The Experts below are selected from a list of 12051 Experts worldwide ranked by ideXlab platform
Frank K. Lu - One of the best experts on this subject based on the ideXlab platform.
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DNS of Detonation Wave and isotropic turbulence interaction
2020Co-Authors: Hari Narayanan, Frank K. LuAbstract:A direct numerical simulation of Detonation Wave with compressible homogeneous isotropic turbulence is carried out with three different Detonation Mach numbers to study the effect of Detonation Wave on turbulence and vice versa. The analysis is based on the integration of the three dimensional chemically reactive Navier–Stokes equations using a Runge–Kutta scheme and a fifth-order WENO spatial discretization. The interaction of the Detonation Wave and turbulence resulted in higher amplification of the turbulent statistical parameters (such as, turbulent kinetic energy, Taylor length scale and Kolmogorov length scale, rms of the velocity, pressure and thermodynamic parameters) than those observed in the shockturbulence interaction case. The study also revealed that the amplification of turbulence statistics is proportional to the heat release and activation energy.
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Summary of Recent Research on Detonation Wave Engines at UTA
2020Co-Authors: Donald R Wilson, Frank K. LuAbstract:A survey of recent research at UTA on Detonation Waves related to propulsion is presented in this paper. A brief historical review of the early pulse Detonation engine (PDE) research at UTA is provided to lay the background for the development of a large-scale PDE Ground Demonstrator. Also current activities related to the development of rotating Detonation Wave engines (RDE) are reviewed. System integration studies for both PDE- and RDE-based propulsion systems are summarized, followed by a brief description of two programs focusing on application of Detonation Waves to hypersonic flow simulation and power generation.
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airbreathing rotating Detonation Wave engine cycle analysis
Aerospace Science and Technology, 2013Co-Authors: Eric M Braun, Frank K. Lu, Donald R Wilson, Jose A CamberosAbstract:Abstract A cycle analysis model for an airbreathing, rotating Detonation Wave engine (RDE) is presented. The engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A Detonation Wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. A model for the side relief is used to find the pressure distribution around the combustor. Air and fuel enter the combustor when the rarefaction Wave pressure behind the Detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel radial width with respect to the isolator channel. Performance of this engine is considered using several parametric studies and compared with rocket-mode computational results. A hydrogen–air RDE reaches a specific impulse of 3800 s and can reach a flight speed of Mach 5.
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testing of a continuous Detonation Wave engine with swirled injection
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 2010Co-Authors: Eric M Braun, Nathan L Dunn, Frank K. LuAbstract:Two different continuous Detonation Wave engines with swirl to improve mixing were developed. The reactants were ignited with an ordinary automotive spark plug. Mixing and Detonation occurred in a common annular chamber in the first engine but occurred separately in the second. Deflagration-to-Detonation transition could be observed in the first engine. The number of revolutions of the Detonation Wave was limited due to the inability of the supply to deliver sufficient flow. For the second engine, Detonations were sustained for a longer duration. The data indicate that Detonation was achieved with multiple Detonation Waves traveling in one direction. Adding an endcap raised the pressure in the Detonation chamber.
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DNS of Detonation Wave and Isotropic Turbulence
19th AIAA Computational Fluid Dynamics, 2009Co-Authors: Hari Narayanan Nagarajan, Frank K. Lu, Luca MassaAbstract:A direct numerical simulation of Detonation Wave with compressible homogeneous isotropic turbulence is carried out with three different Detonation Mach numbers to study the effect of Detonation Wave on turbulence and vice versa. The analysis is based on the integration of the three dimensional chemically reactive Navier–Stokes equations using a Runge–Kutta scheme and a fifth-order WENO spatial discretization. The interaction of the Detonation Wave and turbulence resulted in higher amplification of the turbulent statistical parameters (such as, turbulent kinetic energy, Taylor length scale and Kolmogorov length scale, rms of the velocity, pressure and thermodynamic parameters) than those observed in the shockturbulence interaction case. The study also revealed that the amplification of turbulence statistics is proportional to the heat release and activation energy.
Changsheng Zhou - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on propagation characteristics of rotating Detonation Wave with a hydrogen ethylene acetylene fuel
Acta Astronautica, 2019Co-Authors: Shengbing Zhou, Sihe Chen, Yepan Zhong, Changsheng ZhouAbstract:Abstract It is attracting much attention that the hydrocarbon mixtures are used as the fuel of rotating Detonation engine when the oxidizer is air. In this study, a hydrogen-ethylene-acetylene mixture was used as the fuel of rotating Detonation combustor to investigate the propagation characteristics of rotating Detonation Wave. An annular combustor, with an inner diameter of 124 mm and an outer diameter of 152 mm, was used in this research. The air and fuel were separately injected into the combustor through a slot-orifice injection structure. High-frequency pressure sensors and ionization probes were used to measure the Detonation characteristics. Experiments could obtain a stable Detonation Wave whose velocity was about 65% of the C-J value, showing that there was a large velocity loss compared to hydrogen fuel, which reached a C-J velocity value of 94%. The Detonation intensity for the hydrogen-ethylene-acetylene mixture is weaker than that of hydrogen. The equivalence-ratio range of forming a Detonation Wave with hydrogen-ethylene-acetylene mixture was narrower than that of hydrogen fuel with the same mass flow rate. The Detonation-Wave height of hydrogen-ethylene-acetylene mixture had similar results with hydrogen fuel.
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propagation process of h2 air rotating Detonation Wave and influence factors in plane radial structure
International Journal of Hydrogen Energy, 2018Co-Authors: Changfei Zhuo, Changsheng ZhouAbstract:Abstract The rotating Detonation Wave (RDW) propagation processes and influence factors are simulated in the plane-radial structure. The effects of inner radii of curvature, domain widths and stagnation pressures on propagation mode are studied. The RDW is initiated, and two kinds of propagation mode are obtained and analyzed. The flow field structure, parameters variation and influence factors on unstable propagation mode are explored in depth, and the geometrical and injection conditions of the unstable propagation are obtained. Results indicate that the decoupling and re-initiation occur repeatedly during the unstable propagation mode of the RDW, and the angular velocities of leading shock Wave vary accordingly. When the domain width remains constant, the range of stagnation-pressure under unstable propagation mode increases as the inner radius increases. But the RDW propagates steadily when the inner radius increases to a certain value (Larger than 40 mm in this study). The effect of curvature radius and initial pressure ahead of Detonation Wave on the unstable propagation mode in this calculation model is similar to that in a curved channel. When ri +0.464pa > 80.932 or ri ≥ 40 mm, the Detonation Wave can propagate steadily in the annular domain. When the curvature radius remains constant, the stagnation-pressure range of the unstable propagation mode decreases as the domain width increases.
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Investigation on the propagation process of rotating Detonation Wave
Acta Astronautica, 2017Co-Authors: Li Deng, Hu Ma, Can Xu, Changsheng ZhouAbstract:Abstract Effects of mass flow rate and equivalence ratio on the Wave speed performance and instantaneous pressure characteristics of rotating Detonation Wave are investigated using hydrogen and air mixtures. The interaction between air and fuel manifolds and combustion chamber is also identified. The results show that the rotating Detonation Waves are able to adapt themselves to the changes of equivalence ratio during the run, the rotating Detonation Waves decayed gradually and then quenched after the shutdown of reactants supply. The Wave speed performance is closely related to the mass flow rate and the pressure ratio of the fuel to air manifolds at different equivalence ratios. The blockage ratio of the air manifold increases with the increasing of the Wave speed due to high-pressure Detonation products, while increasing of the equivalence ratios will reduce the blockage ratio of the hydrogen manifold. Higher equivalence ratio can enhance the stabilization of the rotating Detonation Wave and lower equivalence ratio will lead to the large fluctuations of the lap time and instantaneous pressure magnitude. The overpressure of rotating Detonation Wave is determined by the combination of mass flow rate and equivalence ratio, which increases with the increasing of mass flow rate in the equivalence ratio ranges that the rotating Detonation Wave propagates stably. The secondary spike in the instantaneous pressure and ionization signals indicates that a shocked mixing zone exists near the fuel injection holes and the reflection of shock in the mixing zone induces the reaction.
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effects of a turbine guide vane on hydrogen air rotating Detonation Wave propagation characteristics
International Journal of Hydrogen Energy, 2017Co-Authors: Shengbing Zhou, Shuai Li, Changsheng ZhouAbstract:Abstract The rotating Detonation engine is a new machine that can generate thrust via continuous rotating Detonation Waves (RDWs). In this study, experiments were performed on a structure combining a rotating Detonation combustor (RDC) and a turbine guide vane to investigate the propagation characteristic of hydrogen-air RDW. The results showed that the velocity of Detonation Wave initially increased and then decreased with the increase of equivalence ratio, and it got a velocity of 84% Chapman-Jouguet value. The velocity of Detonation Wave generally rose by 4.31% comparing with the no guide vane tests, while the scope of steady-operation state became narrow. The oscillation pressure was reduced by 64% after passing through the guide vane, and the magnitude of pressure was only 0.4 bar at the guide vane exit. Meanwhile, part of the shock Wave was reflected back to combustor resulting in some small pressure disturbances, and the propagation mode of reflected Wave was related to the propagation direction of RDW.
A V Fedorov - One of the best experts on this subject based on the ideXlab platform.
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exit of a heterogeneous Detonation Wave into a channel with linear expansion ii critical propagation condition
Combustion Explosion and Shock Waves, 2018Co-Authors: A V Fedorov, T A Khmel, Sergey LavrukAbstract:Propagation of a Detonation Wave in monodisperse suspensions of reacting particles (based on the model of the suspension of aluminum particles in oxygen) in channels with linear expansion is studied within the framework of mechanics of heterogeneous reacting media. Reduced kinetics is described with allowance for the transitional (from diffusion to kinetic) regime of combustion of micron-sized and submicron-sized spherical aluminum particles. The effects of the channel width, particle diameter, and expansion angle on propagation conditions and Detonation regimes are determined. The critical channel width is found to be a nonmonotonic function of the expansion angle, which is associated with qualitatively different Wave patterns behind an oblique step. Flow charts are constructed, and the results are compared with solutions of problems of heterogeneous Detonation Wave propagation in channels with a backward-facing step and with sudden expansion.
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exit of a heterogeneous Detonation Wave into a channel with linear expansion i propagation regimes
Combustion Explosion and Shock Waves, 2017Co-Authors: A V Fedorov, T A Khmel, Sergey LavrukAbstract:Propagation of a plane Detonation Wave in a stoichiometric mixture of a gas and aluminum particles in a plane channel with a linear expansion section is studied by methods of numerical simulation. The slope of the wall is varied from 15 to 60°. The basic regimes of Detonation propagation are analyzed: supercritical (without Detonation failure), critical (with partial failure and re-initiation), and subcritical (with complete separation of the shock front and combustion front and with Detonation failure). The Detonation configuration formed in the expanding section can be a cellular structure with large differences in cell sizes at large angles of expansion or a close-to-uniform structure at the wall angle of 15°.
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mathematical modeling of Detonation Wave suppression by cloud of chemically inert solid particles
Combustion Science and Technology, 2014Co-Authors: D A Tropin, A V FedorovAbstract:The effect of volume concentration and particle diameter on the velocity of the Detonation Wave (DW) in hydrogen/oxygen and a methane/oxygen mixtures with addition of inert particle cloud was investigated based on the developed physical and mathematical model of weakening and suppressing the Detonation process in the mixtures, which takes into account the detailed kinetics of chemical reactions. The concentration limits (by volume concentration of particles) of Detonation in mixtures of hydrogen/oxygen, methane/oxygen, and methane/hydrogen/oxygen were obtained. The comparison of the Detonation suppression data in these mixtures revealed that the critical volume concentration quenching DW highest in the methane/hydrogen/oxygen mixture and the lowest in the hydrogen/oxygen mixture. Geometric limits of Detonation are determined, and a comparison with similar results predicted by the simple “frozen” model is performed.
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simple kinetics and Detonation Wave structure in a methane air mixture
Combustion Explosion and Shock Waves, 2014Co-Authors: A V Fedorov, P A Fomin, D A TropinAbstract:A reduced two-stage model of Detonation combustion of methane in oxygen and air for equimolar and fuel-lean mixtures is proposed. One-dimensional structures of the Detonation Wave are calculated for different ratios of the fuel and oxidizer corresponding to the overdriven and Chapman-Jouguet regimes. A comparison of the calculated dependences of the Detonation velocity on the methane concentration in the methane-air mixture with available published data reveals their reasonable agreement.
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calculation of Detonation Wave propagation in a gas suspension of aluminum and inert particles
Combustion Explosion and Shock Waves, 2013Co-Authors: A V Fedorov, Yu V KratovaAbstract:Propagation of a Detonation Wave in a plane channel filled by a gas suspension of fine aluminum particles and inert particles in oxygen is studied. Heterogeneous Detonation of aluminum particles in oxygen propagates in the Chapman-Jouguet regime. Two types of the flow resulting from Detonation interaction with a cloud of particles are found: continuous propagation with a smaller Detonation velocity and flow with Detonation failure. The influence of physical and spatial parameters of the inert component of the cloud on these regimes is found, including the mechanism of suppression of heterogeneous Detonation, which means separation of the ignition and combustion Wave from the leading shock front. Dependences of the velocity deficit on the mass fraction and size of inert particles are determined.
Kungming Chung - One of the best experts on this subject based on the ideXlab platform.
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detection of shock and Detonation Wave propagation by cross correlation
Mechanical Systems and Signal Processing, 2009Co-Authors: Frank K. Lu, A. A. Ortiz, J M Li, Kungming ChungAbstract:The propagation speed of a shock or Detonation Wave in a shock tube is usually determined by a time-of-flight method by dividing the distance between two transducers with the propagation time of the disturbance signal. Some arbitrariness is inherent in determining the propagation time by this method. An improved method for objectively determining the propagation time using a nonstationary cross-correlation technique is described. The method requires the choice of an integration window that includes the nonstationary event. The method was first tested against a number of model functions with different noise levels. It was then applied to propagating and reflected shock and Detonation Waves, including an example of a transitioning Detonation Wave propagating past six transducers. In addition, the nonstationary CCF technique was also applied to evaluate the uncertainty in estimating the deflagration-to-Detonation transition run-up distance. In all cases, the time delay and its standard deviation could be obtained.
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experimental study on transmission of an overdriven Detonation Wave from propane oxygen to propane air
Combustion and Flame, 2008Co-Authors: J Li, Kungming Chung, Frank K. LuAbstract:Two sets of experiments were performed to achieve a strong overdriven state in a weaker mixture by propagating an overdriven Detonation Wave via a deflagration-to-Detonation transition (DDT) process. First, preliminary experiments with a propane/oxygen mixture were used to evaluate the attenuation of the overdriven Detonation Wave in the DDT process. Next, experiments were performed wherein a propane/oxygen mixture was separated from a propane/air mixture by a thin diaphragm to observe the transmission of an overdriven Detonation Wave. Based on the characteristic relations, a simple Wave intersection model was used to calculate the state of the transmitted Detonation Wave. The results showed that a rarefaction effect must be included to ensure that there is no overestimate of the post-transmission Wave properties when the incident Detonation Wave is overdriven. The strength of the incident overdriven Detonation Wave plays an important role in the Wave transmission process. The experimental results showed that a transmitted overdriven Detonation Wave occurs instantaneously with a strong incident overdriven Detonation Wave. The near-CJ state of the incident Wave leads to a transmitted shock Wave, and then the transition to the overdriven Detonation Wave occurs downstream. The attenuation process for the overdriven Detonation Wave decaying to a near-CJ state occurs in all tests. After the attenuation process, an unstable Detonation Wave was observed in most tests. This may be attributed to the increase in the cell width in the attenuation process that exceeds the detonability cell width limit.
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Experimental study on transmission of an overdriven Detonation Wave from propane/oxygen to propane/air
Combustion and Flame, 2008Co-Authors: J Li, Kungming Chung, Frank K. LuAbstract:Two sets of experiments were performed to achieve a strong overdriven state in a weaker mixture by propagating an overdriven Detonation Wave via a deflagration-to-Detonation transition (DDT) process. First, preliminary experiments with a propane/oxygen mixture were used to evaluate the attenuation of the overdriven Detonation Wave in the DDT process. Next, experiments were performed wherein a propane/oxygen mixture was separated from a propane/air mixture by a thin diaphragm to observe the transmission of an overdriven Detonation Wave. Based on the characteristic relations, a simple Wave intersection model was used to calculate the state of the transmitted Detonation Wave. The results showed that a rarefaction effect must be included to ensure that there is no overestimate of the post-transmission Wave properties when the incident Detonation Wave is overdriven. The strength of the incident overdriven Detonation Wave plays an important role in the Wave transmission process. The experimental results showed that a transmitted overdriven Detonation Wave occurs instantaneously with a strong incident overdriven Detonation Wave. The near-CJ state of the incident Wave leads to a transmitted shock Wave, and then the transition to the overdriven Detonation Wave occurs downstream. The attenuation process for the overdriven Detonation Wave decaying to a near-CJ state occurs in all tests. After the attenuation process, an unstable Detonation Wave was observed in most tests. This may be attributed to the increase in the cell width in the attenuation process that exceeds the detonability cell width limit.
Quan Zheng - One of the best experts on this subject based on the ideXlab platform.
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influence of equivalence ratio on the propagation characteristics of rotating Detonation Wave
Experimental Thermal and Fluid Science, 2018Co-Authors: Baoxing Li, Chunsheng Weng, Yuwen Wu, Quan ZhengAbstract:Abstract An experimental study on a rotating Detonation engine was carried out to analyze the initiation and propagation characteristics of rotating Detonation Wave. Propellants were hydrogen/air mixture and ignited by a pre-detonator. The rotating Detonation Wave was initiated and propagated successfully with various equivalence ratios. Piezoelectric pressure transducers were used to monitor high-frequency pressure signals. Experimental results indicated that after the ignition, the rotating Detonation Wave was not initiated directly. With the increase of the equivalence ratio, the formation time of rotating Detonation Wave decreased rapidly. Meanwhile, the rotating Detonation Wave sequentially exhibited three propagation modes: dual-Wave to single-Wave transition mode, single-Wave with the propagation direction reversal mode, and single-Wave one-way mode. The maximum propagation frequency and velocity of the rotating Detonation were obtained at the equivalence ratio of 1.0, while the minimum frequency fluctuation was obtained at the equivalence ratio of 0.89. In addition, the rotating Detonation Wave height and the bending angle β of the oblique shock Wave were obtained. This research determined the boundary of the stable propagation modes of rotating Detonation Waves and found that their frequency fluctuations substantially increase when the equivalence ratio is below about 0.7.
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experimental research on the propagation process of continuous rotating Detonation Wave
Defence Technology, 2013Co-Authors: Quan Zheng, Chunsheng WengAbstract:Abstract In order to study the propagation mechanism of continuous rotating Detonation Wave, the H 2 /air continuous rotating Detonation engine ignited by tangentially installed H 2 /O 2 pre-Detonation tube is studied experimentally using a tilt slot injector structure. The experimental results show that the stable rotating Detonation Wave can be gained successfully with the equivalent ratio of 0.93. The propagation frequency and velocity of rotating Detonation Wave range from 5200 to 5500 Hz and from 1518.5 to 1606.1 m/s, respectively. Three propagation modes, such as rotation, reversal and bifurcation, of Detonation Wave are verified through the analysis of propagation mechanism of rotating Detonation Wave.