Jet Ignition for Super-Efficient Power Generation and Propulsion

poster abstractJet Ignition for Super-Efficient Power Generation and Propulsion Global environmental concerns and energy price hikes compel more efficient transport and power generation with disruptively different technologies. Wave rotor technology developed at IUPUI employs new combustion and ignition processes that develop high pressure and increased power resulting in enormous energy and cost savings. The wave rotor combustor (WRC) uses pressure wave compression and confined combustion in multiple rotating chambers. For ignition, partially combusted gas in a transient jet from a pre-chamber penetrates and ignites the main chamber lean mixture, over multiple ignition points. This intense ignition overcomes mixture non-uniformity and improves efficiency and emission. Chemically active radicals and fast turbulent mixing in the jets create an explosion two orders more energetic than a spark. Jet ignition offer the advantage of fast ignition and rapid complete combustion of leaner and stratified mixtures, mitigate heat losses to the walls and minimize pollutant emissions, while enabling higher engine efficiency

Wave Rotor Combustor Aerothermodynamic Design and Model Validation

poster abstractWave Rotor Combustor Aerothermodynamic Design and Model Validation based on Initial Testing. Tests of combustion in a wave-rotor constant-volume combustor (WRCVC) provided a demonstration of the potential of pressure-gain combustion using a wave rotor. Experimental data showed good agreement with numerical model predictions, validating the aerothermodynamic design of the combustor and the numerical model used. A time-dependent, one-dimensional gas dynamic and combustion model used for design of the WRCVC is shown to capture major features and trends of the measured gas dynamic and combustion processes. Experimental test cases with different configurations are shown and the results are analyzed and compared to the numerical simulations to calibrate the numerical model. Simulations discussed in the paper illustrate the likely explanations for test cases with and without evidence of combustion, and give insights into spillage during the filling process and mixture requirements for consistent torch ignition

Assessment of Combustion Modes for Internal Combustion Wave Rotors

Combustion within the channels of a wave rotor is examined as a means of obtaining pressure gain during heat addition in a gas turbine engine. Three modes of combustion are assessed: premixed autoignition (detonation), premixed deflagration, and non-premixed autoignition. The last two will require strong turbulence for completion of combustion in a reasonable time in the wave rotor. The autoignition modes will require inlet temperatures in excess of 800 K for reliable ignition with most hydrocarbon fuels. Examples of combustion mode selection are presented for two engine applications

Longitudinally Stratified Combustion in Wave Rotors

A wave rotor may be used as a pressure-gain combustor, effecting wave compression and expansion, and intermittent confined combustion, to enhance gas-turbine engine performance. It will be more compact than an equivalent pressure-exchange wave-rotor system, but will have similar thermodynamic and mechanical characteristics. Because the allowable turbine blade temperature limits overall fuel-air ratio to subftammable values, premixed stratification techniques are necessary to burn hydrocarbon fuels in small engines with compressor discharge temperatures well below autoignition conditions. One-dimensional, nonsteady numerical simulations of stratified-charge combustion are performed using an eddy-diffusivity turbulence model and a simple reaction model incorporating a flammability limit temperature. For good combustion efficiency, a stratification strategy is developed that concentrates fuel at the leading and trailing edges of the inlet port. Rotor and exhaust temperature profiles and performance predictions are presented at three representative operating conditions of the engine: full design load, 40% load, and idle. The results indicate that peak local gas temperatures will cause excessive temperatures in the rotor housing unless additional cooling methods are used. The rotor temperature will be acceptable, but the pattern factor presented to the turbine may be of concern, depending on exhaust duct design and duct-rotor interaction

Thermodynamic Limits of Work and Pressure Gain in Combustion and Evaporation Processes

Combustion and evaporation processes occurring in a closed chamber can result in significant pressure rise and direct work transfer. The pressure and volumetric changes that accompany such processes allow substantial work potential to be achieved in cyclic nonsteady devices, such as internal combustion engines and pulsed combustion or detonation engines. The ideal pressure gain or work production is a function of the prescribed inflow and outflow conditions, volumetric confinement, fluid properties, and other parameters. The generalized thermodynamic limits of pressure gain and work production in such devices are investigated. Analytic and iterative methods are provided to evaluate cyclic combustion and evaporation processes for enhancing airbreathing combustion engine performance

Pressure-Gain Combustion Clean Efficient Jet Engines and Power Plants

poster abstractThe gas turbine has been an enormously successful power plant for aircraft and marine propulsion, and electric power generation, due to its light weight, smooth and reliable operation, low emissions, and varied applications. Nevertheless, it is not very efficient in converting fuel energy to useful work, due to fundamental thermodynamic limitations imposed by turbomachinery technology. I am investigating potential alternative thermodynamic cycles and pulsed combustion systems for propulsion and gas turbine applications, developing a key new component called a wave rotor combustor

Image findings of cranial nerve pathology on [18F]-2- deoxy-D-glucose (FDG) positron emission tomography with computerized tomography (PET/CT): a pictorial essay.

This article aims to increase awareness about the utility of (18)F -FDG-PET/CT in the evaluation of cranial nerve (CN) pathology. We discuss the clinical implication of detecting perineural tumor spread, emphasize the primary and secondary (18)F -FDG-PET/CT findings of CN pathology, and illustrate the individual (18)F -FDG-PET/CT CN anatomy and pathology of 11 of the 12 CNs

Electronic properties of thin phosphor films

Electronic properties of thin films of zinc silicate phosphor (Zn(_2)SiO(_4):Mn-willemite) prepared by a high temperature reaction between evaporated films of silicon monoxide and zinc fluoride, have been studied using metal electrodes. The samples were made using precise control of cleanliness and processing conditions. Silica substrates gave mechanical defects in sputtered films of platinum used as the base electrode for the thin film samples. This was due to the thermal mismatch between the two materials and it led to erratic conduction results. These defects do not occur using highly polished sapphire substrates with which reproducible characteristics have been obtained. Aluminium top contacts having a diameter of 0.04 cm were used both on the willemite films and on a section of the oxide for a comparison of their current-voltage characteristics. A few other electrode metals were also used. The high temperature bake in oxygen used for the formation of the willemite also makes the oxide films more resistive and increases their breakdown strength. With platinum top contacts such films show bulk limited Poole-Frenkel type of conduction, but with aluminium, strong polarity dependence is shown. This is explained by the presence of a thin film of aluminium oxide, believed to form under the metal with the particular fabrication techniques used. The willemite films were very brightly cathodoluminescent at thicknesses down to about 200 Ǻ. Some thicker films also showed very weak but reproducible d.c. electroluminescence. In the conditions used, the willemite forms, leaving a considerable thickness of unreacted oxide underneath. Conduction features of these films were generally similar to those of the oxide, and they have been explained by a simple band model. Electroluminescence is believed to arise due to the tunnelling of electrons through the aluminium oxide layer. The results of the work may have applications in the development of a further thin film display device

Guided Tour in a Civil Law Library: Sources and Basic Legal Materials in French Civil and Commercial Law

Lawyers everywhere rely upon their books with eagerness and confidence. The larger their libraries, the better equipped they feel to answer the questions of their clients. The composition of an average library differs somewhat in France and in the United States. In this country the law reports, in their familiar, substantial and elegant bindings, are displayed on the prominent shelves, while in Europe, the law reports-often merely paper bound-are relegated to some corner. The front place is reserved for the leather bindings and the gilt letters of the treatises bearing the names of outstanding authors in the various fields of the law. It could be said that a law library reflects the legal system of a given country. The patient labor required of a European lawyer to understand the American system of law is, in a sense, but a long journey during which he finds, step by step, an answer to the wonders which surrounded him when first visiting an American law library. The same is certainly true for the American lawyer who desires to learn something about another system of law. Extensive research on the meaning and the content of the books seen on the shelves of a foreign law library will be required

Numerical Study of Stratified Charge Combustion in Wave Rotors

A wave rotor may be used as a pressure-gain combustor effecting non-steady flow, and intermittent, confined combustion to enhance gas turbine engine performance. It will be more compact and probably lighter than an equivalent pressure-exchange wave rotor, yet will have similar thermodynamic and mechanical characteristics. Because the allowable turbine blade temperature limits overall fuel/air ratio to sub-flammable values, premixed stratification techniques are necessary to burn hydrocarbon fuels in small engines with compressor discharge temperature well below autoignition conditions. One-dimensional, unsteady numerical simulations of stratified-charge combustion are performed using an eddy-diffusivity turbulence model and a simple reaction model incorporating a flammability limit temperature. For good combustion efficiency, a stratification strategy is developed which concentrates fuel at the leading and trailing edges of the inlet port. Rotor and exhaust temperature profiles and performance predictions are presented at three representative operating conditions of the engine: full design load, 40% load, and idle. The results indicate that peak local gas temperatures will result in excessive temperatures within the rotor housing unless additional cooling methods are used. The rotor itself will have acceptable temperatures, but the pattern factor presented to the turbine may be of concern, depending on exhaust duct design and duct-rotor interaction