Visualized experimental investigation on the hydraulic characteristics of two-phase flow in a single smooth and single rough rock fractures

Chen Wang,Yujing Jiang,Jiankang Liu,Changsheng Wang,Satoshi Sugimoto 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.3

In present engineering applications, calculations of hydraulic properties in two-phase flow are still highly dependent on empirical or semi-empirical equations obtained from experiments. However, the empirical equations that can reproduce the experiment data on a certain fracture specimen may have errors on other specimens. Researchers have obtained results that show quite different evolution forms of hydraulic characteristics of two-phase flow, which is induced by the variety of the influencing factors in two-phase flow. This paper aims at expanding the experimental results on the hydraulic characteristics of two-phase flow in rock fractures. With a newly developed experiment system, visualized two-phase flow experiments were introduced. The difference in the surface morphology of the fractures leads to totally different flow structures, which indicates the role of capillary pressure differs due to different fracture surfaces. The relative permeability in the rough specimen approximately follows the Corey model, which confirmed that the pressure drop is in this rough fracture is dominated by the capillary pressure, but the relative permeability is not only the function of saturation, but also the function of water flow velocities. However, the relative permeability is not perfect for evaluating the difference of two-phase hydraulic characteristics induced by the fracture surface morphology. On the contrary, the Lockhart-Martinelli model is appropriate for evaluating the difference in the two-phase hydraulic characteristics between the smooth fracture and the rough fracture, which indicates that the two-phase flow turbulence is obviously increased by the fracture roughness.

Mechanism of shear deformation, failure and energy dissipation of artificial rock joint in terms of physical and numerical consideration

Xuepeng Zhang,Yujing Jiang,Gang Wang,Jiankang Liu,Dong Wang,Changsheng Wang,Satoshi Sugimoto 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.3

The physical and mechanical change processes of rock are closely related to energy transformation, and its deformation and failure is an instability phenomena driven by energy exchange. This study investigated mechanism of shear deformation, failure and energy dissipation of joint using both physical and numerical direct shear tests under constant normal load (CNL) condition. Three kinds of joint surface were artificially prepared. An acoustic emission system was employed to monitor acoustic emission in physical test, and rupture frequency was recorded in numerical test to represent micro-crack development. By research of numerical micro-crack development accompanied with physical acoustic emission results, mechanism of shear deformation and failure of joints were illustrated schematically. By definition of dissipation energy, captured using the particle flow code (PFC2D), energy releasing and dissipation were discussed with microscopic damage evolution of joints. Results showed that joints under shearing present a dissipation trend of four stages including a slow rise stage, a rapid rise stage, a shock rise stage and a rapid decline stage.

Effects of Ambient Pressure and Injection Pressure on Diesel and Natural Gas Dual Fuel Spray

( Changsheng Shao ),( Qian Wang ),( Xiaoqiang Tan ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

Dual fuel engines operating with direct injected natural gas (NG) and pilot diesel has been attracted by many engine researchers. With this system, small quantities of diesel auto-ignite, and NG is then ignited by the pilot diesel flame. This stratified combustion technique provides better fuel economy and more efficient combustion, maintaining the power output of an equivalently-sized conventional diesel engine. Comparatively lower emissions of NOx and particulate matter were also recorded. For the further understanding of dual fuel spray, effects of ambient pressure and injection pressure on diesel and NG dual fuel spray are investigated. Both NG and diesel are directly injected into an optical constant volume chamber by a dual fuel injector combiner for different injection pressure and ambient pressure. Schlieren photography is used to visualize the development of dual fuel spray. A Matlab processing script was developed to extract useful qualitative and quantitative information from each video frame. A comparison is made between NG jet characteristics in single fuel model (SFM) and dual fuel model (DFM). Results shows that in both SFM and DFM, the tip penetration decreased with the increase of the ambient pressure and the decrease of NG injection pressure, while the cone angle increased with the increase of the ambient pressure and the decrease of NG injection pressure. At different ambient pressure, the diesel spray has little influence on NG tip penetration, however it has impact on NG cone angle. The cone angle in DFM is higher than that in SFM. With the increase of ambient pressure, the diesel spray has less impact on NG cone angle. At different NG injection pressure, the diesel spray has influence on both NG tip penetration and cone angle. With the increase of NG injection pressure, diesel spray has less impact on NG cone angle.

Input Disturbance Suppression for Port-controlled Hamiltonian System via the Internal Model Method

Changsheng Li,Yuzhen Wang 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.2

This paper investigates the input disturbance suppression problem for nonlinear Port-Controlled Hamiltonian (PCH) system and presents a number of new results on the controllers design via the internal model approach. Different from the existing results on this topic we consider two cases. Firstly, the case of the disturbance generated from a linear Hamiltonian system acts through a channel other than the input channel is studied by adopting a method of decomposing the control into two parts and designing an internal model to zero the effect of the exogenous disturbance. Secondly, the case of the disturbance generated from a bounded nonlinear exosystem is studied by presenting a procedure of designing a nonlinear internal model to cancel the effect of the disturbance under two fundamental as-sumptions. Moreover, to further improve the suppression, a more effective internal model is also de-signed under less hypotheses. Finally, as an useful application, a corollary is presented by applying these results on PCH system to general nonlinear affine system. Simulations of a third-order synchro-nous generator model with disturbance generated from a nonlinear exosystem show the effectiveness of the designed internal model.

Research on Preparation Methods of Ultrafine Softwood Powder

Changsheng Fan,Dongxia Yang,Hongling Wang,Yan Sun,Hua lou,Hongru Yang 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.4

Pine wood sawdust is used as raw materials for experimental processing into ultrafine wood powder. Sizes of ultrafine wood powder particles serve as a standard for measuring ultrafine processing. The core part of the experimental processing equipment is the millstone which can exert great shear force and grinding force on strong fiber materials so as to ensure the successful preparation of ultrafine particles. The “equilibrium orbit” model is used to simulate processed superfine particles in calculating separation performance. Moreover, the CFD is chosen for simulating separation performance of wood powder particles with different sizes in the two-phase flow field, so as to ensure the successful separation and grading of wood powder particles with different sizes in the practical processing. Research is made on physical properties of collected wood powder as samples with different sizes and influence on composite material properties when ultrafine wood powder is taken as padding. Research on ultrafine wood powder provides meaningful experimental data and theoretical support for the future research on micro-nano fibrils.

Effects of injection rate on combustion and emissions of a pilot ignited direct injection natural gas engine

Qian Wang,Changsheng Shao,Qing Liu,Zhourong Zhang,Zhixia He 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.4

Effects of Injection rates on combustion process and emissions of engines operating with directly injected natural gas and pilot diesel were numerically investigated. Injection rates of natural gas and diesel were investigated separately utilizing five types of injection rates. An impact factor was defined to present the effects of the initial and terminal injection rates of diesel and natural gas on the combustion and emissions more intuitionally. Based on the simulation results, cylinder pressure and temperature were more sensitive to terminal injection rates of pilot diesel than initial injection rates, and lower terminal injection rates of pilot diesel can achieve lower NO and Soot emission level. However, there is a trade-off between NO and Soot emissions affected by different natural gas injection rates. The impact factors of pilot diesel injection rates on pressure show a double-peak trend. However, the impact factors of natural gas injection rates on pressure show a single-peak trend.

Investigation of morphological changes of HPS membrane caused by cecropin B through scanning electron microscopy and atomic force microscopy

Han Hu,Changsheng Jiang,Binzhou Zhan,Nan Guo,Zhonghua Li,Xiaozhen Guo,Yang Wang,Binlei Liu,Qigai He 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.5

Background: Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents. Objectives: This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments. Results: Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 μg/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM. Conclusions: Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.

Correlation Between the Microstructural Defects and Residual Stress in a Single Crystal Nickel-Based Superalloy During Different Creep Stages

Fangjie Mo,Erdong Wu,Changsheng Zhang,Hong Wang,Zhengye Zhong,Jian Zhang,Bo Chen,Michael Hofmann,Weimin Gan,Guangai Sun 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5

The present work attempts to reveal the correlation between the microstructural defects and residual stress in the singlecrystal nickel-based superalloy, both of which play the signifi cant role on properties and performance. Neutron diff ractionwas employed to investigate the microstructural defects and residual stresses in a single crystal (SC) nickel-based superalloy,which was subjected to creeping under 220 MPa and 1000 °C for different times. The measured superlattice andfundamental lattice refl ections confi rm that the mismatch and tetragonal distortions with c / a > 1 exist in the SC superalloy. At the initially unstrained state, there exists the angular distortion between γ and γ’ phases with small triaxial compressivestresses, ensuring the structural stability of the superalloy. After creeping, the tetragonal distortion for the γ phase is largerthan that for the γ’ phase. With increasing the creeping time, the mismatch between γ and γ’ phases increases to the maximum,then decreases gradually and fi nally remains unchanged. The macroscopic residual stress shows a similar behaviorwith the mismatch, indicating the correlation between them. Based on the model of shear and dislocations, the evolution ofmicrostructural defects and residual stress are reasonably explained. The effect of shear is dominant at the primary creepstage, which greatly enlarges the mismatch and the residual stress. The dislocations weaken the effect of shear for the furthercreep stage, resulting in the decrease of the mismatch and relaxation of the residual stress. Those fi ndings add some helpfulunderstanding into the microstructure-performance relationship in the SC nickel-based superalloy, which might provide theinsight to materials design and applications.

The Analysis and Fabrication of a Novel Tin-Nickel Mixed Salt Electrolytic Coloured Processing and the Performance of Coloured Films for Al-12.7Si-0.7Mg Alloy in Acidic and Alkali Corrosive Environments

Yan Shang,Linshan Wang,Changsheng Liu,Carlos Fernandez,L.Rajendran,M. Kirthiga,Yuhong Wang,Dun Niu,Dongdong Liu 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.1

We present for the first time the analysis and fabrication of a novel Tin-Nickel mixed salt electrolytic coloured processing and the performance of coloured films for Al-12.7Si-0.7Mg alloy. This alloy is a novel alloy containing high silicon aluminum alloy extrusion profile which presents excellent mechanical properties as well as broad market prospects. Nevertheless, this kind of material is urgent in need of surface treatment technology. The orthogonal design and single factor tests were applied to optimize for electrolytic coloured technological conditions. By controlling operation conditions, the uniform electrolytic coloured films with different color were obtained. Analysis of microstructure showed that tin particles had been deposited in the coloured film. The coloured films, about 10 μm thick, were uniform, dense and firmly attached to the substrate. After the coloured samples were maintained at 400ºC for 1 h, or quenched from 300ºC to room temperature, the coloured films did not change, demonstrating excellent thermostability and thermal shock resistance. Acid and alkali corrosion tests and potentiodynamic polarization showed that corrosion resistance of coloured sample was much better than those of untreated samples. After 240 h neutral salt spray test, protection ratings and appearance ratings of coloured films were Grade 9.

Characteristics of SiC inverter powertrains on common-mode EMI noise

Jia, Xiaoyu,Dong, Bitao,Wang, Hui,Hu, Changsheng,Xu, Dehong The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2

This paper studies the characteristics of SiC inverter powertrains on common-mode (CM) EMI emission. First, a CM noise source model of an EV powertrain is built. Then, the factors of switching frequency, switching speed, and switching ringing on the CM noise source are analyzed. Finally, experiments on a conducted EMI test-bed are carried out to verify the influence of SiC inverters on conducted CM EMI emission in EV powertrains.