CFD Software Research Articles

The Influence of Stilling Basin Length on Velocity Changes Using Computational Fluid Dynamics Analysis

There are many ways to model hydraulic structures. Making prototype of hydraulic structures are costly, so alternative methods need to make an efficient model. Computational Fluid Dynamics is reliable to perform the variations model of hydraulic structures, which means enabling to create of many simulations without dangering people and safely at the cost. This paper discussed the influence of the stilling basin length variation on velocity changes. The stilling basin model draws on a 3-dimensional computer-aided design with three differences in length and export files as .stl. The analysis of Computational Fluid Dynamics is using Simflow open-source CFD software. The simulation is performed at a constant Flow Rate of 65 m3/s. There are three points of velocity monitoring, namely P1, P2, and P3. The position of P1 is located at the center of the stilling basin. P2 and P3 are located at the bottom and the top of the End Sill. The final stage of simulation showed that the stilling basin with the 10 meters length has a velocity at P1, P2, and P3 of 9.43, 7.16, and 5.25 m/s. Other velocity results for 9.5 meters length (P1, P2, P3) are approximately 9.55, 7.92, and 5.78 m/s. The last case using 9 meters length has results of 9.61, 8.30, and 5.83 m/s of velocity. The conclusions of the results showed that shortening the stilling basin length is affecting an increase in the velocity.

Effect of sinusoidal pulsating speed enhancement on the mixing performance of plastics machinery

Abstract Numerous vibration-assisted methods have been adopted to solve problems in polymer processing, but the introduction of vibration fields is typically done on small extruders or injectors in school laboratories and industrial research rooms, which profoundly limits the application of vibration technology. The purpose of this study is to put forward a simple vibration excitation method for all scale extruders or injection molding machines. To recover the mixing performance of that excitation method, a numerical investigation was carried out using the CFD software ANSYS POLYFLOW 19.2, and the analysis and comparison were made between the mixing performance of a simplified screw element with and without a sinusoidal pulsating speed field. The results showed that not all dynamic states with the superimposed excitation field have better mixing performance than the steady state without any pulsating field. Nevertheless, the introduction of a pulsating speed field under certain parameters setting can indeed enhance the stretching rate, reduce the separation scale, increase the mixing efficiency, and lower the screw force. These findings are of great importance and provide valuable references for the development and application of vibration-assisted molding technology in plastics machinery.

Numerical study of turbulent heat transfer of annular fuel assembly in a sodium-cooled fast reactor by a SST k-ω-kθ-εθ model

ABSTRACT The annular fuel has two cooling surfaces inside and outside, which can fully take away the heat of the fuel assemblies. It is urgent to conduct research on sodium-cooled fast reactor annular fuel assemblies. The Prandtl number Pr of liquid sodium is much less than 1 (Pr ˂˂ 1). The problem is that using the traditional constant turbulent Prandtl number Pr t of 0.85 ~ 0.9, which will greatly affect the accuracy of the numerical prediction of the thermal-hydraulic properties of liquid sodium. In order to address this issue, the turbulent heat transfer characteristics of the bare and wire spacers 7-pin annular fuel assembly for a sodium-cooled fast reactor are investigated by a SST k-ω-k θ -ε θ model. The open-source CFD software OpenFOAM is used for this calculation. In order to verify the validity of the present calculation method, some classical liquid metal heat transfer correlations are used to compare and analyze the results of the present calculation method (k θ -ε θ model), the results of the Reynolds analogy hypothesis (Pr t = 0.85 model), and the results of the turbulent Prandtl number correlation (Pr t = kays model). It is shown that the SST k-ω-Pr t = 0.85 model overestimates the Nusselt number Nu of the annular fuel assembly. The SST k-ω-k θ -ε θ model agrees well with the SST k-ω-Pr t = Kays model of the bare and wire spacers 7-pin annular fuel assembly . It suggests that the numerical calculation results of the SST k-ω-k θ -ε θ model are reliable in both the simple and complex fuel assembly models. In brief, the SST k-ω-k θ -ε θ model is more capable of predicting the turbulent heat transfer characteristics of the bare and wire spacers 7-pin annular fuel assembly in sodium-cooled fast reactors. In addition, the thermal-hydraulic characteristics of annular fuel assemblies with wire spacers for sodium-cooled fast reactors have been investigated. This research can provide a reference for the study of turbulent heat transfer characteristics of annular fuel assemblies in sodium-cooled fast reactor.

MODIFICATION OF THE CENTRIFUGAL PUMP IMPELLER USING CAD

Currently, during the design of hydraulic machines, specialized software is widely used. The work presents an overview of modern programs that use a system of automated design of centrifugal pumps. The modern approach to the design of centrifugal pumps is based on the joint solution of direct and inverse problems of the theory of the working process in hydraulic machines. The purpose of the work is to develop the impeller of a centrifugal sectional pump with the following parameters: a liquid volume of 6 m3 per hour and a pressure of 140 m. The pump is used to supply crude oil to the recuperators of the small distillation unit SDU-20 of the oil refinery. In the sectional pump, it is possible to compose packages of impellers of various designs. The lack of publicly available geometric dimensions of the impeller of a centrifugal sectional pump for the required parameters makes it difficult to choose an effective mode of operation. Therefore, the task of designing and researching the impellers of the VNS type pump using CAD in the ANSYS CFD software environment is relevant. The work uses the free academic version of ANSYS CFD. The work presents a description of the main stages of design and research of a centrifugal pump. The geometric dimensions and kinematic parameters of the pump were analyzed and selected according to the jet classical theory and calculation results in the Vista CPD program. The overall efficiency of the pump at the preliminary design stage reaches 50 %. At the second stage, the direct task of computer 3D modeling in the Ansys CFX software environment is solved. Determination of the hydrodynamic and energy characteristics of the pump is carried out. The paper presents the results of a numerical study of three variants of the pump impeller, which are used to predict the mode of efficient operation of a centrifugal pump.

Using STAR-CCM+ Software in Aerodynamic Performance of Bogies under Crosswind Conditions

INTRODUCTION: STAR-CCM+ is a CFD software that uses continuum mechanics numerical techniques and is a tool for thermodynamic and fluid dynamics analysis. STAR-CCM+has expanded the functions of surface treatment, such as surface wrapper, surface remesh, and volume mesh generation.With the increase of train speed, the aerodynamic phenomena become more prominent, and the aerodynamic phenomena of high-speed trains in crosswind environment become more complicated. OBJECTIVES: Bogie is an important part of high-speed train. It is of great significance to study the aerodynamic performance Three groups of trains operating in a strong wind environment are modeled, and the surface pressure distribution characteristics of the car body and bogie, as well as the aerodynamic and aerodynamic torque distribution characteristics of each car and bogie, are analyzed when the train operates at 350km/h under a Class 12 crosswind condition. RESULTS: The results of the study show the variation rules of surface pressure, aerodynamic force and aerodynamic moment of the car body and bogie with wind speed. CONCLUSION: The windward surface pressure of the vehicle body increases linearly with the increase of wind speed, and the surface pressure of the roof and leeward side decreases linearly with the increase of wind speed.

CORNICE MODULAR WIND COLLECTOR © FOR COLLECTION AND AMPLIFICATION OF THE VERTICAL WIND COMPONENT IN BUILDINGS FOR GENERATION OF SMALL WIND ELECTRIC ENERGY

The generation of small wind electric energy in urban spaces in general and buildings in particular has an indisputable potential for practical applications. Notwithstanding, up until now, advances in this field have been less than expected. In order to take advantage of small wind energy, research in buildings requires the construction of a scale model for wind tunnel simulation. The difficulties regarding the construction of scale models and the availability of wind tunnels have slowed down a great deal this kind of research. New CDF (COMPUTATIONAL FLUID DYNAMICS) software techniques have made it possible to do research in buildings for small wind energy exploitation. A virtual scale model of the building under study is developed utilizing CAD. Subsequently, the model created with CAD is inserted into the CFD software and a simulation is conducted as if in a virtual wind tunnel. Considering the results obtained from research conducted with CFD software as well as from experimental validations in a wind tunnel, the research groups in La Rioja University known as “Modeling simulation and optimization of electrical industrial and automated fabrication systems” and “Integral Design Group“ have designed an optimization system for collection of small wind energy in buildings, for electric energy production through renewable sources.

Deeper Flow Behavior Explanation of Temperature Effects on the Fluid Dynamic inside a Tundish

The continuous casting tundish is non-isothermal due to heat losses and temperature variation from the inlet stream, which generate relevant convection forces. This condition is commonly avoided through qualitative fluid dynamic analysis only. This work searches to establish the conditions for which non-isothermal simulations are mandatory or for which isothermal simulations are enough to accurately describe the fluid dynamics inside the tundish by quantifying the buoyant and inertial forces. The mathematical model, simulated by CFD software, considers the Navier-Stokes equations, the realizable k-ε model for solving the turbulence, and the Lagrangian discrete phase to track the inclusion trajectories. The results show that temperature does not significantly impact the volume fraction percentages or the mean residence time results; nevertheless, bigger velocity magnitudes under non-isothermal conditions than in isothermal conditions and noticeable changes in the fluid dynamics between isothermal and non-isothermal cases in all the zones where buoyancy forces dominate over inertial forces were observed. Because of the results, it is concluded that isothermal simulations can accurately describe the flow behavior in tundishes when the flow control devices control the fluid dynamics, but simulations without control devices or with a weak fluid dynamic dependence on the control devices require non-isothermal simulations.

CFD simulation analysis of air curtain applications in vulcanization machines

Abstract This study simulates the vulcanization gas generated during the processing of the vulcanizing machine. During the simulation process, the influence of different angles and flow rates of the gas curtain on its flow field is simulated. Since the rubber has to go through the vulcanization process of the vulcanizer during the manufacturing process, the original liquid rubber is turned into a viscoelastic rubber solid. During the process, toxic and high-temperature vulcanization gas will be generated due to high-temperature hot pressing. If a large amount of this gas is inhaled, it will cause harm to the human body. Therefore, this study uses the CFD software Flow Vision to simulate the opening of the vulcanizing machine, and observes the flow field with different air curtains to find the most suitable air curtain wind speed and angle. Then, make a simple model for actual experiments, using CO2 instead of sulfide gas and installing a CO2 sensor at the nose of the mannequin, using the sensor to observe whether there is excessive CO2 diffused to the mannequin to judge the air curtain. Whether the gas is successfully prevented from spreading to the position where the personnel is located, to facilitate the observation of the gas diffusion, a smoke machine and a ray generator are added so that the gas diffusion status can be observed in real-time. In the end, finding the 9 m/s flow rate and a 90° air curtain angle positioned near the machine can greatly reduce the inhalation of excessive sulfide gas by machine operators and reduce the potential harm to the human body during work.

Thermal performance of medium-deep U-type borehole heat exchanger based on a novel numerical model considering groundwater seepage

The medium and deep U-type borehole heat exchanger (MDUBHE) system is a novel technology to extract deep geothermal energy for building heating. The thermal performance of MDUBHE is influenced by multiple factors, where groundwater seepage is one of the most significant factors. To our best knowledge, the effects of groundwater seepage on MDUBHE are still unclear. In this paper, a novel numerical heat transfer model for MDUBHE considering groundwater seepage is proposed, and validated by CFD simulation and experimental data, with root mean square errors of 0.5 °C and 1.8 °C, respectively. Based on the novel numerical model, the effects of groundwater seepage on thermal performance of MDUBHE and thermal recovery characteristics of rock-soil are investigated. The results show that the computational efficiency of the novel numerical model is improved by two orders of magnitude compared with CFD software in the same case. The heat extraction rate of MDUBHE gradually increases with increase of seepage velocity. The heat extraction rate is improved by 13.63 % when the seepage velocity is 5.0 × 10−7 m/s. Furthermore, groundwater seepage can improve the thermal recovery rate of rock-soil. Compared with no groundwater seepage, the thermal recovery rate is improved by 7.60 % when the seepage velocity is 1.0 × 10−7 m/s. This study is significant for revealing the effect of groundwater seepage on the MDUBHE system.

Low-Reynolds-number turbulent forced-convection flow over graded baffle plates

The thermo-hydraulic behaviors of turbulent forced-convection heat transfer flow over a rectangular cross section baffled channel are numerically examined in various graded baffle plate ratio configurations ‘GBR = 0.10, 0.11, 0.12, 0.13, 0.14, and 0.15) at different Reynolds numbers, ranging from 12,000 to 32,000. The governing equations that describe the flow are integrated by the finite volumes method, in two dimensions, employing the Commercial CFD software FLUENT 6.3 with low-Reynolds-number k-E model to describe the turbulence. The velocity and pressure terms of momentum equations are solved with SIMPLE-algorithm. In particular, axial velocity, turbulence intensity, pressure, and temperature fields, average Nusselt number and friction loss are obtained. The numerical runs are carried out for different values of Reynolds numbers and graded baffle ratios at constant wall temperature condition along the top and bottom walls. Results were compared with available experimental data from the literature and good agreement is obtained.

Noble MXene nanofluids' impact on solar collector effectiveness enhancement: a CFD numerical evaluation

The thermal flat plate solar collector (FPSC) is a versatile solar harvesting system that may be integrated into various designs and base fluids. This study presents a novel investigation of using nanofluids to transfer thermal energy in an FPSC system. Using the governing equations in CFD simulations, the performance of an FPSC is studied numerically. The base fluid has been defined as a 60:40 blend of ethylene glycol and water. The effects of three distinct volume fractions of MXene nanofluids in the 0.01–0.1% range on the efficiency are investigated. The numerical findings revealed that employing MXene nanofluid increases outlet temperature efficiency by about 5.83%, 6.06%, and 6.31% when 0.01%, 0.05%, and 0.1% volume fractions of nanofluids are used, respectively. The research aims to create a validated numerical model that can be used to assess the effectiveness of FPSC utilizing ethylene glycol and water or other nanofluids of any mass fraction as a working fluid. To examine the overall effectiveness of the FPSC, a numerical model was created using Solidworks software and ANSYS ICEM CFD. The numerical findings revealed that (i) increasing the proportion of MXene nanofluid in the FPCS enhances efficiency to 0.1% volume fraction, and (ii) MXene nanoparticles may be used in the solar collector to improve efficiency.

CFD Analysis of De Laval Nozzle of a Hybrid Rocket Engine

: The study gives a general overview of the CFD-simulated gas flow via the nozzle of a De Laval rocket engine. In CFD software, the mesh is generated using the nozzle’s geometry. In this work, CFD methods are used to compare a number of factors with those derived from classical theory, such as pressure, velocity, temperature, and arear ratios. The results of computational modelling of CFD simulation are comparable to those found from theoretical calculations.

Computational fluid dynamics analysis for improving the uniformity of flow field in heat air drying kilns

Because the uniformity of the wind speed flow field in the hot air drying kiln directly affects the distribution of the temperature field in the kiln, to improve the uniformity of air distribution in the existing wood hot air drying kiln, CFD software was used to analyze the three-dimensional flow field of each improved scheme. A combination of visual comparison and analysis methods and data comparison and analysis methods be used, to serve as the basis for assessing the feasibility and rationality of the improvement schemes. Without adding baffle plates or altering the structure to incorporate right-angle surfaces, the kiln's structure was optimized by adjusting the position of the air outlet and installing airflow distribution chambers. This paper innovatively introduces the Theory of Inventive Problem Solving?TRIZ ?to analyze and solve the flow field optimization problem in the kiln. The difference between this method and the existing research methods is that the solution process is more logical and the solution to the fundamental problem is more accurate. The experimental results show that when the air supply speed of scheme S8 is 3m/s~7m/s, the flow field of kiln Zone C (material drying area) meets the ideal range of 1m/s~3m/s. In addition, under the same working condition (3m/s), the velocity differences of scheme S8 is closer to 0 than that of scheme S0, and the velocity unevenness coefficient is reduced by 18.44%.

Design and manufacturing of forming molds for thermal storage materials and analysis of their thermal storage structures

In response to the shortcomings of concentrated stress, difficult forming, and short service life of commonly used honeycomb ceramic thermal storage materials with square lattice holes, the author has developed a new type of low stress honeycomb ceramic thermal storage material by studying the structure, forming mold, and extrusion forming material of the thermal storage body. The author introduced the changes in specific surface area and porosity of heat storage materials with different geometric structures, and analyzed and compared the structural characteristics of two types of heat storage materials, namely heat storage balls and honeycomb bodies, under the premise of equal heat storage capacity. The trajectory of air-flow in the heat storage chamber was simulated using CFD software, and the pressure loss and centerline velocity changes of different shapes of honeycomb were analyzed. The flow characteristics, pressure distribution, and heat transfer performance of gas inside different shapes of honeycomb were calculated. The experimental results showed that the closer to the circular shape, the smaller the pressure loss of the centerline. The larger the equivalent diameter, the smaller the resistance along the path. From the perspective of cold pressure loss alone, regular quadrilateral holes and regular circular holes are the best choices for the shape of honeycomb openings. The centerline velocity of the equilateral triangle hole is the largest, indicating that the smaller the equivalent diameter is, the greater the average velocity at the outlet is. The resistance along the path of the round hole is the smallest, the regular quadrilateral hole is slightly larger, and the pressure loss of the equilateral triangle hole is the largest, which exceeds the round hole by nearly 1/3. Taking into account factors such as heat storage, specific surface area, flow characteristics, and heat transfer characteristics, quadrilateral honeycomb cells are the best choice.

Effect of Number of Blades with Turbine Efficiency for Radial Turbine

Radial turbines are pivotal components in various engineering applications, playing a fundamental role in power generation, propulsion systems, and energy conversion processes. The efficiency and performance of these turbines are influenced by numerous design parameters, with the number of blades being a critical factor affecting overall efficiency. In this research, the effect of the number of blades is observed by using the numerical approach with CFD software. First, a turbine is designed, which refers to operational conditions. Next, the blade model is created by using blade design software. Then, three cases with 10,13 and 15 blades are conducted and simulated. The result shows that more blades give more power because more surface to extract the energy from the fluid.

Thermal Optimization Design of a Intelligent Programmable Controller Based on CFD Software

With the increasing functionality of intelligent programmable controllers and the continuous improvement in power and component density, the problem of rapidly rising temperatures during operation has become increasingly prominent, directly affecting the controller's lifespan and stability[1]. Therefore, improving the heat dissipation efficiency of intelligent programmable controller modules has become a key focus of research. This paper introduces a method of installing aluminum alloy heat sinks on the core chip of the controller and carefully designing the fin shape and size of the heat sink to enhance heat conduction and heat convection effects, improving heat dissipation performance. This paper also constructs a thermal equivalent model of the controller and simulates the impact of different fin parameters on heat dissipation performance. Experimental results show that when the fin height is 5 millimeters, thickness is 2 millimeters, and spacing is 4 millimeters, the heat sink exhibits the highest thermal conductivity and the lowest thermal resistance, achieving optimal heat dissipation effectiveness.

Flow Patterns in Two Nanorefrigerants R600a/CuO and R410A/CuO During the Boiling Process

The present study aims to know the flow patterns in two nanorefrigerants R600a / CuO and R410A / CuO throughout the forced boiling process in horizontal square pipes. Those are obtained using the thermophysical properties of the refrigerants R600a and R410A in state liquid and vapor, as well as the properties of the CuO nanoparticles. The analysis was carried out using two methods: analytical and numerical. The analytical method was established by formulas and correlations through scientific articles and books to find an improvement in the two-phase heat transfer, under the conditions at an inlet temperature of 8 ° C and with a quality range of 0 to 1. This allowed to verify that by adding nanoparticles to the refrigerant, the transition between the flow regimes increases progressively, while the quality of the vapor decreases. For the numerical method, the different transition limits are specified in a simulation process in the Ansys Fluent CFD Software, under established design conditions, which consequently increases the general efficiency of any refrigeration system.

Internet of things temperature control of indirect dual tank heat storage system in solar photo-thermal power plant

In order to study the temperature control of the IoT for indirect dual tank heat storage systems in solar thermal power plants, the author proposes a refined design method for heat storage systems. Through CFD software FLUENT analysis, the author proposes a temperature control scheme for storage tanks in solar thermal power plants and applies this method to the temperature control and salt injection processes of actual commercial power plants. The refined design of a systematic heat storage system mainly involves precise calculation of molten salt content and refined analysis of overall and local stresses in the storage tank. For molten salt storage tanks with a diameter of about 30 m, every 1 cm of liquid level design error will result in economic losses of tens of thousands of Yuan. In addition, the design process of storage tanks should fully consider temperature control, salt injection, and some special operating conditions during operation. By numerically simulating the flow process of flue gas and molten salt in the storage tank and the real-time wall temperature of the storage tank, a temperature control scheme that does not exceed the maximum allowable wall temperature difference of the storage tank is obtained to reduce thermal stress during the temperature control process of the storage tank, reduce the risk and failure rate of the storage tank. The temperature control scheme has achieved good results in practical projects.

Implementation of a New Actuator Disk Model based on BEM Theory in SU2 CFD SOFTWARE

Implementation of a New Actuator Disk Model based on BEM Theory in SU2 CFD SOFTWARE

Validation of Smagorinsky LES turbulence model in FluidX3D LBM: In-place vs central difference

Lattice Boltzmann method (LBM) has been rapidly developing as a CFD approach throughout the last three decades. The rise of new computational architectures like GPU in the last decade pawed the way to emergence of high-performance CFD software based on this method. The most outstanding of such is FluidX3D, utilizing locality of algorithm operations in connection with massive parallelism of GPU. High performance and memory efficiency of this software make it a promising idea to apply FluidX3D to challenging CFD problems, like turbulence simulation. In this work an effort is put into validation of Smagorinsky LES turbulence model implemented in this software. In addition, direct central difference implementation of this model is added to verify existing approach. The validation is done on the turbulent plane channel flow at Reτ = 180. Reasonable agreement between two LES model results was obtained. The convergence of LES profiles to DNS profiles with sufficient resolution proves correctness of implemented model.