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Experimental characteristics of oblique shock train upstream propagation

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Chinese Journal of Aeronautics 2017年第2期30卷 663-676页

作者： wang chengpeng Xue Longsheng Tian Xuang College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The structure and dynamics of an oblique shock train in a duct model are investigated experimentally in a hypersonic wind *** of the pressure distribution in front of and across the oblique shock train have been taken and the dynamics of upstream propagation of the oblique shock train have been analyzed from the synchronized schlieren imaging with the dynamic pressure *** formation and propagation of the oblique shock train are initiated by the throttling device at the downstream end of the duct *** reflected shocks,expansion fans and separated flow bubbles exist in the unthrottled flow,causing three adversepressure-gradient phases and three favorable-pressure-gradient phases upstream the oblique shock *** leading edge of the oblique shock train propagates upstream,and translates to be asymmetric with the increase of *** upstream propagation rate of the oblique shock train increases rapidly when the leading edge of the oblique shock train encounters the separation bubble near the shock reflection point and the adverse-pressure-gradient phase,while the oblique shock train slow movement when the leading edge of the oblique shock train is in the favorablepressure-gradient phase for unthrottled *** asymmetric flow pattern and oscillatory nature of the oblique shock train are observed throughout the whole upstream propagation process.

关键词： Boundary layer separation Compressible flow Shock train Oscillating flow Wind tunnel testing

An integration method based on a novel combined flow for aerodynamic configuration of strutjet engine

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Chinese Journal of Aeronautics 2021年第9期34卷 156-167页

作者： Longsheng XUE Chuan CHENG chengpeng wang Keming CHENG College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China Aerospace System Engineering Shanghai Shanghai 201100China

In this paper a novel design method of aerodynamic configuration is proposed to integrate forebody,strut and inlet for strutjet engine,and a model at design point of Mach number6 is generated to investigate the aerodynamic performance by both simulations and *** basic flow field employed by proposed method is a combined flow named IBB,which is combined by Internal Conical Flow A(ICFA),truncated Busemann flow I(BI)for external section,and truncated Busemann flow II(BII)for internal *** model configuration is generated by streamline tracing method from basic flow field,in which the forebody section is traced from ICFA and BI flows,and the inlet as well as strut section is traced from BII *** simulations in Mach number 4,5,and 6 demonstrate uniform starting flow fields with relatively high total pressure recovery,which agree well with experiments in wind ***,in low Mach number cases,this inlet could start at Mach number 3 while it is unstarted at Mach number 2.7;in high Mach number cases,a uniform flow could still exist in Mach number 6.5 while a relatively strong shock wave boundary layer interaction is found in cowl area of Mach number 7 case,indicating the inlet designed by proposed method works in a relatively wide Mach number range.

关键词： Airframe-propulsion integration Busemann flow Combined flow Hypersonics Wind tunnel test

Review on modified and novel techniques of severe plastic deformation

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Science China(Technological Sciences) 2012年第9期55卷 2377-2390页

作者： wang chengpeng LI FuGuo wang Lei QIAO HuiJuan State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China School of Materials Science and Engineering Northwestern Ploytechnical UniversityXi'an 710072China

This review highlights very recent achievements and new developments of severe plastic deformation(SPD) technology for producing bulk ultrafine-grain(UFG) and even nanocrystalline(nc) *** numerous modified and novel SPD methods include cyclic forward-backward extrusion,axi-symmetric forward spiral extrusion,vortex extrusion,simple shear extrusion,planar twist extrusion,tubular channel angular pressing,cone-cone method,high-pressure tube twisting,tube channel pressing and elliptical cross-section spiral equal-channel *** to classification,these new methods are categorized into the extension of equal-channel angle pressing(ECAP),high-pressure torsion(HPT),twist extrusion(TE) and constrained groove pressing(CGP),*** principles of various new SPD technologies are described in *** addition,the microstructure revolution characteristics and mechanical properties of materials produced by SPD process,as well as the applications of SPD techniques to UFG materials,are also ***,this article reviews recent progresses in determining the refinement and/or deformation mechanisms,*** deformation mechanism,twin deformation mechanism and grain boundary sliding and torsional deformation mechanism,and further orientation of SPD technology.

关键词： plastic deformation ultrafine-grain refinement

Micro-plasticity Constitutive Model Taking Account of Size Effects for Pure Aluminum by Microindentation

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Journal of Wuhan University of Technology(Materials Science) 2013年第6期28卷 1101-1106页

作者： wang chengpeng LI Fuguo CHEN Bo wang Lei State Key Laboratory of Solidification Processing Northwestern Polytechnical University College of Materials Science and Engineering Taiyuan University of Technology

The macro-plasticity power function constitutive model （MPFCM）, the modified macro- plasticity power function constitutive model （MMPFCM） and the micro-plasticity constitutive model （MCM） taking the material intrinsic length were established to characterize the microindentation size effects of pure aluminum, respectively. The experimental results indicated MPFCM only determined precisely in the great indentation load. While a modified one named MMPFCM was subsequently established taking account of the parameters variation with the increase of indentation depth. The conventional dimensional analysis method was employed to determine the strength coefficient K and the strain hardening exponent n of this modified model. And then MCM taking account of size effects was proposed based on the Taylor dislocation model. The first- order steepest gradient descent method was adopted to obtain the material intrinsic length for the geometrically necessary dislocations. The parameters of MCM were identified by using the UMAT subroutine of ABAQUS software. The average absolute relative error of MCM is relatively lower than that of the macro-one. Although the precision of the modified one is also high, the applied scope is limited, only for the microindentation material. In addition, the intrinsic length 5.09 bun of pure aluminum is also obtained based on the strain gradient theory.

关键词： constitutive model size effects pure aluminum microindentation

Evolution of wall flow structure and measurement of shear stress issuing from supersonic jet with extended shelf

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Chinese Journal of Aeronautics 2021年第11期34卷 94-105页

作者： Yun JIAO chengpeng wang Jiaqi XIE Kang LI Kerning CHENG College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper reports an experimental study on the supersonic jet surface flow structure visualization and shear stress field measurement issuing from a rectangular nozzle with extended shelf. The evolution of the near-field surface flow structures with an increased Nozzle Pressure Ratio(NPR) is successfully captured by the surface oil flow, infrared detection technology, and the Shear-Sensitive Liquid Crystal Coating(SSLCC) technique. Results reveal that under smaller NPR, the wall flow structure is similar to that of a jet without the extended shelf i.e., clean jets,and this is caused by insufficient effect on the boundary layer. However, at higher amplitudes of NPR, there exists a significant effect of the boundary layer, as a near triangular separation forms on the trailing edge of the Mach stem due to the adverse pressure gradient, which is visualized for the very first time in this paper. Furthermore, the vector field of shear stress is measured quantitatively by SSLCC technique. Results shows that the magnitude of shear stress heightened with NPR increasing, and the directions of shear stress changes across the shock wave and expansion fans. In addition, surface streamlines measured by SSLCC is significantly consistent with the streamlines visualized using the oil flow technique.

关键词： Evolution of shock structure Flow visualization Quantitative measurement Shear stress Supersonic jet

Analysis of Unstarted Hypersonic Flow Unsteadiness Based on Schlieren Image Processing

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Transactions of Nanjing University of Aeronautics and Astronautics 2019年第5期36卷 856-867页

作者： wang chengpeng wang Wenshuo XUE Longsheng XU Pei YANG Jinfu College of Aerospace Engineering Nanjing University of Aeronautics & Astronautics

The unstarted flow field in a hypersonic inlet model at a design point of Ma 6 is studied *** time-resolved spatial flow characteristics of the separation shock oscillation,which is induced by the unstarted flow,are analyzed based on a high-speed Schlieren system and an image processing *** motion of the separation shock detected by the shock-detection algorithm is compared to the results of fast-response wall-pressure measurements,and good agreement is demonstrated by comparing the frequency components in the power spectral density contours between shock oscillation and pressure *** hysteresis of the pressure and separation shock during oscillation cycles is observed from the time history of the shock motion,which means that the unsteady flow pattern of the unstarted hypersonic flow can be accurately clarified by time-resolved Schlieren image *** results convincingly demonstrate that the shock-detection technique is successfully applied to an unstarted hypersonic flow case.

关键词： shock-detection system hypersonic inlet flow unstarted flow

Optimization of structural parameters for elliptical cross-section spiral equal-channel extrusion dies based on grey theory

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Chinese Journal of Aeronautics 2013年第1期26卷 209-216页

作者： wang chengpeng Li Fuguo Lu Hongya Yuan Zhanwei Chen Bo State Key Laboratory of Solidification Processing Northwestern Polytechnical University Department of Mechanical Engineering Tsinghua University

The elliptical cross-section spiral equal-channel extrusion （ECSEE） process is simulated by using Deform-3D finite element software. The ratio m of major-axis to minor-axis length for ellipse-cross-section, the torsion angle u, the round-ellipse cross-section transitional channel L1, the elliptical rotation cross-section transitional channel L2 and the ellipse-round cross-section transitional channel L3 are destined for the extrusion process parameters. The average effective strain eave on cross-section of blank, the deformation uniformity coefficient a and the value of maximum damage dmax are chosen to be the optimize indexes, and the virtual orthogonal experiment of L16 （45） is designed. The correlation degree of the process factors affecting eave, a and dmax is analyzed by the numerical simulation results using the weights and grey association model. The process parameters are optimized by introducing the grey situation decision theory and the ECSEE optimal combination of process parameters is obtained： u of 120 , m of 1.55, L1 of 7 mm, L2 of 10 mm, and L3 of 10 mm. Simulation and experimental results show that the material can be refined with the optimized structural parameters of die. Therefore, the optimization results are satisfactory.

关键词： Correlation degree Elliptical cross-section spiral equal-channel extrusion (ECSEE) Grey theory Optimization Orthogonal design Simulation

Oblique shock train motion based on schlieren image processing

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Chinese Journal of Aeronautics 2023年第3期36卷 30-41页

作者： Longsheng XUE Chuan CHENG chengpeng wang Lantian ZHANG Kang LI Keming CHENG College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Unsteady Aerodynamics and Flow Control Ministry of Industry and Information TechnologyNanjing University of Aeronautics and AstronauticsNanjing 210016China Beijing Institute of Tracking and Telecommunication Technology Beijing 100094China Aerospace System Engineering Shanghai Shanghai 201109China

In this paper,shock train motion in a Mach number 2.7 duct is studied experimentally,and large numbers of schlieren images are obtained by a high-speed *** image processing method based on Maximum Correlation Detection(MCD)is proposed to detect shock train motion from the schlieren images,based on which the key structures,e.g.,separation positions and separation shock angles on the top and bottom walls,can be analysed in *** oscillations of the shock train are generated by rhombus and ellipse shafts at various excitation *** to the analysis of MCD results,the distributions of the frequency components of shock train oscillation generated by the two shafts are distinctly different,in which the motion generated by the ellipse shaft is much smoother;shock train motion is mainly characterized by the oscillation of separation position while the separation shock strength is not so sensitive to downstream disturbance;there is a hysteresis loop relation between the downstream pressure and separation position.

关键词： Frequency components Hysteresis loop Maximum Correlation Detection(MCD) Schlieren image processing Shock train oscillation

An efficient CRISPR/Cas9 platform for targeted genome editing in rose(Rosa hybrida)

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Journal of Integrative Plant Biology 2023年第4期65卷 895-899页

作者： chengpeng wang Yang Li Na wang Qin Yu Yonghong Li Junping Gao Xiaofeng Zhou Nan Ma Beijing Key Laboratory of Development and Quality Control of Ornamental Crops Department of Ornamental HorticultureChina Agricultural UniversityBeijing 100193China School of Applied Chemistry and Biotechnology Shenzhen PolytechnicShenzhen 518038China Key Laboratory of East China Urban Agriculture Ministry of Agriculture and Rural AffairsInstitute of Leisure AgricultureShandong Academy of Agricultural SciencesJinan 250100China

The clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-related nuclease 9(Cas9)system enables precise,simple editing of genes in many animals and ***,this system has not been applied to rose(Rosa hybrida)due to the genomic complexity and lack of an efficient transformation technology for this ***,we established a platform for screening single-guide RNAs(sgRNAs)with high editing efficiency for CRISPR/Cas9-mediated gene editing in rose using suspension *** used the Arabidopsis thaliana U6-29 promoter,which showed high activity for driving sgRNA expression,to modify the CRISPR/Cas9 *** used our highly efficient optimized CRISPR/Cas9 system to successfully edit RhEIN2,encoding an indispensable component of the ethylene signaling pathway,resulting in ethylene insensitivity in *** optimized CRISPR/Cas9 system provides a powerful toolbox for functional genomics,molecular breeding,and synthetic biology in rose.

关键词： CRISPR/CAS9 gene editing RhEIN2 rose