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Critical Decay Time Model for Direct detonation Initiation Energy in Gaseous Mixtures

JOURNAL OF PROPULSION AND POWER 2024年第1期40卷 94-110页

作者： Liu, Yuen Xie, Qing Chen, Yuxuan Mevel, Remy Ren, Zhuyin Tsinghua Univ Sch Aerosp Engn Beijing 100084 Peoples R China Tsinghua Univ Inst Aero Engine Beijing 100084 Peoples R China Tsinghua Univ Ctr Combust Energy Beijing 100084 Peoples R China

A critical decay time (CDT) model is developed to predict the critical energy of direct detonation initiation in gaseous mixtures. It is based on the global initiation criterion that the energy deposit should allow the decaying shock speed to stay in a specific range below the Chapman-Jouguet (CJ) speed at least for a critical decay time. The speed range is estimatedwith the sub-CJ Zel'dovich-vonNeumann-Doring (ZND) simulations. The critical decay time is calculated as the minimum time to reach unity Mach number in the sub-CJ ZND simulations. The lower-speed bound is taken as a characteristic extinction speed below (which means the lower-speed bound) which the direct initiation should fail. This speed is calibrated using one-dimensional simulations for hydrogen (H-2)-oxygen (O-2)-argon (Ar) mixtures. The calibrated CDT model is then applied to estimate the critical initiation energy with the point-blast theory. The model yields better agreement with experimental data for hydrogen-fueled mixtures such as H-2-O-2-Ar and H-2-air mixtures than the well-known critical decay rate model. For small hydrocarbon-fueled mixtures such as acetylene (C2H2)-O-2-Ar, methane (CH4)-air, ethylene (C2H4)-air, and ethane (C2H6)-air mixtures, the predicted critical energies also agree well with experimental results. The CDT model provides an efficient tool to evaluate the detonability of fuel-oxidizer mixtures, which could be beneficial for ignition initiation in propulsion and power devices such as rotating detonation engines.

关键词： deflagration to detonation transition Aerodynamics Hydrocarbon Fuels Rotating detonation Engine Hydrogen Fuels Propulsion and Power detonation Waves Adaptive Mesh Refinement Chemical Energy Fluid Dynamics

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Synchronized Initiation of Two Cylindrical Rotating detonation Engines

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JOURNAL OF PROPULSION AND POWER 2024年第6期40卷 849-858页

作者： Sakata, Rinpei Inada, Masahiro Itouyama, Noboru Matsuoka, Ken Kasahara, Jiro Kawasaki, Akira Matsuo, Akiko Funaki, Ikkoh Nagoya Univ Dept Aerosp Engn Nagoya 4648603 Japan Shizuoka Univ Dept Mech Engn Hamamatsu 4328561 Japan Keio Univ Dept Mech Engn Yokohama 2238522 Japan JAXA Inst Space & Astronaut Sci Sagamihara 2525210 Japan

A coupled cylindrical rotating detonation engine (RDE) with two cylindrical RDEs (both combustors had a combustor inner diameter of 23 mm and an axial length of 30 mm) placed next to each other was tested for rocket clustering application. The objective of the experiment was to achieve two-engine synchronized initiation with a single igniter. Experiments were conducted on the inner wall of the combustors with different connecting-hole diameters and wall heights to evaluate the ignition delay time, combustion mode, and propulsion performance. The propellants were gaseous ethylene and oxygen, and experiments were conducted under constant conditions of mass flow rate (40 +/- 2 g/s), equivalence ratio (1.0 +/- 0.1), and backpressure (approximately 10 kPa). When the two combustion chambers were completely separated by a wall, ignition occurred with a time delay of 260 ms in the chamber without an igniter. However, when a large hole (10-mm diameter) was placed in the wall separating the two combustion chambers, synchronous initiation was successful. Synchronous initiation was also successful when the wall height was lowered (7-mm height). Under both conditions, the same level of specific impulse was achieved as for RDEs operating at the same mass flux.

关键词： Combustors Combustion Chambers Ignition Systems Rockets deflagration to detonation transition detonation Waves Rotating detonation Engine Rotating detonation Combustor detonation Ignition Timing

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Numerical study on detonation initiation of aviation kerosene-hydrogen-air mixtures in an obstructed tube under various hydrogen ratios and initial pressures

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2025年 137卷 114-124页

作者： Hui, Yuxiang Wang, Zhiwu Qin, Weifeng Xiao, Jingtao Liu, Yongfeng Li, Dingming Zhang, Man Northwestern Polytech Univ Sch Power & Energy Xian 710072 Peoples R China Northwestern Polytech Univ Shenzhen Res Inst Shenzhen 518057 Peoples R China AECC Commercial Aircraft Engine Co LTD Shanghai 200241 Peoples R China

Aviation kerosene mixed with hydrogen provides a promising approach to improve the detonation initiation performance of aviation kerosene. In this study, the detonation initiation processes in an obstructed tube fueled with aviation kerosene/hydrogen mixtures were numerically investigated, covering hydrogen ratios from 0.1 to 0.5 and initial pressures from 0.5 atm to 2 atm. The mechanism of flame acceleration and detonation initiation was analyzed, and the effects of hydrogen ratio and initial pressure on detonation initiation were explored. The results indicated that the detonation initiation process in the obstructed tube could be divided into three stages: flame acceleration, deflagration to detonation transition (DDT), and self-sustaining detonation. The variations in detonation initiation time, detonation initiation distance, DDT run up time, DDT run up distance, the time and distance required for the DDT process under different hydrogen ratios and initial pressures were summarized. Additionally, the effects of hydrogen ratio and initial pressure on detonation velocity were also investigated.

关键词： Aviation kerosene Hydrogen ratio Initial pressure deflagration to detonation transition detonation initiation

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Comprehensive studies on suitable reaction mechanisms to predict the behavior of high speed reacting flows

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CHEMICAL ENGINEERING COMMUNICATIONS 2023年第4期210卷 504-515页

作者： Soleimanpour, Reza Nemati, Hossain Zare, Azam Azad Univ Marvdasht Sch Mech Engn Marvdasht Iran

In this work, the two dimensional transition of H-2-O-2 deflagration-to-detonation was examined in some porous closed-ducts by an in-house high speed reacting flow solver in OpenFoam package-a pressure-based/density-based hybrid solver coupled with Godunov-type schemes, including advection Upstream Splitting Method, Roe, Roe and Pike, and Harten-Lax-van-Leer-contact. Initially, the results of different reaction mechanisms were compared with experimental data. Then, some porous zones and wall roughness of porous duct as well as porous obstacles and their blockage ratio are applied to evaluate the DDT process in different working conditions. The results revealed that the addition of a porous zone could decrease the flame tip velocity and increase the maximum temperature of the process by up to 20.74%. Furthermore, the ratio of the wall roughness height to the channel width of 0.03 was found to be the optimal value to control the time and length of deflagration-to-detonation transition. Also, changes in the interval between the porous obstacles and their blockage ratio led to significant variations in the detonation flow structure. Finally, using a porous zone and porous obstacles have proved to be an advanced method to control the deflagration-to-detonation transition process.

关键词： deflagration to detonation transition porous duct porous obstacles roughness height in-house solver

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Operation and Power Generation of a Disk-Shaped Pressure Gain Combustor

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JOURNAL OF PROPULSION AND POWER 2023年第6期39卷 920-935页

作者： Huang, Xin Chang, Po-Hsiung Li, Jiun-Ming Teo, Chiang Juay Khoo, Boo Cheong Natl Univ Singapore Singapore 117411 Singapore

The objective of this experimental study is to evaluate the power generation capability of an ethylene-air disk-shaped pressure gain combustor (DPGC). The main content of this paper focuses on discussing the DPGC testing results, consisting of detonation wave dynamics, power generation, and accompanying combustion instabilities. The experiments can be grouped into two stages. In the first stage, the DPGC was tested under atmospheric back condition. Continuous detonation wave dynamics were evaluated among various testing conditions. Evolution of the detonation wave velocity with respect to changes in the equivalence ratio has been discussed. In the second stage of the experiments, the DPGC was tested with a turbocharger installed. Shaft power extracted by the turbocharger turbine from the DPGC exhaust was used as a metric for evaluating the DPGC power output. During the operation of the DPGC and turbocharger, low- and intermediate-frequency combustion instabilities were observed, which coexisted with the high-frequency component associated with the circumferentially propagating detonation wave. The experimental results suggest that the DPGC shows superiority in compactness relative to conventional combustion power systems. However, more improvements need to be made with regard to overall thermal efficiency in order to achieve the benefits from detonation combustion.

关键词： Energy Production Annular Combustor detonation Waves deflagration to detonation transition Thermodynamic Properties Energy Transfer Air Mass Flow Rates Flow Conditions Flow Control Valves Centrifugal Compressor

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A dynamical system approach for solving the steady structure of high speed deflagrations

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PROCEEDINGS OF THE COMBUSTION INSTITUTE 2023年第3期39卷 2945-2955页

作者： Rakotoarison, Willstrong Radulescu, Matei I. Univ Ottawa Dept Mech Engn Ottawa ON Canada

High-speed deflagrations have burning velocities much higher than laminar ones, and compressible effects become important. In the present paper, we study the structure of such high speed deflagrations in the thick-ened flame limit for a one-step Arrhenius rate law, whereby the transport coefficients are increased to give rise to buring velocities of finite Mach number. We study their steady structure and compare with the lam-inar low-Mach classical structure. The singular nature of both the fresh and burned gases conditions in the compressible regime, i.e., for large values of flame propagation Mach number, which are both saddle points, precludes the application of simple shooting methods to obtain their structure. The steps leading to the flame structure borrow techniques used to treat mathematical features commonly found in the study of dynamical systems (phase portrait of the flame structure equations system, eigenvalue decomposition of its linearized version), that can also be used to further comment on the nature of high-speed flames. The method proposed per mits to deter mine the structure of deflagrations propagating up to speeds of aproximately 0.95 of the CJ -deflagration burning velocity, for a wide range of gas parameters commonly found in the field of numerical simulation of accelerating flames and their transitions to detonations. We comment on how the increasing role of compressibility modifies the structure of the laminar flame. & COPY;2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

关键词： Flame structure High-speed flames Chapman-Jouguet deflagrations deflagration to detonation transition

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Experimental Research for Clustering with the Coupled Cylindrical Rotating detonation Engine

Experimental Research for Clustering with the Coupled Cylind...

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AIAA SciTech Forum

作者： Sakata, Rinpei Inada, Masahiro Itouyama, Noboru Matsuoka, Ken Kasahara, Jiro Kawasaki, Akira Matsuo, Akiko Funaki, Ikkoh Nagoya Univ Dept Aerosp Engn Nagoya Aichi 4648603 Japan Shizuoka Univ Dept Mech Engn Hamamatsu Shizuoka 4328561 Japan Keio Univ Dept Mech Engn Yokohama Kanagawa 2238522 Japan JAXA Inst Space & Astronaut Sci Sagamihara Kanagawa 2525210 Japan Inst Space & Astronaut Sci Sagamihara Kanagawa 2525210 Japan

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

It is possible to achieve a high flow rate and high thrust by clustering small cylindrical rotating detonation engines while reducing the axial length of the engines. In this study, a coupled cylindrical rotating detonation engine with two cylindrical RDEs (both combustors had a combustor inner diameter of 23 mm and an axial length of 30 mm) placed next to each other was fabricated and tested for clustering. The objective of the experiment was to achieve two-engine synchronized initiation with a single igniter. Experiments were conducted on the inner wall of the combustor with different connecting hole diameters d and wall heights h to evaluate the ignition mechanism, combustion mode, and propulsion performance. The propellants were gaseous ethylene and oxygen, and experiments were conducted under constant conditions of mass flow rate (the range of 40 +/- 2 g/s), equivalent ratio (the range of 1 +/- 0.1), and back pressure (approximately 10 kPa). The experimental results showed that when the two combustion chambers were completely separated by a wall, ignition occurred with a time delay in the chamber without an igniter. However, when a large hole (10 mm diameter) was placed in the wall separating the two combustion chambers, the flame propagated through the hole and synchronous initiation was successful. Synchronous initiation was also successful when the wall height was lowered (7 mm height), and high performance was obtained under both conditions. The flame was visualized by a high-speed camera during ignition and combustion, and the difference in combustion mode was confirmed. Frequency analysis was performed from the self-illuminated images taken by the high-speed camera to classify the combustion mode. Theoretical thrust obtained by the control surface method from pressure and other measured values was compared with the actual measured thrust.

关键词： Rotating detonation Engine Combustors Combustion Chambers Propellant Total Mass Flow Rate deflagration to detonation transition detonation Waves Ignition Systems Static Pressure Control Surfaces

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Experimental Investigation of a Small-Scale Oxygen-Hydrogen Rotating detonation Rocket Combustor

Experimental Investigation of a Small-Scale Oxygen-Hydrogen ...

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AIAA SciTech Forum

作者： Armbruster, Wolfgang Boerner, Michael Bee, Alexander Martin, Jan Knapp, Bernhard General, Stephan Hardi, Justin S. Bard, Ewen DLR Inst Space Prop Rocket Prop Technol Dept D-74239 Hardthausen Germany Univ Paris Saclay DMPE ONERA F-91123 Palaiseau France

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

This study presents the design methodology and results from initial testing of an experimental hydrogen-oxygen rotating detonation combustor (RDC). A small-scale heat sink chamber was designed for studying rotating detonative combustion for rocket propulsion applications. Initial testingwas performed to verify the design methodology. The initial tests used gaseous propellants with oxidizer-to-fuel mixture ratios between 5 and 9 and total mass flow rates between 16 and 70 g/s. During the tests pressure oscillations were observed which showed significantly higher frequencies than the expected frequency for one wave calculated with the theoretical detonation (CJ) velocity. The imaging from a high-speed camera directed upstream into the annular combustion chamber was analyzed with different post-processing methods and the results indicated 2 to 5 traveling waves, depending on the operating conditions. The multiple waves explain the high pressure oscillation frequency. For most of the cases, the calculated wave speed was around 1700 m/s and thus low compared to the theoretical detonation velocity of oxygen-hydrogen. The data indicates that for these conditions no stable detonation wave dynamics are achieved, but a rather chaotic behavior with counter-rotating waves, longitudinal thermoaocustic modes and switching wave directions. However, there are also short periods for which evenly distributed co-rotating waves were observed. For that case the wave speed exceeded 2000 m/s and reached 72% of the CJ-velocity.

关键词： deflagration to detonation transition Aerospike Nozzle Propellant Rotating detonation Combustor Total Mass Flow Rate detonation Waves Combustion Chambers Traveling Wave Rocket Propulsion System Heat Sinks

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A Comparison of Re-shock Mixing due to Richtmyer-Meshkov Instability in a Laboratory Channel and Free-Field Domain

A Comparison of Re-shock Mixing due to Richtmyer-Meshkov Ins...

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AIAA SciTech Forum

作者： Panchal, A. Menon, S. Georgia Inst Technol Sch Aerosp Engn 270 Ferst Dr Atlanta GA 30332 USA

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

A comparison of Re-Shock mixing and Richtmyer-Meshkov instability (RMI) in free-field domain and lab-scale systems is conducted computationally. A planar channel with an incident shock, a spherical blast in a confined domain as used in conventional RMI (experimental and simulation) studies, and a realistic free domain spherical blast configuration with a high explosive charge are considered. Both 2D and 3D studies are considered with re-shock and the configuration details are selected using normalized parameters to allow a one-to-one matching between all. A heavy-fluid curtain is placed to interact with the shock or the blast wave with a multi-modal initial perturbation and its thickness is varied to study its effect on the growth and mixing. Finally, the effect of confinement and charge-size effects are considered and these are compared against free-field computations. Results suggest there are some significant differences between a channel re-shock RMI and a free field detonation and mixing layer growth is problem dependent. Comparison of spherical blast with and without confinement show that proper scaling is required to capture re-shock mixing that is not sensitive to boundary conditions.

关键词： Blast Wave deflagration to detonation transition Mach Number Hydrodynamic Instability Scale Space Scramjet Viscosity

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Statistical Variability of Quasi-2D Hydrocarbon detonations

Statistical Variability of Quasi-2D Hydrocarbon Detonations

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AIAA SciTech Forum

作者： Berson, Joshua Cideme, Robyn Brown, Taylor Hytovick, Rachel Ahmed, Kareem Univ Cent Florida Ctr Adv Turbomachinery & Energy Res Dept Mech & Aerosp Engn Orlando FL 32816 USA

ISBN: (数字)9781624107115

ISBN: (纸本)9781624107115

This work details the investigation into the propagation of hydrocarbon fuel detonations in a thin channel. As detonations are being implemented into modern combustion technologies to benefit from the efficiency gain, their properties need to be fully characterized. Of main interest is hydrocarbon fuels given the substantially higher energy density over hydrogen. In thin channels detonations have been known to appear nominally 2D allowing for higher detail line-of-sight imaging techniques. Many studies have investigated hydrocarbon detonations in this mode but have not evaluated the consistency of the key detonation properties. A statistical approach is used in this study by ensemble averaging over many realizations of the detonation to determine these properties. The experimental data was collected by igniting a pre-mixed Ethylene-Oxygen-Nitrogen mixture in a confined channel. The detonating wave travels through a converging nozzle to reduce the channel width to 2 mm. The detonation is then observed through high-speed shadowgraph. This data is then processed to provide quantified statistics for the axial wave speed. Additionally, the presence and structure of transverse detonation waves are discussed.

关键词： deflagration to detonation transition detonation Waves Hydrocarbon Fuels Energy Density Probability Density Functions Rotating detonation Combustor Mass Flow Rate Shock Tube International Standards Organization Propulsion and Power

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