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Author: Haider Hekiri
Publisher:
ISBN: 9780542448836
Category : Aerospace engineering
Languages : en
Pages :
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Book Description
The performance of an ejector-driven pulse detonation engine (PDE) with an afterburner is analytically estimated. In the analysis, the PDE was modeled as a straight tube, closed at the front end and open at the other. A detonation wave starts to travel after it is ignited at the closed end, causing a Chapman-Jouguet detonation wave followed by a Taylor rarefaction to travel to the open end. At that point, rarefaction waves are reflected back to the closed end. The result is a high thrust due to both the primary and secondary flows of the ejector-driven PDE. A theoretical analysis is made to determine the average thrust density and the impulse density per cycle of the primary flow. The mixed flow of the PDE tube and the ejector is then subjected to afterburning. The overall engine performance was eventually derived.
Author: Haider Hekiri
Publisher:
ISBN: 9780542448836
Category : Aerospace engineering
Languages : en
Pages :
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Book Description
The performance of an ejector-driven pulse detonation engine (PDE) with an afterburner is analytically estimated. In the analysis, the PDE was modeled as a straight tube, closed at the front end and open at the other. A detonation wave starts to travel after it is ignited at the closed end, causing a Chapman-Jouguet detonation wave followed by a Taylor rarefaction to travel to the open end. At that point, rarefaction waves are reflected back to the closed end. The result is a high thrust due to both the primary and secondary flows of the ejector-driven PDE. A theoretical analysis is made to determine the average thrust density and the impulse density per cycle of the primary flow. The mixed flow of the PDE tube and the ejector is then subjected to afterburning. The overall engine performance was eventually derived.
Author: Ronnachai Vutthivithayarak
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Research over the last two decades has shown the potential advantages of pulse detonation engines (PDEs) over existing aero-engines in terms of improved thermodynamics efficiency, improved thrust performance, simplicity of design, and exibility to operate over a wide speed range. The inherently unsteady characteristic of PDEs makes it di culty to analyze and evaluate their performance. The conventional method that relies on steady-state assumptions cannot be directly applied. PDE studies have to employ unsteady gasdynamics behavior. In this study, the thermodynamic cycle of a PDE, which can be called the ZND cycle, is theoretically analyzed. A parametric analysis of turbojet PDEs is considered for both ideal and non-ideal cases. The conventional turbojet with a Brayton cycle is brought in the comparison to verify that PDEs can provide better performance.
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: Maryam Sadrzadeh Moghadam
Publisher:
ISBN:
Category :
Languages : en
Pages : 75
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Book Description
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: Rafaela Bellini
Publisher:
ISBN:
Category : Electric power
Languages : en
Pages :
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Book Description
Over the last few decades, considerable research has been focused on pulse detonation engines (PDEs) as a promising replacement for existing propulsion systems with potential applications in aircraft ranging from the subsonic to the lower hypersonic regimes. On the other hand, very little attention has been given to applying detonation for electric power production. One method for assessing the performance of a PDE is through thermodynamic cycle analysis. Earlier works have adopted a thermodynamic cycle for the PDE that was based on the assumption that the detonation process could be approximated by a constant volume process, called the Humphrey cycle. The Fickett-Jacob cycle, which uses the one-dimensional Chapman-Jouguet (CJ) theory of detonation, has also been used to model the PDE cycle. However, an ideal PDE cycle must include a detonation based compression and heat release processes with a finite chemical reaction rate that is accounted for in the Zeldovich - von Neumann - Döring model of detonation where the shock is considered a discontinuous jump and is followed by a finite exothermic reaction zone. This work presents a thermodynamic cycle analysis for an ideal PDE cycle for power production. A code has been written that takes only one input value, namely the heat of reaction of a fuel-oxidizer mixture, based on which the program computes all the points on the ZND cycle (both p-v and T-s plots), including the von Neumann spike and the CJ point along with all the non-dimensionalized state properties at each point. In addition, the program computes the points on the Humphrey and Brayton cycles for the same input value. Thus, the thermal efficiencies of the various cycles can be calculated and compared. The heat release of combustion is presented in a generic form to make the program usable with a wide variety of fuels and oxidizers and also allows for its use in a system for the real time monitoring and control of a PDE in which the heat of reaction can be obtained as a function of fuel-oxidizer ratio. The Humphrey and ZND cycles are studied in comparison with the Brayton cycle for different fuel-air mixtures such as methane, propane and hydrogen. The validity and limitations of the ZND and Humphrey cycles related to the detonation process are discussed and the criteria for the selection of the best model for the PDE cycle are explained. It is seen that the ZND cycle is a more appropriate representation of the PDE cycle. Next, the thermal and electrical power generation efficiencies for the PDE are compared with those of the deflagration based Brayton cycle. While the Brayton cycle shows an efficiency of 0 at a compressor pressure ratio of 1, the thermal efficiency for the ZND cycle starts out at 42% for hydrogen-air and then climbs to a peak of 66% at a compression ratio of 7 before falling slowly for higher compression ratios. The Brayton cycle efficiency rises above the PDEs for compression ratios above 23. This finding supports the theoretical advantage of PDEs over the gas turbines because PDEs only require a fan or only a few compressor stages, thereby eliminating the need for heavy compressor machinery, making the PDEs less complex and therefore more cost effective than other engines. Lastly, a regeneration study is presented to analyze how the use of exhaust gases can improve the performance of the system. The thermal efficiencies for the regenerative ZND cycle are compared with the efficiencies for the non-regenerative cycle. For a hydrogen- air mixture the thermal efficiency increases from 52%, for a cycle without regeneration, to 78%, for the regenerative cycle. The efficiency is compared with the Carnot efficiency of 84% which is the maximum possible theoretical efficiency of the cycle. When compared to the Brayton cycle thermal efficiencies, the regenerative cycle shows efficiencies that are always higher for the pressure ratio studied of 5 is less than or equal to [pi]c is less than or equal to 25, where [pi]c the compressor pressure ratio of the cycle. This observation strengthens the idea of using regeneration on PDEs.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
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: James T. Peace
Publisher:
ISBN:
Category : Aerospace engineering
Languages : en
Pages : 312
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Book Description
The pulsed detonation engine (PDE) is an advanced propulsion system that makes use of intermittent detonations to provide thrust. In recent decades, the PDE has been at the center of various propulsion research efforts focused on practical implementation of a reliable detonation-based engine for aerospace propulsion applications. However, many design challenges remain to be solved due to the PDEs unsteady operating characteristics. In particular, the unsteady nature of the thrust chamber flow field inherent to the PDE operation makes the design of nozzles aimed at adequately expanding the burned detonation products especially difficult. In order to address this design challenge, a series of related analytical, numerical, and experimental studies have been conducted, which are focused on investigating the manner in which the PDE propulsive performance is governed by the various gasdynamic processes occurring within the thrust chamber and nozzle flow fields. In this study, three primary PDE configurations are considered. These configurations include fully- and partially-filled PDEs, and PDEs equipped with diverging nozzles. For each configuration, a comprehensive description of the PDE flow field is provided, whereby details concerning the evolution and interaction of various gasdynamic waves and discontinuities are discussed. Additionally, the dominant gasdynamic processes within the thrust chamber and nozzle flow fields are identified, as these processes must be appropriately modeled in order to accurately evaluate the propulsive performance.The collision of a detonation wave with a contact surface separating detonable and non-combustible mixtures is a fundamental gasdynamic interaction process that takes place every cycle in the cyclic operation of the PDE. This interaction can drastically influence the evolving thrust chamber flow field and the subsequent propulsive performance metrics. To improve its understanding, this gasdynamic interaction is investigated analytically in order to predict the resulting transmitted shock wave properties, and the necessary conditions for a shock, Mach, or rarefaction wave to reflect at the contact surface. Concurrently, this interaction is investigated experimentally with the use of a detonation-driven shock tube. The analytical and experimental results indicate that the transmitted shock can either be amplied or attenuated depending on the reflection type at the contact surface, and the ratio of the acoustic impedance across the interface. A quasi-one-dimensional method of characteristics (MOC) model is developed to evaluate the single-cycle gasdynamic flow field and associated propulsive performance of general PDE configurations. The model incorporates the current detonation-contact surface interaction results in order to accurately treat the one-dimensional collision of a detonation wave with a contact discontinuity. Additionally, the MOC model is developed using a simplified unit process approach with an explicit inverse time marching algorithm in order to readily construct the complex thrust chamber flow field along a predefined grid. A thorough validation of the model is presented over a broad range of operating conditions with existing higher-fidelity numerical and experimental performance data for fully- and partially-filled PDEs, and PDEs equipped with diverging nozzles. This includes PDEs operating with a variety of detonable fuels, non-combustible inert mixtures, ll fractions, blowdown pressure ratios, and nozzle expansion area ratios. Lastly, a detailed discussion of the model limitations is provided, and particular operating conditions that lead to a breakdown of the assumptions used in the development of the model are addressed. A simplified analytical model is developed based on control volume analysis for evaluating the primary performance metrics of a general fully-filled PDE. The MOC model is used to justify and establish a simplified thrust relation based solely on the ow properties at the exit plane of a fully-filled PDE. A detailed analytical description of the thrust chamber flow field is provided, from which an analytical piece wise expression for thrust is derived based on the exit plane pressure history. This expression is then used to evaluate the specific impulse, total impulse, and time-averaged thrust of a fully-filled PDE. This simplified model is validated against the current MOC model and higher-fidelity numerical and experimental performance data for a variety of detonable fuels, equivalence ratios, and blowdown pressure ratios.Using the current MOC model, the single-cycle propulsive performance of partially-filled PDEs is investigated. The results of the detonation-contact surface interaction study are used to tailor the acoustic impedance of the non-combustible mixture at a fixed fill fraction in order to demonstrate the sensitivity of the thrust chamber flow field to the non-combustible acoustic impedance. Subsequently, the detonable fill fraction and noncombustible acoustic impedance are varied simultaneously in order to characterize the general partially-lled PDE performance. The partial-filling performance benefit is also investigated by varying the initial pressure and temperature of the non-combustible mixture in order to highlight the advantage of using a cold purge gas during operation, and disadvantage of operating in sub-atmospheric environments. It is demonstrated that the partially-filled specific impulse performance results generated with the MOC model from these various parametric investigations are successfully modeled using a previously developed scaling law, whereby this scaling law is extended in the current work to partially-filled total impulse and time-averaged thrust.Similarly, the single-cycle propulsive performance of PDEs with diverging nozzles is examined. A parametric investigation is conducted to characterize the combined effects of nozzle expansion area and blowdown pressure ratios on the resulting thrust chamber and nozzle flow fields. Detailed discussion of the transient nozzle flow field is provided in order to emphasize the influence of non-combustible acoustic impedance on the partial-fill effect in diverging nozzles. Moreover, a comparative study is used to demonstrate the performance advantages of a diverging nozzle in sub-atmospheric environments compared to a straight extension nozzle. Lastly, a detailed parametric investigation is conducted by simultaneously varying the nozzle length, expansion area ratio, and blowdown pressure ratio in order to determine the optimum nozzle performance characteristics. An analytical model is formulated to predict the strength and motion of a transmitted shock wave through a general contour diverging nozzle for PDEs. The model is derived on the basis of a two-equation approximation of the generalized CCW (Chester Chisnell Whitham) theory for treating general shock dynamics in non-uniform channels. A major feature of the two-equation model is the ability to incorporate non-uniformity in the flow immediately following the shock wave, which turns out to be essential for describing the transmitted shock dynamics in PDE nozzles. This model is then used to demonstrate the effects of thrust chamber length on the magnitude of ow non-uniformity behind the transmitted shock entering the nozzle, and how drastically this can influence the nature of shock attenuation within the nozzle. Further, the shock dynamics model is used in conjunction with the MOC model to demonstrate how different nozzle wall curvature influences the PDE propulsive performance, due to the changes in transmitted shock attenuation and gasdynamic over-expansion in the nozzle flow field during the nozzle starting process.
Author: Andrew Ryan Mizener
Publisher:
ISBN:
Category : Acoustic phenomena in nature
Languages : en
Pages : 226
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Book Description
The rotating detonation engine (RDE) is a promising propulsion concept that has the potential to offer increased thermodynamic performance in a compact package with no moving parts. A series of analytical and experimental investigations was carried out on RDEs with the joint goal of investigating swirl, torque, and a range of other design parameters of interest. The model and experimental facility were then applied to related problems with the goal of advancing the understanding of RDE applications. A flexible, low-order, semi-empirical model for a rotating detonation engine was presented. The model was formulated to be able to run broad parametric analyses more efficiently than numerical modeling. The presence of swirl at the exit plane of RDEs is still debated, so the model was formulated to leave open this possibility. Parametric analysis was conducted to determine the effect of a range of engine design parameters on performance. Exit swirl and torque were shown to be small but not uniquely zero. The model was combined with a waverider forebody model. Together, these were used to conduct parametric analysis of the sensitivity of integrated performance to freestream, waverider forebody, and RDE design parameters. Practical limitations on the Mach number of detonation engines operating in supersonic flows were presented and discussed. Peak performance was seen at the point of maximum forebody pressure recovery. Thrust and torque were shown to be sensitive to body shape and freestream parameters, while specific impulse and thrust-specific fuel consumption were not. The design of a rotating detonation engine and experimental test facility were presented and discussed. The facility was designed and instrumented to allow the measurement of resultant torque on the engine as well as take thrust and pressure readings. A series of tests was conducted using the engine, with no steadily-propagating detonation waves detected. Pressure, torque, thrust, and frequency data were presented and discussed. A high-speed camera was used to visualize the exhaust plume and the flame structure inside the annulus, which similarly failed to detect a detonation wave. The camera was then used to conduct high-speed visualizations of the ignition process inside the engine for both spark plug and predetonator igniters. Both methods showed the creation of two counter-rotating detonation waves which intersected and canceled each other out on the far side of the annulus. Pressure waves were observed to continue to rotate for several periods before dying out. The qualitative observations from the visualizations were supported by the pressure data. Detailed visualizations were performed to quantitatively investigate the propagation of the initial combustion front around the annulus for varying degrees of injector swirl. Predetonator ignition was observed to directly initiate a detonation, whereas deflagration-to-detonation transition was observed for spark plug ignition. Injector swirl promoted transition in combustion waves propagating into the swirl and depressed it in waves propagating with the swirl. Overdriven detonations were observed for both ignition methods. A discussion of the possible causes for the failure to sustain a detonation wave was presented and discussed.
