Computational Fluid Dynamics ANSYS Research Articles

Review on Condenser Heat Transfer of Computational FluidDynamic System Using ANSYS

Condenser is a high pressure side heat exchanger in which heated vapor enters and gets converted into liquid form by condensation process. In the condenser coil, gaseous substance is condensed into liquid by transferring latent heat content present in it to the surrounding. In the whole process, mode of heat transfer is conduction in condenser coil and forced convection between refrigerant and condenser. Any refrigeration system's backbone is comprised of condensers. It aids in the transfer of heat from the refrigerant to the universal sink, which is the atmosphere. The latent heat of the refrigerant is lost in the condenser. At the entry of the condenser, vapours from the compressor enter, and during the length of the condenser, the vapours are converted to liquid form, resulting in refrigerant in the form of saturated or even sub-cooled liquid form at the condenser's exit. In several sectors of chemical and petroleum engineering, computational fluid dynamics (CFD) is a common tool for simulating flow systems. As a branch of fluid mechanics, computational fluid dynamics (CFD) is an appropriate tool for investigating and modelling the ANSYS Program. The applicability of CFD studies for simulating the ANSYS Program was reviewed in this work. Ansys CFD is one of the industry's most powerful simulation packages

Constructal design of two-phase stacked microchannel heat exchangers for cooling at high heat flux

Constructal design of high heat flux two-stacked horizontal microchannel heat sinks are presented for cooling of electronic devices. Using ANSYS Computational Fluid Dynamics (CFD) code for subcooled nucleate boiling, fixed volume constraints were invoked for the heat sinks and microchannels to achieve optimal flow velocities and pressure drops at global minimum thermal resistances of the microchannel heat sinks; this is in line with constructal design principle. Validation of the CFD code was done by comparing its results with those of experimental data in the open literature. The closeness of the two results showed the CFD code to be accurate in predicting subcooled flow boiling for cooling of microelectronic devices. Heat fluxes of 1100 and 1200 W/cm2 (1.1 × 107 W/m2 and 1.2 × 107 W/m2) were used in the simulations and optimizations. The thermal resistance, pumping power and Bejan number were based on microchannels that an optimal heat sink of 1 cm width could accommodate. The thermal resistances and base temperatures for optimal microchannel heat sinks at these high heat fluxes (the focus of the study) are low; the pumping power requirements are also low, which show that they are useable in the cooling of electronic devices and other similar applications. Also, this is an indication that optimal two-stacked microchannel heat sinks operating in subcooled flow boiling could be considered as a viable alternative in the cooling of electronics. Optimal two-stacked microchannel heat sink operating at 1200 W/cm2 and in counterflow and parallel flow arrangements, was used for the critical heat flux study and the results show that both have good CHF performance, although counterflow arrangement was better.

Design of Fixed-Wing and Multi-Copter Hybrid Drone System for Human Body Temperature Measurement during COVID-19 Pandemic

The purpose of this research is to conduct aerodynamics study and design a hybrid drone system of fixed-wing and multi-copter. The mission of this drone is to measure human body temperature during COVID19 pandemic. The specific aim of the drone is to fly and cover larger industrial areas roughly about 50 km2 with longer flying time than the conventional drone, of about 1.5 hours. The applications of the simulation software such as XFLR5 and ANSYS have a big impact in identifying areas that need to be improved for the drone system. XFLR5 software was used to compare the characteristics of different airfoils with highest lift over drag, L/D ratio. Based on the airfoil selection, it was found that NACA 4412 airfoil produces the highest L/D ratio. The detailed geometry of the drone system includes a fuselage length of 1.9 meters and wingspan of 2 meters. Moreover, 10 sheets of solar panels were placed along the wing for sustainable flight operation to cover wider areas of mission. The structural analysis was done on ANSYS to test the elastic stress, equivalent strain, deformation, factor of safety pressure as well as lift and drag forces under various operational conditions and payloads. The landing gear was analyzed for harsh landing. ANSYS Computational Fluid Dynamics (CFD) was utilized to study the aerodynamics of the drone at different parameters such as the velocities and angles of attack during the operation. This design ensures the stability of the drone during the temperature measurement phase. The best thermal-imaging camera for such purpose would be the Vue Pro R 336, 45° radiometric drone thermal camera with a resolution of 640 x 512 pixels. This camera has the advantage of a permanent continuous out focus that give the ability of taking measurements even if there was changing on the altitude or any kind of vibrations.

An Overview of Hybrid RANS–LES Models Developed for Industrial CFD

An overview of scale-resolving simulation (SRS) methods used in ANSYS Computational Fluid Dynamics (CFD) software is provided. The main challenges, especially when computing boundary layers in large eddy simulation (LES) mode, will be discussed. The different strategies for handling wall-bound flows using combinations of RANS and LES models will be explained, along with some specific application examples. It will be demonstrated that the stress-blended eddy simulation (SBES) approach is optimal for applications with a mix of boundary layers and free shear flows due to its low cost and its ability to handle boundary layers in both RANS and wall-modeled LES (WMLES) modes.

Simulation of Thermal Dispersion in Location of Development of Diesel Power Plant Using Computational Fluid Dynamics Methods

Electrical energy is one of the important energy needs in human life. To meet the electricity needs in the North Maluku area, it was planned to build a diesel power plant (PLTD) in the coastal area of Halmahera. In the activity of the power plant, it produces heat wastewater from the rest of the radiator cooling process. This study, conducted a numerical simulation to determine the thermal dispersion pattern of waste heat from PLTD cooling water in Halmahera waters. Modeling the dispersion of heat waste temperature of PLTD cooling water is carried out using the Ansys CFD (Computational Fluid Dynamics) method in 3D. The input data are in the form of heat water discharge of 4,000 tons/hour, with heat wastewater temperature 37.5 °C. Ambient seawater temperature is 30.5 °C and seawater density is 1022 kg/m3. Hydrodynamic modeling of oceanic currents is modeled with two variations, namely constant current of 0.4 m/s and UDF current. UDF currents have different current values for each depth with a current velocity of 0.005 m/s up to 0.4 m/s. The simulated results of a constant current show the spread of heat to the environment occurs as far as 210 m to the north of the discharge outlet. The highest temperature value is 37.14°C, the lowest is 30.8°C. For these UDF current models, the heat spread is 210 m to the north of the discharge outlet with the highest temperature value is 37.13°C the lowest is 30.61°C.

Thermoelectric generator (TEG) technologies and applications

• The state-of-the-art of thermoelectric generators is reviewed comprehensively. • The materials used in TEGs, Figure of Merit, improvement techniques are introduced. • Different configurations of experimental set-ups and prototypes are explored. • The performance of TEGs is investigated with different simulation software packages. Nowadays humans are facing difficult issues, such as increasing power costs, environmental pollution and global warming. In order to reduce their consequences, scientists are concentrating on improving power generators focused on energy harvesting. Thermoelectric generators (TEGs) have demonstrated their capacity to transform thermal energy directly into electric power through the Seebeck effect. Due to the unique advantages they present, thermoelectric systems have emerged during the last decade as a promising alternative among other technologies for green power production. In this regard, thermoelectric device output prediction is important both for determining the future use of this new technology and for specifying the key design parameters of thermoelectric generators and systems. Moreover, TEGs are environmentally safe, work quietly as they do not include mechanical mechanisms or rotating elements and can be manufactured on a broad variety of substrates such as silicon, polymers and ceramics. In addition, TEGs are position-independent, have a long working life and are ideal for bulk and compact applications. Furthermore, Thermoelectric generators have been found as a viable solution for direct generation of electricity from waste heat in industrial processes. This paper presents in-depth analysis of TEGs, beginning with a comprehensive overview of their working principles such as the Seebeck effect, the Peltier effect, the Thomson effect and Joule heating with their applications, materials used, Figure of Merit, improvement techniques including different thermoelectric material arrangements and technologies used and substrate types. Moreover, performance simulation examples such as COMSOL Multiphysics and ANSYS-Computational Fluid Dynamics are investigated.

Comparison between Model Test and Three CFD Studies for a Benchmark Container Ship

An alternative to experiments is the use of numerical model tests, where the performances of ships can be evaluated entirely by computer simulations. In this paper, the free surface viscous flow around a bare hull model is simulated with three Computational Fluid Dynamics (CFD) software packages (FINE Marine, ANSYS CFD and SHIPFLOW) and compared to the results obtained during the experimental tests. The bare hull model studied is the Duisburg Test Case (DTC), developed at the Institute of Ship Technology, Ocean Engineering and Transport Systems (ISMT) for benchmarking and validation of the numerical methods. Hull geometry and model test results of resistance, conducted in the experimental facility at SVA Postdam, Nietzschmann, in 2010, are publicly available. A comparative analysis of the numerical approach and experimental results is performed, related to the numerical simulation of the free surface viscous flow around a typical container ship. Further, a comparative analysis between the results provided by NUMECA, ANSYS and SHIPFLOW is performed. Regarding the solution obtained, a satisfactory agreement between the towing test results and the computation results can be noticed. The minimum mean error was obtained through the SHIPFLOW case, 2.011%, which proved the best solution for the case studied.

Numerical investigation of the effect of triangle strut in vertical axis wind turbine (VAWT)

Strut is used in vertical axis wind turbine (VAWT) to restraint the framework. In this study, struts are analyzed to show the pressure losses in VAWT. ANSYS computational fluid dynamics (CFD) software is used to investigate triangle strut in VAWT. This study aims to show a CFD simulation of struts, which affects the aerodynamic of VAWT. In CFD software, the aerodynamic of VAWT can be analyzed in terms of pressure losses in the struts. The simulation method starts by making a struts model, then meshing and setting up ANSYS's boundary conditions. The last iteration runs in ANSYS until convergence. Our results show the percentage of pressure losses with the variation of the angle of wind 0°, 20°, 40°, and 60° are 0.67 %, 0.52 %, 0.48 %, and 0.52 %. The effect of triangle strut in VAWT did not affect the wind flow to the VAWT blade. The results also indicated that the triangle strut could be applied in the multi-stage of VAWT system.

Assessing the Horizontal Homogeneity of the Atmospheric Boundary Layer (HHABL) Profile Using Different CFD Software

One of the main factors affecting the reliability of computational fluid dynamics (CFD) simulations for the urban environment is the Horizontal Homogeneity of the Atmospheric Boundary Layer (HHABL) profile—meaning the vertical profiles of the mean streamwise velocity, the turbulent kinetic energy, and dissipation rate are maintained throughout the streamwise direction of the computational domain. This paper investigates the preservation of the HHABL profile using three different commercial CFD codes—the ANSYS Fluent, the ANSYS CFD, and the Siemens STAR-CCM+ software. Three different cases were considered, identified by their different inlet conditions for the inlet velocity, turbulent kinetic energy, and dissipation rate profiles. Simulations were carried out using the RANS k-ε turbulence model. Slight variations in the eddy viscosity models, as well as in the wall boundary conditions, were identified in the different software, with the standard wall function with roughness being implemented in the Fluent applications, the scalable wall function with roughness in the CFX applications, and the blended wall function option in the STAR-CCM+ simulations. There was a slight difference in the meshing approach in the three different software, with a prism-layer option in the STAR-CCM+ software, which allowed a finer mesh near the wall/ground boundary. The results show all three software are able to preserve the horizontal homogeneity of the ABL—less than 0.5% difference between the software—indicating very similar degrees of accuracy.

Analysis of a Battery Pack with a Phase Change Material for the Extreme Temperature Conditions of an Electrical Vehicle

Thermal management in an electric vehicle is important to extend the life of the battery. This paper is about modelling and analysis of a 6-kW battery module for improving the thermal performance of the lithium ion battery in electric vehicles with PCMs (phase change materials). For a battery thermal management system, we considered phase change materials such as RT15 (Rubitherm15), RT31, EG5 (Expanded Graphite5), and EG26 PCMs with different thermal properties. The ambient temperature conditions range considered was over 40 °C and below −10 °C, also tested on the hot and cool soaking conditions. The lithium polymer pouch single battery was designed and simulation analysis was performed with and without PCMs to enhance heat transfer rate. The simulation and experiment results on a single battery were satisfied to control the battery temperature within the safe operating conditions. Hence the proposed battery thermal management system (BTMS) was applied on a 6-kW battery pack. The design of the battery module was done in AUTOCAD and analysis was done in ANSYS CFD (computational fluid dynamics) software tool.

Design and development of small wind turbine for power generation through high velocity exhaust air

Large scale wind turbines have been extensively examined for decades, but a very few studies have been conducted on small-scale wind turbines especially for the applications where artificial wind speed is of the order of 15 m per second. This study provides systematic effort towards design and development of small scale wind turbine aimed to operate at high wind speeds. The drag-based wind turbine has an enormous potential for small-scale power generation in cement manufacturing plant. It uses bag filter to prevent environmental pollution so as to let out the clean high velocity exhaust air through the duct. The work reported here presents to utilize exhaust air for electrical power generation. Exhaust air flow has been analysed in Ansys Fluent Software. Ansys Computational Fluid Dynamics (CFD) technology was adopted to evaluate the performance of the wind turbine. The results of torque assessment of the wind turbine in its static as well as dynamic condition have been presented. Experimental setup consisting turbine, generator, battery and load has been tested and validated.

Comparison of low wind speed aerodynamics of unsymmetrical blade H-Darrieus rotors-blade camber and curvature signatures for performance improvement

Unsymmetrical blade Vertical axis wind turbine (VAWT) can be nicely adapted in the built environment because of its improved performance, self-starting ability, simple construction, easy maintenance and capability to adapt to wind direction changes. For proliferation of such VAWT installations, the challenge is to improve its efficiency in low wind speed condition (usually less than 10 m/s) of the built environment, which depends on its blade profile design. In an unsymmetrical blade, blade thickness-to-chord ratio, percentage camber, blade curvature around aerodynamic moment center are the controlling parameters for effective blade-fluid interactions for performance improvement, thus requiring a detailed investigation of the aerodynamics of unsymmetrical blade VAWT. The objective of this paper is to compare low wind speed aerodynamics of two different unsymmetrical airfoil blade profiles to obtain design information of blade camber and blade curvature around aerodynamic moment center for performance improvement of H-Darrieus VAWT, which is hardly available in the existing literature. Detailed blade-fluid interactions are analysed by Ansys Computational Fluid Dynamics (CFD) software for different low wind speeds between 4 m/s and 8 m/s. It is found that more rounded curvature of the suction side surface of advancing S815 blade around aerodynamic moment center and thicker blade profile (maximum thickness is 26.2% at 25.7% chord) has a distinct influence for performance improvement of the rotor in the power stroke. In the returning stroke, the VAWT is benefited from higher camber of EN0005 blade (maximum camber percentage of 10% at 55% chord) and lesser blade curvature of the blade suction side. Next, vorticity structures of each blade profile have also been monitored at different azimuthal positions and necessary performance insights with regards the development of static/deep stall vortices and other boundary layer features have been drawn. Further, blade polars, power performance, and blade loading have also been obtained and compared with published results. Overall better designs of unsymmetrical blade profiles have also been recommended. The present study leads to the understanding of the design blade camber and curvature signatures in both power and returning strokes for possible performance improvement of small-sized VAWT in low wind speed condition.

Experimental and CFD analyses of corrugated-plate solar collector by force convection

ABSTRACTSolar energy is the best among all renewable energy sources owing to its low effective cost and eco-friendly character. In this study, the header and riser pipe design is studied using an absorber plate and the outlet water temperature of a corrugated-plate solar collector (CPSC). The CPSC is affected by different working parameters, such as atmospheric temperature, inlet and outlet water temperatures, solar radiation, and wind speed. Two mass flow rates (0.0167 kg/s and 0.025 kg/s) have been used in this paper. Outlet water temperatures of up to 56° and 48.5° could be easily obtained by the CPSC for mass flow rates of 0.0167 kg/s and 0.025 kg/s, respectively. The heat transfer and fluid flow analyses in a CPSC using experimental and CFD ANSYS 17.2 models have been presented in this work. It is established that experimental and computational fluid dynamics (CFD) results give good agreement.

Study on deepwater conductor jet excavation mechanism in cohesive soil

Conductor casing jetting technique has been increasingly applied in deepwater drilling. The insight into the jetting excavation mechanisms is critical in guiding a successful conductor casing jetting operation. The real- time continuous jet excavation process is simulated with the volume of fluid (VOF) multiphase method of CFD (Computational Fluid Dynamics) ANSYS Fluent calculation software in the current study. The cohesive soil is modelled by using a kind of viscous fluid with Herschel-Bulkley model. In addition, a laboratory half round nozzle jet excavation test is designed for verification by comparison of the observed jet excavation profile with the numerical results. The sensitivity parameters affecting the conductor jetting excavation mechanism in cohesive soil are thus investigated. It is found that the application of Herschel-Bulkley (HB) model for cohesive soil and the VOF method of Fluent can provide a good simulation of jet excavation process. The maximum excavation depth can be determined by the undrained ultimate bearing capacity of the circular foundation with a bearing capacity factor of 6.7. The nozzle position, jet velocity and soil strength have significantly influence on the depth and width of the jet excavation profile in conductor oblique jet.

Моделирование дефекта внутренней поверхности струйного кавитатор

Introduction. The investigation of the hydrodynamic cavitator operation used under the erosion impact on a solid body surface, and of the device structure optimization for increasing the damage capability of the cavitating jet is presented. The effect of a sporadic defect of the combined nozzle inside on the volume fraction of the vapor content and the cavitation region geometry is considered. The work objective is to identify the influence pattern of the inside defect of cavitators of various sizes on the hydrodynamic and cavitational characteristics of the nozzle through numerical modeling. Materials and Methods. The features of the ANSYS Workbench finite-element analysis software package and the integrated optimization module of the development and design process in the domain of the computational fluid dynamics ANSYS CFX are used. The simulation is based on the experimental data obtained under the nozzle water discharge at a specially designed laboratory bench under the cavitation condition. Research Results . Graphic dependences of the volume fraction of the vapor content, total pressure and thelength of the cavitation region on the distance along the axis of the jet for different defect sizes are obtained and presented. Two phases of the cavitating jet flow in a nonideal cavitator are identified, and the transition effect on the velocity distribution in the device section is shown. Discussion and Conclusions. The occurrence of an internal defect on the surface of the conical pattern of a combined nozzle with the size of less than a quarter-diameter of the central cylindrical portion may not cause visual changes in the cavitation region geometry, but it significantly reduces the erosive capacity of the cavitation jet. A further defect increase results in a total suppression of the cavitation flow, but maintains its dynamic behavior. The obtained results contribute to the improvement of the hydrodynamic cavitators design, to the enhancement of their erosive impact with the use of cavitation for cleaning underwater structures and mechanisms.

Comparison of STAR-CCM+ and ANSYS Fluent for simulating indoor airflows

Suitable air distributions are essential for creating thermally comfortable and healthy conditions in indoor spaces. Computational fluid dynamics (CFD) is widely used to predict air distributions. This study systematically assessed the performance of the two most popular CFD programs, STAR-CCM+ and ANSYS Fluent, in predicting air distributions. The assessment used the same meshes and thermo-fluid boundary conditions for several types of airflow found in indoor spaces, and experimental data from the literature. The programs were compared in terms of grid-independent solutions; turbulent viscosity calculations; heat transfer coefficients as determined by wall functions; and complex flow with complicated boundary conditions. The two programs produced almost the same results with similar computing effort, although ANSYS Fluent seemed slightly better in some aspects.

Simulation of single phase non-Newtonian flow characteristics of heavy crude oil through horizontal pipelines

ABSTRACTThe effect of diameter, velocity, and temperature on flow properties of heavy crude oil in three horizontal pipelines using computational fluid dynamics (CFD) was studied. The flow characteristics were simulated by using CFD software, ANSYS Fluent 6.2. The mesh geometry of the pipelines having inner diameter of 1, 1.5, and 2 inch were created by using Gambit 2.4.6. From grid independent study, 221, 365 mesh sizes were selected for simulation. The CFD ANSYS Fluent 6.2 Solver predicted the flow phenomena, pressure, pressure drop, wall shear stress, shear strain rate, and friction factor. A good agreement between experimental and CFD simulated values was obtained.

Performance improvement of an oil pump: Design of port assembled with gerotor (2-ellipses-combined lobe)

An internal gerotor pump is used to enhance the oil hydraulics of machine tools, automotive engines and compressor. In particular, this type of pump is used to supply lubricants in an automotive engine. Recently, improvements in automobile fuel efficiency and the reduction of noise have become critical issues. Thus, gerotor internal oil pumps have been studied for high flow rate and low noise through designs of multiple combined lobe shapes. In this study, in order to address the problems of existing oil pumps, design of a new lobe shape with 2-ellipses was developed in order to decrease a sharp change of curvature. Performance parameters of an improved gerotor (2-ellipses) were calculated and compared with those of the existing gerotor (circle and 3-ellipses). Also, we performed a computational fluid dynamics (CFD) analysis of an oil pump with the improved gerotor 2-ellipses-combined lobe shape. By using the commercial software ANSYS CFD, geometric parameters relating to the port shape, which affect the performance of flow rate and irregularity, were investigated. A re-design of the port shape was performed in order to improve fuel efficiency and reduce the noise of the oil pump.

Comparison of numerical simulation and experimental study on indoor air quality of air-conditioned office building in desert climate

This paper is a study of the air temperature distribution of an air-conditioned office room equipped with a double-glazed window in a desert climate. The study includes both experimental and theoretical works using a computational fluid dynamics (CFD) simulation program. The experimental results were compared with the CFD program results. The commercial computational fluid dynamics ANSYS CFD V.13.0, solver FLUENT software, and three-dimensional flow finite difference of k-e for analysis and validation experimental work were used. The main objective of the study is to evaluate the temperature difference between the outdoor and indoor environments, as well as the distribution of air temperature in the room. The computational results for internal air temperatures of the office ranged from 23°C to 26°C, while the airflow velocity was low at less than 0.3 m/s. The temperature differences between the indoor and outdoor spaces varied between 9 °C and 15 °C. Good agreement was achieved between the computed and measured temperature results. The error percentage varied from 0.3% to 0.8%. The experimental and numerical results showed that well-designed double glazing can reduce the emission of sunshine and heat inside desert buildings, even using the northeastern facade, in sunny climates.

Study on Wing Aspect Ratio on the Performance of a Gliding Robotic Fish

In this paper, the performance of a gliding robotic fish with different wing aspect ratio is investigated. The gliding robotic fish, developed by Michigan State University, has the energy efficient locomotion of an underwater glider and high maneuverability of a robotic fish. ANSYS Computational Fluid Dynamics turbulence model was used to determine lift and drag coefficients for various wing aspect ratios at different angle of attack. Subsequently, the corresponding glide angle and velocity were determined analytically based on its dynamic model. The simulation results compare well with published experimental data and shows that the drag and lift coefficients are inversely proportional to the wing aspect ratio. As such, a gliding robotic fish with a low wing aspect ratio is suitable for shallow waters only, due to the high lift forces generated for a given angle of attack, requiring greater energy to sustain the glide velocity and vice versa.