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Effects of aggregate size distribution and carbon nanotubes on the mechanical properties of cemented gangue backfill samples under true triaxial compression

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 311-324页

作者： Qian Yin Fan Wen Zhigang Tao Hai Pu Tianci Deng Yaoyao Meng Qingbin Meng Hongwen Jing Bo Meng Jiangyu Wu State key laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China State key laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China State key laboratory for Geomechanics&Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China key laboratory of Xinjiang Coal Resources Green Mining Ministry of EducationXinjiang Institute of EngineeringUrumqi 830023China

The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious ***,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of *** mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically *** results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,***,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the ***σ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite ***ε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse *** increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.

关键词： cemented gangue backfill materials particle size distribution true triaxial compression test carbon nanotubes mechanical properties failure modes

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Mechanical properties of nanocrystalline nanoporous gold complicated by variation of grain and ligament: A molecular dynamics simulation

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Science China(Technological Sciences) 2018年第9期61卷 1353-1363页

作者： LI JieJie XIAN YueHui ZHOU HongJian WU RunNi HU GuoMing XIA Re key laboratory of Hydraulic Machinery Transients Ministry of Education Wuhan University hubei key laboratory of waterjet theory and new technology Wuhan University

A series of large-scale molecular dynamics(MD) simulations has been performed to study the effects of grain size and ligament diameter on the mechanical properties of nanocrystalline nanoporous gold. Such simulations indicate that the principal deformation mechanism is a combination of grain boundary sliding, grain rotation and dislocation movement. The results of uniaxial tensile tests reveal the presence of a reverse Hall-Petch relation between strength and nominal grain size, rather than the conventional Hall-Petch relationship in the present range of nominal grain size(7.9–52.7 nm). An increase of flow stress may possibly attribute to the lower total proportion of grain boundary sliding and grain rotation in the deformation of samples with larger grain size. The Young's modulus shows a linear relation with the reciprocal of nominal grain size, which depends largely on the volume fraction of grain boundaries and thus decreasing grain size leads to relatively lower Young's modulus. MD simulations on samples with ligament diameter ranging from 4.07 to 8.10 nm are also carried out and results show that the increasing ligament diameter resulted in decreased flow stress and increased Young's modulus.

关键词： nanocrystalline nanoporous gold grain-size effect ligament-size effect mechanical properties molecular dynamics

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Numerical investigation of unsteady cavitating turbulent flows around twisted hydrofoil from the Lagrangian viewpoint

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Journal of Hydrodynamics 2016年第4期28卷 709-712页

作者：程怀玉龙新平季斌祝叶周加建 Wuhan University hubei key laboratory of waterjet theory and new technology Wuhan University Science and technology on Water Jet Propulsion laboratory

Unsteady cavitating turbulent flow around twisted hydrofoil is simulated with Zwart cavitation model combined with the filter-based density correction model（FBDCM）.Numerical results simulated the entire process of the 3-D cavitation shedding including the re-entrant jet and side-entrant jet dynamics and were compared with the available experimental *** distribution of finite-time Lyapunov exponent（FTLE） was used to analyze the 3-D behavior of the re-entrant jet from the Lagrangian viewpoint,which shows that it can significantly influence the particle trackers in the attached *** analysis indicates that the different flow behavior on the suction side with different attack angle can be identified with Lagrangian coherent structures（LCS）.For the area with a large attack angle,the primary shedding modifies the flow pattern on the suction *** the decrease in attack angle,the attached cavity tends to be steady,and LCS A is close to the upper wall.A further decrease in attack angle eliminates LCS A in the boundary *** FTLE distribution also indicates that the decreasing attack angle induces a thinner boundary layer along the foil surface on the suction side.

关键词： viewpoint twisted correction Lagrangian suction unsteady attached coherent exponent turbulent

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Effect of low-speed waterjet pressure on the rock-breaking performance of unsubmerged cavitating abrasive waterjet

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Petroleum Science 2024年第4期21卷 2638-2649页

作者： Chen-Xing Fan Deng Li Yong Kang Hai-Tao Zhang hubei key laboratory of waterjet theory and new technology Wuhan UniversityWuhan430072HubeiChina School of Power and Mechanical Engineering Wuhan UniversityWuhan430072HubeiChina

Unsubmerged cavitating abrasive waterjet(UCAWJ)has been shown to artificially create a submerged environment that produces shear cavitation,which effectively enhances rock-breaking *** shear cavitation generation and collapse intensity depend on the pressure difference between the intermediate high-speed abrasive waterjet and the coaxial low-speed ***,the effect of the pressure of the coaxial low-speed waterjet is *** this purpose,the effect of low-speed waterjet pressure on rock-breaking performance at different standoff distances was experimentally investigated,and the effects of erosion time and ruby nozzle diameter on erosion performance were ***,the micromorphology of the sandstone was observed at different *** results show that increased erosion time and ruby nozzle diameter can significantly improve the rock-breaking *** different standoff distances,the mass loss increases first and then decreases with the increase of low-speed waterjet pressure,the maximum mass loss is 10.4 g at a low-speed waterjet pressure of0.09 *** surface morphology of cavitation erosion was measured using a 3D profiler,the increase in both erosion depth and surface roughness indicated a significant increase in the intensity of the shear cavitation *** a low-speed waterjet pressure of 0.18 MPa,the cavitation erosion surface depth can reach 600μm with a roughness of 127μm.

关键词： Rock-breaking Coaxial low-speed waterjet pressure Abrasive waterjet Cavitation Unsubmerged environment

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Isomorphism analysis on generalized modules oriented to the distributed parameterized intelligent product platform

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Frontiers of Mechanical Engineering 2020年第1期15卷 12-23页

作者： Shasha ZENG Weiping PENG Tiaoyu LEI hubei key laboratory of waterjet theory and new technology School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China

The distributed parameterized intelligent product platform(DPIPP)contains many agents of a product minimum approximate autonomous subsystem(generalized module).These distributed agents communicate,coordinate,and cooperate using their knowledge and skills and eventually accomplish the design for mass customization in a loosely coupled *** this study,a new method of isomorphism analysis on generalized modules oriented to DPIPP is ***,on the basis of the bill of material partition and generalized module mining,the parameters of the main characteristics are extracted to construct the main characteristic parameter ***,similarity calculation of generalized modules is realized by improving the clustering using representatives algorithm,and isomorphism model sets are *** modules with a similar structure are combined to complete the isomorphism *** effectiveness of the proposed method is verified by taking high-and medium-pressure valve data as an example.

关键词： distributed parameterized intelligent product platform generalized module isomorphism analysis product family

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Investigation of the hydrodynamics of slug flow in airlift pumps

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2391-2402页

作者： Zhineng Wang Yong Kang Xiaochuan Wang Shijing Wu Xiaoyong Li key laboratory of Hydraulic Machinery Transients Ministry of Education Wuhan University hubei key laboratory of waterjet theory and new technology Wuhan University School of Power and Mechanical Engineering Wuhan University

A slug flow model considering the dispersed bubbles entrained from the tail of Taylor bubble(TB) and recoalesced with the successive TB was proposed. Experiment was conducted to test the validity of this model by using a high-speed camcorder and particle image velocimetry(PIV). It was found that the model was valid for predicting the characteristics of slug flow in airlift pump within average error of 14%. Moreover, large pipe diameter was found to accelerate the rise velocity of TB and decreases void fraction in liquid slug by a small margin.

关键词： Airlift pump Flow regimes Bubble Mass transfer Hydrodynamics

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Large eddy simulation of turbulent flow structure and characteristics in an annular jet pump

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Journal of Hydrodynamics 2017年第4期29卷 702-715页

作者：徐茂森杨雪龙龙新平吕桥 hubei key laboratory for waterjet theory and new technology Wuhan University School of Power and Mechanical Engineering Wuhan University Research Institute of Nuclear Power Operation

The large eddy simulation（LES） of the flow characteristics in an annular jet pump（AJP） is conducted, and the flow characteristics are systematically analyzed from both time-averaged and instantaneous aspects. The jet expansion, the velocity distribution and the energy are considered to analyze the time-averaged evolution of the flow field in the AJP. The transient flow characteristics can also be acquired from the analysis of the turbulence intensity and the Reynolds stress. The simulation demonstrates that in the time-averaged characteristics, the potential cores increase linearly with the increase of the flow ratio. With the flow development, the jet half-width gradually increases and the residual energy coefficient decreases. Compared with the distribution of the time-averaged axial velocity, that of the instantaneous velocity is more complex and disorderly. The high intensity of the axial turbulence mainly occurs in the mixing layer and the near-wall regions of the diffuser. The annular distribution of the Reynolds stress is mainly in the mixing layer and the recirculation region. There is a low-stress zone between the mixing layer and the high-stress region in the wall-boundary layer. The intensity of the spanwise vortexes is larger than that of the streamwise vortexes, and therefore, the former make greater contribution to the total vorticity. This research provides a better understanding of the flow characteristics in the AJP.

关键词： Annular jet pump large eddy simulation(LES) flow characteristics vortex

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Rock breaking performance of the newly proposed unsubmerged cavitating abrasive waterjet

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International Journal of Mining Science and technology 2023年第7期33卷 843-853页

作者： Chenxing Fan Haitao Zhang Yong Kang Hanqing Shi Deng Li hubei key laboratory of waterjet theory and new technology Wuhan UniversityWuhan 430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China

To improve the rock breaking ability, cavitating waterjet and abrasive waterjet are combined by using a coaxial low-speed waterjet generated around the periphery of a high-speed abrasive waterjet, and a new type of waterjet called unsubmerged cavitating abrasive waterjet(UCAWJ) is thus produced. The rock breaking performance of UCAWJ was compared with submerged cavitating abrasive waterjet(SCAWJ)and unsubmerged abrasive waterjet(UAWJ) by impinging sandstone specimens. Moreover, the effects of jet pressure, standoff distance, abrasive flow rate and concentration were studied by evaluating the specific energy consumption, and the area, depth, and mass loss of the eroded specimen. The results show that the artificially generated submerged environment in UCAWJ is able to enhance the rock breaking performance under the same operating parameters. Furthermore, the rock breaking performance of UCAWJ is much better at higher jet pressures and smaller standoff distances when compared with UAWJ. The greatest rock breaking ability of UCAWJ appears at jet pressure of 50 MPa and standoff distance of 32 mm, with the mass loss of sandstone increased by 370.6% and the energy dissipation decreased by 75.8%. In addition, under the experimental conditions the optimal abrasive flow rate and concentration are 76.5 m L/min and 3%, respectively.

关键词： Rock breaking Abrasive waterjet Unsubmerged cavitation Erosion Specific energy consumption

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Verification and validation of URANS simulations of the turbulent cavitating flow around the hydrofoil

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Journal of Hydrodynamics 2017年第4期29卷 610-620页

作者：龙云龙新平季斌槐文信钱忠东 State key laboratory of Water Resources and Hydropower Engineering Science Wuhan University hubei key laboratory of waterjet theory and new technology School of Power and Mechanical EngineeringWuhan University Science and technology on Water Jet Propulsion laboratory

In this paper, we investigate the verification and validation（V＆V） procedures for the URANS simulations of the turbulent cavitating flow around a Clark-Y hydrofoil. The main focus is on the feasibility of various Richardson extrapolation-based uncertainty estimators in the cavitating flow simulation. The unsteady cavitating flow is simulated by a density corrected model（DCM） coupled with the Zwart cavitation model. The estimated uncertainty is used to evaluate the applicability of various uncertainty estimation methods for the cavitating flow simulation. It is shown that the preferred uncertainty estimators include the modified Factor of Safety（FS1）, the Factor of Safety（FS） and the Grid Convergence Index（GCI）. The distribution of the area without achieving the validation at the U v level shows a strong relationship with the cavitation. Further analysis indicates that the predicted velocity distributions, the transient cavitation patterns and the effects of the vortex stretching are highly influenced by the mesh resolution.

关键词： Cavitating flow cavitation verification and validation(V&V) uncertainty

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Characteristics of Oscillation in Cavity of Helmholtz Nozzle Generating Self‑excited Pulsed waterjet

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Chinese Journal of Mechanical Engineering 2022年第3期35卷 264-274页

作者： Miao Yuan Deng Li Yong Kang Hanqing Shi Haizeng Pan hubei key laboratory of waterjet theory and new technology Wuhan UniversityWuhan 430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China

Cavity flow oscillations in the axisymmetric cavity are critical to the operating efficiency of self-excited pulsed waterjets,which are widely employed in many practical *** this study,the behaviors of a turbulent flow in axisymmetric cavities causing cavity flow oscillations are investigated based on wall pressure *** are performed using four Helmholtz nozzles with varying length-to-radius ratios at flow velocities of 20–80 m/*** orders of hydrodynamic modes in axisymmetric cavity are obtained through the spectral analysis of wall *** on the experimental results,the empirical coefficient of Rossiter’s formula is modified,and the values of the parameter phase lag and the ratio of convection velocity to free stream velocity are obtained as 0.061 and 0.511,*** addition,the spectral peak with a relatively constant frequency shows that the flow-acoustic resonance is excited significantly.A modified model is introduced based on the fluidic networks to predict the lockon *** results obtained can provide a basis for the structural optimization of the nozzle to improve the performance of self-excited pulsed waterjets.

关键词： Self-excited cavitation waterjet Flow-excited oscillations Frequency characteristics Vibration analysis

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