Plate Wall Research Articles

Themo-bioconvection of gyrotactic microorganisms in a polymer solution near a perforated Riga plate immersed in a DF medium involving heat radiation, and Arrhenius kinetics

In modern era, thermo-migration of microorganisms is an appealing research topic in bio-nanotechnology, bio engineering, and biomedical. In this context, a mathematical model describing thermo-bioconvection of Sutterby nanofluid flow including motile gyrotactic microorganisms near a perforated Riga plate under the physical impacts of heat radiation, and Arrhenius kinetics associated with binary chemical reaction is formulated and simulated here. The Darcy-Forchheimer (DF) law is applied to determine the porosity of porous media. The Grinberg term is taken for the Lorentz force owing to the parallel Riga plate wall. Appropriate translations are discharged to turn the constitutive partial differential equations (PDEs) into ordinary differential equations (ODEs), that are numerically computed by opting the Runge–Kutta-Fehlberg method (RKF-45) along with shooting strategy. The physical insights of various controlling variables on the transport profiles, Sherwood number, Nusselt number, and microorganisms density number are exemplified through requisite graphs and tables. It must be admitted that with enlarging Darcy number, the nanofluid velocity declines, while Forchheimer number has opposite consequence on it. The motile microorganisms density sharply decreases for improving values of activation parameter. The present modeling would provide preliminary guidances in a variety of biotechnological and industrial applications.

Seismic design and performance of a steel frame-shear plate shear wall with self-centering energy dissipation braces structure

The steel plate shear wall with self-centering energy dissipation braces (SPSW-SCEDB) is a new seismic lateral resistant component. This paper outlines the performance requirements of the steel frame-shear plate shear wall with self-centering energy dissipation braces (SF-SCSPSW) structure and presents a direct displacement-based seismic design method for the structure. A combined strip model of the SPSW-SCEDB that considers the effect of the bolted connection on the wall plate is established. The comparison of the simulated and experimental results shows that the model can accurately predict the strength and hysteretic behavior under cyclic loading. The 8- and 15-story prototype buildings were designed using the presented method. The results of nonlinear dynamic analysis showed that larger inter-story deformations occurred on the lower floors, and the inter-story ratios gradually decreased with an increase in the number of floors. The maximum inter-story drift ratio (1.73%) of the 8-story structure under mega earthquakes and the maximum residual drift ratio (0.018%) of the 15-story structure under large earthquakes were less than the limit values (2% and 0.5%). Local yielding occurred between the brace connection and the column under mega earthquakes, but the columns remained in an elastic state. The seismic responses of the SPSW-SCEDBs in the two structures met the performance requirements of being elastic and suffering light and moderate and serious damage under frequent, medium, large, and mega earthquakes, respectively. The effectiveness of the proposed design method was verified.

Microstructure related analysis of tensile and fatigue properties for sand casting aluminum alloy cylinder head

The microstructure and mechanical properties of top plate, force wall and bottom plate in low-pressure sand-casting aluminum alloy cylinder head were evaluated at room temperature. The results of the comparison study showed that with different positions of the cylinder head, the microstructure and mechanical properties were considerably different. For the convenience of analysis and discussion, the quality index (Q) was used to characterize tensile test data, which equals ultimate tensile strength plus 150 log elongation. The top plate has the best tensile performance with Q of 443.5 MPa, while the Q of the force wall (292 MPa) and bottom plate (355.5 MPa) is only 66% and 80% of that on the top plate. The tensile properties of the cylinder head are mainly controlled by dendrite arm spacing (DAS), including primary dendrite arm spacing (PDAS) and second dendrite arm spacing (SDAS). The influence intensity varies with the value of DAS. In general, the tensile properties decreased with the increase of DAS. When the aluminum alloy specimen has small DAS (PDAS ≤ 46.49 µm, SDAS ≤ 33.64 µm), Q increases rapidly with the decrease of DAS. However, when PDAS ≥ 104.33 µm, SDAS ≥ 49.82 µm, the effect intensity of DAS on tensile properties is partially reduced. When the number of cycles is 2.5 × 107, the fatigue stress limits of the top plate (69.2 MPa) and bottom plate (70.0 MPa) are highly comparable, which is mainly due to the similar SDAS and eutectic Si average area. Porosity defects also have a significant impact on fatigue performance. The presence of porosity defects increases the scatter of fatigue properties. In addition, more than 90% of the fractures are caused by porosity defects, which indicates that porosity defects are the main factor causing fatigue cracking of low-pressure sand-casting aluminum alloy cylinder head. Therefore, the casting process should be optimized to avoid porosity defects as much as possible in order to improve fatigue performance.

Influence of maintenance methods on temperature and thermal stress of utility tunnel at early-age

In order to reduce and control the generation and development of early cracks in the concrete utility tunnel, ABAQUS finite element software was used to model the temperature field and thermal stress of early-age concrete of a thin-walled box structure. For the accuracy of simulation, the hydration heat of cementitious materials was tested by TAM air method, and the actual working conditions were used. Different curing methods were modeled, such as formwork type, formwork removal time, and curing time. Simulation results showed that steel formwork shall be selected for construction in summer, and the recommended formwork removal time was 3 days, which was better to resist temperature induced cracks. Moreover, the sooner the formwork was removed, the smaller temperature difference between concrete surface and center, but it would bring difficulties to the cooling rate control. Also, higher temperature occurred at bottom plate, especially in the junction area between bottom plate and partition wall. The maximum thermal stress was found at the junction between top plate and partition. Last but not lease, attention should be paid to the occurrence of peak temperature in 26 h, temperature difference control for 26–50 h, and cooling rate control during 2–5 days.

An experimental investigation into the effects of front wall geometry on OWC performance for various levels of applied power take off dampings

Despite the achieved progress, exploiting wave energy in a competitive and efficient manner is still a grand challenge problem. This study aims to improve the performance of an Oscillating Water Column (OWC) by experimentally testing different streamlined front wall underlip geometries. Results show that the proposed geometries have an important bearing on OWC hydrodynamic performance provided that OWC does not operate in sloshing mode. Relative to rectangular front wall plate, underlip geometry with a circular cross-section, provided a maximal increase of 21.2% in capture width ratio via reducing vortex shedding and increasing conveyed amount of incident wave energy into the chamber. Observations indicate that the value of Power Take-off (PTO) damping has a crucial impact on the amount of acquired performance improvement. Therefore, applied PTO damping is a key parameter that has to be determined with care. All tested geometries failed to diminish the sloshing present in the chamber which highlights the fact that sloshing phenomenon is only associated with incident wave characteristics independent of wave-structure interaction. Introduced front wall shapes are also found significant from structural design point of view as they are beneficial in attenuating large vortex induced shear stresses that OWC front wall has to endure.

Simulation of a Trombe wall with a number of semicircular fins placed on the absorber plate for heating a room in the presence of nano-PCM

This article numerically examines a Trombe wall for a mild winter climate. A number of semicircular fins are mounted on the Trombe wall. The inside of the fins is filled with phase change material (PCM). Graphene nanoparticles are also used in PCM. The wall is positioned at the south side of the building and is installed to heat a 4 × 4 room. Room and Trombe walls are simulated at 100, 300, and 500 W/m2 using ANSYS FLUENT software. The effect of factors such as Trombe wall height, distance between the glass wall and absorber plate, number of fins, presence or absence of PCM in fins, and flux quantity on average room temperature (TRA) is investigated. The findings reveal that the quantity of heat flux provided to the wall has a considerable influence on the room temperature (TRO), therefore increasing the applied heat flux raises the TRA. An increase in the air gap of the Trombe wall reduces the TRA. Adding fins by up to 11 enhances the TRO, but further increasing reduces the TRO. The use of PCM in the fins lowers the TRO during the day but stores the energy for the times with low solar flux and heats the room in the afternoon.

Metallurgical assessments on 316L stainless steel thin walled plate fabricated through GMAW based typical Wire Arc Additive Manufacturing

Wire Arc Additive Manufacturing (WAAM) is developing trendy process for the fabrication of metal components nowadays. In the present study, the concept of WAAM is employed but typical concept is used for fabricating a thin walled plate sample using AISI 316L grade of stainless steel. The plate size is limited for ease up to laying only three weld beads in traverse direction rather than vertically as in the case of additive manufacturing. The chemical composition of fabricated sample is analysed for checking the use of WAAM for metal component fabrication. The ferrite number is also found and reported for supporting the fabricated component to withstand the corrosion. The low carbon steel was used as a parent metal to deposit the fabricating stainless steel thin plate. Microstructure of interface between base metal and fabricating metal is also revealed for confirming defect free component fabrication. These results are found to be satisfactory enough and thus the WAAM shall be used for the fabrication of desired components also especially in stainless steels.

Stability analysis and experimental research on ultrasonic cutting of wave-absorbing honeycomb material with disc cutter

To address the problem of the poor stability of ultrasonic machining of wave-absorbing honeycomb material, this study takes ultrasonic cutting of wave-absorbing honeycomb material with a disc cutter as the research object and establishes a multi-degree-of-freedom mathematical model of the cutting system based on the relative positions of the tool, the wave-absorbing honeycomb material, and the motion characteristics of the tool. On this basis, modal analysis of the disc cutter and the honeycomb cell wall plate is carried out to draw the Lobe diagram of ultrasonic cutting stability, the process experimental parameters are determined to accord to the solved stability Lobe diagram, and machining stability verification experiments are carried out. The experimental results show that the machining parameters in the stable zone of the Lobe diagram result in a neat and clean surface, less fibre pullout, a complete outer substrate, and less tool wear than those in the critical and unstable zones, thus verifying the correctness of the theoretical model and the stability Lobe diagram.

Computation of magnetohydrodynamic electro-osmotic modulated rotating squeezing flow with zeta potential effects

Motivated by exploring novel intelligent functional materials deployed in electromagnetic squeezing flows such systems, a comprehensive mathematical model is developed to investigate the squeezing flow of a smart viscous ionic magneto-tribological fluid with zeta potential effects, intercalated between two parallel plates rotating in unison, under the simultaneous application of electric and magnetic fields. The lower disk permits lateral mass flux (suction or injection). Continuity and momentum equations are represented in the proposed three-dimensional mathematical model by a set of partial differential equations. The electro-viscous effects resulting from distorted electric double-capacity flow fields are comprehensively examined for various intensities of applied plate motion. The formulation features a more robust approach to the traditional Poisson-Boltzmann equation model. A similarity transformation is used to translate the governing equations into ordinary differential equations, which are then numerically solved with appropriate boundary conditions at the disks using MATLAB software. Via graphical visualization of velocity profiles, pressure gradients and the upper wall coefficient of skin friction, several characteristics of squeezing flow are analysed. The computations show that there is a rise in pressure near the plate walls and a fall in pressure in the centre with increment in rotational, electroosmosis, electric field, and magnetic parameters. However, by selecting the appropriate squeezing velocity, the viscous drag on the lower plate can be effectively reduced. It is also observed that as the disk (wall) suction parameter increases, both radial and transverse velocities are damped. The current study generalizes previous investigations with the novelty of rotation and also pressure gradient computations. Furthermore, it provides a useful benchmark for alternative numerical simulations.

Magnetohydrodynamic mixed convection in a non‐Newtonian third‐grade fluid flowing through vertical parallel plates: A semianalytical study of flow and heat transfer

AbstractBuoyancy assisted and buoyancy opposed mixed convection of a third‐grade fluid, which flows through vertically oriented parallel plates, subjected to uniform and constant wall heat fluxes, under the effect of an externally applied magnetic field, are investigated. The coupled, nonlinear conservation equations of momentum and energy are solved employing the collocation method (CM) and velocity and temperature distributions are solved semianalytically. The results produced by the CM and the results of exact solution are compared for the buoyancy assisted and buoyancy opposed flow of a Newtonian fluid through the vertically oriented parallel plates arrangement without the effect of the externally applied magnetic field. An excellent agreement is exhibited by demonstrating the efficacy of the CM. The effects of the third‐grade fluid parameter, Hartmann number, and mixed convection parameter on the dimensionless velocity, temperature, and Nusselt number are studied. The results imply that in the case of buoyancy assisted flow, an increment in the non‐Newtonian third‐grade fluid parameter causes a decrease in the fluid velocity near the plate walls, which finally causes an increase in the velocity in the central core of the plates. In buoyancy opposed flow, the effect of the same parameter is to oppose the flow reversal near the walls and with higher values of this parameter, it can totally prevent the flow reversal near the walls. The results of the present study can be useful in the fields of flow and heat transfer of various grades of polymers, paints, and food processing.

Flowing characteristics of aluminum droplets impacting curved surface

In order to reveal the mechanism of reaction between aluminum droplet and curved wall, a numerical calculation model based on the volume of fluid method of aluminum droplet impacting curved wall is established. By analyzing the influence law of Weber number, Ohnesorge number and wall curvature on the process of droplet impacting the wall, the spreading characteristics and flow mechanism of droplet on curved surface are studied. The results show that the flow characteristics of aluminum droplets after impacting the wall are affected not only by inertial force, surface tension, and viscous force, but also by the structure of the wall. The behavior patterns of the droplets contain adhesion, rebound and splash under different Weber numbers. Because energy dissipation is produced in both spreading process and retracting process, the retracting speed of droplet is always less than its spreading speed. During the flow of the droplet, there are two pressure peaks and velocity peaks at the contact point, while the two peaks appear respectively at the moment when the droplet impacts the wall and when the droplet is about to rebound. In the behavioral mode of rebound, as Ohnesorge number increases, the maximum spreading diameter of the droplet gradually decreases, and the contact time is shorter. In the behavioral mode of adhesion, the spreading radius of the droplets is of oscillatory decay. Within the same period, the maximum spreading coefficient of the larger-Ohnesorge number droplets is smaller, and the decay rate is faster and the oscillation period is shorter. With the increase of wall curvature, the maximum spreading coefficient of droplet increases and that on the plane is the minimum. Based on the calculation results, the empirical formula is revised. Compared with the previous formula, it can well predict the maximum spreading coefficient on the curved surface, whose average error is within 3%. Further, according to the conservation of energy, theoretical models which predict the maximum spreading coefficients when droplets impact a curved and plate wall are also established. Compared with the scenario on the plane, the spreading coefficient of droplet on the curved surface is related to not only the motion parameters of droplet and the wettability of wall surface, but also the ratio of wall curvature to droplet curvature. More importantly, the new theoretical model takes into account the coupling effects of Weber number, Reynolds number, curvature ratio and contact angle, so it has stronger applicability and better robustness. The research results in this work will provide the theoretical basis for practical engineering application.

Numerical Analysis of the Structure of High-Strength Double-Layer Steel Plate Concrete Shaft by Drilling Method of Water-Bearing Weak Rock Formation

In order to ensure the safety of coal mine shaft construction, a double-layer steel plate concrete composite shaft wall structure was proposed. However, fewer studies were conducted on this structure, which made engineers too confused to fully recognize its feasibility of this structure. Hence, based on the previous experimental research on the Taohutu mine construction project in Ordos in Inner Mongolia, this research paper aims to provide a widely deep numerical analysis by the usage of the finite element software, in fact, to establish the corresponding numerical analysis model and make a comparison with the experimental data to get the rationality of the verified model. The influence of the composite characteristics of the steel plate and concrete on the ultimate bearing capacity and stress field of the shaft wall structure is studied here through the method of multi-factor analysis. Also, the optimal design scheme of the double-layer steel plate and concrete composite shaft wall structure is proposed in this research paper.

Explicit dynamics finite element analyses of asymmetrical roll bending process

In this article, results obtained from a preliminary study that contains a set of explicit dynamics finite element analyses of a metal plate bending process are presented through 3D asymmetrical three roller models. ANSYS Ls-Dyna explicit dynamics finite element (ED-FEA) preprocessor and solver were used to carry out dynamic simulations. Explicit dynamics of a low-velocity process such as the roll-bending of a metal plate is a computationally expensive method. Since plastic deformation occurs on the plate in addition to elastic flexure to eventually possess a circular geometry, the plate material is considered a non-linear material. In this particular study, an aluminum plate was modeled with the Bilinear Kinematic Hardening model including plasticity parameters such as the tangent modulus. A very significant parameter called the mass scaling factor was taken into account to be able to define a specific time-step that was used to determine the computation time interval and the total temporal cost. However, exaggerated reduction of the computation time results in unphysical consequences. The results were presented before and after redesigning the lower and side rolls having a convex geometry and the peripheral velocity of upper roll rotation was decreased to minimize the distortion that occurred on the pre-bent side walls of the aluminum plate.

Study on heat transfer characteristics of indirect evaporative cooling system based on secondary side hydrophilic

Hydrophilic materials have been widely used in heat exchangers. On the Secondary side of heat exchanger, water film generated on the plate wall could affect overall heat transfer performance of the heat exchanger. In this study, an experimental analysis of two different hydrophilic materials of indirect evaporative cooler (IEC) systems was carried out. The two plate heat exchangers were finished either with TiO2 coating or a novel hydrophilic Graphene coating. First, a three-dimensional mathematical model coupled with a Volume of Fluid (VOF) model and a continuum surface force (CSF) model for heat and mass transfer of IEC was developed. The surface tension was achieved by changing the contact angle and thermal conductivity. Simulation results obtained from the developed model with and without the hydrophilic coating were in good agreement with experimental results. The deviation is within ±10% which proved the good accuracy and reliability of the model. Second, the influence of hydrophilic coating on enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP (coefficient of performance) of IEC was investigated under different boundary conditions. Compared with non-hydrophilic materials, the enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP of IEC system coated with TiO2 increased by 5.33%, 9.91%, 0.25 and 3.22, respectively. The enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP of the Graphene coated IEC system increased by 14.75%, 12.07%, 0.85 and 7.69, respectively, as compared to IEC without the hydrophilic coating. In addition, the enthalpy efficiency, wet-bulb efficiency, enlargement coefficient and COP of the Graphene coated IEC system increase by 11.67%, 7.76%, 0.76 and 6.08, respectively, as compared to the TiO2 coated IEC system.

Cyclic Loading Response of Composite Corrugated Steel Plate Shear Walls - Smart Technic

The structural element within the whole structure contains structural elements like beams, slabs, columns and reinforced concrete walls. One of the most vertical structural elements is shear wall that built to giving stability to the building, resisting lateral force such as earthquake and wind and to reduce the building deformations. In present study, the analysis of corrugated vertical steel plate shear walls using finite element method by ABAQUS software is examined. Four different modes are analysed in which the first model is vertical corrugated steel shear wall plate, second is the composite shear wall with full interaction, third is the composite shear wall and finally the fourth model is composite shear wall with gap between concrete panel and steel frame to check out the full performance of different shear wall under the effects of cyclic loadings. Displacement, drift and energy dissipation will investigate throughout analysis. Analysis results indicated that the gap and composite action between steel and concrete panel play an important role on the performance of shear wall under cyclic loading. The decrease in displacement of composite shear wall as compared with the steel shear wall reach 11.86%.

Experimental Study on the Distribution of Temperature and Deformation in the Water Walls of an Opposed Firing Boiler under Variable Load Conditions

To study the operational problems of an opposed firing boiler in continuously changing working conditions, the temperature, strain, and thermal stress of water walls were measured to analyze the distribution and relationship between temperature and deformation. The results showed that the asymmetrical arrangement of the burners in flexible operation can cause serious nonuniform distribution of the water wall temperature. The high temperature will induce extreme compressive stress, and the temperature difference between the high- and low-temperature areas will aggravate the tensile stress, which can induce bulge deformation and cracking of the water walls. We proposed replacing water wall plates with arc-shaped plates and adjusting the arrangement of burners to reduce the thermal stress. In addition, experimental equations were obtained between stress and temperature under steady and unsteady states by the least-squares method. These equations can be used to estimate the approximate range of high-stress areas based on the temperature of water walls. Finally, we found that the time hysteresis between temperature and thermal stress can be ignored. This study highlights the distribution and relationship of temperature and thermal stress on water walls under variable load conditions to guide their safe operation.

Assessment of radiation damage of the first wall of a fusion neutron source DEMO-FNS with a blanket for the transmutation of minor actinides

The design of the demonstration fusion neutron source (DEMO-FNS) demonstration fusion–fission hybrid facility is carried out at the National Research Center ‘Kurchatov Institute’ in Russia. For the implementation of the DEMO-FNS project, it is important to assess the effect of the fast neutron spectrum on radiation-induced damage to the device materials, primarily the materials of the first wall, which is the most problematic unit of the device. Due to the lack of real hybrid fusion devices, the study can only be carried out using computer simulations of the experiment. A computer simulation using the Monte Carlo method was carried out to calculate the developed three-dimensional full-scale model of the DEMO-FNS reactor with a blanket for the transmutation of minor actinides. The MCNP-4 code was used with cross-sections from the FENDL-2.1 and ENDF/B-6 files, as well as with cross sections for calculating radiation displacements. The neutron spectrum in the first wall of DEMO-FNS was determined at the power of a volumetric deuterium–tritium neutron of 1.42 × 1019 n s−1. It was found that beryllium as a plasma-facing material has too short lifetime under the neutron load on the first wall and divertor plates of DEMO-FNS. The replacement beryllium to tungsten is problematic and requires special study. Copper alloys have sufficient resistance to the effects of neutron radiation of DEMO-FNS for one full power year, but will require several replacements when operating the device for more than 10 years. The steels used in fast reactors can meet the operational requirements of the first wall of DEMO-FNS. To solve the problem of choosing materials for the first wall of DEMO-FNS, new experimental researches on changes in the physical properties of these materials in the fast neutron spectrum are needed.

Influences on the drying behavior of a concrete ceiling below a cold attic

The article describes the current state of a project examining the influences on the moisture distribution in cold attics above concrete ceilings of residential buildings. Considerable research has been done on moisture damages in cold attics, especially in Scandinavia and North America, focussing on spaces above wooden ceilings. The project (ongoing until Sept 2021) underlying the article deals with cold attics above concrete ceilings resting on masonry walls, a frequent variant in Austria. Research was triggered by a regional Austrian building industry association to shed light onto recent detrimental moisture accumulation in the wooden wall plate (= bearing for the rafters along the eaves) and in the two EPS insulation layers on top of the ceiling. Suspected reasons for the moisture problems and for the local moisture distribution are 1) a too small diffusion resistance of the vapour retarder covering the ceiling, 2) insufficient (natural) attic ventilation and 3) convection, e. g. in the gap between the polystyrene blocks. In order to rank these potential causes by influence and also to find a practical solution a two stage experimental approach was chosen: 1) A handy small scale replica (order of dimension: 1m) of the situation was exposed to the according indoor and outdoor climate in a climate chamber. Different vapour retarders on top of the ceiling were chosen. 2) A larger 1:1 replica has been erected as well but not yet delivered monitoring data. In parallel, a hygrothermic model taking convection into account was established and simulations carried out. The project will deliver a contribution to the Austrian standard on moisture safety 8110-2 on how to judge the moisture safety of joints via simulation.

Heat transfer at the step of a CANDU calandria during a severe accident

Abstract During the in-vessel stage of a severe accident in a CANDU 6 reactor, decay heat from a collapsed core would be rejected through the calandria walls into the surrounding water. At the step in the calandria wall, the subshell and annular plate meet at a right angle pointing into the calandria. The geometry at this joint could concentrate the exiting heat flux, potentially leading to calandria failure. Finite element analysis is used to study the heat transfer near the welded joint. Different weld profiles, boundary conditions, and decay heat characteristics are considered, and the local concentration of exiting heat flux is calculated.

Design and Comparison Analysis of Various Flow Configurations in Bipolar Plates via Numerical Simulation

Bipolar plates play a major role in the overall performance of fuel cells, hence their proper design and optimization are essential. In this regard, pressure drop across bipolar plates has a major impact on the efficiency. Therefore, it is crucial to minimize the friction between the plate walls and the working fluid, with a proper flow configuration, to eliminate pressure drops. The study, involved the simulation of various modified pin-flow bipolar plate configurations where a comparative analysis was carried out. A parametric study was performed to optimize various designs and operating parameters such as fluid flow, velocity and pressure. Computational fluid dynamics (CFD) was employed for the numerical simulation to ensure the optimum uniformity of fluid distribution. Results showed that the pressure drop is proportional to the velocity magnitude in the laminar region. Moreover, the pressure drop was minimized by eliminating the sharp edges in the flow channels.