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Theories and methods for designing hypersonic high-enthalpy flow nozzles

Chinese Journal of Aeronautics 2022年第1期35卷 318-339页

作者： Yunpeng WANG zonglin jiang State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Hypersonic high-enthalpy wind tunnels have been a challenge to ground tests in aerospace research area for decades and its test flow uniformity is one of the most important parameters for evaluating wind tunnel *** to the performance requirement,theories and methods for designing hypersonic flow nozzles at high enthalpy conditions are quite difficult,but very interesting topics,especially when air molecule dissociations take place in wind tunnel test gas *** this paper,fundamental theories and important methods for nozzle designs are briefly reviewed with the emphasis on two-dimensional axisymmetric nozzles for hypersonic high-enthalpy wind tunnels,including the Method of Characteristics(MOC),the graphic design method,the Sivells method,the theory for boundary correction,and the CFD-based design optimization *** theories and methods had been proposed based on several physical issues,respectively,which play important roles in nozzle flow expansion *** issues cover the expansion wave generation and reflection,the boundary layer development,the real gas effect of hypersonic high-enthalpy *** arising from applications of these methods in hypersonic high-enthalpy nozzle design are discussed in detail and the state of the art of the nozzle design technologies that have reached for decades is summarized with some brief ***,the prospect for the hypersonic nozzle design methods,and its numerical and experimental verifications are provided with from authors’viewpoint for readers’reference.

关键词： Boundary layer correction High-enthalpy flow Hypersonic wind tunnel Nozzle design Real-gas effects

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Wave dynamic processes in cellular detonation reflection from wedges

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Acta Mechanica Sinica 2007年第1期23卷 33-41页

作者： Zongmin Hu zonglin jiang LHD institute of Mechanics CAS Beijing 100080 China ReCAPT Gyeongsang National University Jinju Kyeongnam 660-701 South Korea

When the cell width of the incident detonation wave （IDW） is comparable to or larger than the Mach stem height, self-similarity will fail during IDW reflection from a wedge surface. In this paper, the detonation reflection from wedges is investigated for the wave dynamic processes occurring in the wave front, including transverse shock motion and detonation cell variations behind the Mach stem. A detailed reaction model is implemented to simulate two-dimensional cellular detonations in stoichiometric mixtures of H2/O2 diluted by Argon. The numerical results show that the transverse waves, which cross the triple point trajectory of Mach reflection, travel along the Mach stem and reflect back from the wedge surface, control the size of the cells in the region swept by the Mach stem. It is the energy carried by these transverse waves that sustains the triple-wave-collision with a higher frequency within the over-driven Mach stem. In some cases, local wave dynamic processes and wave structures play a dominant role in determining the pattern of cellular record, leading to the fact that the cellular patterns after the Mach stem exhibit some peculiar modes.

关键词： Cellular detonation Wedge Reflection Wave dynamics Simulation

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Reconsideration on the role of the specific heat ratio in Arrhenius law applications

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Acta Mechanica Sinica 2008年第3期24卷 261-266页

作者： Yunfeng Liu zonglin jiang Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of SciencesBeijing 100080 China

Arrhenius law implicates that only those molecules which possess the internal energy greater than the activation energy Ea can react. However, the internal energy will not be proportional to the gas temperature if the specific heat ratio y and the gas constant R vary during chemical reaction processes. The varying y may affect significantly the chemical reaction rate calculated with the Arrhenius law under the constant γ assumption, which has been widely accepted in detonation and combustion simulations for many years. In this paper, the roles of variable γ and R in Arrhenius law applications are reconsidered, and their effects on the chemical reaction rate are demonstrated by simulating one- dimensional C-J and two-dimensional cellular detonations. A new overall one-step detonation model with variable γ and R is proposed to improve the Arrhenius law. Numerical experiments demonstrate that this improved Arrhenius law works well in predicting detonation phenomena with the numerical results being in good agreement with experimental data.

关键词： Arrhenius law Detonation Specific heat ratio

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Force measurement using strain-gauge balance in shock tunnel based on deep learning

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Chinese Journal of Aeronautics 2023年第8期36卷 43-53页

作者： Shaojun NIE Yunpeng WANG zonglin jiang State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of ScienceBeijing 100049China

When a force test is conducted in a shock tunnel,vibration of the Force Measurement System(FMS)is excited under the strong flow impact,and it cannot be attenuated rapidly within the extremely short test duration of milliseconds *** output signal of the force balance is coupled with the aerodynamic force and the inertial *** interference can result in inaccurate force measurements,which can negatively impact the accuracy of the test *** eliminate inertial vibration interference from the output signal,proposed here is a dynamic calibration modeling method for an FMS based on deep *** signal is processed using an intelligent Recurrent Neural Network(RNN)model in the time domain and an intelligent Convolutional Neural Network(CNN)model in the frequency *** processed with the intelligent models show that the inertial vibration characteristics of the FMS can be identified efficiently and its main frequency is about 380 *** processed by the intelligent models,the inertial vibration is mostly eliminated from the output ***,the data processing results are subjected to error *** relative error of each component is about 1%,which verifies that the modeling method based on deep learning has considerable engineering application value in data processing for pulse-type strain-gauge ***,the proposed dynamic calibration modeling method has the potential to improve the accuracy and reliability of force measurements in shock tunnel tests,which could have significant implications for the field of aerospace engineering.

关键词： Convolutional neural net-works Deep learning Frequency domain analysis Forcemeasurement Time domain analysis Recurrent neural networks

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Effects of different product phases in aluminum dust detonation modeling

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Science China(Physics,Mechanics & Astronomy) 2013年第11期56卷 2178-2185页

作者： TENG HongHui jiang zonglin State Key Lab of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences

Modeling aluminum(Al)dust detonation is difficult due to uncertainties in the product species and *** experiments indicate both gaseous and solid alumina may appear in the detonation product,but only the gaseous one was considered *** resolve this drawback,we study the effects of different product phases on the detonation parameters with the hybrid combustion model proposed *** results demonstrate that the assumption of gaseous product induces high velocity and pressure,while the assumption of solid product induces low velocity and *** clarify how close-to-experiment results have been obtained with one phase assumption,we revisit previous studies and analyze the *** inconsistency between the product phase and heat release is found,and then one model with variable heat release dependent on the product phase is *** simulations with both the gaseous and solid products are carried out,and results reveal the necessity of establishing a relationship between the heat release and reaction products.

关键词： detonation aluminum multiphase

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Numerical investigation on the thermal protection mechanism for blunt body with forward-facing cavity

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Science China(Technological Sciences) 2016年第7期59卷 1120-1129页

作者： LI XinDong HU ZongMin jiang zonglin State Key Laboratory of High Temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences

Numerical experiments are carried out using the standard hypersonic ballistic-type model(HB-2) to investigate the effect of forward-facing cavity on the aerodynamic heating. A general concept is proposed which utilizes the flow disturbances generated passively in the nosed subsonic region to weaken the detached shock wave. Several aspects are mainly studied, including shock shape and standoff distance, surface heat flux and pressure, flowfield feature and cooling mechanism. The numerical results indicate that shock strength and standoff distance increase with an increase in the L/D ratio of the cavity. Interestingly, a bulge structure of the detached shock associated with a deep cavity is observed for the first time. Local surface heat flux and pressure around the concave nose are much lower respectively than those at the stagnation point of the baseline model. In addition, both surface heat and pressure reductions are proportional to the L/D ratio. A negative heating phenomenon may occur in the vicinity of a sharp lip or on the base wall of a deep cavity. If the L/D ratio exceeds 0.7, the detached shock appears as a self-sustained oscillation which can be referred to as the cooling mechanism.

关键词： hypersonic flow aerodynamic heating thermal protection system forward-facing cavity

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Oblique detonation wave triggered by a double wedge in hypersonic flow

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Chinese Journal of Aeronautics 2022年第4期35卷 176-184页

作者： Honghui TENG Yuhang ZHANG Pengfei YANG zonglin jiang School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences University of Chinese Academy of SciencesBeijing 100049China

Pressure-gain combustion has gained attention for airbreathing ramjet engine applications owing to its better thermodynamic efficiency and fuel consumption rate. In contrast with traditional detonation induced by a single wedge, the present study considers oblique shock interactions attached to double wedges in a hypersonic combustible flow. The temperature/pressure increases sharply across the interaction zone that initiates an exothermic reaction, finally resulting in an Oblique Detonation Wave(ODW). Compared with the case for a single-wedge ODW, the double-wedge geometry has great potential to control the initiation of the ODW. As a tentative study, two-dimensional compressible Euler equations with a two-step induction-reaction kinetic model are used to solve the detonation dynamics triggered by a double wedge. The effects of the wedge angles and wedge corner locations on the initiation structures are investigated *** results show an ODW complex comprising three Oblique Shock Waves(OSWs), an induction zone, a curved detonation front, and an unburned/low-temperature gas belt close to the surface of the second wedge. Both the increasing wedge angle and downstream wedge corner location lead to an abrupt OSW–ODW transition type, whereas the former corresponds to the shock–shock interaction and the later has a greater effect on the exothermic chemical process. Analysis of the shock polar and flow scale confirms that the OSW–ODW initiation structure mainly depends on the coupling of shocks and heat release in a confined initiation zone.

关键词： Double wedge Hypersonic flow Initiation structures Oblique detonation Shock interactions

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Theoretical approach to one-dimensional detonation instability

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Applied Mathematics and Mechanics(English Edition) 2016年第9期37卷 1231-1238页

作者： Chun WANG Gaoxiang XIANG zonglin jiang State Key Laboratory of High Temperature Gas Dynamics Chinese Academy of Sciences

Detonation instability is a fundamental problem for understanding the microbehavior of a detonation front. With the theoretical approach of shock dynamics, detonation instability can be mathematically described as a second-order ordinary difference equation. A one-dimensional detonation wave can be modelled as a type of oscillators. There are two different physical mechanisms controlling the behaviors of a detonation. If the shock Mach number is smaller than the equilibrium Mach number, the fluid will reach the sonic speed before the end of the chemical reaction. Then, thermal chock occurs, and the leading shock becomes stronger. If the shock Mach number is larger than the equilib- rium Mach number, the fluid will be subsonic at the end of the chemical reaction. Then, the downstream rarefaction waves propagate upstream, and weaken the leading shock. The above two mechanisms are the basic recovery forces toward the equilibrium state for detonation sustenance and propagation. The detonation oscillator concept is helpful for understanding the oscillating and periodic behaviors of detonation waves. The shock dynamics theory of detonation instability gives a description of the feedback regime of the chemical reaction, which causes variations of the leading shock of the detonation. Key words detonation wave, detonation instability, shock wave, chemical reaction

关键词： detonation wave detonation instability shock wave chemical reaction

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Advances in critical technologies for hypersonic and high-enthalpy wind tunnel

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Chinese Journal of Aeronautics 2020年第12期33卷 3027-3038页

作者： zonglin jiang Zongmin HU Yunpeng WANG Guilai HAN State Key Laboratory of High-temperature Gas Dynamics(LHD) Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China

Hypersonic and high-enthalpy wind tunnels and their measurement techniques are the cornerstone of the hypersonic flight era that is a dream for human beings to fly faster,higher and *** great progress has been achieved during the recent years and their critical technologies are still in an urgent need for further *** are at least four kinds of hypersonic and high-enthalpy wind tunnels that are widely applied over the world and can be classified according to their operation *** wind tunnels are named as air-directly-heated hypersonic wind tunnel,light-gas-heated shock tunnel,free-piston-driven shock tunnel and detonation-driven shock tunnel,*** critical technologies for developing the wind tunnels are introduced in this paper,and their merits and weakness are discussed based on wind tunnel performance *** techniques especially developed for high-enthalpy flows are a part of the hypersonic wind tunnel technology because the flow is a chemically reacting gas motion and its diagnosis needs specially designed *** kinds of the measurement techniques considered to be of primary importance are introduced here,including the heat flux sensor,the aerodynamic balance,and optical diagnosis *** techniques are developed usually for conventional wind tunnels,but further improved for hypersonic and high-enthalpy *** hypersonic ground test facilities have provided us with most of valuable experimental data on high-enthalpy flows and will play a more important role in hypersonic research area in the ***,several prospects for developing hypersonic and high-enthalpy wind tunnels are presented from our point of view.

关键词： High-enthalpy flow Hypersonic wind tunnel Aerospace vehicle Aerodynamic balance Heat flux sensor Optical measurement technique

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Theories and technologies for duplicating hypersonic flight conditions for ground testing

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National Science Review 2017年第3期4卷 290-296页

作者： zonglin jiang Hongru Yu State Key Laboratory of High-temperature Gas Dynamics Institute of Mechanics Chinese Academy of Sciences School of Engineering Sciences University of Chinese Academy of Sciences

INTRODUCTION The development of aeronautics and astronautics,from its practical beginning with the Wright brothers’first airplane on 17 December 1903,has been driven by one primary aim to fly faster,higher

关键词： for of it on as is test Theories and technologies for duplicating hypersonic flight conditions for ground testing

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