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Ignition of Hydrocarbon-Air Supersonic Flow by Volumetric Ionization

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Journal of Thermal Science 2015年第6期24卷 583-590页

作者： Marat A.Goldfeld George A.Pozdnyakov Khristianovich Institute of theoretical and applied mechanics SB RAS

The paper describes the results of the electron-beam initiation of the combustion in the mixtures of hydrogen,natural gas or kerosene vapors with *** beam characteristics were studied in closed volume with immobile *** researches included definition of an integrated current of an electronic beam,distribution of a current density and an estimation of average energy of *** of fuel mixtures ignition by means of this approach in the combustor at high velocity at the entrance was *** were carried out at Mach numbers of 4 and *** of ignition and combustion under electron beam action was *** was revealed that ignition of mixture occurs after completion of electron gun *** obtained have confirmed effectiveness of electron beam application for ignition of hydrogen and natural *** numerical simulation of the combustion of mixture in channel was carried out by means of ANSYS CFD 12.0 instrumentation on the basis of Reynolds averaged Navier-Stokes equation using SST/k-ωturbulence *** combustion modeling,a detailed kinetic scheme with 38 reactions of 8 species was implemented taking into account finite rate *** have shown that the developed model allow to predict ignition of a mixture and flame propagation even at low flow temperatures.

关键词： supersonic flow combustor electron bean ignition delay numerical simulation.

Numerical and Experimental Studies of 3D Hypersonic Inlet

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Journal of Thermal Science 2002年第3期11卷 198-206,219页

作者： MaratA.Goldfeld RomanV.Nestoulia Institute of theoretical and applied mechanics Novosibirsk Russia

The results of numerical and experimental studies of a new configuration of 3D hypersonic inlet with the minimum throat area, which was called a convergent inlet, are presented in this paper. It is shown that the use of this inlet configuration allows one to reduce the drag and thermal protection of surfaces of a hypersonic engine within the entire range of flight velocities. The calculations were performed within the framework of inviscid gas model by the method of finite volumes. The flow and inlet characteristics, taking account of viscosity, were also calculated using the boundary layer equations. The experimental studies were performed within the Mach number range from 2 to 10.7 and Reynolds number based on the model inlet height of Re=1-5×106. The results included the flow parameters on the external compression surface and in the inlet duct, the Mach number in the throat, the air flow rate, the total pressure recovery coefficient, the inlet drag, and the boundary layer characteristics on

关键词： hypersonic inlet convergent inlet boundary layer.

Ignition Process Evolution at High Supersonic Velocities in Channel

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Journal of Thermal Science 2009年第2期18卷 166-172页

作者： M.A.Goldfeldl A.V.Starov K.Yu.Timofeev V.A.Vinogradov Institute of theoretical and applied mechanics Central Institute of Aviation Motors

The results of experimental research of multi-injector combustors in the regime of the attached pipe are *** a source of high-enthalpy working gas (air), hot shot wind tunnel IT-302M of ITAM, the Siberian Branch ofthe Russian Academy of Sciences was used. Tests have been carried out at Mach numbers 3,4 and 5, in a range ofchange of total temperature from 2000K up to 3000K and static pressure from 0.08MPa up to 0.23MPa. Injectorsection has been manufactured in two versions with a various relative height of wedge-shaped injectors with parallelfuel injection. Influence of conditions on the entrance of the combustion chamber on ignition and a stablecombustion of hydrogen was investigated. Intensive combustion of hydrogen has been received only at Machnumbers 3 and 4. Advantage of injector section with the greater relative height of injectors is revealed. Themechanism of fuel ignition in the combustion chamber of the given configuration was investigated: two-step ignitionprocess including 'kindling' and intensive combustion over all channel volume.

关键词： supersonic combustor ignition stable combustion.

Skin Friction Gage for Measurements in Hypersonic Flow

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Journal of Thermal Science 2003年第1期12卷 44-50页

作者： Francois Falempin Marat Goldfeld Roman Nestoulia EADS Aerospatiale Matra Missiles ChatillonInstitute of Theoretical and Applied Mechanics NovosibirskInstitute of Theoretical and Applied Mechanics Novosibirsk France Russia Russia

A description and results of tests of a new small-scale gage for direct measurement of skin friction force are presented in the *** gage design provides separated measurement of longitudinal and transversal component of friction *** of this scheme provides high sensitivity and necessary high-frequency response of the *** tests of the gage were carried out in a blow down wind tunnel at Mach numbers of 2 and 4 within the range of Reynolds numbers Rex from 0.8 to 5 million and in the hot-shot wind tunnel at Mach number 6 and Reynolds numbers Rex=2.5-10 *** measurements of skin friction were carried out on a flat plate and on a ramp beyond the shock *** with the direct measurement of friction in the blow down wind tunnel,the measurements of profiles of average velocities and mass flow rate pulsations were *** of measurement errors has shown that the friction gage permits to measure skin friction coefficient on a flat plate with mistake not more than 10%.

关键词： skin friction gage hypersonic flow scramjet.

The detection, extraction and parameter estimation of extreme-mass-ratio inspirals with deep learning

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Science China(Physics,mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 86-96页

作者： Qianyun Yun Wen-Biao Han Yi-Yang Guo He Wang Minghui Du Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences Shanghai Astronomical Observatory Chinese Academy of Sciences School of Physics and Astronomy Shanghai Jiao Tong University School of Astronomy and Space Science University of Chinese Academy of Sciences Taiji Laboratory for Gravitational Wave Universe (Beijing/Hangzhou) University of Chinese Academy of Sciences Lanzhou Center for theoretical Physics Key Laboratory of Theoretical Physics of Gansu Province Key Laboratory of Quantum Theory and Applications of MoE Lanzhou University Institute of theoretical Physics & Research Center of Gravitation Lanzhou University International Centre for theoretical Physics Asia-Pacific (ICTP-AP) University of Chinese Academy of Sciences (UCAS) Center for Gravitational Wave Experiment National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences

One of the primary goals of space-borne gravitational wave detectors is to detect and analyze extreme-mass-ratio inspirals(EMRIs). This task is particularly challenging because EMRI signals are complex, lengthy, and faint. In this work, we introduce a2-layer convolutional neural network(CNN) approach to detect EMRI signals for space-borne detectors, achieving a true positive rate(TPR) of 96.9% at a 1% false positive rate(FPR) for signal-to-noise ratio(SNR) from 50 to 100. Especially, the key intrinsic parameters of EMRIs such as the mass, spin of the supermassive black hole(SMBH) and the initial eccentricity of the orbit can also be inferred directly by employing a neural network. The mass and spin of the SMBH can be determined at 99% and 92% respectively. This will greatly reduce the parameter spaces and computing cost for the following Bayesian parameter *** model also has a low dependency on the accuracy of the waveform model. This study underscores the potential of deep learning methods in EMRI data analysis, enabling the rapid detection of EMRI signals and efficient parameter estimation.

关键词： gravitational wave EMRIs deep-learing

The Research of Laminar-Turbulent Transition in Hypersonic Three-Dimensional Boundary Layer

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Journal of Thermal Science 2005年第2期14卷 103-107页

作者： Marat A.GOLDFELD Evgeniy V.ORLIK Institute of theoretical and applied mechanics 4/1 Institutskaya Str. Novosibirsk 630090RussiaInstitute of Theoretical and Applied Mechanics 4/1 Institutskaya Str.Novosibirsk 630090Russia

The results of experimental investigation of laminar-turbulent transition in three-dimensional flow under the high continuous pressure gradient including the flow with local boundary layer separation are presented. The experimental studies were performed within the Mach number range from 4 to 6 and Reynolds number 10-60×106 1/m, the angles of attack were 0° and 5°. The experiments were carried out on the three-dimensional convergent inlet model with and without sidewalls. The influence of artificial tubulator of boundary layer on transition and flow structure was studied. The conducted researches have shown that adverse pressure gradient increase hastens transition and leads to decrease of transition area length. If pressure gradient rises velocity profile fullness increases and profile transformation from laminar to turbulent occurs. As a result of it the decrease of separation area length occurs. The same effect was reached with Reynolds number increase. These results are compared with the data on two-dimensional model with longitudinal curvature.

关键词： hypersonic boundary layer transition convergent inlet adverse pressure gradient.

Thermal Wave Effect and Sintering Activation Energy at the Initial Stage of Field Assisted Sintering Process for Non-conductive Al_2O_3 Powders

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Journal of Wuhan University of Technology(Materials Science) 2018年第6期33卷 1416-1421页

作者： ZHANG Long Department of theoretical and applied mechanics Chongqing University of Science and Technology Department of Engineering mechanics Chongqing University

The effect of thermal wave at the initial stage for non-conductive Al_2 O_3 powders compact in field assisted sintering technique(FAST) was investigated. The Lord and Shulman type generalized thermoselastic theory was introduced to describe the influence of thermal-mechanical interaction, as well as the heat transport and thermal focusing caused by thermal wave propagation. The expression of vacancy concentration difference of the particles was deduced by considering transient thermal stress. Subsequently, the relationship between activation energy and vacancy concentration difference was obtained. The mechanism of surface diffusion, volume diffusion, simultaneous surface and volume diffusion was analyzed. The numerical simulations indicate that low sintering temperature can obtain high local temperature by the superposition effect of thermal wave. Vacancy concentration differences were improved during FAST compared with hot-pressure and pressureless sintering, thereby decreasing the sintering time. By contrast, the activation energy declined with the decrease of vacancy concentration difference in the neck growth process.

关键词： field assisted sintering technique generalized thermoelastic theory thermal wave vacancy concentration difference sintering activation energy

The Boundary Layer Interaction with Shock Wave and Expansion Fan

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Journal of Thermal Science 2000年第2期9卷 109-114页

作者： Marat A. Goldfeld Roman V. Nestoulia Alexei V. Starov Institute of theoretical and applied mechanics, 4/1, Institutskaya Str., Novosibirsk 630090, Russia. Institute of theoretical and applied mechanics Novosibirsk Russia

The results of experimental investigation of a turbulent boundary layer on compression and expansion surfaces are presented. They include the study of the shock wave and/or expansion fan action upon the boundary layer, boundary layer separation and its relaxation. Complex events of paired interactions and the flow on compression convex-concave surfaces were studied. The possibility and conditions of the boundary layer relaminarization behind the expansion fan and its effect on the relaxation length are presented. Different model configurations for wide range conditions were investigated. Comparison of results for different interactions was carried out.

关键词： boundary layer shock wave expansion fan relaxation separation.

AN EFFICIENT METHOD FOR MULTIOBJECTIVE OPTIMAL CONTROL AND OPTIMAL CONTROL SUBJECT TO INTEGRAL CONSTRAINTS

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Journal of Computational Mathematics 2010年第4期28卷 517-551页

作者： Ajeet Kumar Alexander Vladimirsky Department of theoretical & applied mechanics Cornell University Department of Mathematics Cornell University

We introduce a new and efficient numerical method for multicriterion optimal control and single criterion optimal control under integral constraints. The approach is based on extending the state space to include information on a ＂budget＂ remaining to satisfy each constraint; the augmented Hamilton-Jacobi-Bellman PDE is then solved numerically. The efficiency of our approach hinges on the causality in that PDE, i.e., the monotonicity of characteristic curves in one of the newly added dimensions. A semi-Lagrangian ＂marching＂ method is used to approximate the discontinuous viscosity solution efficiently. We compare this to a recently introduced ＂weighted sum＂ based algorithm for the same problem [25]. We illustrate our method using examples from flight path planning and robotic navigation in the presence of friendly and adversarial observers.

关键词： Optimal control Multiobjective optimization Pareto front Vector dynamic programming Hamilton-Jacobi equation Discontinuous viscosity solution Semi-Lagrangian discretization.