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Computational diagnostics for flame acceleration and transition to detonation in a hydrogen/air mixture

COMBUSTION AND FLAME 2023年第Part2期258卷

作者： Lai, S. Tang, S. Xu, C. Sekularac, N. Fang, X. Shanghai Jiao Tong Univ SJTU Sch Aeronaut & Astronaut Shanghai Peoples R China Argonne Natl Lab Transportat & Power Syst Div Lemont IL 60439 USA CERFACS 42 Ave Gaspard Coriolis F-31057 Toulouse France Univ Oxford Dept Engn Sci Oxford OX1 3PJ England Univ Calgary Schulich Sch Engn Dept Mech & Mfg Engn Calgary AB T2L 1Y6 Canada

A new computational diagnostic method for pressure-induced compressibility is proposed by projecting its local contribution to the chemical explosive mode (CEM) in the chemical explosive mode analysis (CEMA) framework. The new method is validated for the study of detonation development during the deflagration-to-detonation transition (DDT) process. The flame characteristics are identified through the quantification of individual CEM contributions of chemical reaction, diffusion, and pressure-induced compressibility. Numerical simulations are performed to investigate the DDT processes in a stoichiometric hydrogen-air mixture. A Godunov algorithm, fifth-order in space, and third-order in time are used to solve the fully compressible Navier-Stokes equations on a dynamically adapting mesh. A single-step, calibrated chemical diffusive model (CDM) described by Arrhenius kinetics is used for energy release and conservation between the fuel and the product. The new diagnostic method is first applied to onedimensional (1D) canonical flame configurations followed by two-dimensional (2D) simulations of DDT in an obstructed channel where different detonation initiation scenarios are examined using the new CEMA projection formulation. Detailed examinations of the idealized configuration of detonation initiation through shock focusing mechanism at a flame front are also studied using the new formulation. A comparison of the currently proposed CEMA projection and the original formulation by the authors suggests that including the pressure-induced compressibility is essential for the use of CEMA in DDT process. The results also show that the new formulation of CEMA projection can successively capture the detonation initiation through either a gradient mechanism or a direct initiation mechanism, and therefore can be used as an effective local analytical tool for the computational diagnostics of detonation initiation in a DDT process. It was found that detonation development is chara

关键词： Numerical simulation Turbulent combustion deflagration to detonation transition Chemical explosive mode analysis

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Self-excited wave stabilization in a linear detonation combustor

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COMBUSTION AND FLAME 2023年第Part2期257卷

作者： Ullman, Michael Prakash, Supraj Jackson, Deborah Raman, Venkat Slabaugh, Carson Bennewitz, John Univ Michigan Dept Aerosp Engn Ann Arbor MI 48109 USA Purdue Univ Sch Aeronaut & Astronaut W Lafayette IN USA Univ Alabama Mech & Aerosp Engn Dept Huntsville AL USA

Detonative combustors, such as rotating detonation engines, have increasingly been viewed as next-generation propulsion and power generation systems because they offer higher theoretical thermal ef-ficiencies than conventional constant-pressure combustors. In order for these systems to be realized in a practical context, the impacts of inflow and outlet conditions, reactant mixing, and interactions between counter-propagating waves must be better understood. To examine these phenomena in a simplified ge-ometry, the present work considers a methane-oxygen reflective shuttling detonation combustor with an open-closed chamber configuration. High-fidelity simulations are conducted for two equivalence ra-tio conditions (lean and rich), and comparisons are made to complementary experiments. The results show that self-sustained steady-state wave behavior consists of minimally-reacting left-running waves and right-running detonation waves. The lean case is found to establish steady-state operation after a shorter time and exhibit detonation waves after a shorter distance from the closed end of the chamber. The simulations are able to predict the experimentally observed trends in the wave velocity in the di-rection of propagation. Wave-relative averaged flow fields show considerable reactant stratification and parasitic combustion ahead of the waves, likely contributing to their low speeds and pressures relative to ideal detonations. Conditional statistics ahead and behind the waves indicate that peaks in heat release occur at both lean and rich conditions near the open end of the chamber, and incomplete fuel oxidation in the primary detonation waves leads to delayed oxygen consumption and higher temperatures down-stream.(c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

关键词： Self-excitation detonation engine deflagration to detonation transition detonation wave structure

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The Effect of Ignition Pressure Pulse on Light-Off in an RDE

The Effect of Ignition Pressure Pulse on Light-Off in an RDE

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Stevens, Christopher A. Fotia, Matthew L. Hoke, John L. Schumaker, Stephen ISSI Inc Dayton OH 45459 USA Air Force Res Lab Wright Patterson AFB OH 45433 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

The typical method of igniting Rotating detonation Engines is a small, premixed, gaseous detonation tube commonly referred to as a predetonator. The reasoning for the predetonator is the aspiration that the detonation emerging from the device will couple directly into a detonation in the RDE. The reality is that the detonation emerging from the predetonator typically decouples and at least one deflagration to detonation transition occurs before a stable detonation is established in the RDE. The remaining benefits of the predetonator are high energy discharge, and good penetration into the RDE flow. The disadvantages are complexity when compared to traditional torch or spark igniters. Predetonators require precise timing and flow control that a torch does not. In this paper, we compare the ignition behavior of an RDE ignited by a predetonator to the same engine ignited by a torch. The predetonator was insufficient to directly initiate a detonation in the RDE channel, and DDT was always observed. Ignition via torch resulted in similar ignition behavior at higher flowrates, and slower ignition at very low flowrates. Counterintuitively, torch ignition resulted in larger pressure excursions than the predetonator possibly due to the steady blockage caused by the torch plume.

关键词： Rotating detonation Engine deflagration to detonation transition Mass Flow Pressure Transducers Ignition Systems Air Force Research Laboratory Acoustic Excitation Heat Transfer Experiments Liquid Rocket Engine Gas Turbine Engines

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Wave Dynamics, Power Production and Combustion Instabilities of a Disk-Shaped Pressure Gain Combustor

Wave Dynamics, Power Production and Combustion Instabilities...

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AIAA Propulsion and Energy Forum / IEEE Electric Aircraft Technologies Symposium (EATS)

作者： Huang, Xin Chang, Po-Hsiung Li, Jiun-Ming Teo, Chiang Juay Khoo, Boo Cheong Natl Univ Singapore 21 Lower Kent Ridge Rd Singapore 119077 Singapore

ISBN: (数字)9781624106118

ISBN: (纸本)9781624106118

This paper presents the experimental results regarding the detonation wave dynamics, power production and combustion instabilities of a disk-shaped pressure gain combustor (DPGC). Ethylene-air mixture was used for the DPGC experiments, and the experiments can be classified into two stages. For the first stage of the experiments, the DPGC was tested under the atmospheric back condition with a test duration of two seconds. The continuous detonation has been proven to be successfully established through the evidence from the dynamic wall pressure measurements. detonation wave dynamics have been evaluated among various testing conditions at the air mass flow rate of similar to 0.15 kg/s from fuel-lean to rich conditions. The results show that the characteristic wave frequencies continuously change during the tests, which could be associated with the variations of the combustor thermal environment upon the existence of the detonation waves. Meanwhile, the reactant injection pressures have also been found to be affected, showing the air and fuel plenum pressures change with similar trends to the wave frequency shifts. The detonation wave onset frequencies are selected out from the pressure spectrograms at 0.1 s from the ignition for further discussion. The result shows that the detonation wave velocities produced in this combustor fall in between the classical CJ detonation wave velocities and the sonic velocities in the burnt gas. For the second stage of the experiments, the DPGC was coupled with a turbocharger, aiming to use the shaft power extracted by the turbocharger turbine to evaluate the DPGC power production. A demonstration case is exhibited in this paper, which shows a power of 21.71 kW was extracted by the turbine from the DPGC exhaust when the combustion air flow rate was similar to 0.19 kg/s and the equivalence ratio was similar to 0.83. Coexisting with the detonation wave characteristic frequencies, low and intermediate frequency combustion instabilities sh

关键词： deflagration to detonation transition Annular Combustor detonation Waves Air Mass Flow Rates Air Flow Rate Power Spectral Density Compressor Efficiency Chamber Pressure Fuel Injection Air Flowing

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Large-Eddy Simulations of Methane-Oxygen Combustion in a Rotating detonation Rocket Engine

Large-Eddy Simulations of Methane-Oxygen Combustion in a Rot...

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AIAA Propulsion and Energy Forum / IEEE Electric Aircraft Technologies Symposium (EATS)

作者： Pal, Pinaki Demir, Sinan Kundu, Prithwish Som, Sibendu Argonne Natl Lab Div Energy Syst 9700 S Cass Ave Lemont IL 60439 USA Argonne Natl Lab Div Energy Syst MultiPhys Computat 9700 S Cass Ave Lemont IL 60439 USA

ISBN: (数字)9781624106118

ISBN: (纸本)9781624106118

Rotating detonation engines (RDEs) are a novel class of pressure gain combustion devices that are well-suited for high-speed propulsion applications, as they offer significant advantages over deflagrative combustion in terms of pressure gain from reactants to products, faster heat release, higher thermal efficiency, and higher thrust. Well-validated computational tools capable of capturing the operational characteristics in realistic RDE configurations can provide critical insights, and can be further utilized to improve and optimize RDE design. To this end, high-fidelity large-eddy simulations (LES) with detailed chemistry (12 species, 37 reactions) are performed to capture the supersonic combustion phenomena in a full-scale methane-oxygen non-premixed rotating detonation rocket engine (RDRE). The computational fluid dynamics (CFD) modeling approach employs adaptive mesh refinement (AMR) to achieve a good trade-off between simulation runtime and accuracy. Three different operating conditions are simulated. Overall, it is demonstrated that the high-fidelity LES modeling approach is able to predict the main qualitative and quantitative features of detonation wave dynamics (number of waves, wave speed, and axial pressures) and their sensitivity to operating conditions reasonably well.

关键词： Rocket Engine deflagration to detonation transition Computational Fluid Dynamics Rotating detonation Engine Adaptive Mesh Refinement detonation Waves Thermal Efficiency Reynolds Averaged Navier Stokes Air Force Research Laboratory Combustors

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detonation of Gases Containing A Single Molecular Species: NO & N₂H₄ (Hydrazine)

Detonation of Gases Containing A Single Molecular Species: N...

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AIAA Propulsion and Energy Forum / IEEE Electric Aircraft Technologies Symposium (EATS)

作者： Yang, L. C. La Canada Flintridge 91011 CA United States

ISBN: (数字)9781624106118

ISBN: (纸本)9781624106118

Detailed analyses using newly established analytic detonation formulations based on specific explosion or reaction energy have performed for interpretation and prediction of detonability of simple compositions including nitric oxide (NO), nitrous oxide (N2O) and hydrazine (N2H4) in solid, liquid and gaseous phases. A generalized Hess's law approach is effectively tailored for tracking the temperature dependent thermo-physical parameters. Generally, the results are successful in correlating experimental detonation tests data reported in literature and covering un-tested areas in solid and liquid N2H4, and gaseous N2O. The success also provided additional confirmation on the wide applicability of the new detonation formulations. Sonic velocity in the mediums of interest was identified as an important criterion for the detonability evaluation.

关键词： deflagration to detonation transition Heat of Vaporization Thermo physical Properties detonation Waves Heat Capacity Cryogenic Temperature Melting Points Propellant Solid Energetic Materials Conservation of Energy

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Improving the Stability and Operating Envelope for a Small Scale, High Frequency Rotating detonation Engine (RDE)

Improving the Stability and Operating Envelope for a Small S...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Fiorinol, Nathan T. Dechert, Joseph R. Snow, Nathan J. Schauer, Frederick R. Polanka, Marc D. Schumaker, S. Alexander Sell, Brain C. Air Force Inst Technol Aeronaut Engn Wright Patterson AFB OH 45434 USA Air Force Res Lab Aerosp Syst Directorate AFRL RQTC Wright Patterson AFB OH 45433 USA Innovat Sci Solut Inc Dayton OH 45459 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

Rotating detonation Engine (RDE) design has matured to the point that nominal sizing relations of critical RDE components such as channel gap, channel length, and channel diameter are well understood and documented. However, the actual bounds of these ideal ranges are not well understood and current interest resides in investigating the limits of what can be operable. The objective of this research was to build upon a recently developed Micro-RDE design with an outer diameter of 28mm operating on Nitrous Oxide and Ethylene. Previously, unstable detonation with a wave frequency of 14.0 kHz was achieved using a jets in crossflow (JIC) injection scheme. Current design changes to this injection scheme have been made and a limited evaluation of the new resultant operating map was conducted. Testing was done over a range of mass flows (0.035-0.075 kg/s) and equivalence ratios (Phi =1.1- 1.2) with a focus on how the changes affected stability. A stable one wave mode with frequencies up to 16.8 kHz was observed indicating improved stability. Longer run times are required to further substantiate the current results.

关键词： Rotating detonation Engine deflagration to detonation transition Mass Flow Rate Chamber Pressure detonation Waves Thermodynamic Cycles Aerospike Nozzle Air Force Research Laboratory Fuel Injection Combustors

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Experimental Study of a Racetrack-Type Rotating detonation Rocket Engine with Shear-Coaxial Injectors Run on Gaseous Methane and Oxygen

Experimental Study of a Racetrack-Type Rotating Detonation R...

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AIAA Propulsion and Energy Forum / IEEE Electric Aircraft Technologies Symposium (EATS)

作者： Unruh, Evan Venters, James Hemming, Michaela Lineberry, David Xu, Kunning G. Frederick, Robert Univ Alabama Huntsville Prop Res Ctr Mech & Aerosp Engn Dept Huntsville AL 35899 USA

ISBN: (数字)9781624106118

ISBN: (纸本)9781624106118

A model Rotating detonation Engine (RDE) has been developed at The University of Alabama in Huntsville that facilitates study of cyclical detonation and injection processes within the combustor section during operation. The engine is a 4-inch "Racetrack" type combustor designed with optical access to the injection and combustion region via the use of flat windows that minimize unwanted lensing effects. The engine was tested with Gaseous Methane (CH4) and Gaseous Oxygen (GO(2)) across a range of operating conditions in order to validate operability and characterize performance. Propellants are injected through 50 discrete GO(2)-centered shear-coaxial elements, spaced evenly along the centerline of the combustor channel. The engine was tested over total propellant mass flow rates from approximately 0.10 to 0.45 lbm/sec (0.045 to 0.20 kg/sec) and equivalence ratios from 0.64 to 2.8. detonation waves were observed in 4, 6, and 8 counterpropagating wave modes with average wave speeds ranging from 3447 to 4680 ft/sec (1051 to 1426 m/sec). The number of waves appear to be correlated to the average wave velocity, with the highest velocities observed in the 4-wave mode. Detonative operation was observed across equivalence ratios from 0.64 to 2.04, with the highest wave velocities observed at approximately 1.75.

关键词： deflagration to detonation transition Coaxial Injector Aerospike Nozzle Propellant Combustor Design Rotating detonation Engine Mass Flow Rate detonation Waves Chamber Pressure Pressure Transducers

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Calibrating the chemical-diffusive model using the detonation cell data

Calibrating the chemical-diffusive model using the detonatio...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Lu, Xiaoyi Kaplan, Carolyn R. Oran, Elaine S. Texas A&M Univ Dept Aerosp Engn College Stn TX 77843 USA Univ Maryland Dept Aerosp Engn College Pk MD 20742 USA Texas A&M Univ Dept Aerosp Engn ODonnell Fdn College Stn TX 77843 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

This paper presents an alternative approach to calibrate the chemical-diffusive model (CDM) for numerical simulations of detonations and deflagration-to-detonation transitions (DDTs). CDMis a chemicalmodel for compressible reactive fluid flows, in which model parameters are calibrated to reproduce key properties of a one-dimensional standard laminar flame and the Zel'dovich-Neumann-Doring (ZND) detonation. Multidimensional parameters, in particular, the detonation cell size, are not explicitly constrained in the current model. This work presentsmultidimensional numerical simulations of unstable detonations for hydrogen-airmixtures using the CDM. It is shown that the calibrated model using all zero- or one-dimensional properties cannot ensure correct detonation cellular structure. Instead, we introduce a new approach that exploits a well known cell-size correlation and is able to directly optimize the model parameters using specified experimental data.

关键词： deflagration to detonation transition Numerical Simulation Navier Stokes Equations Numerical Modeling Universal Gas Constant detonation Wave Engines Pre Exponential Factor Chemical Equilibrium Numerical Algorithms Compressible Fluid

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Experimental research on operation performance and acoustic behavior of two-phase dual-tube pulse detonation engine

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING 2022年第13期236卷 2829-2841页

作者： Huang, Xiaolong Li, Ning Weng, Chunsheng Kang, Yang Nanjing Univ Sci & Technol Natl Key Lab Transient Phys 200 Xiao Lingwei Rd Nanjing 210094 Jiangsu Peoples R China

In order to research the operation synchronous of dual-tube pulse detonation engine, the operation performance and acoustic behavior of dual-tube pulse detonation engine under different fill fractions are studied experimentally. The results show that the instability of deflagration to detonation transition is the main reason for the non-synchronous work of the two tubes. With the increase of fill fraction, the detonation sound pressure increases gradually. In the region near the tube exit, the pressure and velocity of the shock wave attenuate rapidly, and the attenuation speed gradually slows down while the propagation distance increases. The time interval of detonation waves arriving at the tube exit of the two tubes can significantly affect the peak sound pressure and the duration of the sound wave outside the tube. With the increase of time interval, the peak sound pressure decreases and the total duration as well as the duration of the positive pressure increase. The synchronization of the working process of the dual-tube pulse detonation engine can be diagnosed by analyzing the pressure and duration of the sound wave outside the tube. The research results in this paper have certain reference significance for improving the synchronous of multi-tube pulse detonation engine and will be useful for the application of multi-tube pulse detonation engine in aircraft power system.

关键词： dual-tube pulse detonation engine deflagration to detonation transition synchronization acoustic behavior fill fraction

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