Alternative Pulse Detonation Engine Ignition System Investigation Through Detonation Splitting PDF Download
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Author: August J. Rolling
Publisher:
ISBN: 9781423511281
Category : Detonation waves
Languages : en
Pages : 115
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Book Description
A Pulse Detonation Engine (PDE) combusts fuel air mixtures through a form of combustion: detonation. Recent PDE research has focused on designing working subsystems. This investigation continued this trend by examining ignition system alternatives. Existing designs required spark plugs in each separate thrust tube to ignite premixed reactants. A single thrust tube could require the spark plug to fire hundreds of times per second for long durations. The goal was to minimize hardware and increase reliability by limiting the number of ignition sources. This research used a continuously propagating detonation wave as both a thrust mechanism and an ignition system and required only one initial ignition source. This investigation was a proof of concept for such an ignition system. First a systematic look at various geometric effects on detonations was made. These results were used to further examine configurations for splitting detonations, physically dividing one detonation wave into two separate detonation waves. With this knowledge a dual thrust tube system was built and tested proving that a single spark could be used to initiate detonation in separate thrust tubes. Finally, a new tripping device for better deflagration to detonation transition (DDT) was examined. Existing devices induced DDT axially. The new device attempted to reflect an incoming detonation to initiate direct DDT in a cross flow.
Author: August J. Rolling
Publisher:
ISBN: 9781423511281
Category : Detonation waves
Languages : en
Pages : 115
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Book Description
A Pulse Detonation Engine (PDE) combusts fuel air mixtures through a form of combustion: detonation. Recent PDE research has focused on designing working subsystems. This investigation continued this trend by examining ignition system alternatives. Existing designs required spark plugs in each separate thrust tube to ignite premixed reactants. A single thrust tube could require the spark plug to fire hundreds of times per second for long durations. The goal was to minimize hardware and increase reliability by limiting the number of ignition sources. This research used a continuously propagating detonation wave as both a thrust mechanism and an ignition system and required only one initial ignition source. This investigation was a proof of concept for such an ignition system. First a systematic look at various geometric effects on detonations was made. These results were used to further examine configurations for splitting detonations, physically dividing one detonation wave into two separate detonation waves. With this knowledge a dual thrust tube system was built and tested proving that a single spark could be used to initiate detonation in separate thrust tubes. Finally, a new tripping device for better deflagration to detonation transition (DDT) was examined. Existing devices induced DDT axially. The new device attempted to reflect an incoming detonation to initiate direct DDT in a cross flow.
Author: Jiun-Ming Li
Publisher: Springer
ISBN: 3319689061
Category : Technology & Engineering
Languages : en
Pages : 246
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Book Description
This book focuses on the latest developments in detonation engines for aerospace propulsion, with a focus on the rotating detonation engine (RDE). State-of-the-art research contributions are collected from international leading researchers devoted to the pursuit of controllable detonations for practical detonation propulsion. A system-level design of novel detonation engines, performance analysis, and advanced experimental and numerical methods are covered. In addition, the world’s first successful sled demonstration of a rocket rotating detonation engine system and innovations in the development of a kilohertz pulse detonation engine (PDE) system are reported. Readers will obtain, in a straightforward manner, an understanding of the RDE & PDE design, operation and testing approaches, and further specific integration schemes for diverse applications such as rockets for space propulsion and turbojet/ramjet engines for air-breathing propulsion. Detonation Control for Propulsion: Pulse Detonation and Rotating Detonation Engines provides, with its comprehensive coverage from fundamental detonation science to practical research engineering techniques, a wealth of information for scientists in the field of combustion and propulsion. The volume can also serve as a reference text for faculty and graduate students and interested in shock waves, combustion and propulsion.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 13
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Book Description
A Pulse Detonation Engine (PDE) combusts a fuel air mixture through detonation. Existing designs require spark plugs in each separate thrust tube to ignite premixed reactants. A single thrust tube could require the spark plug to fire hundreds of times per second for long durations. This paper reports on the use of a continuously propagating detonation wave as both a thrust producer and a single ignition source for a multi-tube system. The goal was to minimize ignition complexity and increase reliability by limiting the number of ignition sources. The work includes a systematic investigation of single tube geometric effects on detonations. These results were subsequently used to further examine conditions for splitting detonations i.e. the division of a detonation wave into two separate detonation waves. Einally a dual thrust tube system was built and tested that successfully employed a single spark to initiate detonation in separate thrust tubes.
Author: Robert B. Driscoll
Publisher:
ISBN:
Category :
Languages : en
Pages : 241
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Book Description
An experimental study is conducted on a Pulse Detonation Engine-Crossover System to investigate the feasibility of repeated, shock-initiated combustion and characterize the initiation performance. A PDE-crossover system can decrease deflagration-to-detonation transition length while employing a single spark source to initiate a multi-PDE system. Visualization of a transferred shock wave propagating through a clear channel reveals a complex shock train behind the leading shock. Shock wave Mach number and decay rate remains constant for varying crossover tube geometries and operational frequencies. A temperature gradient forms within the crossover tube due to forward flow of high temperature ionized gas into the crossover tube from the driver PDE and backward flow of ionized gas into the crossover tube from the driven PDE, which can cause intermittent auto-ignition of the driver PDE. Initiation performance in the driven PDE is strongly dependent on initial driven PDE skin temperature in the shock wave reflection region. An array of detonation tubes connected with crossover tubes is developed using optimized parameters and successful operation utilizing shock-initiated combustion through shock wave reflection is achieved and sustained. Finally, an air-breathing, PDE-Crossover System is developed to characterize the feasibility of shock-initiated combustion within an air-breathing pulse detonation engine. The initiation effectiveness of shock-initiated combustion is compared to spark discharge and detonation injection through a pre-detonator. In all cases, shock-initiated combustion produces improved initiation performance over spark discharge and comparable detonation transition run-up lengths relative to pre-detonator initiation. A computational study characterizes the mixing processes and injection flow field within a rotating detonation engine. Injection parameters including reactant flow rate, reactant injection area, placement of the fuel injection, and fuel injection distribution are varied to assess the impact on mixing. Decreasing reactant injection areas improves fuel penetration into the cross-flowing air stream, enhances turbulent diffusion of the fuel within the annulus, and increases local equivalence ratio and fluid mixedness. Staggering fuel injection holes produces a decrease in mixing when compared to collinear fuel injection. Finally, emulating nozzle integration by increasing annulus back-pressure increases local equivalence ratio in the injection region due to increased convection residence time.
Author: R. J. Litchford
Publisher:
ISBN:
Category : Detonation waves
Languages : en
Pages : 52
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Book Description
Author: Andrew George Naples
Publisher:
ISBN:
Category : Engines
Languages : en
Pages : 155
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Book Description
Abstract: An experimental study was done to examine the effects of elevated initial tube pressure in the PDE. Measured parameters were the ignition time, DDT run-up distance, DDT times, and C-J velocity. Mixed with air, three fuels, i.e., aviation gasoline, ethylene, and hydrogen, were tested at various initial pressures and equivalence ratios. A stock automotive ignition system was employed, along with a transient and thermal plasma ignition system, to quantify the benefits of each. Measured results show a reduction in the ignition time of roughly 50% and in the DDT distance of roughly 30%, for all three fuels at an initial tube pressure of 3 atmospheres. At roughly 2 atmospheres of initial pressure the thermal plasma ignition system showed no benefit over the stock automotive ignition system. In addition to the experimental results, a brief Chemkin analysis was done to model the stock automotive ignition system.
Author: Robert B. Driscoll
Publisher:
ISBN:
Category :
Languages : en
Pages : 105
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Book Description
An experimental investigation was carried out to study the travel of a shockwave through a crossover tube and analyze the ability to cause shock initiated detonation. This concept involved using a pulse detonation engine (PDE) as a driver to produce a shockwave. This shockwave travelled to a second, adjacent detonation tube. In this driven PDE, the shockwave would reflect off of the inner, concaved wall causing shock initiated detonation. A preliminary study using a dual PDE crossover tube system yielded experimental results that have shown successful cases where reflected shockwaves are used to cause direct detonation initiation. For that study, two reactant-filled PDEs were connected through an air-filled crossover tube, with the driver PDE ignited. High speed pressure sensors were used to verify combustion wave speeds. Preliminary results showed shock initiated detonation to be possible when using a dual PDE crossover system. Additionally, a parametric study was carried out to investigate shock initiated detonation within a dual PDE crossover system. Shockwaves produced by a driver PDE were carried through crossover tubes of varying lengths and bends to the driven PDE. The driving PDE was ignited using a traditional spark plug. From burning wave speeds measured by high speed pressure sensors, results have shown a transferred shockwave reflecting off the wall of the driven PDE will achieve shock initiated detonation. However, the results have also yielded cases where the initial shockwave reflection does not directly initiate a detonation in the driven PDE, but rather causes ignition leading to accelerated deflagration to detonation transition (DDT). Overall results have shown that for specific tube geometries, there is a maximum effective crossover tube length in which shock initiated detonation is possible. Furthermore, shadowgraph techniques were used to capture and study the propagation of a transferred shockwave produced by a driving detonation tube. To accomplish this, a single PDE was used to drive a shockwave through a clear, composite, transfer tube. Shock attenuation data was gathered during this study. This information created a relation between shock strength and crossover tube length. Also, regardless of the filling conditions of the transfer tube, all shock waves reach similar attenuation rates at relatively the same transfer tube length. Moreover, a vortex plume study was carried out to capture and study shock Mach number decay as a planar shockwave transitions to a spherical shockwave at the exit of a transfer tube. Transfer tubes of varying lengths and bends were used in the study. General Attenuation Law was used to further understand the relation between spherical shock strength and propagation distance. Results showed that a bend placed at the end of the transfer tube enhances the strength of a planar shockwave. Finally, with the aid of the two shadowgraph experiments, a correlation between maximum effective crossover tube length and shock strength was created. Performance in the driven PDE begins to decrease when the incident shock strength decreases below M = 2.0.
Author: Alexander R. Hausman
Publisher:
ISBN:
Category : Detonation waves
Languages : en
Pages : 158
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Book Description
Author: John P. Robinson
Publisher:
ISBN: 9781423536000
Category :
Languages : en
Pages : 94
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Book Description
The feasibility of utilizing detonations for air-breathing propulsion is the subject of a significant research effort headed by the Office of Naval Research. Pulse Detonation Engines (PDE) have a theoretically greater efficiency than current combustion cycles. However, pulse detonation technology must mature beginning with research in the fundamental process of developing a detonation wave. This thesis explores various ignition conditions which minimize the deflagration-to- detonation transition distance (Xddt) of a single detonation wave in a gaseous mixture.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
Pulsed detonation engines (PDEs) depend on rapid ignition and transition from deflagration to detonation. The prospect of converting the PDE from experimental to operational use necessitates a considerable reduction in the time required to ignite and detonate a liquid hydrocarbon fuel in air, such as JP-8. This research effort is focused on PDE operation enhancements using dual detonation tube, concentric-counter-flow heat exchangers to elevate the fuel temperature levels sufficiently to induce thermal cracking. Additionally, a zeolite catalytic coating is applied to the heat-exchanger surfaces to stimulate further cracking of the fuel and reduce coke deposition. To quantify the PDE performance, three parameters are examined: ignition time, deflagration-to-detonation transition (DDT) time, and DDT distance. Once cracked, the JP-8/air mixture results in a shorter ignition time, DDT time, and DDT distance for the majority of equivalence ratios, with a reduction in ignition time of up to 60% at 908 K, as compared to flash vaporized JP-8/air mixtures. Furthermore, both the ignition and detonability limits are expanded by cracking the fuel, with lean limits at an equivalence ratio of 0.75. Coke deposition found in the fuel filter consists of carbon as well as substantial concentrations of silicon and aluminum, due to breakdown of the silica-alumina zeolite structure. Additionally, poisoning of the catalyst is shown to occur after five hours of operation, although no degradation in performance was observed.
