ENVIRONMENTALLY FRIENDLY METHOD OF GASEOUS FUEL COMBUSTION WITH THE USE OF QUASI-OPTICAL MICROWAVE

Subject of Research.The paper deals with the problem of developing low emission combustors operating on natural gas or LPG, to reduce emissions of nitrogen oxides NOx. The possibility of burning very lean fuel mixtures is studied. To initiate the ignition and combustion stabilization the discharge generated by the quasi-optical microwave is used. Main Results. Initiating ignition by streamer microwave discharge increases the rate of combustion and combustion efficiency about four times as compared with the conventional spark ignition. Streamer discharge ignition by very lean fuel-air mixture is demonstrated with the factor of oxiding agent excess greater than the limit of explosive range under normal conditions. According to indirect indicators, ignition by microwave discharge created by quasi-optical radiation is of non-thermal nature. Microwave discharge excites oxygen atoms, and intense ultra-violet radiation is generated as a result that causes formation of cold nonequilibrium plasma with avalanche growth of free electrons. Streamer discharge propagates at a speed of 5 km /s, so the initiation of the ignition occurs immediately throughout. The temperature of the fuel mixture at the point of ignition initiation does not exceed 400 К.There is no area with a temperature sufficient to initiate thermal Zeldovich mechanism of emission of nitrogen oxides. Combustion rate is high. As a result the Fenimore mechanism of "fast nitrogen oxides" has no chance to be progressing, and NOx emissions in appreciable quantities are excluded. Energy costs are comparable with spark ignition.Practical Relevance. The studied technology is designed for low emission internal combustion engines, power gas turbines, gas compressor units, fueled by natural gas

Ignition of premixed air/fuel mixtures by microwave steamer discharge

A variety of methods exists for fast and efficient combustion of air-fuel mixtures. In this study, a microwave subcritical streamer discharge is used to ignite propane-air mixtures at atmospheric pressure. The streamer is initiated at the inner surface of a dielectric tube with the help of a passive half-wave vibrator. By creating a network of ignition lines, the streamer discharge forms the network of burning channels with large total surface area. This leads to the apparent speed of combustion propagation along the cylinder in excess of 100 m/s, which is more than 200 times the laminar flame propagation speed. The axial propagation of the combustion front in a cylindrical tube filled with the air/propane mixture is investigated by high speed video recording in visible light. A simple model is presented to explain observed results

Применение гравитационно-оптического резонанса для регистрации высокочастотных гравитационных волн

The gravitational waves predicted by the general theory of relativity and detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) have typical frequencies in the range of 30 ... 300 Hz. Current theories of gravity predict the existence of high-frequency gravitational waves with frequencies of 10 ... 100 MHz, including those of cosmological origin, induced by quantum fluctuations of the scalar field at the stage of cosmological inflation in the early Universe.Multi-beam optical resonators, in particular the Fabry-Perot interferometers, can be used to detect high-frequency gravitational waves. When using multi-beam optical resonators, it is possible to use the phenomenon of low-frequency optical resonance, which allows us to have a selective response to the gravitational wave effect. The gravitational-optical resonance in a multi-beam interferometer occurs if the condition is fulfilled that an integer number of half-waves of gravitational radiation is along the length of the resonator.The use of a multi-beam interferometer to detect high-frequency gravitational waves does not require the creation of a complex system for decoupling mirrors used for gravitational antennas operating in the low-frequency part of the spectrum. This is due to the fact that the frequency of mechanical vibrations of the interferometer mirrors is significantly less than the frequency of the gravitational wave.The paper considers possible optical schemes of a high-frequency gravitational antenna: based on the traditional Michelson interferometer, in the arms of which two Fabry-Perot interferometers are available, and on the basis of the Mach-Zehnder optical scheme, where Fabry-Perot interferometers can be made in the form of two perpendicular arms, with reflecting mirrors at the bend of the beam. The advantage of the second scheme is that three photo-detectors, one being main and two others being auxiliary, can be used, and there is a possibility to detect radiation transmitted by Fabry-Perot interferometers.To prove that detection of high-frequency gravitational waves is possible, a potential sensitivity of the high-frequency gravitational antenna has been estimated in the paper.Гравитационные волны, предсказанные теорией относительности и зарегистрированные лазерно-интерферометрической гравитационно-волновой обсерваторией (LIGO), имеют характерные частоты в районе 30…300 Гц. Современные теории гравитации предсказывают существование высокочастотных гравитационных волн с частотами 10…100 МГц, в том числе космологического происхождения, индуцированных квантовыми флуктуациями скалярного поля на стадии космологической инфляции в ранней Вселенной.Для регистрации высокочастотных гравитационных волн могут применяться многолучевые оптические резонаторы, в частности интерферометры Фабри-Перо. При применении многолучевых оптических резонаторов возможно использование явления низкочастотного оптического резонанса, которое позволяет получить селективный отклик на гравиволновое воздействие. Гравитационно-оптический резонанс в многолучевом интерферометре возникает, если выполняется условие, что на длине резонатора укладывается целое число полуволн гравитационного излучения.Использование многолучевого интерферометра для регистрации высокочастотных гравитационных волн не требует создания сложной системы развязки зеркал, применяющейся для гравитационных антенн, работающих в низкочастотной части спектра. Это связано с тем, что частота механических колебаний зеркал интерферометра оказывается существенно меньше частоты гравитационной волны.В работе рассмотрены возможные оптические схемы высокочастотной гравитационной антенны: на основе традиционного интерферометра Майкельсона, в плечи которого помещены два интерферометра Фабри-Перо, и на основе оптической схемы Маха-Цендера, где интерферометры Фабри-Перо могут быть выполнены в виде двух перпендикулярных плечей, с отражательными зеркалами в месте излома луча. Преимуществом второй схемы является возможность использования трех фотоприемников, одного основного и двух вспомогательных, и регистрация излучения, прошедшего интерферометры Фабри-Перо.Для подтверждения возможности регистрации высокочастотных гравитационных волн в работе проведена оценка потенциальной чувствительности предлагаемой высокочастотной гравитационной антенны

ON THE POSSIBILITY OF BURNING ACCELERATION IN THE COMBUSTION CHAMBERS OF ADVANCED JET ENGINES BY DEEPLY SUBCRITICAL MICROWAVE DISCHARGE

The paper deals with the problem of increasing the speed of propagation of the flame front as applied to the problems of reducing noxious emissions of nitrogen oxides formed during operation of jet engines and industrial turbines, as well as the stabilization of a supersonic combustion. We investigate the possibility of reducing the induction time using non-equilibrium cold plasma produced by an electromagnetic vibrator in beam quasi-optical MW radiation. The positive effect of cold non-equilibrium plasma on increasing the rate of occurrence of oxidation reactions in the air is well known and undisputed. The presented results of the experiments demonstrate the advantage of the method developed in terms of efficiency and suppression of nitrogen oxide emissions. Also they show that combustion stabilization is achieved similarly in a supersonic flow