The shock-acoustic waves generated by earthquakes

We investigate the form and dynamics of shock-acoustic waves generated by earthquakes. We use the method for detecting and locating the sources of ionospheric impulsive disturbances, based on using data from a global network of receivers of the GPS navigation system and requiring no a priori information about the place and time of associated effects. The practical implementation of the method is illustrated by a case study of earthquake effects in Turkey (August 17, and November 12, 1999), in Southern Sumatera (June 4, 2000), and off the coast of Central America (January 13, 2001). It was found that in all instances the time period of the ionospheric response is 180-390 s, and the amplitude exceeds by a factor of two as a minimum the standard deviation of background fluctuations in total electron content in this range of periods under quiet and moderate geomagnetic conditions. The elevation of the wave vector varies through a range of 20-44 degree, and the phase velocity (1100-1300 m/s) approaches the sound velocity at the heights of the ionospheric F-region maximum. The calculated (by neglecting refraction corrections) location of the source roughly corresponds to the earthquake epicenter. Our data are consistent with the present views that shock-acoustic waves are caused by a piston-like movement of the Earth surface in the zone of an earthquake epicenter.Comment: EmTeX-386, 30 pages, 4 figures, 3 tabl

Improving the technical and environmental performance of piston engines by upgrading the fuel system

The article presents the results of an experimental study of the dispersion of superheated water through cylindrical channels and nozzles of piston internal combustion engines under different initial conditions. The advantages and disadvantages of modern diesel engine fuel systems are discussed in the article. The process of explosive boiling in relation to the fuel system of a piston engine is formulated and briefly described. A description of the laboratory setup and methods of conducting experiments is given in the article. The results of the visualization of sprayed superheated water through a cylindrical channel and through a diesel engine nozzle of 21/21 dimension are presented. The original scheme of the fuel system for a diesel engine using the effect of explosive boiling is proposed. Preliminary estimates have shown that the use of such a fuel system will increase the reliability of the combustion chamber elements of a piston engine, reduce specific fuel consumption (up to 2%) and reduce the amount of harmful substances in exhaust gases (an average of 12% compared with traditional fuel systems). © The Authors, published by EDP Sciences

Complex analysis and statistics of emergency shutdowns of gas turbines at compressor stations

The problems of monitoring the state of the gas compressor station, the main causes of emergency shutdowns, the urgency of measures to extend the life of parts and assemblies, the creation of repair bases near compressor stations are considered. The authors proposes the creation of a program for monitoring the residual resources of parts and assemblies, planning repair, analyzing the parameters of the gas turbine before and after repair, as well as evaluating the effectiveness of its operation.Рассматриваются проблемы мониторинга состояния ГПА, основные причины аварийных остановов, актуальность проведения мероприятий по продлению ресурса деталей и узлов, создание ремонтных баз вблизи компрессорных станций. Авторы предлагают создание программы для мониторинга остаточных ресурсов деталей и узлов, планирования ТОиР, анализа параметров работы ГПА до и после ремонта, а так же оценки эффективности её работы

Enhancement of construction of water chambers of network water heaters of steam turbine for combined heat and energy production

The report explores the possibility of using partitions of network heater chambers as anchor ties and examples of their design are presented. The results of calculations of such chambers are presented. Based on the results of these calculations, it is concluded that using the anchor partitions makes it possible to significantly reduce bending stresses in the bottom and tube plate, reduce the load on the flange connection, use a flat bottom instead of the elliptical one, significantly reduce the longitudinal stresses in the tubes, which increases the life of the most damageable heater element.В докладе рассматривается возможность использования перегородок водяных камер сетевых подогревателей в качестве анкерных связей и примеры их конструктивного исполнения. Приводятся результаты расчетов таких камер. По результатам этих расчетов сделаны выводы, что использование анкерных перегородок позволяет существенно уменьшить изгибные напряжения в днище и трубной доске, уменьшить нагрузку на фланцевое соединение, вместо эллиптического днища использовать плоское, существенно уменьшить продольные напряжения в трубках, что повышает ресурс самого повреждаемого элемента подогревателя

Ansys multiphysics simulation applying for work blade near steam extraction

В статье ставится задача применения междисциплинарного анализа при расчете околоотборных ступеней паровых турбин. На основе опубликованных работ описываются проблемы, которые необходимо решать при расчете и проектировании лопаточного аппарата. Описывается необходимость разработки унифицированной методики прочностного расчета рабочих лопаток околоотборных ступеней.The purpose of this work is ansys multiphysics simulation applying for work blade near steam extraction. The problems that must be addressed in calculation and design of blading describes on the basis of published works. The development applicability of standardized methods of work blade strength calculation is describe

Numercial simulation of flow in a exhaust hood of steam turbine Т-6376-8,8

The paper considers the main stages of modeling process of working fluid in the exhaust hood of a steam turbine T-63/76-8.8. The analysis of calculation results is carried out, the coefficient of total losses is determined, the zones of non-optimal flow are identified.В работе рассматриваются основные этапы моделирования процесса течения рабочего тела в выхлопном патрубке паровой турбины Т-63/76-8,8. Выполняется анализ результатов расчёта, определяется коэффициент полных потерь, выявляются зоны неоптимального течения рабочего тела

Increase steam turbine last stage blades reliability

В работе рассматриваются вопросы надежности существующих конструкций лопаток последних ступеней теплофикационных паровых турбин. Проанализирована статистика поломок лопатки последней ступени паровой турбины Т-250/300-240. Выявлены возможные варианты изменения конструкции с целью увеличения надежности и экономичности данной ступени.The paper deals with the reliability of the existing structures of the blades of the last stages of cogeneration steam turbines. It analyzes the last stage blades failures statistics of the steam turbine T-250 / 300-240. Identified possible design changes in order to increase the reliability and efficiency of this stage

Errors in the demodulation algorithm with a generated carrier phase introduced by the low-pass fi

In this paper, we study the errors of the homodyne demodulation method based on arctangent function solutions (PGCATAN) which are associated with the use of a low-pass filter (LPF) in this signal phase demodulation algorithm. The method of demodulation of an interference signal by PGC-ATAN method is investigated in order to detect and consider in more detail the errors at the filtering stage (the article considers the moving average method), and corrections to the signal are analytically calculated, taking into account the error introduced by the low-pass filter. We obtained formulas for calculating corrections to the signals S1(t), S2(t), S3(t), S4(t) which received by filtering the original signal multiplied by the reference oscillator signal, the calculations were compared with the results of mathematical modeling of the interference signal processing by the PGC-ATAN method. The demodulation of the signal, taking into account the corrections, showed that, in general, the effect on the signal phase is small at a low heating rate, however, for high-speed processes, the error can lead to serious distortions of the desired signal phase. These calculated corrections for processed interference signal will improve the demodulation method based on the calculations of the arc tangent function and more accurately calculate the desired phase of the signal

Modelling fluid dynamics of turbine stages located near steam extraction

The purpose of this work is computational fluid dynamics of turbine stages № 19, 20 located near steam extraction. Design of stages model is described. The main steps of calculations and expected results are presents.Ставится задача проведения газодинамического анализа околоотборного отсека 19-20 ступеней турбины типа Т-100 производства АО «УТЗ». Описывается рассчитываемая модель околоотборного отсека с указанием зон, в которых возможно нарушение равномерного потока. Определяются основные этапы расчеты и ожидаемые результаты