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Numerical research on slamming characteristics of aircraft landing on water

Journal of Hydrodynamics 2023年第1期35卷 171-184页

作者： Dao-sheng Ning Ya-jun Shi gui-yong zhang Heng Wang Huan Hu Zhi-fan zhang State Key Laboratory of Structural Analysis for Industrial Equipment School of Naval Architecture EngineeringDalian University of TechnologyDalian116024China China Ship Scientific Research Center Wuxi200136China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai200240China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

In order to investigate the impact characteristic of an aircraft landing on water,a computational fluid dynamics(CFD)simulation is conducted to explore the slamming characteristics of the NACA TN 2929 A *** flow around the model is solved by using Reynolds-averaged Navier-Stokes equations with the shear stress transport(SST)k—ωturbulence model,based on finite volume method(FVM).The free surface is captured by using the volume of fluid(VOF)method,and the aircraft impact process is realized with help of overset mesh ***,the effects of horizontal and vertical velocities and initial pitch angle on the slamming load,attitude change,impact pressure and flow field evolution are *** results reveal that the horizontal velocity has a considerable influence on whether the aircraft’s horizontal tail hits the water,and further affects the maximum vertical load as well as the maximum pitch angle throughout the impact *** vertical velocity determines the slamming load before the horizontal tail strikes the water,while the horizontal velocity has a significant effect on the load after the horizontal tail hits the water.A smaller initial pitch angle results in not only a heavier slamming load but also a more dramatic change of the posture after the aircraft impacts the *** impact pressure of the aircraft is maximized at the junction of the approaching surface of the fuselage and the free *** some cases,the pressure is also concentrated on the undersurface of the horizontal tail.

关键词： Computational fluid dynamics(CFD) aircraft landing water entry slamming load motion attitude change

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A sharp-interface immersed smoothed point interpolation method with improved mass conservation for fluid-structure interaction problems

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Journal of Hydrodynamics 2020年第2期32卷 267-285页

作者： Bo-qian Yan Shuangqiang Wang gui-yong zhang Chen Jiang Qi-hang Xiao Zhe Sun State Key Laboratory of Structural Analysis for Industrial Equipment School of Naval ArchitectureDalian University of TechnologyDalian116023China Department of Fisheries and Oceans Bedford Institute of OceanographyDartmouthCanada Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai200240China Key Laboratory of Traffic Safety on Track of Ministry of Education School of Traffic and Transportation EngineeringCentral South UniversityChangsha410076China Joint International Research Laboratory of Key Technology for Rail Traffic Safety Central South UniversityChangsha410076China National and Local Joint Engineering Research Center of Safety Technology for Rail Vehicle Central South UniversityChangsha410076China

To solve the problem of inaccurate boundary identification and to eliminate the spurious pressure oscillation in the previously developed immersed smoothed point interpolation method(IS-PIM),a new sharp-interface IS-PIM combining mass conservation algorithm,called Sharp-ISPIM-Mass,is proposed in this *** on the so called sharp-interface method,the technique of quadratic local velocity reconstruction has been developed by combining with the mass conservation algorithm,which enables the present method improve the accuracy of the velocity field and satisfy the mass conservation condition near the boundary *** the proposed method would not encounter the problem of spurious mass *** addition,a new form of FSI force evaluation considering pressure and viscous force to perform a whole function from the fluid domain to fictitious fluid domain is introduced,which makes the present method obtain more accurate results of FSI force than the original *** the numerical studies of a number of benchmark examples,the performance of the Sharp-ISPIM-Mass has been examined and illustrated.

关键词： Sharp-interface technique immersed type method mass conservation algorithm fluid-structure interaction(FSI)

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Analysis on contaminants transport process through clay-solidified grouting curtain in MSW landfills

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Journal of Central South University of Technology 2005年第Z1期12卷 168-172页

作者： CHEN yong-gui zhang Ke-neng HUANG Chang-bo School of Bridge and Structural Engineering Changsha University of Science and Technology Changsha 410076 China College of Civil Engineering Hunan University Changsha 410082 China School of Geoscience and Environmental Engineering Central South University Changsha 410083 China China Construction First Group Corporation Limited Beijing 100073 China

Clay-solidified grouting curtains are commonly used for remediation by containment or pollution prevention, in addition to their use as a barrier to water flow in municipal solid waste(MSW) landfills. A hydrological *** water flow and a hydrodynamic model of contaminant are presented to simulate the migration of leachate through clay-solidified grouting curtain in MSW landfills, with particular attention paid to the role of diffusive and adsorptive fluxes in contaminant transport. The models were applied to simulate the sensitivity of the curtain's behavior to changes in parameters, such as thickness, depth, permeability coefficient, diffusion coefficient,resistance coefficient and concentration, and also to demonstrate the contaminant distribution on the evolution of travel time and offset distance of clay-solidified grouting curtain in landfills. It is found that a part of leachate components stays or is retarded in clay-solidified grouting curtain by precipitate or exchange, the retention rate is closely related to composition of clay-solidified grouting curtain, more than 800%, and the maximum occurs at the cementclay ratio of 2: 4 under experimental conditions. Contamination distribution is variable on travel time and offset distance, the highest concentration takes place where the contamination intensity is nearest to the pollution resource or takes place at early middle period of transport, and the pollutant attenuates gradually. The results indicate that claysolidified grouting curtain with a proper thickness, a low permeability coefficient and a high resistance coefficient might serve as a sufficiently effective vertical barrier against leachate seepage and contamination migration in MSWlandfills.

关键词： clay-solidified grouting curtain contaminant transport landfills

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Numerical simulation of the effect of waves on cavity dynamics for oblique water entry of a cylinder

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Journal of Hydrodynamics 2020年第6期32卷 1178-1190页

作者： gui-yong zhang Zhao Hou Tie-zhi Sun Hai-peng Wei Ning Li Bo Zhou Ying-jie Gao School of Naval Architecture Liaoning Engineering Laboratory for Deep-Sea Floating StructuresDalian University of TechnologyDalian 116024China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Shanghai 200240China Beijing Institute of Astronautical Systems Engineering Beijing 100076China Marine Design and Research Institute of China Shanghai 200011China

The water entry process associated with complicated unsteady structures,with consideration of the influence of the waves,is not well *** the present work,the oblique water entry of a cylinder under different regular waves is numerically *** volume of fluid(VOF)method and the sub-grid scale(SGS)stress model based on the large eddy simulation(LES)method are adopted for the 3-D simulation with six degrees of *** present numerical model is based on a wave model,and as shown by the previous work that the predicted cavity evolution in the calm water agrees well with the experimental *** present model is validated and it is shown that it could be used to predict the correct wave periods and *** cavity evolution mechanism,the dynamic characteristics and the vortex structures are *** cavity of the water entry with waves closes more quickly than in the calm water ***,several parametric studies of the water entry with different wave heights and water entry locations are carried *** results provide insights into the effects of the waves on the cavity dynamics for oblique water entry problems.

关键词： Large eddy simulation(LES) wave oblique water entry cavity dynamics

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Impact of human immunodeficiency virus infection on the course of hepatitis C virus infection: A meta-analysis

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World Journal of Gastroenterology 2009年第8期15卷 996-1003页

作者： Li-Ping Deng Xi-En gui yong-Xi zhang Shi-Cheng Gao Rong-Rong Yang Department of Infectious Diseases Zhongnan Hospital Wuhan University Wuhan 430071 Hubei Province China

AIM: To analyze the influence of human immunodeficiency virus (HIV) infection on the course of hepatitis C virus (HCV) infection. METHODS: We performed a meta-analysis to quantify the effect of HIV co-infection on progressive liver disease in patients with HCV infection. Published studies in the English or Chinese-language medical literature involving cohorts of HIV-negative and -positive patients coinfected with HCV were obtained by searching the PUBMED, EMBASE and CBM. Data were extracted independently from relevant studies by 2 investigators and used in a fixed-effect meta analysis to determine the difference in the course of HCV infection in the 2 groups. RESULTS: Twenty-nine trails involving 16 750 patients were identified including the outcome of histological fibrosis or cirrhosis or de-compensated liver disease or hepatocellular carcinoma or death. These studies yielded a combined adjusted odds ratio (OR) of 3.40 [95% confidence interval (CI) = 2.45 and 4.73]. Of note, studies that examined histological fibrosis/ cirrhosis, decompensated liver disease, hepatocellular carcinoma or death had a pooled OR of 1.47 (95% CI = 1.27 and 1.70), 5.45 (95% CI = 2.54 and 11.71), 0.76 (95% CI = 0.50 and 1.14), and 3.60 (95% CI = 3.12 and 4.15), respectively. CONCLUSION: Without highly active antiretroviral therapies (HAART), HIV accelerates HCV diseaseprogression, including death, histological fibrosis/ cirrhosis and decompensated liver disease. However, the rate of hepatocellular carcinoma is similar in persons who had HCV infection and were positive for HIV or negative for HIV.

关键词： Human immunodeficiency virus Hepatitis C virus Coinfection Disease progression Meta-analysis

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3.0T 1H magnetic resonance spectroscopy for assessment ofsteatosis in patients with chronic hepatitis C

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World Journal of Gastroenterology 2015年第21期21卷 6736-6744页

作者： Qian zhang Hui-Mao zhang Wen-Qian Qi yong-gui zhang Ping Zhao Jian Jiao Jiang-Bin Wang Chun-Yu zhang Department of Gastroenterology China Japan Union Hospital Affiliated to Jilin University Department of Radiology 1~(st) Hospital Affiliated to Jilin University

AIM To investigate the utility of 1H magneticresonance spectroscopy （1H MRS） as a noninvasivetest for steatosis in patients infected with hepatitis ***： Ninety patients with chronic hepatitisC and pathology data underwent 3.0T 1H MRS, andthe results of MRS and pathological analysis ***： This group of patients included 26 peoplewith mild fatty liver （28.89%）, 16 people withmoderate fatty liver （17.78%）, 18 people with severefatty liver （20.0%）, and 30 people without fatty liver（33.33%）. The water peak was near 4.7 parts permillion （ppm）, and the lipid peak was near 1.3 *** of variance revealed that differences in thelipid peak, the area under the lipid peak, ratio of thelipid peak to the water peak, and ratio of the areaunder the lipid peak to the area under the waterpeak were statistically significant among the ***, as the severity of fatty liver increased, thevalue of each index increased correspondingly. In thepairwise comparisons, the mean lipid peak, area underthe lipid peak, ratio of the lipid peak to the waterpeak, and ratio of the area under the lipid peak to thearea under the water peak were significantly differentbetween the no fatty liver and moderate fatty liver groups, whereas no differences were noted betweenthe severe fatty liver group and the mild or moderatefatty liver group. Area under the ROC curve （AUC） ofarea ratio in lipid and water and ratio in lipid and waterin the no fatty liver group to mild fatty liver group, mildfatty liver group to moderate fatty liver group, andmoderate fatty liver disease group to severe fatty livergroup, were 0.705, 0.900, and 0.975, ***： 1H MRS is a noninvasive techniquethat can be used to provide information on the effectof liver steatosis on hepatic metabolic processes. Thisstudy indicates that the 1H MRS can be used as anindicator of steatosis in patients with chronic hepatitis C.

关键词： 1H Magnetic resonance spectroscopy HepatitisC Antiviral therapy

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Numerical investigation and modeling of sweep effects on inlet flow field of axial compressor cascades

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Chinese Journal of Aeronautics 2024年第2期37卷 296-308页

作者： Jiancheng zhang Donghai JIN Xingmin gui School of Energy and Power Engineering Beihang UniversityBeijing 100191China Jiangxi Research Institue of Beihang University Nanchang 330096China

Swept blades are widely utilized in transonic compressors/fans and provide high load,high through-flow,high efficiency,and adequate stall ***,there is limited quantitative research on the mechanism of the effect of swept blades on the flow field,resulting in a lack of direct quantitative guidance for the design and analysis of swept blades in fans/*** better understand this mechanism,this study employs a reduced-dimensional force equilibrium method to analyze more than 1500 swept cascades *** verify that circumferential fluctuation terms are responsible for inducing radial migration in the inlet airflow field of the swept blade,resulting in variations in the incidence angle and consequently leading to changes in the characteristics of the swept ***,a combination of simple functions and machine learning is utilized to model the circumferential fluctuation terms and quantify the sweep *** prediction accuracy of the model is high,with coefficient of determination greater than 0.95 on the test *** the model is applied in a meridional flow analysis program,the calculation accuracy of the program for the incidence angle is improved by 0.4°and 0.6°at the design and off-design conditions respectively,compensating for the program’s original ***,the model can also provide quantitative guidance for the design of swept blades,thereby reducing the number of design iterations and improving design efficiency.

关键词： Turbomachinery Sweep aerodynamics Quasi-3D method Incidence angle Circumferential fluctuation Machine learning

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Recent advances in multifunctional shape memory photonic crystals and practical applications

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Nano Research 2024年第1期17卷 79-96页

作者： yong Qi Shufen zhang State Key Laboratory of Fine Chemicals Frontier Science Center for Smart MaterialsDalian University of TechnologyDalian 116024China

Shape memory photonic crystals(SMPCs)are smart composite materials with changeable structural color integrated by shape memory polymer and photonic *** can produce one or more temporary shapes through nanoscale deformation,memorizing current *** can be recovered to their original shapes or some intermediate states under external stimuli,accompanied by the variation of structural *** porous carriers with built-in sensing properties,SMPCs promoted the interdisciplinary development of nanophotonic technology in materials science,environmental engineering,biomedicine,chemical engineering,and ***,the recent progress on multifunctional SMPCs and practical applications,including traditional and cold programmable SMPCs,is summarized and *** primary concern is shape programming at the nanoscale that has demonstrated numerous attractive functions,including smart sensing,ink-free printing,solvent detection,reprogrammable gradient wetting,and controllable bubble transportation,under variations of the surface *** aims to figure out the nanoscale shape memory effects on structural color conversion and additional performance,inspiring the fabrication of the next generation of ***,perspectives on future research directions and applications are also *** is believed that multifunctional SMPCs are powerful nanophotonic tools for the interdisciplinary development of numerous disciplines in the future.

关键词： photonic crystal shape memory structural color cold programmable shape recovery

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Neighbor Sum Distinguishing Total Choosability of Planar Graphs with Maximum Degree at Least 10

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 211-224页

作者： Dong-han zhang You Lu Sheng-gui zhang Li zhang School of Mathematics and Statistics Northwestern Polytechnical UniversityXi’an710129China School of Mathematics and Computer Application Shangluo UniversityShangluo726000China

A neighbor sum distinguishing(NSD)total coloringφof G is a proper total coloring of G such thatΣz∈EG(u)U{u}φ(z)≠Σz∈EG(v)U{v}φ(z)for each edge uv∈E(G),where EG(u)is the set of edges incident with a vertex *** 2015,Pilśniak and Wozniak conjectured that every graph with maximum degreeΔhas an NSD total(Δ+3)-***,Yang et *** that the conjecture holds for planar graphs withΔ≥10,and Qu et *** that the list version of the conjecture also holds for planar graphs withΔ≥*** this paper,we improve their results and prove that the list version of the conjecture holds for planar graphs withΔ≥10.

关键词： planar graphs neighbor sum distinguishing total choosibility combinatorial nullstellensatz discharging method

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A three-dimensional inverse method based on moving no-slip boundary for profiled end wall design

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Chinese Journal of Aeronautics 2024年第10期37卷 221-233页

作者： Hanwen GUO Donghai JIN Jiancheng zhang Xingmin gui School of Energy and Power Engineering Beihang UniversityBeijing 100191China Jiangxi Research Institute of Beihang University Nanchang 330096China

How to utilize existing flow control mechanisms to make profiled end wall design more flexible,efficient,and physical is a meaningful *** study presents a three-dimensional inverse method for profiled end wall design to achieve the application of flow control *** predetermined pressure distribution on the end wall is reached by modifying the end wall geometry during flow field calculation.A motion velocity model is derived from the normal momentum equation of the moving no-slip boundary to modify the end wall geometry.A Reynolds-Averaged Navier-Stokes(RANS)solver based on the Semi-Implicit Method for Pressure Linked Equations(SIMPLE)algorithm is adopted to simulate the flow *** on the mechanism understanding obtained through numerical optimization results,this study adopts the inverse method to redesign an optimized end wall in a compressor *** results indicate that the redesigned end wall exhibits better loss reduction,reducing the overall total pressure loss by 5.5%,whereas the optimized end wall reduces it by 3%.The inverse method allows the imposition of desired influences on the end wall flow without constructing a database,making it highly flexible,efficient,and physical.

关键词： Compressor Flow control Corner separation Profiled end wall Inverse method

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