Download or read book Experimental Studies of Plasma assisted Ignition and MHD Supersonic Flow Control written by Rodney Meyer and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toward Plasma Assisted Ignition in Scramjets written by and published by . This book was released on 2003 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Air Force plasma ignition program is assessing the prospect of main-fuel ignition with plasma generating devices in a supersonic flow. As the study progresses baseline conditions of operation are being established such as the required operational time of the device to initiate a combustion shock train. The two plasma torches currently under investigation consist of a DC constricted-arc design from the Virginia Polytechnic Institute and State University and an AC unconstricted-arc design based on a modified spark-plug from Polytechnic University. The plasma torches are realistic in size and operate within current power constraints while differing substantially in orifice geometry. In order to compare the potential of each concept the flow physics of each part of the igniter/fuel-injector/combustor system are being studied. In each step of the program, we utilize CFD and experiments to help define and advance the ignition process. To understand the constraints involved with ignition process of a hydrocarbon fuel jet an experimental effort to study gaseous and liquid hydrocarbons is underway, involving the testing of ethylene and JP-7 fuels with nitrogen and air plasmas. Results from the individual igniter studies have shown the plasma igniters to produce hot pockets of highly excited gas with peak temperatures up to (and in some cases above) 5000 K at only 2-kW total input power. In addition ethylene and JP-7 flames with a significant level of OH as determined by OH PLIF were also produced in a Mach-2 supersonic flow with a total temperature and pressure of 590 K and 5.4 atm respectively.

Download or read book Plasma Assisted Combustion and Flameholding in High Speed Cavity Flows written by Joseph Aloysius Heinrichs and published by . This book was released on 2012 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis presents an experimental study of non-equilibrium, low temperature, large volume plasma assisted ignition and flameholding in high-speed, non-premixed fuel-air flows. The plasma is produced between two electrodes powered by a high-voltage, nanosecond pulse generator operated at a high pulse repetition rate. Ignition in this type of plasma occurs due to production of highly reactive radicals by electron impact excitation and dissociation, as opposed to more common thermal ignition. Previously, it has been shown that this type of plasma can reduce ignition delay time and ignition temperature. The experiments performed in this thesis focus on application of these plasmas to ignition, and flameholding in high-speed cavity flows. The experiments discussed in this thesis continue previous work using a high-speed combustion test section with a larger cavity, and the previous results are compared to the present work. Several modifications have been made to the test section and electrodes compared to the design used in previous work in order to reduce the cavity effect on the main flow and maintain diffuse plasma between the electrodes in the cavity. The electrodes used in these experiments are placed in a cavity recess, used to create a recirculation flow region with long residence time, where ignition and flameholding can occur. In order to analyze the nanosecond pulse plasma and the flame, various diagnostics were used, including current and voltage measurements, UV emission measurements, ICCD camera imaging, static pressure measurements, and time-averaged emission spectroscopy. The experiments in this thesis were performed at relatively low pressures (P=150-200 torr) using hydrogen and ethylene fuels injected into the cavity. Current and voltage measurements showed that ~1-2 mJ was coupled to the plasma by each pulse. ICCD imaging and UV emission data revealed that the plasma sustained in quiescent air was diffuse. When ethylene was injected into the cavity to ignite the flow, ICCD imaging and UV emission data showed arcing to bare metal surfaces in the test section occurred shortly after ignition, which prompted switching to hydrogen fuel. Using hydrogen, ICCD imaging and UV emission showed that the plasma remained diffuse and confined to the area between electrodes. Time-average emission spectroscopy measurements revealed that the air-flow temperature remained low until fuel was injected and ignition occurred. Pressure and UV emission measurements were used to find velocity limits within which the flow ignited. It was found that the upper limit of velocity depends strongly on the static pressure in the test section. The highest flow velocity at which combustion was achieved in H2-air flows was 270 m/s at 180 torr. This represents considerable improvement compared to previous work using nanosecond pulse discharge for ignition in cavities. Preliminary results show that plasma generation and ignition are possible using a smaller diameter electrode such that the cavity size can be further reduced, and that a supersonic flow can be produced in the present test section using a Mach 2 nozzle placed upstream of the cavity. The appendix details a study on the production of oxygen atoms using a pulsed excimer laser.

Download or read book Shock Control and Power Extraction by MHD Processes in Hypersonic Air Flow written by and published by . This book was released on 2006 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project was a theoretical and experimental research effort on the use of MHD body forces and plasmas for boundary layer control and power extraction in supersonic flow, and on the development of new diagnostics for plasmas and for high-speed flows. The first part of this final report addresses MHD processes for control and power extraction. This section includes the constricted DC driven "snowplow arc" discharge that can potentially be used to accelerate the boundary layer for suppression of separation, volumetric MHD for power extraction, and volumetric MHD for flow control. In order to accomplish volumetric MHD in cold air, a high repetition rate, short pulse sustainer concept is developed and applied for the first demonstration of power extraction from cold supersonic air. The following section addresses non MHD plasma methods of flow control and power extraction, particularly through the use of a dielectric barrier discharge and through a new pulse sustained thermionic power generator embedded into the hot walls of the vehicle engine. Finally, two new diagnostic methods are introduced in the third section: magnetically modulated microwave attenuation for the measurement of electron number density and electron collision frequency, and Radar REMPI for the localized measurement of flow velocity.

Download or read book Study of Internal and External Plasma Assisted Combustion in Supersonic Gas Flow written by and published by . This book was released on 2005 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Project is devoted to basic study on the field of external and internal plasma assisted combustion. This effort consists of three Tasks: Task #1 is titled "Internal plasma assisted combustion controlled by improved plasma generators in metal channel at conditions similar to Scramjet"; Task #2 is tilted "External plasma combustion experiment in a supersonic flow (Mtilde2, Pst=1 Bar)". This is a study of flow around model F with plasma combustion generator in wind tunnel; Task #3 is tilted "Study of supersonic flow around model E with combined plasma generator (PG Comb= PG HF +E beam)". Here. the main plasma parameters could be changed independently in PG- Comb. Electron concentration will be controlled by E-beam. Electron temperature could be controlled by external HF electric field. The main goals of this work is a study of following: Optimal radical generation in fuel/air mixture and combustion control by non equilibrium plasmoids, Advanced mixture of fuel in gas flow by structural plasmoids.

Download or read book 35th AIAA Plasmadynamics and Lasers Conference 04 2435 04 2743 written by and published by . This book was released on 2004 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 36th AIAA Plasmadynamics and Lasers Conference 05 5037 05 5390 written by and published by . This book was released on 2005 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microwave Driven Air Plasma Studies for Drag Reduction and Power Extraction in Supersonic Air written by and published by . This book was released on 2004 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: Program involving modeling and experiment to explore the utility of plasmas and magnetohydrodynamics (MHD) for aerodynamic applications. Anomalous behavior of shocks on weakly ionized plasmas has been explained in terms of conventional gas dynamics with temperature gradients. Theoretical and computational models have been developed for plasma aerodynamics and nonequilibrium MHD. Models include a new theory of nonequilibrium dissociation and vibrational relaxation and kinetics of plasmas generated by electron beams and high-voltage nanosecond pulses. Aerodynamic steering using plasma energy addition has been explored using the newly developed microwave-driven supersonic plasma wind tunnel. Potential performance of hypersonic MHD devices with electron beam ionization has been outlined. Plasma and MHD control of hypersonic flows and scramjet inlets was studied. On-ramp MHD device with ionization by electron beams was shown to be capable of maintaining the shock-on-lip condition at Mach numbers higher than the design one, while generating net power. For mass capture increase at Mach numbers lower than the design one, a new concept of virtual cowl" was proposed and tentatively studied. In preparation for experimental studies of MHD control of cold-air high-speed flows, ionization by repetitive high-voltage nanosecond pulses was studied theoretically, and a plasma sustained by such pulses was made operational.

Download or read book 41st AIAA Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 2003 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma assisted Combustion in a Supersonic Flow written by Hyungrok Do and published by . This book was released on 2009 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AIAA Aerospace Sciences Meeting and Exhibit 42nd written by and published by . This book was released on 2004 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Supersonic Plasma Flow Control Experiments written by and published by . This book was released on 2005 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: A magneto aerodynamic channel was designed and constructed to investigate plasma flow control. Detailed, spatially resolved measurements of dc discharges in the channel freestream were obtained. The flow exaggerated nonuniformities in number density and conductivity. Conductivity was highest near the cathode, and air flow increased conductivity by 2 orders of magnitude near the cathode, compared to a no-flow discharge. There was no significant increase in translational temperature, except near electrode surfaces. There was some limited evidence of vibrational relaxation downstream. Longitudinal dc discharges were created between surface electrodes on a flat plate. Transverse magnetic fields applied parallel to the plate surface created Lorentz forces either into or out of the plate surface. With no applied magnetic field, the discharge increased surface pressure through boundary layer heating and subsequent viscous interaction. A Lorentz force directed into the plate inhibited surface pressure increases, and a Lorentz force in the opposite direction enhanced them. Although this is consistent with a Lorentz force acting on the fluid, joule heating is the dominant effect.

Download or read book Plasma Induced Ignition and Plasma Assisted Combustion in High Speed Flow written by and published by . This book was released on 2003 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper is dedicated to the experimental demonstration of plasma technology abilities in the field of high speed combustion. It is doing in three principal directions: control of the structure and the parameters of the duct driven flows; the ignition of air fuel composition at low mean gas temperature; and the mixing intensification inflow.

Download or read book Fine Furniture Metalwork Pewter Clocks Sculpture Works of Art and Rugs and Carpets Including the Property of the Late Mr E Van Dam Rotterdam written by and published by . This book was released on 1989 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experiments on Supersonic Plasma Flow Along Magnetic Fields Classic Reprint written by D. Finkelstein and published by Forgotten Books. This book was released on 2017-11-24 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excerpt from Experiments on Supersonic Plasma Flow Along Magnetic Fields It is clear that for an extremely dilute plasma in a strong external field, Alfven perturbation theory provides answers to these questions. However we are here concerned with the domain of parameters in which the plasma flow acts strongly upon the magnetic field. The result is a self -consistent problem and is more difficult. (see however. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

Download or read book Using Plasmas for High speed Flow Control and Combustion Control written by Saurabh Keshav and published by . This book was released on 2008 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Experiments on characterization of Localized Arc Filament Plasma Actuators used for high-speed flow control, as well as experimental studies of chemiluminescence and chemi-ionization for flame emission and combustion control have been discussed. Pulsed DC and pulsed RF actuator discharge power measurements and plasma temperature measurements demonstrated that rapid localized heating, at a rate of 1000 degrees C / 10 us, can be achieved at low time-averaged actuator powers, 10-20 W for 10% duty cycle. Kinetic modeling of a pulsed arc filament demonstrated formation of strong compression waves due to rapid localized heating, which have also been detected in the experiments. The effect of electrons in chemi-ionized supersonic flows of combustion products on flow emission is studied experimentally. For this, a stable ethylene/oxygen/argon flame is sustained in a combustion chamber at a stagnation pressure of P0=1 atm. Electron density in M=3 flow of combustion products has been measured using Thomson discharge. The results show that nearly all electrons can be removed from the flow by applying a moderate transverse electric field. No effect of electron removal on CH and C2 emission from the flow has been detected. Also, electron removal did not affect NO [beta] band and CN violet band emission when nitric oxide was injected into the combustion product flow. Chemi-ionization current measured in the supersonic flows of combustion products has been used for feedback combustion control. The experiments showed that time-resolved chemi-ionization current is in good correlation with the visible emission (CH and C2 bands) in the combustor at unstable combustion conditions, and is nearly proportional to the equivalence ratio at stable combustion conditions. Chemi-ionization current signal from the combustion product flow has been used to control an actuator valve in the fuel delivery line and to maintain the equivalence ratio in the combustor at the desired level.

Download or read book Low temperature Supersonic Flow Control Using Repetitively Pulsed MHD Force written by Munetake Nishihara and published by . This book was released on 2006 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The dissertation presents results of the low-temperature supersonic flow experiments using magneto-hydrodynamic (MHD) interaction. The M=3 flow in test section was ionized by a high voltage, short pulse duration, high repetition rate pulsed discharge. Transverse electric current was sustained by transverse DC discharge with the electric field applied in the direction perpendicular to the magnetic field direction. Flow temperature with and without 1.4 kW DC discharge inferred from the N2 emission spectra was T=180"20 K, indicating that 90% of the input power is stored in the nitrogen vibrational energy mode. Results of flow visualization using Mie scattering, combined with the results of boundary layer density fluctuation spectra measurements using the Laser Differential Interferometry (LDI) diagnostics, suggest that boundary layer turbulent transition occurs at stagnation pressures of P0~200-250 torr. LDI measurements detected an MHD effect on the ionized boundary layer density fluctuations. Retarding Lorentz force produced an increase of the density fluctuation intensity by up to 2 dB, compared to the accelerating force of the same magnitude applied to the same flow. Static pressure measurements in the MHD section showed that a retarding Lorentz force applied to the flow produced a static pressure increase of up to 17-20%, while accelerating force of the same magnitude applied to the same flow resulted in a static pressure increase of up to 5-7%. The fraction of the discharge input power going into Joule heat in nitrogen and dry air, [alpha]=0.1, has been inferred from the present experiments. Results of kinetic modeling of the crossed pulser-sustainer discharge in magnetic field are also presented. The model predictions are compared with the experimental discharge current-voltage characteristics and time-dependent current traces, both in the absence and presence of magnetic field, showing satisfactory agreement. In the presence of magnetic field, the model predicts electron and ion drift due to Lorentz force in the ExB direction. This effect creates a mechanism for the neutral species flow acceleration or deceleration by collisional momentum transfer from the ions to the neutrals. The results of the present work demonstrate feasibility of low-temperature MHD flow control in well-characterized laboratory experiments, for the first time.