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Full-Text Articles in Engineering
Aerodynamics Inside A Rapid Compression Machine, Gaurav Mittal, Chih-Jen Sung
Aerodynamics Inside A Rapid Compression Machine, Gaurav Mittal, Chih-Jen Sung
Dr. Gaurav Mittal
The aerodynamics inside a rapid compression machine after the end of compression is investigated using planar laser-induced fluorescence (PLIF) of acetone. To study the effect of reaction chamber configuration on the resulting aerodynamics and temperature field, experiments are conducted and compared using a creviced piston and a flat piston under varying conditions. Results show that the flat piston design leads to significant mixing of the cold vortex with the hot core region, which causes alternate hot and cold regions inside the combustion chamber. At higher pressures, the effect of the vortex is reduced. The creviced piston head configuration is demonstrated …
Autoignition Of Methylcyclohexane At Elevated Pressures, Gaurav Mittal, Chih-Jen Sung
Autoignition Of Methylcyclohexane At Elevated Pressures, Gaurav Mittal, Chih-Jen Sung
Dr. Gaurav Mittal
Autoignition of methylcyclohexane (MCH) is investigated in a rapid compression machine (RCM). Experiments are conducted for homogeneous MCH/O2/N2/Ar mixtures with equivalence ratios varying from 0.5 to 1.5, at compressed charge pressures of 15.1 and 25.5 bar, and over a compressed gas temperature range of 680–905 K. In the RCM experiments, the mole percentage of MCH is kept constant at 1.047%, while the equivalence ratio is varied through variation in oxygen mole percentage. Ignition delay measurements demonstrate the features of two-stage ignition characteristics and strong negative temperature coefficient (NTC) behavior. The NTC behavior is also noted to …
Autoignition Of Toluene And Benzene At Elevated Pressures In A Rapid Compression Machine, Gaurav Mittal, Chih-Jen Sung
Autoignition Of Toluene And Benzene At Elevated Pressures In A Rapid Compression Machine, Gaurav Mittal, Chih-Jen Sung
Dr. Gaurav Mittal
Autoignition of toluene and benzene is investigated in a rapid compression machine at conditions relevant to HCCI (homogeneous charge compression ignition) combustion. Experiments are conducted for homogeneous mixtures over a range of equivalence ratios at compressed pressures from 25 to 45 bar and compressed temperatures from 920 to 1100 K. Experiments varying oxygen concentration while keeping the mole fraction of toluene constant reveal a strong influence of oxygen in promoting ignition. Additional experiments varying fuel mole fraction at a fixed equivalence ratio show that ignition delay becomes shorter with increasing fuel concentration. Moreover, autoignition of benzene shows significantly higher activation …
Ignition Delay Study Of Moist Hydrogen/Oxidizer Mixtures Using A Rapid Compression Machine, Apurba Das, Chih-Jen Sung, Yu Zhang, Gaurav Mittal
Ignition Delay Study Of Moist Hydrogen/Oxidizer Mixtures Using A Rapid Compression Machine, Apurba Das, Chih-Jen Sung, Yu Zhang, Gaurav Mittal
Dr. Gaurav Mittal
Autoignition of moist hydrogen/oxidizer mixtures has been studied experimentally using a rapid compression machine (RCM). This work investigated the effect of water addition on ignition delays of stoichiometric hydrogen/oxidizer mixtures in the end of compression temperature range of TC = 907–1048 K at three different end of compression pressures viz. PC = 10 bar (1 MPa), 30 bar (3 MPa), and 70 bar (7 MPa). RCM experiments were conducted with 0%, 10%, and 40% molar percentages of water in the reactive mixture. At PC = 30 bar and 70 bar, the presence of 10% and 40% water vapor was shown …
An Aerosol Rapid Compression Machine For Studying Energetic-Nanoparticle-Enhanced Combustion Of Liquid Fuels, Casey Allen, Gaurav Mittal, Chih-Jen Sung, Elisa Toulson, Tonghun Lee
An Aerosol Rapid Compression Machine For Studying Energetic-Nanoparticle-Enhanced Combustion Of Liquid Fuels, Casey Allen, Gaurav Mittal, Chih-Jen Sung, Elisa Toulson, Tonghun Lee
Dr. Gaurav Mittal
The use of energetic nanoparticles offers a promising means of adjusting the reactivity of liquid fuels for enhanced combustion stability in next generation propulsion systems. This work outlines the development of a novel aerosol rapid compression machine (RCM) for studying the impact of energetic nanoparticles on reducing the ignition delay of liquid fuels, and a proof-of-concept demonstration is presented using ethanol and JP-8. Fuel droplets are generated using an ultrasonic nozzle. The seeding of 50 nm aluminum nanoparticles in the liquid fuel is achieved by using a combination of chemical surfactants in addition to mixing in an ultrasonic bath. The …
Autoignition Of Ethanol In A Rapid Compression Machine, Gaurav Mittal, Sinead Burke, Varun Davies, Bikash Parajuli, Wayne Metcalfe, Henry Curran
Autoignition Of Ethanol In A Rapid Compression Machine, Gaurav Mittal, Sinead Burke, Varun Davies, Bikash Parajuli, Wayne Metcalfe, Henry Curran
Dr. Gaurav Mittal
Ethanol is a renewable source of energy and significant attention has been directed to the development of a validated chemical kinetic mechanism for this fuel. The experimental data for the autoignition of ethanol in the low temperature range at elevated pressures are meager. In order to provide experimental data sets for mechanism validation at such conditions, the autoignition of homogeneous ethanol/oxidizer mixtures has been investigated in a rapid compression machine. Experiments cover a range of pressures (10–50 bar), temperatures (825–985 K) and equivalence ratios of 0.3–1.0. Ignition delay data are deduced from the experimental pressure traces. Under current experimental conditions …