Fluid-solid Coupling Analysis Research Articles

Fluid-Solid Coupling Analysis of the Propeller and Optimization of Boss Cap Fin Parameters

In order to ensure the accuracy of propeller modelling and hydrodynamic performance prediction, first of all, compared with atlas modelling and OpenProp modelling, it is pointed out that the characteristics of the blade model established by PropCad are more complete. Secondly, through the analysis and discussion of the computational domain distribution, grid independence verification and turbulence model, the CFD calculation model is established systematically. Thirdly, the hydrodynamic analysis of AU5-80 propeller is carried out under different advance ratios, and the simulation results are in good agreement with the open water test data. The accuracy of CFD calculation model is proved. Then, the fluid-solid coupling analysis of the propeller is performed, and it is verified that the stress field of the propeller meets the material strength requirement. It provides support for the further optimization design of propeller structure. Finally, through the design and analysis of the PBCF propeller, some optimization parameters of the PBCF are obtained. Because the PBCF can diffuse and weaken the hub vortex, the propeller thrust, and efficiency are improved.

Fluid–solid coupling analysis of the whole spiral organ of Corti

Fluid–solid coupling analysis of the whole spiral organ of Corti

Fluid-solid coupling model and analysis on pulse wave propagation properties of iliac artery

In this work, we investigated the influence of the bifurcation geometry of the iliac artery on the propagation properties of the pulse wave, and applied software to establish the straight bifurcation and curved bifurcation bi-directional fluid-solid coupling finite element analysis models based on the iliac artery, and compared and analyzed the influence of the bifurcation angle of the blood vessel on the propagation characteristics of the pulse wave. It was found that the bifurcation geometry had a significant effect on the pulse wave propagation in the iliac arteries, and the pressure and velocity pulse wave amplitudes predicted by these two models had a good agreement with that before the vessel bifurcation in a cardiac cycle. The curvilinear bifurcation model predicted the pulse wave amplitude to be lower and the pressure drop to be smaller after the bifurcation, which was more in line with the actual situation of the human body. In addition, the bifurcation point is accompanied by the stress concentration phenomenon in the vessel wall, and there is a transient increase in the velocity pulse waveform amplitude, which was consistent with the fact that the bifurcation site is prone to phenomena such as arterial stenosis and hardening. The preliminary results of this paper will provide some reference for the use of pulse waveforms in the diagnosis of arterial diseases.

Collaborative optimization on cooling channel flow resistance and winding temperature for integrated cooling of motor and controller

The efficiency and working performance of the motor and controller system in micro-electric vehicles depends mainly on its thermal performance, which is contingent upon effective and active cooling. The working temperature of the motor and controller may be too high during operation, which properly causes motor power reduction or motor breakdowns. Therefore, it is crucial to design a good cooling channel for better cooling the integrated motor and controller system. This work proposes an integrated cooling channel of motor and controller, and the fluid-solid coupling analysis is applied for analyzing the velocity, pressure distributions of the cooling channel, and temperature distributions of motor solid components. Meanwhile, the collaborative optimization method based on the multi-island genetic algorithm (MIGA) is used to attain optimal design parameters of the integrated cooling channel of the motor and controller for obtaining a better cooling channel design with lower flow resistance and lower winding temperatures. Results show that the original cooling channel’s flow resistance and maximum winding temperature are 31.87 kPa and 120.04°C, respectively. The flow resistance and winding temperature are pretty significant. After optimization, the local vortex flow and zero velocity area in optimal cooling channel design are improved, the coolant flow velocity becomes more uniform, and the flow resistance is significantly reduced. The flow resistance and maximum winding temperature of the optimal cooling channel design are 12.5 kPa and 116.76°C, respectively, which are decreased compared with the original cooling channel structure, with a decrease of 39.4% and 2.7%, respectively. The research findings in this work can provide theoretical reference for solid components temperature evaluation of motor and give valuable data to cooling performance evaluation and optimization of integrated cooling channel for motor and controller system.

Fluid–solid coupling analysis of submerged water jet cavitation micro-forming

Submerged cavitating waterjet micro-forming is a novel jetting technology. Existing detection devices cannot accurately detect bubble distribution in still water domains and target workpiece processing areas. To investigate bubble generation and distribution in still water domains and their influence on target micro-forming, a submerged cavitating waterjet micro-forming fluid–solid coupling numerical model was established in this paper. The distribution of submerged cavitating waterjet cavitation effects and the hammering of micro waterjets on metal plates under the action of cavitation bubbles, as well as the coupled forces, were analyzed. The results show that bubble distribution in still water domains is closely related to turbulence, vortices, and pressure distributions. The collapse of cavitation bubbles generates enormous pressure, and the pressure generated by the collapse of cavitation bubbles causes the micro waterjet hammers to produce annular deformation zones on the metal plates. The bubble distribution laws and theoretical basis of cavitation micro-forming technology in submerged waterjets are provided in this study, which has very important engineering application significance.

Temperature gradient effect on high-speed railway frame structure yard based on fluid-solid coupling analysis

As the frame structure can effectively save the lower space and optimize overall layout of the yard, it was first applied in the railway double-layers yard in Beijing Fengtai, including the elevated high-speed yard and the ground common-speed yard. To identify the most unfavorable temperature gradient effect on railway frame structure yard, the present study combined with CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) to analyze the temperature gradient and corresponding temperature stress of the structure, and utilizes ray tracing method to analyze the shielding effect between components of structure under the sunlight. The results show that, the temperature gradients of the slab need to be focused. Both positive and negative temperature gradients are observed in the vertical direction of the slab at the end of September (autumn equinox), which are 80.95℃/m and −29.85℃/m, respectively. Under the most unfavorable temperature gradient, the maximum principal tensile stress of the structure lies at the junction of positive and negative temperature gradients of the slab, accounting for 45.6% of the concrete tensile strength, which is the controlling index of the frame structure.

Fiber movement during twisting in air vortex spinning

In order to clarify the twisting mechanism of the air vortex spinning machine, this paper investigates the motion law of air vortex spinning fiber from the guided access into the twisting chamber during the whole process. While considering the bi-directional coupling effects of the airflow and fiber, the airflow–fiber fluid–solid coupling solution model of the guiding parts is established, and the fluid–solid bi-directional coupling solution platform is built based on ANSYS Workbench software. The movement trajectories of fibers in the process of single and double fibers entering the twisting zone from the guiding channel to the hollow spindle guiding channel were obtained, respectively. Through the fluid–solid coupling analysis, (1) under the action of airflow, the fiber movement is complex and variable, while the movement of the fiber affects the distribution of the surrounding airflow velocity and pressure. (2) Due to the asymmetric structure of the guiding channel, the airflow distribution on both sides of the fiber in motion is uneven, so that the fiber as a whole is wavy forward, and from time to time collisions occur with the tube wall. (3) The fibers are sucked into the twisting chamber under the effect of pressure difference, and the fibers are twisted under the combined effect of axial airflow and tangential airflow. The head end of the fiber enters the guided access in the middle of the hollow spindle under the guidance of the guiding pins. (4) In double fiber movement, there will be mutual adsorption, fibers becoming closer together, contact, stagger, separation and other phenomena that also affect the fiber in the airflow under the action of the twisting winding movement process.

Thermal–Fluid–Solid Coupling Analysis on the Effect of Cooling Gas Temperature on the Fatigue Life of Turbine Blades with TBCs

The application of thermal barrier coatings (TBCs) can increase the blade’s operating temperature and fatigue life. Previous studies have neglected the effects of cooling gas temperature variations on the temperature field, stress field, and fatigue life of blades and TBCs. For this reason, this paper considers the inhomogeneity of the high-temperature gas inlet temperature, the internal cooling gas temperature, the periodicity of the external flow field, etc., and establishes a finite element model of the gas turbine blade with TBCs. Then, the life of the blade and the TBCs is predicted based on the Ncode 2020R2. Finally, the effect of the cooling gas temperature on the temperature, stresses, and life of the blade and the TBCs is analyzed. The results show that the fatigue life of the TBCs is lower than that of the blade, and the low-life region of the TBCs is located at the leading edge of the blade, which is consistent with the TBCs shedding region of the real blade and verifies the accuracy of the life prediction method in this paper. The fatigue life of the blade and TBCs firstly increases and then decreases with the increase in the cooling gas temperature, and the trend of the stress changes in the opposite direction. When the cooling gas temperature is increased from 573 K to 873 K, the minimum life of the blade is increased by 358.5%, and that of the TBCs is increased by 138.7%. The conclusions can provide guidance for the design of long-life turbine blades with TBCs.

An Efficient Dynamic Coupling Calculation Method for Dam–Reservoir Systems Based on FEM-SBFEM

In the dynamic analysis of dam–reservoir interactions, the computational efficiency of coupling system is relatively low. When numerical methods such as the scaled boundary finite element method (SBFEM) or the finite element method (FEM) are used to deal with hydrodynamic pressure, the additional mass matrix for the hydrodynamic pressure of incompressible reservoir water obtained is the full matrix. In this study, an efficient three dimensional (3D) dynamic fluid–solid coupling analysis method for dam–reservoir systems based on the FEM-SBFEM is proposed and applied to the dynamic calculation and analysis of an arch dam under seismic conditions, which adopts the SBFEM to solve the hydrodynamic pressure of the reservoir and employs the FEM to discretize the dam. In the proposed method, the hydrodynamic pressure additional mass matrix is simplified according to the physical meaning and distribution characteristics of the additional matrix with only a reduction coefficient α (0 < α ≤ 1.0), which is simple and easy to implement. The suggested value of the reduction coefficient α for the added mass matrix of the hydrodynamic pressure is selected to be 0.6 so as to ensure that the error of the maximum value of the dynamic response of the dam is limited within 5%, which is acceptable, and the elapsed time of calculation can be reduced to one twentieth of the accurate solution, which is a great jump in calculation efficiency. The proposed method provides a practical and effective process for the analysis of dam–reservoir dynamic interaction systems with a large computational scale and a fine grid scale.

Mechanical response of dropping a Hall anchor and its penetration depth in riverbed silt

To ensure the safety of an underwater pipeline embedded within riverbeds, it is essential to evaluate its burial depth and penetration depth during the emergency anchoring of a ship. In this research, the mechanical behaviour of the entire anchoring process with considering the penetration depth of the Hall anchor in the riverbed silt, was holistically examined using experimental measurements, theoretical calculations and computational analysis. Mock-up Hall anchors (5 and 7.5 kg) were dropped at five different heights beforehand, and their transient velocities during the underwater motion were measured using a 2D image sonar. When the water is deep enough, the velocity of Hall anchor when it touches the ground is predominantly determined by its weight with regardless of the height of the drop. Moreover, a theoretical analysis was employed to investigate the behaviours of uniform motion at the state of equilibrium and infinite depths of water, and the exact coefficient of fluid resistance of the Hall anchor was presented. Computational analysis based on the formulation of the arbitrary Lagrangian–Eulerian method was proposed to examine the anchor in the riverbed silt and predict its penetration depth with considering the influence of boundary restrictions. In addition, the riverbed silt with a high moisture content was considered as a material with fluid features, which will be examined for fluid–solid coupling analysis with a Hall anchor by means of a constraint algorithm with a penalty function. The predicted value of the maximal penetration depth is reasonable and reliable compared with the empirical formula, which is crucial to evaluate the burial depth of underwater pipelines. A research approach for the penetration depth of a Hall anchor in riverbed silt was proposed and demonstrated by considering the entire anchor process through a combination of experimental, theoretical, and computational analyses.

Face stability of shallowly buried large-section EPB box jacking crossing the Beijing-Hangzhou Grand Canal

The mechanical response of conditioned soil in an earth chamber is crucial for maintaining the face stability of earth pressure balance (EPB) box jacking. This study presents the project of a shallowly buried large-section box jacking crossing the Beijing-Hangzhou Grand Canal in Suzhou, China. The characteristics of tunneling parameters, such as the earth chamber pressure pe, total jacking force Pf and frictional force Ffric, were revealed by field measurements. A refined three-dimensional finite difference model was developed using the fluid–solid coupling analysis mode to evaluate the tunnel face stability, in which the geometric configurations of box jacking machine and the contact interfaces between different components were considered explicitly. In addition, the differences between driving and stoppage of box jacking machine were also considered. Upon the successful calibration of the numerical model, the transfer mechanism and the face support efficacy of conditioned soil are evaluated. In the end, a parametric study was conducted to discuss the influences of conditioned soil permeability, shear strength and thickness. The results indicate that the permeability of conditioned soil has no significant influence on its mechanical response, and a larger shear strength can obviously enhance the stress level at the lower part of the earth chamber. In addition, a larger thickness of conditioned soil can reduce its transfer coefficient and the fluctuation of earth chamber pressure.

Finite Element Simulation and Structural Optimization of Structural Flow Sequential Field for Sequential Boost Switching Valve

Turbocharging technology is an important part of engine technology. Under the working condition of 730 °C and 0.5 MPa, the valve plate opening and closing will bear the high pressure of the internal fluid medium, resulting in the deformation of the switching valve. In this paper, ANSYS finite element simulation software is used to establish the valve fluid domain model, and the stress field and deformation law of the valve under the valve plate opening of 0 °~ 90 °are simulated and analyzed. Based on the fluid-solid coupling theory, the deformation and stress distribution of the valve plate structure are obtained by simulation analysis. The simulation results show that the smaller the opening of the valve plate, the more disordered the flow condition. As the opening increases, the flow tends to be stable. When the opening is 30 °, the negative pressure inside the valve is the largest; combined with the fluid-solid coupling analysis, the maximum stress load on the valve plate appears at the connection between the valve plate and the long valve shaft and the short valve shaft, and the maximum pressure appears at the opening of 60 °, which is 37.144 MPa; the maximum deformation occurs at the outer edge of the valve plate. Based on the results of this simulation analysis, the corresponding multi-objective structural optimization of the valve structure is carried out to provide technical reference for the structural design of similar valves.

Fluid-solid Coupling Analysis of Riser based on CFD

The riser is the only channel connecting the submarine pipeline oil gas and offshore platform structures, offshore oil and gas development and utilization of lifelines, offshore pipeline system is the weakest vulnerable link. Due to its long and thin structure, the marine riser is easy to failure and failure in the complex working conditions. Marine vibration pipe safety or not directly affects the marine engineering and the surrounding environment and marine biology, in the event of damage, can cause the economic loss and environmental pollution, will result in a casualties, and even cause serious secondary disasters. Therefore, the safety and reliability of marine riser has been the focus of marine oil and gas industry research. In order to ensure the safety and reliability of the marine riser, it is usually necessary to evaluate the safety and reliability of the marine riser. The two-way fluid-solid coupling analysis of the riser system with a water depth of 500m is carried out by Ansys workbench software. The results show that the maximum flow rate of the flow field at the interface between the fluid and the riser occurs in the middle of the riser near the two ends. As time increases, the maximum flow rate will gradually shift from both ends to the middle of the riser, and the maximum value is 0.85m/s; the maximum stress of the riser will appear at the upper and lower end points, the maximum is 81.43Mpa; the lateral displacement of the upper end of the riser reaches the maximum, about 0.69m; indicating that these positions are the vortex induced lateral vibration of the riser dangerous area; therefore, this part can be improved by structural design or protection to increase the working life of the riser.

Optimization of Wing Structure Based on Fluid-solid Coupling and Vibration Model

With the development of ages, human beings have made more efforts to develop the sky, and aircraft is widely used as the main tool for human beings to set foot in the sky. Therefore, optimizing wing structure is positive for saving resources and improving efficiency. In this paper, by establishing the conventional wing structure model and the wing model after changing its rib density, we compared results based on fluid-solid coupling and vibration mode analysis. It is found that: The wing structure optimization should appropriately increase or decrease the wing-rib aperture (i.e., increase/decrease by 10%) based on ensuring the flight performance of the wing, and it can effectively reduce the overall deformation of the wing and ensure the flight performance of the wing, which provides a valuable reference for the design of the wing structure.

Stability Analysis of a High-Steep Dump Slope under Different Rainfall Conditions

The existing slope stability research, which is based on the fluid–solid coupling theory, is mainly focused on the slopes of central and eastern China. The impact of rainfall on the stability of the dump slope has often been ignored. It is worthwhile to reveal the mechanism of the fluid–solid coupling mechanics of dump slopes in the arid desertification area of northwest China under the maximum precipitation. The method of combining the seepage mechanics theory with the geomechanics theory was adopted. Darcy’s law and the mass conservation law were introduced to derive and establish the fluid–solid coupling analysis method. Taking the Xinxing Coal Mine in Wuhai City, China, as an example, the finite element software ABAQUS was used to construct the fluid–solid coupling model for slope stability analysis with unsaturated soil. The equivalent rainfall intensity of 68 mm/h for 1 h and 18 mm/h for 24 h was designed in the simulation, respectively. Four different types of initial water content (i.e., 1.72%, 7.34%, 14.69%, and 22.03%) of the dump slopes were defined as the initial conditions. The high-steep slope was compared to the standard slope. Therefore, a set of sixteen rainfall schemes was proposed. The variation regularity of slope stability was thoroughly discussed in regards to four areas: vertical deformation, pore water pressure distribution, equivalent plastic strain, and safety factor. As was expected, the research showed that the slope height and angle have a significant effect on the slope stability. When high-intensity rainfall occurs for a short duration, the slope tends to be more stable as the initial water content increases on the slope. When low-intensity rainfall occurs over a long period, the slope stability reduces if the initial water content is too high or too low in the slope.

Effect of Various Rainfall Conditions on the Roadside Stabilisation of Slopes in Gippsland

A distinctive slope stabilisation method that integrates two well-developed methods for slope stabilisation is analysed in this paper. The slope stabilisation method utilises embedded piles and geogrid-reinforced retaining walls with gabion basket wall facing. To study the effect of this integrated slope stabilisation method on the stability of the slope under the negative impacts of rainfall, a three-dimensional finite element model with fluid–solid coupling is adopted to indicate the rainfall infiltration process and investigate the corresponding slope responses. The shear strength reduction method is applied after fluid–solid coupling analysis to investigate the impact of various rainfall intensities and rainfall patterns on the stability of slopes with different configurations. The results from the comparison of slope responses among various configurations indicate that under the highest rainfall intensity, the integrated method improves the stability of the slope up to 41.2% and restrains the displacement increment of the road edge to a maximum of 12.5 mm. The most critical rainfall pattern for the stability of the slope has also been recognised in terms of the factor of safety and the variation in the negative pore-water pressure of the slope. The numerical results indicate that the back-loaded rainfall pattern always yields the lowest factor of safety and induces the highest loss of matric suction, which can be 23 kPa at the toe of the slope. Moreover, a comparison between two construction scenarios under various rainfall intensities was also conducted, which demonstrates that the reinforced filled slope configuration is preferable when the site conditions permit.

Numerical simulation on fluid flow and temperature prediction of motorcycles based on CFD

The temperature distributions of solid parts in motorcycle is of significance to give an quantitative cooling performance evaluation for assuring the feasible running of motorcycles. Therefore, the present work mainly tend to systematically investigate the flow velocity distributions and temperature distributions of motorcycle by constructing a fluid-solid coupling analysis model via CFD using commercial software STAR-CCM+. Based on computational fluid dynamics method (CFD), fluid-solid coupling analysis model of motorcycle is realized by integration of porous media model, heat exchanger model and fluid-solid co-simulation module and numerical investigations on fluid flow and temperature distribution characteristics at maximum running speed 120 km/h is conducted. The thermal management experiment test considering three pressure measuring points, fifty-eight temperature measuring points and two flowrate measuring points is investigated to know its cooling performance of motorcycle experimentally and provide experimental data for validation of simulation model. Results show that CFD results are in good agreement with experimental results and the maximum relative error is less than 10%. Thermal management test results show that left and right cylinder temperature, oil temperature are 183 °C, 190 °C, 120 °C, respectively. Air temperature of radiator at inlet side are from 29 °C to 35 °C, Air temperature of radiator at outlet side are from 60 °C to 90 °C, water temperature of radiator inlet and radiator outlet are 96 °C and 89 °C, respectively. The air temperature around left thigh and right thigh are 31 °C and 34 °C, respectively. CFD results show that there is no flow dead-zone and high temperature area in engine main components and muffler front cover. The temperature around motorcycle covering and both two thigh is not high due to the radiation of high-temperature components and the outlet temperature of exhaust muffler is also not high, which will not cause enough heat feelings to the riders for being uncomfortable. From the temperature field analysis results, there is no obvious poor temperature distributions for thermal comfort of this motorcycle. The results of this work can provide simulation data support and theoretical reference for the design and development of motorcycle and its crucial components. Through engineering applications of fluid-solid coupling model in a two-cylinder engine and electric generator, it verifies the universality of fluid-solid coupling model and it can be an effective way for the temperature predictions of industrial products.

Numerical investigation into fluid-solid coupling characteristics of blade leading edge vortex cooling under different rotation numbers

In this paper, the fluid-solid coupling analysis is carried out on the vortex cooling. Under rotation conditions, the process of high-temperature gas scouring the blade and the vortex coolant cooling the blade is numerically calculated. At the same time, five rotation numbers of 0, 0.183, 0.339, 0.457 and 0.512 are selected. In addition, this paper proposes a method to improve vortex cooling performance under rotation conditions. The results show that at high rotation numbers, the centrifugal force drives coolant to flow downstream of vortex chamber. The downstream chamber accumulates a large amount of coolant to derive centrifugal buoyancy, which causes the back flow of coolant and makes the upstream heat transfer effect poor. As the rotation number increased from 0 to 0.512, the average Nusselt number on the target wall decreased by 35.49%. For the blade solid region, the effect of thermal load plays a major role on blade stress and displacement characteristics. Insufficient cooling performance in the chamber upstream leads to a higher temperature of the blade root, and a higher thermal stress concentration is generated because the blade root is constrained. In addition, by improving the intake chamber into a convergent structure, the coolant flow into the vortex chamber can be promoted, and the effect of back flow can be reduced, thereby obtaining a better vortex cooling performance. The target wall average Nusselt number of the convergent intake chamber structure is 977.17, which is 23.63% higher than that of the original rectangular intake chamber structure.

Numerical simulation of hydraulic fracturing process with consideration of fluid–solid interaction in shale rock

As a critical technology for the efficient exploitation of shale gas, hydraulic fracturing is a two-way fluid-solid coupling interaction process of water-rock. The accurate water pressure calculation in single shale rock fracture during hydraulic fracturing is critical to the fluid-solid coupling analysis. This paper selected the fractured shale rock from the shale reservoir for analysis based on the Saint-Venant principle. Moreover, the water pressure in a single shale rock fracture was calculated by solving the Navier-Stokes equations. Meanwhile, a fluid-solid coupling model of fractured shale rock during hydraulic fracturing was established and evaluated the changing process of hydraulic fracturing. Our results show that in the hydraulic fracturing process, the changing process of water pressure in a single shale fracture with or without fluid-solid coupling is similar, and both have a water hammer effect. Single shale rock fracture opened instantly in an elliptical shape. The maximum instantaneous water pressure at the fracture tip considering fluid-solid coupling was 3.01 times the initial water pressure. The Mises stress at the fracture tip caused by the maximum instantaneous water pressure was 2.97 times the Mises stress at the fracture tip caused by the water pressure in the fracture after stable water pressure change. Mode Ⅰ fracture occurred in the fractured shale rock when high-pressure water rapidly invaded 2/3 of the length of the fracture. The findings in this study may help to understand the hydraulic fracturing mechanism in shale rock.

Hydrodynamics of a Flexible Flipper for an Underwater Vehicle-Manipulator System

Motivated by the requirement for developing a lightweight and nimble underwater vehicle-manipulator system (UVMS), this article presents a novel design of the overall framework and the functional modules for a flippers-driven UVMS (F-UVMS), which is equipped with six biomimetic flipper propulsors to produce thrust. With taking into account the material properties and flexible deformation, the dynamic model of the flexible flipper is derived. The fluid-solid coupling analysis reveals the wake vorticity characteristics and the mechanism of the flexible flipper. Besides, by introducing the dimensionless swimming number <inline-formula><tex-math notation="LaTeX">${{\text{S}}_{\text{w}}}$</tex-math></inline-formula>, the force-parameter relationship of the flexible flipper is revealed. By comparing the hydrodynamic characteristics of the flexible flipper and rigid flipper, it can be concluded that the flexible flipper has higher propulsion efficiency. The motion patterns of the F-UVMS are designed by proposed coordinated control strategy. Moreover, through computational fluid dynamics method, the hydrodynamic effects of the biomimetic flipper propulsors during forward motion are analyzed. Finally, the force measurement experiments and the thrust efficiency experiments validate the practicability of the proposed biomimetic flipper propulsor. The motion feasibility of the F-UVMS is verified bythe motion experiments.