Investigation on Novel Methods to Increase Specific Thrust in Pulse Detonation Engines Via Imploding Detonations PDF Download
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Author:
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 95
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Book Description
Pulse Detonation Engines (PDE) are seen to be the next generation propulsion systems due to enhanced thermodynamic efficiencies based on the Humphrey cycle. One of the limitations in fielding practical designs has been attributed to tube diameters not exceeding 5 inches as the shock wave takes a long run distance for transition to detonation, thus potentially affecting specific thrust. Novel methods via imploding detonations were investigated to remove such limitations. During the study, a practical computational cell size was first determined so as to capture the required physics for transient detonation wave propagation using a Hydrogen-Air test case. Through a grid sensitivity analysis, one-quarter of the induction length was found sufficient to capture the experimentally observed initial wave transients. Test case models utilizing axisymmetric head-on implosions were studied in order to understand how the implosion process reinforces a detonation wave as it expands. This in effect creates localized overdriven regions, which maintains the transition process to full detonation. A parametric study was also performed to determine the extent of diameter increase and it was found that the detonations could be supported with no change in run distance even when the tube diameter exceeds 5 inches.
Author:
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 95
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Book Description
Pulse Detonation Engines (PDE) are seen to be the next generation propulsion systems due to enhanced thermodynamic efficiencies based on the Humphrey cycle. One of the limitations in fielding practical designs has been attributed to tube diameters not exceeding 5 inches as the shock wave takes a long run distance for transition to detonation, thus potentially affecting specific thrust. Novel methods via imploding detonations were investigated to remove such limitations. During the study, a practical computational cell size was first determined so as to capture the required physics for transient detonation wave propagation using a Hydrogen-Air test case. Through a grid sensitivity analysis, one-quarter of the induction length was found sufficient to capture the experimentally observed initial wave transients. Test case models utilizing axisymmetric head-on implosions were studied in order to understand how the implosion process reinforces a detonation wave as it expands. This in effect creates localized overdriven regions, which maintains the transition process to full detonation. A parametric study was also performed to determine the extent of diameter increase and it was found that the detonations could be supported with no change in run distance even when the tube diameter exceeds 5 inches.
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: 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: Fouad Sabry
Publisher: One Billion Knowledgeable
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 349
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Book Description
What Is Pulse Detonation Engine A pulse detonation engine (PDE) is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture. The engine is pulsed because the mixture must be renewed in the combustion chamber between each detonation wave and the next. Theoretically, a PDE can operate from subsonic up to a hypersonic flight speed of roughly Mach 5. An ideal PDE design can have a thermodynamic efficiency higher than other designs like turbojets and turbofans because a detonation wave rapidly compresses the mixture and adds heat at constant volume. Consequently, moving parts like compressor spools are not necessarily required in the engine, which could significantly reduce overall weight and cost. PDEs have been considered for propulsion since 1940. Key issues for further development include fast and efficient mixing of the fuel and oxidizer, the prevention of autoignition, and integration with an inlet and nozzle. To date, no practical PDE has been put into production, but several testbed engines have been built and one was successfully integrated into a low-speed demonstration aircraft that flew in sustained PDE powered flight in 2008. In June 2008, the Defense Advanced Research Projects Agency (DARPA) unveiled Blackswift, which was intended to use this technology to reach speeds of up to Mach 6 How You Will Benefit (I) Insights, and validations about the following topics: Chapter 1: Pulse Detonation Engine Chapter 2: Nuclear Pulse Propulsion Chapter 3: Rotating Detonation Engine Chapter 4: AIMStar Chapter 5: Antimatter-catalyzed nuclear pulse propulsion Chapter 6: Antimatter rocket Chapter 7: Nuclear electric rocket Chapter 8: Nuclear power in space Chapter 9: Nuclear propulsion Chapter 10: Nuclear thermal rocket Chapter 11: Project Pluto Chapter 12: Fission-fragment rocket (II) Answering the public top questions about pulse detonation engine. (III) Real world examples for the usage of pulse detonation engine in many fields. (IV) 17 appendices to explain, briefly, 266 emerging technology in each industry to have 360-degree full understanding of pulse detonation engine' technologies. Who This Book Is For Professionals, undergraduate and graduate students, enthusiasts, hobbyists, and those who want to go beyond basic knowledge or information for any kind of pulse detonation engine.
Author: R. J. Litchford
Publisher:
ISBN:
Category : Detonation waves
Languages : en
Pages : 52
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Book Description
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:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Recent efforts in PDRE research at AFRL-West have focused on basic studies of the detonation or constant-volume combustion of multiphase mixtures. A collaborative effort is under way for developing models appropriate for PDRE application studies. This effort includes a new facility for the collection of data on liquid oxygen/gaseous fuel detonations. The facility has been designed to provide accurate and flexible control over the initial conditions of the multiphase mixtures and complete characterization of detonation parameters including initiation energies, wave speeds, pressures and rates of heat transfer. Model development is being performed by Metacomp Technologies and University of Colorado. A second experimental effort is examining the feasibility of a monopropellant-fueled pulse combustor. Analytical and numerical studies have shown the performance benefits of this approach and a preliminary system study has shown that there are significant benefits in satellite applications. An experimental demonstration of the concept is under way.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 377
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Book Description
The current focus on utilizing detonations for air-breathing propulsion has shifted from long-term studies of the possibility of fuel energy transformation in stabilized oblique detonation waves to investigations and practical development of propulsion engines operating on propagating detonations in a pulse mode. Contrary to the oblique-detonation concept that is applicable to hypersonic flight at velocities comparable or higher than the Chapman-Jouguet detonation velocity of the fuel-air mixture, the concept of a pulse detonation engine (PDE) is attractive for both subsonic and supersonic flight with the PDE as a main propulsion unit or as an afterburner in turbojet or turbofan propulsion system. In particular, PDE-based propulsion is attractive for flight Mach number up to about 4. Within this range of Mach number, solid rocket motors are known to be very efficient in terms of simplicity and high-speed capability, but they have a limited powered range. Turbojet and turbofan engines, due to their high specific impulse, provide longer range and heavier payloads, but at flight Mach number exceeding 2-3, they get too expensive. Ramjets and ducted rockets designed for flight Mach number up to 4 require solid rocket boosters to accelerate them to the ramjet take over speed, which increase the complexity and volume of a propulsion system. Combined-cycle engines, such as turborockets or turboramjets, are also very complex and expensive for similar applications.
Author: Aaron J. Glaser
Publisher:
ISBN:
Category :
Languages : en
Pages : 241
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Book Description
The acoustic signature of a pulse detonation engine was characterized in both the near-field and far-field regimes. Experimental measurements were performed in an anechoic test facility designed for jet noise testing. Both shock strength and speed were mapped as a function of radial distance and direction from the PDE exhaust plane. It was found that the PDE generated pressure field can be reasonably modeled by a theoretical point-source explosion. The effect of several exit nozzle configurations on the PDE acoustic signature was studies. These included various chevron nozzles, a perforated nozzle, and a set of proprietary noise attenuation mufflers.
Author: Christopher Tate
Publisher:
ISBN:
Category : Detonation waves
Languages : en
Pages : 272
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Book Description
Detonation and constant volume combustion is well known to be thermodynamically more efficient than the typically utilized constant pressure. There have been numerous approaches of achieving detonation through deflagration-to-detonation transition most of which use evenly spaced obstacles with a specified constant blockage ratio to generate turbulence and pressure fluctuations. There have been few efforts to study effects of varying blockage ratio as a function of axial distance. This research analyzes the effect of variable blockage ratio on deflagration-to-detonation transition in ethylene-air mixtures. The experiments show that with certain blockage ratio functions detonation is more repeatable and produces a smaller variation in both peak pressure and wave velocity representative of consistently stable detonations.
