Liquid-solid Coupling Research Articles

Dynamic Load Analysis of an Centrifugal Pump Axle using FSI Simulation

The mechanical characteristics of the impeller are important indicators that determine the working characteristics of the pump. The pump is subjected to periodic hydraulic loads during the working process. This load will cause the dynamic deformation of the impeller and the impeller shaft, thereby further affecting the distribution of the fluid. Liquid-solid coupling is used. Method, the rated operating point of centrifugal pump is analyzed, and it is proved that the dynamic stress of the impeller and the impeller shaft meets the requirements, which lays a foundation for the formulation of the control strategy of the impeller.

An improved gas–liquid–solid coupling model with plastic failure for hydraulic flushing in gassy coal seam and application in borehole arrangement

Hydraulic flushing can increase the efficiency of gas extraction by artificially modifying the coal reservoir. Considering the plastic failure of coal mass, an improved gas–liquid–solid coupling model for hydraulic flushing and gas extraction is constructed. The parameter evolution in the hydraulic flushing process was numerically investigated to determine the optimal borehole arrangement of hydraulic flushing. The results show that the relative permeability of gas gradually increases with the initial dewatering. The gas rates of both regular extraction and hydraulic flushing enhanced extraction show an increasing–decreasing trend. An increased and delayed peak gas rate is observed comparing with the regular extraction, caused by the hydraulic flushing induced new fractures. The area around of borehole is divided into the failure zone, the plastic softening zone, and the elastic zone after hydraulic flushing. The failure zone has the greatest increase in coal permeability, followed by the plastic softening zone, while the elastic zone keeps no significant change. The larger difference between the horizontal stress and vertical stress, the more obvious the elliptical shape of the permeability change area near the borehole, as well as the pressure drop in the elliptical zone. With the increase in the hydraulic flushing radius, the permeability increasing zone and gas pressure decreasing zone gradually increase. Subsequently, the equivalent effective radius and equivalent influencing radius were obtained, as well as the optimal borehole spacing for hydraulic flushing by cross-layer drilling. Finally, the optimal borehole spacing is obtained for different borehole diameters and efficient extraction times. These provide a theoretical guidance for field application of hydraulic flushing in a low-permeable coal seam.

Application of CFD Numerical Simulation Methods in the Field of UAV Research

Unmanned aerial vehicle (UAV) has become one of the hot topics in today’s research. A drone’s short life has always been one of the main drawbacks, and fluid mechanics is related to the development of computer technology. CFD was used to simulate the aerodynamic parameters of UAVs and has become a more economical choice, which can greatly save the cost of materials. Solid-liquid coupling calculation generally chooses the SST k - Ω model to calculate and will also include an energy equation in the calculation. Then, according to the precision needs to choose a different order of upwind format. Choose either steady state or transient simulation according to different needs. CFD is widely used in research on the overall stability and reliability of UAVs and the experiment on the aerodynamic characteristics of UAV components.

Deformation characteristics and inertial effect of complex aluminum alloy sheet part under impact hydroforming: experiments and numerical analysis

Impact hydroforming (IHF), as a novel sheet metal forming technology with the advantages of high strain rate forming and flexible liquid loading, is highly suitable for efficiently manufacturing aluminum complex-shaped sheet parts. In this paper, deformation characteristics of complex sheet parts under IHF are systematically investigated. The mechanical properties of 2024 aluminum alloy under a wide range of strain rates (10−3 s−1–3.3×103 s−1) were studied. It indicated that the elongation of 2024 aluminum alloy was improved by 116.01% under strain rates of 3.306 × 103 s−1, referring to 10−3 s−1. Further, a complex-shaped part with symmetrical and asymmetrical structures was selected. The deformation characteristics of sheet and role of inertial effect under IHF were investigated with well-developed solid–liquid coupling finite element (SLC-FE) model with high accuracy. Differentiating deformation tendency is found for symmetrical structure with notably prior deformation at central zone, showing a “bulging” profile at initial forming stage. Whereas, synchronous deformation is presented for asymmetrical structure with a “flat” profile. Additionally, distinctive inertial effect was observed at different positions change for both symmetrical and asymmetrical structures, in which lower values were resulted at their central regions. Meanwhile, the inertial effect evolved with the impacting speed. Specially, larger difference of inertial effect was observed with increasing impacting speed.

Experimental method and application of the slurry “diffusion-bleeding-seepage” of isolated overburden grout injection

Isolated overburden grout injection (IOGI) is a green mining method to control surface subsidence. Slurry water significantly influences grouting effectiveness and mining safety. This study establishes a three-dimensional visualization experimental system for slurry “diffusion-bleeding-seepage” to investigate the seepage law of slurry water. The system is composed primarily of a transparent box (1.2 m × 0.5 m × 0.25 m) and support, with the solid–liquid coupling seepage similar material and modules for mining, grouting injection, slurry pressure and displacement monitoring, overburden saturation monitoring, and water leakage monitoring of the working face. A similar material with good permeability and non-disintegration is obtained by hydrophilic, water absorption, and permeability tests. Grouting and mining are simulated by pulling acrylic sheets and pumping slurry. With the fly ash slurry entering the injection layer, the slurry undergoes water–cement separation, and the water bleeding is formed to seep into the similar material. The volumetric water content of the similar material is obtained by arranging multiple groups of volumetric water content sensors into the similar material. The corresponding saturation is obtained by theoretical calculation. The experimental system is used to simulate the seepage of slurry water in a high initial saturation overburden, and the characteristics of injection slurry diffusion and water bleeding are obtained. The profile distribution of seepage of slurry water is found to possess a semi-elliptical shape. Under the condition of high initial saturation, slurry water appears in the working face. The system provides a convenient method for further research of IOGI slurry water seepage.

Study of fatigue damage to the cochlea

In order to explore the hearing loss resulting from exposure to continuous or intermittent loud noise. A three-dimensional liquid-solid coupling finite element model of spiral cochlea was established. The reliability of the model was verified, and the stress and amplitude of the basilar membrane of the pivotal structure in cochlea were analyzed. The results show that under the action of the same high-pressure sound, the preferential fatigue area of the cochlear high-frequency area mainly causes fatigue in the cochlear. The safer area is a sound pressure level below 70 dB, while one above 90 dB accelerates damage to the ear.

Characteristic analysis with new liquid solid coupling dynamics model of high-clearance sprayer during liquid variation

Characteristic analysis with new liquid solid coupling dynamics model of high-clearance sprayer during liquid variation

Nonlinear dynamic analysis of liquid-solid coupling and rubbing on drill string

Natural deposit of natural gas hydrate (NGH) exists in the colder regions on the earth, which is an unconventional energy and has great potential. About 97% of the NGH is located in the offshore and only 3% is located on the land. Due to its sensitivity to the external environment and easy decomposition, it is necessary to suppress the external environment changes caused by the complex vibration of the drill string during its exploitation. In this paper, the fluid-solid coupling nonlinear vibration of drill string is studied. The nonlinear dynamic model of drill string with drilling fluid is established. The relationship between variable parameters of drill string and complex dynamics of drill string is analyzed. Furthermore, the bifurcation diagram is given. The results have certain significance for discussing the non-linear dynamic mechanism of drill string under complex conditions and reasonably selecting the drilling process parameters of NGH.

Study on wear characteristics of friction pair in high pressure and high-speed axial piston pump

Axial piston pump is the core component of electro-hydraulic control system. High-pressure and high-speed development of the axial piston pump can significantly improve the power density of the system, but it also causes a series of problems, such as the reduction of energy conversion efficiency, the enhancement of solid-liquid coupling, the intensification of vibration and noise, and the deterioration of service conditions of friction pairs, which poses a serious challenge to the service reliability of the axial piston pump. Therefore, the friction wear experiments of key friction pairs of axial piston pump are carried out in this paper to explore the influence of various factors on the friction wear performance and the wear mechanism of friction pairs under normal stress. And the results are expected to be used to find out the matching materials of friction pairs which is the key to improve the working efficiency and the service reliability of axial piston pump.

Investigation of stability and synchronization properties of two oscillators in a solid–liquid coupling system

Investigation of stability and synchronization properties of two oscillators in a solid–liquid coupling system

Research on Gas Extraction and Cut Flow Technology for Lower Slice Pressure Relief Gas under Slice Mining of Extra-thick Coal Seam.

For extra-thick coal seams, slice mining is a safer mining method than top coal mining, which can effectively reduce the strong mine pressure behavior caused by mining. However, in the slice mining of high-gas and extra-thick coal seams, the gas in the lower slice flows into the goaf, which increases the gas control difficulty on the upper slice working face. It is easy to cause the gas transfinite at the upper corner in the upper slice and reduce the mining efficiency. Therefore, it is of a great significance to carry out the research on gas control technology in slice mining of the extra-thick coal seam. There are some problems in the gas control of slice mining, such as a single gas control method, low control efficiency, and unclear gas migration law. Therefore, it is necessary to study the gas migration law and propose a targeted prevention and control the technical scheme. In order to improve the gas control efficiency of the extra-thick coal seam, the evolution law of permeability of the lower slice is obtained under mining through experimental research. The liquid–solid coupling seepage-flow model for gas migration is established in the lower slice. Comsol Multiphysics software is used to study the migration law of pressure relief gas in the lower slice. Based on the gas migration law, the gas extraction and cut flow technology for the lower slice long borehole is proposed. Through this technology, the amount of gas flowing into the upper slice goaf and the gas content of the lower slice are reduced, and the drilling horizon is optimized. The research results show that the determination of the optimal drilling horizon of the lower slice needs to balance the amount of gas flowing into the goaf and the total amount of gas extraction. The range of 3–7 m horizon in the lower slice is appropriate to the boreholes arranged. When the borehole is located in the lower slice −3 m horizon, the 360 day gas emission quantity of goaf can be reduced to 51.2% of the nondrilled emission quantity, and the total extraction amount is 1143 m3. When the borehole is located in the lower slice −7 m horizon, the 360 day gas emission quantity of goaf can be reduced to 95.31% of the nondrilled emission quantity, and the total extraction amount is 1461 m3. Considering the gas emission capacity of the upper slice and ensuring that the total extraction volume of the lower slice is maximized and the boreholes in the lower slice are not damaged, the boreholes are located in the −6 m horizon of the lower slice.

Development of Similar Materials for Liquid-Solid Coupling and Its Application in Water Outburst and Mud Outburst Model Test of Deep Tunnel

In order to explore the evolution mechanism of water and mud inrush, based on the fluid-solid coupling similarity theory and a large number of matching tests, fault similar materials with mountain sand, gravel, and red clay as raw materials and surrounding similar rock materials with mountain sand, red clay, cement, and water as raw materials are developed. Similar materials’ physical and mechanical properties and hydraulic properties with different ratios are tested and analyzed. The results show that the red clay content influences the mechanical properties of similar materials and their hydraulic properties, and the gravel substrate mainly influences the fault permeability coefficient. Similar material can be adjusted within a certain range of mechanical parameters. The material is simple and suitable for developing similar materials for different low and medium strength rock masses. Finally, a similar material was used in a model test of the tunnel fault fracture zone to reveal the mechanism of water and mud bursts in the tunnel. The study results can be used as a reference for the development of similar materials for tunnel fracture zone surrounding rocks.

Springback inhibition of Ti-6Al-4V sheet with impact hydroforming at room temperature

Springback is a tough issue in sheet forming, and always leads to dimensional inaccuracy of formed parts. Titanium alloy selected as desired light-weight alloy has been playing significant roles in aerospace industry because of its good comprehensive performance. Whereas, titanium alloy components manufactured always exhibit severe springback at room temperature, which greatly restrict their application. To explore the possibility of reducing springback, rectangular lath-shaped parts with Ti-6Al-4V alloy sheet were fabricated by impact hydroforming (IHF) with self-designed equipment. Consequently, much lower springback is obtained using IHF with high strain rate than that formed by conventional stretch-bending with low strain rate. Great efforts are paid to clarify the mechanism of springback restriction under IHF. Different from traditional forming methods, more complex and high-speed interaction behavior between liquid and Ti-6Al-4V alloy sheet occurs. It considerably increases the difficulty for analyzing the deformation process of sheet under IHF. Thus, a novel solid-liquid coupling numerical simulation technology for IHF was developed. To validate the simulation accuracy, experiments with different forming processes and parameters were performed. Given the combined analysis of experimental and simulation results, it is found that distinctive forming paths are introduced between stretch-bending and IHF. Specifically, the preferred deformation region of sheet transfers from middle region for conventional stretch-bending to end regions under IHF, which mainly attributes to the unique loading behavior of liquid at high strain rate.

High-Performance Liquid Metal/Polyborosiloxane Elastomer toward Thermally Conductive Applications.

With the combination of high flexibility and thermal property, thermally conductive elastomers have played an important role in daily life. However, traditional thermally conductive elastomers display limited stretchability and toughness, seriously restricting their further development in practical applications. Herein, a high-performance composite is fabricated by dispersing room-temperature liquid metal microdroplets (LM) into a polyborosiloxane elastomer (PBSE). Due to the unique solid-liquid coupling mechanism, the LM can deform with the PBSE matrix, achieving higher fracture strain (401%) and fracture toughness (2164 J/m2). Meanwhile, the existence of LM microdroplets improves the thermal conductivity of the composite. Interestingly, the LM/PBSE also exhibits remarkable anti-impact, adhesion capacities under complex loading environments. As a novel stretchable elastomer with enhanced mechanical and thermal behavior, the LM/PBSE shows good application prospects in the fields of thermal camouflages, stretchable heat-dissipation matrixes, and multifunctional shells for electronic devices.

A Method for Prediction of Ultrasonic Detectability of Interface Gap Defects on TC4 Diffusion-Bonded Joints.

An analysis method for the detectability of defects on the TC4 (Ti-6Al-4V) diffusion bonding interface was proposed in this study. First, a semi-analytical model of the liquid–solid coupling acoustic field with attenuation characteristics was constructed. Based on this, a method for the selection of transducer parameters was investigated for effective focus on the diffusion bonding interface. Second, according to the characteristics of defects on the diffusion bonding interface, an acoustic response model for diffusion bonding defects was established based on Kirchhoff approximation. The detectability of defects on the diffusion bonding interface was analyzed using transducers of different frequencies with different diffusion bonding interface gaps. Finally, an experiment was conducted to verify the reliability of the simulation. The analysis method proposed shows the advantages in the selection of suitable parameters for detecting specific diffusion bonding interface gaps, providing theoretical predictions of the detectability of diffusion bonding interface defects.

Characteristic analysis with new liquid solid coupling dynamics model of high-clearance sprayer during liquid variation

Characteristic analysis with new liquid solid coupling dynamics model of high-clearance sprayer during liquid variation

Numerical analysis of combined optimization of turbine runner flow pattern and shafting System

This paper attempts to solve the turbine failures reported by a hydropower station, namely, the violent vibration in the runner region under a special working condition and the blade cracking on the outlet edge near the lower ring. For this purpose, the entire flow channel of the turbine was simulated by computational fluid dynamics (CFD) on ANSYS, and the runner strength and mode of shaft assembly system (SAS) were computed by the liquid-solid coupling algorithm. The calculation results show that severe low (negative) pressure appeared on the outlet edge near the lower ring, excess stress was observed in that area, and the resonance occurred as the fifth and sixth order natural frequencies of the SAS were the same with the rotation frequencies of the blade. On this basis, the original blade was modified repeatedly. Through the modification, the flow field distribution in the runner region and the blade strength were both greatly improved, and the SAS natural frequencies were kept away from the various external excitation frequencies, laying a solid basis for the safe and stable operation of the turbine.

Liquid-solid Coupling Analysis and Optimization Design of Tank Vehicle

Liquid-solid Coupling Analysis and Optimization Design of Tank Vehicle

Evolution of solid-liquid coupling combustion characteristics of boron suspension fuel in O2/Ar atmosphere

Boron suspension fuel is considered a good candidate to meet the energy requirements of hypersonic aircraft. As a solid-liquid mixed fuel, its combustion is a complex multi-stage process coupling of solid boron and liquid JP-10 combustion affected by various factors. In this study, A CO2 laser ignition test system was used to obtain the combustion characteristics of boron suspension fuel with solid loading of 10 wt.% in O2/Ar atmosphere. Focus is placed on the key factor of oxygen supply on the evolution of its solid-liquid coupling combustion characteristics. Theoretical analysis of the underlying mechanism of oxygen transportation and consumption caused by boron and JP-10 and their coupling characteristics was carried out for different stages. The results indicate that the combustion process could be divided into ignition, evaporation combustion, agglomerate combustion and extinguishment under full oxygen supply. In ignition stage, boron particles first ignite and promote the rapid ignition of JP-10. Oxygen supply can transfer boron combustion from heterogeneous reaction into homogeneous combustion. In evaporation combustion stage, a clear competition for oxygen between JP-10 and boron is observed. JP-10 is the main oxygen consumer whose flame forms an oxygen-lean zone around the droplet and suppresses boron combustion within the area. Micro-explosion could help carry boron particles into the outer oxygen-rich zone and achieve single-particle combustion. Increasing oxygen content to 60% can effectively compress the oxygen-lean zone area and realize simultaneous combustion of boron and JP-10. Agglomerate combustion stages could only occur when oxygen content is higher than 80%, which is the main energy releasing stage of boron. In extinguishment stage, black smoke is observed due to incomplete combustion of JP-10 when oxygen content is less than 60% while white smoke is observed due to boron oxide cooling deposition. This study provides a reference for the full energy exploitation of boron suspension fuel.

Control factors for mobility of dense and dilute debris flows

<p indent=0mm>Debris flow is a commonly occurring geological hazard in mountainous areas. The solid-liquid coupling makes the debris flows distinct from other geophysical fluids such as debris avalanches and floods. Owing to the complexity of this solid-liquid interaction, current research of debris-flow mobility focuses mainly on dense debris flows with a volumetric solid concentration of ~0.6. However, few studies focus on the physical processes occurring in the transition from dense to dilute debris flows with volumetric solid concentrations of 0.6–0.4. The objectives of this study are to explore the effects of changes in volumetric solid concentration on pore water pressure response and debris-flow mobility and to reveal the mechanisms in the transition from dense to dilute debris flows. Taking the debris-flow volumetric solid concentration and fluid viscosity as variables, a series of well-instrumented flume experiments is conducted. The results show that the high mobility of debris flow is closely related to the state of liquefaction. In the transition from dense to dilute debris flows, the shear dilatancy (state of solid particles) shifts from positive (dilation) to negative (contraction). As a result, the increase in pore water pressure causes the debris flow to liquefy, and the mobility surges accordingly. According to the calculated and measured shear stresses, it is apparent that the shear resistance of dense (dilute) debris flows is dominated by friction between the particles (viscous drag). An employed rheological model shows that the shear resistance in dense debris flows is insufficient for describing the rheological behavior of dilute flows. Models considering the interaction between particles, including friction and collision, and the viscosity of the fluid phase are warranted in future research.