Method for determining the characteristics of a gas-steam chp with a steam turbo drive of a compressor

A new type of maneuverable combined-cycle plant with a steam-turbine drive of a low-pressure compressor is considered. The analysis of its technological processes in the generation of electric and thermal energy in heating and non-heating periods of the year is carried out. It is shown that in heating conditions, the burning of additional fuel in the afterburner between the stages of the evaporator of the utilizer boiler provides an increase in its steam production, maneuverability, thermal and electric power of the CCGT-CHP plant. The influence of the chemical composition and thermophysical properties of natural gas on obtaining the required excess air in the combustion chamber of a combined cycle gas turbine is considered. A mathematical model of technological processes is developed. The influence of deep utilization of the heat of the flue gases of the utilizer boiler on increasing the efficiency and improving the environmental characteristics of the gas-steam plant of a thermal power plant was recorded. © 2020 Institute of Physics Publishing. All rights reserved

Применение метода корреляции цифровых изображений для построения диаграмм деформирования в истинных координатах

This article describes the features of determining strain curves in true stress–true strain coordinates, using samples of circular cross section from Al–Cu–Mg–Zn aluminum alloy. The calculation and experimental methods of determining true stresses and strains were compared Calculation methods based on the condition of volume constancy may not reflect actual regularities of deformation at the stage of strain localization in the considered material. Nevertheless, the use of systems of digital image correlation (DIC) allows measurements of both the geometrical sizes of deformed sample and strain fields on its surface to be performed, including on the sample neck. It was demonstrated that the measurement error of the sample diameter by the coordinate field was 0.02 mm at the instance of destruction. In order to improve the measurement precision, an increase in the recording frequency in proportion to increase in strain rate was proposed, as well as measuring the surface coordinates from both sides of the sample. It is also possible to supplement the strain curves obtained by DIC optical systems with the measurements of true fracture stress, and the true fracture strain determined by calculations on the destructed sample. The presented methods of analysis of plastic flow by direct measurement of field displacements and strains allow actual regularities between true stresses and strains at the interval of irregular plastic strain to be established. This cannot be achieved by analytical conversion of conventional curve. The obtained hardening coefficients and strain curves can be used for simulation and design of machinery structures and parts.Приведены особенности определения диаграмм деформирования в координатах «истинное напряжение – истинная деформация» на образцах круглого сечения из алюминиевого сплава системы Al–Cu–Mg–Zn. Выполнено сравнение расчетных и экспериментальных методов определения истинных напряжений и деформаций. Расчетные методы, основанные на применении условия постоянства объема, могут не отражать действительных закономерностей деформирования на этапе локализации деформации в материале исследуемого образца, в то время как использование систем корреляции цифровых изображений (КЦИ) позволяет проводить измерения как геометрических размеров деформируемого образца, так и полей деформаций на его поверхности, в том числе непосредственно в шейке образца. Показано, что ошибка измерения диаметра образца по полю координат в момент разрушения составила 0,02 мм. С целью повышения точности измерения предложено увеличение частоты съемки пропорционально возрастанию скорости деформирования, а также проведение измерения координат поверхности с двух сторон образца. Также возможно дополнять полученные с помощью оптических систем КЦИ кривые деформирования результатами измерения истинного разрушающего напряжения и истинной разрушающей деформацией, определенными расчетным способом по разрушенному образцу. Представленные способы исследования пластического течения материала непосредственным измерением полей перемещений и деформаций позволяют устанавливать действительные закономерности между истинными напряжениями и деформациями на участке неравномерного пластического деформирования, чего достичь аналитическим пересчетом условной диаграммы невозможно. Полученные коэффициенты упрочения и кривые деформирования могут быть использованы при моделировании и проектировании конструкций и деталей машин

Polarization-Sensitive Nonlinear Optical Interaction of Ultrashort Laser Pulses with HPHT Diamond

The filamentation of focused 300 fs laser pulses with variable polarization azimuth in bulk of synthetic HPHT diamond demonstrates the possibility of polarization-dependent bandgap control for crystal dielectric photoexcitation. This directly affects the value of the filamentation threshold power, which exhibits the distinct dependence on the polarization azimuth angle. The nonlinear photoluminescence yield, when focusing ultrashort laser pulses with variable polarization in bulk of the synthetic diamond, indicates different polarization-dependent regimes in the dynamics of electron-hole plasma formation, arising due to different processes of photoexcitation and recombination of free carriers during the filamentation process. Thus, at the onset of the filamentation process, at relatively low intensities, the photoluminescence yield rate depends on polarization azimuth controlling bandgap, while at high intensities the resulting dense absorbing plasma exhibits isotropy with respect to laser radiation polarization, and photoluminescence yield weakly depends on polarization azimuth

Polarization-Sensitive Nonlinear Optical Interaction of Ultrashort Laser Pulses with HPHT Diamond

The filamentation of focused 300 fs laser pulses with variable polarization azimuth in bulk of synthetic HPHT diamond demonstrates the possibility of polarization-dependent bandgap control for crystal dielectric photoexcitation. This directly affects the value of the filamentation threshold power, which exhibits the distinct dependence on the polarization azimuth angle. The nonlinear photoluminescence yield, when focusing ultrashort laser pulses with variable polarization in bulk of the synthetic diamond, indicates different polarization-dependent regimes in the dynamics of electron-hole plasma formation, arising due to different processes of photoexcitation and recombination of free carriers during the filamentation process. Thus, at the onset of the filamentation process, at relatively low intensities, the photoluminescence yield rate depends on polarization azimuth controlling bandgap, while at high intensities the resulting dense absorbing plasma exhibits isotropy with respect to laser radiation polarization, and photoluminescence yield weakly depends on polarization azimuth