated with tuberculosis was shown according to data given by specialized phthiziopulmonological pathologic anatomy department.Several epidemiological and pathomorphological features of mycobacterial infections, as secondary nosology in HIV/ AIDS cases, were detected. Predominance of generalized forms of tuberculosis with lymphohematogenous progression, potential of development and morphological features of non-tuberculosis mycobacterial infections in above spelled cases were demonstrated and especially attention paid on measures for staff protection during autopsy in modern epidemiological conditions.В работе приведены результаты ретроспективного анализа 264 аутопсийных случаев с ВИЧ-инфекцией. Показан существенный рост числа аутопсий при ВИЧ-инфекции в сочетании с туберкулёзом по данным патологоанатомических вскрытий специализированного фтизио-пульмонологического отделения. Выявлены некоторые эпидемиологические, патоморфологические особенности микобактериальных инфекций, выступающих в качестве вторичных заболеваний при ВИЧ/СПИД. Показано преобладание генерализованных форм туберкулеза с лимфо-гематогенным прогрессированием, возможность развития и морфологические особенности микобактериальных инфекций нетуберкулезной природы в этих случаях, а также обращается внимание на меры защиты медперсонала при проведении аутопсий в современных эпидемиологических условиях