ТЕМПЕРАТУРНІ РЕЖИМИ ЗОН ЗВОРОТНИХ ТОКІВ У БЛИЖНЬОМУ СЛІДІ ЦИЛІНДРИЧНИХ СТАБІЛІЗАТОРІВ ПОЛУМ'Я

The results of experimental studies of the temperature regimes of the back flow zones behind the cylindrical flame stabilizers of microjet burners are presented. The authors have considered a burner device, which is a circular channel with a cylindrical stabilizer placed in it. Circular openings for feeding fuel gas (propane-butane) into the blowing air flow off are located in a circle on the stabilizer. To determine the sizes of the back flow zones in the regions astern of the stabilizer, a method of visualizing the flow using sodium salts was used. The temperature measurement in the back flow zone was carried out by the chromel-alumel thermocouple. The regularities of the influence on the length of the back flows zones and the temperatures in these zones of such regime parameters of the combustion process as the value of the air flow velocity at the inlet to the channel and the air excess coefficient are analysed. Particular attention is paid to the study of the features of the change in the heat state and the length of the back flow zones as a function of the magnitude of the relative pitch of disposition of the gas-supply openings. An increase in the relative pitch of the gas-supplying openings and the air excess coefficient is shown to lead to a decrease in the length of the back flow zones, and an increase in the airflow velocity, on the contrary, increases this length. The influence of the relative pitch of disposition of the gas is noted to supply openings related to the fact that its growth leads to an increase in the injecting action of the fuel gas jets, which consists in a greater attraction of ambient air to the fuel jets. This in turn leads to an additional increase in the degree of rarefaction in the back flows zone beyond the stabilizer, and then to a decrease in the length of this zone. The dependence of the length of the back flow zone on the magnitude of the relative pitch of the gas supply openings is observed to be significant only at relatively high values of the air excess coefficient. With an increase in this pitch and the air-flow velocity, the maximum values of the temperatures are defined to increase. An increase in the air excess coefficient is considered to lead to a drop in maximum temperatures in the back flows zone. The results of the completed studies can be used in energy practice in the design of burner devices for fuel combustion equipment with relatively low power, when it is necessary to ensure the uniformity of heat supply over the fire space.Наведено результати експериментальних досліджень теплового стану мікрофакельних пальникових пристроїв з циліндричними стабілізаторами полум'я. Встановлено особливості формування температурних режимів і геометричних характеристик зон зворотних токів у закормовій ділянці циліндричних стабілізаторів. Проаналізовано закономірності впливу конструктивних і режимних чинників на основні параметри процесу спалювання в розглядуваних пальникових пристроях. Наведено дані щодо залежності довжини зон зворотних токів у закормових ділянках циліндричних стабілізаторів полум'я та величини температур у них від таких режимних параметрів процесу спалювання, як величина швидкості потоку повітря на вході в канал і коефіцієнт надлишку повітря. Встановлено, що зі збільшенням швидкості повітряного потоку протяжність зони зворотних токів зростає, вплив же коефіцієнта надлишку повітря має протилежний характер: довжина зони зворотних токів і рівень температур у них зменшуються зі зростанням коефіцієнта надлишку повітря. Певну увагу приділено дослідженню особливостей зміни теплового стану і протяжності зон зворотних токів за стабілізаторами полум'я від величини відносного кроку розташування газоподавальних отворів. Зазначено, що з огляду на інжектуючу дію струмин паливного газу відбувається скорочення довжини зон зворотних токів зі збільшенням вказаного відносного кроку

PHARMACOEPIDEMIOLOGICAL MONITORING OF ANTIDEPRESSANT USAGE IN PATIENTS WITH ANXIOUS AND DEPRESSIVE SYNDROMES IN INTERNAL MEDICINE

Aim. To study antidepressant usage in treatment of anxious and depressive disorders in real internal medicine practice.Material and methods. Retrospective analysis of 290 charts of patients, which were observed in Pskov region hospital from 2004 to 2005 was held. All patients suffered from different internal diseases and were treated with antidepressants because of anxious and depressive concomitant disorders.Results. Arterial hypertension observed in 28% of patients, ischemic heart disease – in 20%, heart failure – in 14%, cerebrovascular and peripheral nervous system diseases – in 18% and gastroduodenal diseases – in 20% of patients. Amitriptyline took the first place (49%) among antidepressant prescriptions. Next antidepressants according to prescription popularity were paroxetine (22%) and tianeptine (12%). Rate of other antidepressant prescriptions were not higher than 5%. There were differences in antidepressant prescriptions between physicians of different specialties.Conclusion. Reasonable approaches should be used to choose antidepressants. Selective serotonin reuptake inhibitors have benefit for the therapy of concomitant anxious and depressive disorders due to their good tolerability. Nevertheless tricyclic antidepressants are essential in some clinical situations

PHARMACOEPIDEMIOLOGICAL MONITORING OF ANTIDEPRESSANT USAGE IN PATIENTS WITH ANXIOUS AND DEPRESSIVE SYNDROMES IN INTERNAL MEDICINE

Aim. To study antidepressant usage in treatment of anxious and depressive disorders in real internal medicine practice.Material and methods. Retrospective analysis of 290 charts of patients, which were observed in Pskov region hospital from 2004 to 2005 was held. All patients suffered from different internal diseases and were treated with antidepressants because of anxious and depressive concomitant disorders.Results. Arterial hypertension observed in 28% of patients, ischemic heart disease – in 20%, heart failure – in 14%, cerebrovascular and peripheral nervous system diseases – in 18% and gastroduodenal diseases – in 20% of patients. Amitriptyline took the first place (49%) among antidepressant prescriptions. Next antidepressants according to prescription popularity were paroxetine (22%) and tianeptine (12%). Rate of other antidepressant prescriptions were not higher than 5%. There were differences in antidepressant prescriptions between physicians of different specialties.Conclusion. Reasonable approaches should be used to choose antidepressants. Selective serotonin reuptake inhibitors have benefit for the therapy of concomitant anxious and depressive disorders due to their good tolerability. Nevertheless tricyclic antidepressants are essential in some clinical situations

Компьютерное моделирование течения в микрофакельных горелочных устройствах с асимметричной подачей топлива

This article is devoted to the mathematical modeling of the isothermal flow in microjet burner devices with asymmetric jet supply of fuel by the introduction into the flow of an oxidizer. The studies were conducted on the basis of CFD modeling using the Ansys Fluent software. The Detached Eddy Simulation (DES) method, which is a hybrid approach, was used, in which Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models are switched in different subregions of the computational domain. Particular attention in this article is paid to the comparative analysis of the flow characteristics in the presence and absence of flaps installed on the end surface of the flame stabilizers. According to the results of computer predictions, it is shown that, the flow pattern in the burner device changes significantly in the presence of flaps. These changes are also defined to be associated primarily with the formation of vortex structures in the region located behind the stern of the flame stabilizers. The analysis of the effect of flap length on different flow characteristics was performed. An increase in the flap length is shown to lead to a significant increase in the length of the reverse flow zone behind the flame stabilizer. This length is proved to exceed the flap length the greater, the shorter the flap. The features of the velocities distribution within the zone of reverse flows for various values of the flap length are revealed. The analysis of the fields of root-mean-square pulsations of velocity in the considered physical situations was carried out. The subregions corresponding to the highest levels of these pulsations are defined to be located near the boundary of the zone of reverse currents remote from the end of the flame stabilizers. The highest level of these velocity pulsations is revealed to meet the conditions for the absence of flaps on flame stabilizers. Some prospects for further research consist primarily in the analysis of the flow structure in the burner devices considering the conditions of reacting flows. Moreover, the study of the regularities of the mixing of fuel and oxidant is of considerable interest, as well as the burning out of fuel and the formation of temperature fields in the combustion zone.Выявлены основные закономерности изотермического течения топлива и окислителя в микрофакельном горелочном устройстве с односторонней подачей топлива. Получены данные компьютерного моделирования с использованием подхода DES (Detached Eddy Simulation), представляющего собой комбинацию моделей RANS (Reynolds Averaged Navier-Stokes) и LES (Large Eddy Simulation) в разных областях пространства. Установлены эффекты влияния длины закрылка, расположенного на торцевой поверхности стабилизаторов пламени, на различные характеристики течения. Показано, что наличие закрылков приводит к существенному изменению вихревой структуры в следе за стабилизаторами. Оценено влияние длины закрылков на такие параметры течения, как протяженность зоны обратных токов в закормовой области стабилизаторов пламени, уровень среднеквадратичных пульсаций скорости в данных зонах и пр. Установлено, что с увеличением длины закрылков существенно возрастает протяженность зоны обратных токов за стабилизатором. Выявлено также, что чем короче закрылки, тем больше превышает их длину протяженность зоны обратных токов. Выполнен анализ пространственного распределения пульсаций скорости в рассматриваемом горелочном устройстве при наличии и отсутствии закрылков на торцевых поверхностях стабилизаторов пламени. Показано, что наиболее высокий уровень данных пульсаций наблюдается вблизи границы зоны обратных токов, удаленной от торца стабилизатора. Установлено, что уровень среднеквадратичных пульсаций скорости является наиболее высоким в условиях отсутствия закрылка и снижается при увеличении его длины