CFX Simulation Research Articles

Numerical and experimental study of homogenization mechanism of high shear rotor‐stator mixer

AbstractUtilizing computational fluid dynamics (CFD) for analytical purposes, this study developed a fundamental model employing the multiple reference frame (MRF) method, facilitated by the CFX simulation platform. The investigation conducted numerical simulations of the flow field within the rotor‐stator assembly of a high shear mixer, guided by the Navier–Stokes equations and the standard k‐ε turbulence model. To quantify the homogenization efficacy of the high shear mixer under scenarios with and without energy consumption considerations, the study introduced two distinct parameters: the mixing index (γ) and the energy ratio mixing index (λ). The impact of structural parameters such as the number of rotor‐stator teeth, radial clearance, and tooth apex‐base axial clearance on the local flow characteristics—velocity, pressure, turbulent kinetic energy, shear rate distribution, net power consumption, and the specified indices—was meticulously analyzed. This analysis aimed to identify the optimal structural configurations for the mixer, considering energy efficiency and mixing effectiveness, and to determine the relative influence of these structural variations on the mixing index (γ) and the energy ratio mixing index (λ).

Design and Development of Power Generation System for Thermo-Acoustically Driven Devices

This paper explores the emerging field of thermo-acoustic devices, specifically focusing on developing robust bidirectional turbines. Amidst growing concerns about climate change, rising energy demands, and the urgent need for alternative solutions, the study highlights the underexplored domain of bidirectional turbines within thermo-acoustic systems, offering a crucial pathway toward cleaner and more sustainable technologies, thereby providing commercialization potential. It identifies a significant gap in dedicated investigations regarding the interaction, efficiency, and challenges associated with bidirectional turbines and adopts a comprehensive methodology integrating analytical modelling, computational fluid dynamics simulations, and practical experimentation. An axial bidirectional turbine is carefully selected, designed, and optimized using advanced tools such as MATLAB R2016a and CAD software, including PTC Creo 5.0 and Solidworks 2023. The validity of the CAD model is verified through ANSYS 16.2 CFX simulations, followed by experimental validation to corroborate and enhance theoretical insights. The conclusions drawn from this study offer valuable recommendations for further research and practical implementations.

Modeling of heat exchangers in ANSYS CFX for the digital twins development

The paper presents a universal methodology for modeling and optimization of shell-and-tube heat exchanger designs using the ANSYS CFX software package. Mathematical modeling plays a key role in the design and modernization of heat and mass transfer equipment, especially in the petrochemical and oil and gas processing industries, and especially in the creation of digital twins of heat and mass transfer equipment. The modern approach provides prediction of equipment behavior at the development stage, which makes it possible to take into account the peculiarities of the actual geometry of the apparatuses and optimize the interaction of contacting phases. The paper considers the stages of creating a digital model of a heat exchanger, including the construction of an electronic geometric model, creation of a computational grid, selection of mathematical models of hydrodynamics and heat transfer, as well as the setting of boundary conditions and solver parameters. Special attention is paid to the selection of heat transfer and turbulence models suitable for high Reynolds numbers. The results of numerical simulation in ANSYS CFX are compared with analytical solutions and data obtained with ANSYS Fluent. The difference in the results was about 1 °C, which confirms the high accuracy and reliability of the proposed methodology. This indicates the feasibility of using ANSYS CFX for modeling and optimization of technological equipment. The obtained results can be applied to build a digital twin model, to improve the efficiency of heat transfer processes, to reduce the cost of development and modernization of equipment, as well as in further research on the intensification of heat and mass transfer using digital models.

Experimental and Numerical Investigation of Combustion and Noise, Vibrations, and Harshness Emissions in a Drone Jet Engine Fueled with Synthetic Paraffinic Kerosene

<div>Emissions and effects of climate change have prompted study into fuels that reduce global dependence on traditional fuels. This study seeks to investigate engine performance, thermochemical properties, emissions, and perform NVH analysis of Jet-A and S8 using a single-stage turbojet engine at three engine speeds. Experimental Jet-A results were used to validate a CFX simulation of the engine. Engine performance was quantified using thermocouples, pressure sensors, tachometers, flow meters, and load cells fitted to the engine. Emissions results were collected using an MKS Multigas Emissions Analyzer that examined CO, CO₂, H₂O, NOx, and THC. NVH analysis was conducted using a multifield, free-field microphone, and triaxial accelerometer. This study found that Jet-A operates at higher temperatures and pressures than S8, and S8 requires higher fuel flow rates than Jet-A, leading to poorer efficiency and thrust. S8 produced stronger vibrations over 5 kHz compared to Jet-A. S8 showed a decrease in all measured emissions. The CFD model was validated, showing an increase in temperature, pressure, and gas velocity as speed increased. The swirl effect of combustion was examined, improving atomization. Emissions contours were validated by experimental results, showing increases in CO₂, H₂O, and NOx, and a decrease in CO as speed increases.</div>

Influence of macro-roughness on the leading edge of the plate on hydrodynamic losses

The paper presents research into the effects of macro-roughness on the leading edge of the plate imitating excrescences on the fins of humpback whales on the value of hydrodynamic losses. The authors compare calculations with experimental results obtained on a hydrodynamic flume. All studies are performed using the Ansys CFX and Autodesk CFD computer simulation packages. Based on the obtained findings, the authors make conclusions on the feasibility of applying macro-roughening on the leading edge of the plate. The conducted computational and experimental research demonstrates the positive effects of a certain configuration of spherical macro-roughness on the hydrodynamic characteristics of the plate in the case of spillage in an open-type hydrodynamic flume.

МОДЕЛИРОВАНИЕ ПРОЦЕССОВ ТЕПЛООБМЕНА ВНУТРИ ГЕРМЕТИЧНОГО КОРПУСА БИНС В МУЛЬТИФИЗИЧНОЙ ПОСТАНОВКЕ В ANSYS CFX И SYSTEM COUPLING

The article presents a numerical simulation of non-stationary convective-conductive heattransfer of the strapdown inertial navigation system (SINS), developed in the JSC «CNIIAG».The numerical simulation is carried out in the ANSYS Mechanical. The aim of the study is a comprehensiveanalysis of heat exchange processes, which are characteristic to the device operation,including mutual spatial influence of thermal powers on each other, as well as on the block ofsensitive elements. The simulation of heat transfer inside the hermetic case of the SINS is carried out for critical operating conditions in a strongly and weakly coupled consideration with a comparisonof both approaches. ANSYS Mechanical, CFX and System Coupling simulation modulesare chosen for program implementation of each approach. The k-e model of air turbulence withimplicit consideration of the effect in the boundary layers and diffusion correction in shear flows ischosen for this approach. External heat exchange with ambient air is considered by setting convectiveboundary conditions on the external surfaces of the SINS, considering their orientation.To obtain numerical values of the heat transfer coefficients, the orientation of each surface inspace is taken into account by using the appropriate coefficient. The presence of irregularities onthe surfaces of the SINS in the contacts between solid components is considered by using the calculationof thermal resistances of the actual contact and intercontact layer. The simulation resultsof deformed state of SINS structural system, resulting from the action of a non-symmetric thermalfield, is presented. The analysis of the obtained graphs is carried out. Stiffness indicators of theSINS structural system is defined as angles of deviation of sensitivity axes caused by thermal deformations.The obtained results make it possible to evaluate the engineering solutions for thequality of heat removal from the elements of the PCBs, bypassing the sensitive elements of thedevice, adopted at the stage of product layout.

Influence of Internal Flow on the Performance of High-Speed Centrifugal Pumps with a Fully Sealed Structure

A high-speed centrifugal pump with a fully sealed structure has the advantages of a small size, no external leakage, and being pollution-free. The inner leakage passage of a pump with a fully sealed structure includes the tip clearance and the hub clearance. The hub clearance, the lubrication passage of the bearing, and the clearance between the stator and the rotor of the built-in motor constitute the internal flow channel. As a consequence of hub leakage, the complexity of the flow field increases and performance of the pump is affected. However, hub leakage also lubricates the bearing and cools the motor by flowing through the internal flow channel. To obtain the actual flow field distribution and external characteristics of the pump, a coupling calculation based on a conventional CFX simulation and MATLAB was carried out. The results show that hub leakage promotes an increase in tip leakage and changes the distribution of the main flow field. Moreover, hub leakage also significantly affects the efficiency of the pump. Compared with hub leakage, the internal flow has a greater impact on the performance of the pump. The numerical simulation results of the internal flow model are similar to the experimental results, with the maximum absolute error of the head at 0.3 m and the maximum absolute error of the efficiency at 1.7%, indicating that the internal flow model is effective at predicting the performance of the high-speed centrifugal pump with a fully sealed structure.

МЕТОД УЛУЧШЕНИЯ АНАЛИТИЧЕСКИХ РЕЗУЛЬТАТОВ ДЛЯ ВРАЩАЮЩЕЙСЯ ЛОПАСТИ В СРАВНЕНИИ С ПРЯМЫМ ЧИСЛЕННЫМ РАСЧЕТОМ

The paper proposes an analytical method for calculating the value of the driving force of a thin rotating plate. The classical approach represents the plate as a set of plane problems corresponding to the section of the blade. The theory of a thin wing describes the translational motion of the plate. Unlike them, the proposed method allows us to consider a rotating thin plate as a whole. A two-dimensional integral equation permitting to describe a plate of any shape and twist is obtained. The singular terms of the obtained equation qualitatively correspond to the singular terms of the classical equation for the translational motion of the thin plate, and additional regular terms are responsible for the rotational character of the motion. A numerical experiment of rotating thin plate was performed in the ANSYS CFX simulation software. The results of the numerical experiment are compared with the data obtained by the classical method of the plane problem and the proposed analytical method. The proposed method permits reducing the deviation of the draft value obtained analytically from the value obtained numerically by three times – from 200 to 75 %.

Solar chimney street-lighting pole for ventilating polluted urban areas

The increasing air pollution in built environment streets represents a serious health hazard, particularly for pedestrians. This paper presents a novel design of a solar chimney street-lighting pole (SCSLP) that guides away polluted air from the near-surface space to an upper space in street environments. The proposed system creates an updraft air movement through the convection of air heated by passive solar energy gained from the wall and solar collectors of the SCSLP. The current study investigated the performance of the proposed system through ANSYS CFX simulation (SIM) capabilities. The airflow rates and other relevant parameters were calculated and analysed for two selected materials and four geometric configurations of the SCSLP. The results showed that the SCSLP was successful in creating an updraft air movement of 6.970m3/min at 8:35 am on a typical summer day in Riyadh, Saudi Arabia. The performance of the SCSLP was mainly improved by increasing its number of solar collectors, and the thermal conductivity and emissivity of the composed material. The installation of numerous SCSLPs can create a large-scale air ventilation that would drive fresh air from nearby areas to replace the street’s pedestrian-level polluted air, thus providing people with cleaner air to breathe.

Research on Unsteady Characteristics of Pump Turbine in Pumping Mode

A study on the unsteady characteristics of pump turbine in pumping mode was made. Basing on the existing research, this paper is aimed at providing valuable reference for hydraulic design, structure optimization, fault diagnosis of pump turbine. CFX simulation verified by experiment was made to analyze the distribution law and propagation characteristic of pressure and its pulsation in the whole fluid field. Research shows that the pressure pulsation owns different propagation characteristic from the flow velocity pulsation. The pressure pulsation component with guide blade frequency has very special properties in stationary flow passages, while the pressure pulsation component with runner blade passing frequency is absolutely different. Blade constraints have significant effect on the unsteady properties of pressure and flow velocity. Besides, some other analysis was talked about, such as the external characteristics, pressure pulsation near the volute tongue, and so on.

Proposing a solution to reduce heat for control cabinet of self-made CNC milling machine

Today, CNC milling machines appear in almost all areas of production and are widely used in industries. Besides, the CNC controller using LinuxCNC software (LinuxCNC controller) is considered to be quite cheap in price and compact in size. Therefore, it can be widely used to serve the needs of self-manufacturing CNC machines and meet the tastes of the Vietnamese market. During operation, there are many factors that affect the operation of the controller such as temperature and humidity inside the cabinet, Electromagnetic Compatibility (EMC), vibration...etc. Continuous operation for a long time, the release of a large amount of heat due to electrical equipment inside the control cabinet is unavoidable. High ambient temperature inside the control cabinet can affect the stability and responsiveness of the electrical equipment, thereby reducing the accuracy of the CNC machine. The investigation based on experimental measurements will give the best estimates for the cooling option of the switchboard. But such things will take a lot of time, effort and money. By the way, Ansys CFX simulation software is considered a reliable solution to support experimental survey methods. In this paper, first of all, the authors have designed and modeled the electrical cabinet cover and the equipment inside the control cabinet into a 3D model. Then, the authors applied Ansys CFX software to simulate the temperature change inside the control cabinet after applying the cooling methods. The authors propose a solution to limit the high ambient temperature inside the control cabinet and based on the simulation results to evaluate the effectiveness, then select the appropriate method. For small-scale workshops without cooling systems, this survey method can be the right solution. To evaluate the effectiveness of the proposed method to reduce heat, the authors measured and evaluated the position tracking error of the CNC milling machine. Besides, some products have been processed to compare and evaluate the quality. Finally, based on the results obtained in the paper, some conclusions are drawn to verify the effectiveness of this research method.

Идентификация режима работы пропеллера беспилотного летательного аппарата по акустическому сигналу

The paper deals with a special case of identifying the operation mode of an unmanned aircraft (UAV) engine by an acoustic signal (provided that a known type of propellers is used), the main frequency extraction from the signal, and a numerical experiment. A full-scale experiment was performed with the recording of the acoustic signal of a real quadrocopter. The signal is analyzed by the method of frequency filters and Fourier transform. A numerical experiment was performed on a scanned model of a UAV propeller, rotating at a frequency obtained from an acoustic signal. The experiment involved a hybrid finite-volume method on the mesh of the finite element method of the ANSYS CFX simulation environment. The correspondence of the required lifting force with the permissible error is revealed, and as a result, the ability to identify the engine operating mode by an acoustic signal is shown. The field measurements of the acoustic signal are compared with the values recovered from a numerical experiment. A significant amount of data has been obtained suitable for use in the inverse problem and semi-analytic methods.

Design updates and thermo-hydraulic analysis of K-DEMO CS magnets

The K-DEMO superconducting tokamak is being studied for the realization of the fusion plant since 2012. The preliminary design of the conductor of each magnet introduced in 2015 and the design are being updated for solving engineering issues. In the previous study, the K-DEMO CS(Central Solenoid) conductor was modified to reduce the number of the cooling channel. A central cooling spiral was applied to the CS conductor to minimize the pressure drop in a long cooling path and the shape of conductor was changed to square. This design change should guarantee to provide sufficient cooling conditions to reach the full flattop current under a wide range of conditions especially, the selected for the plasma ramp-up sequence development of CS coils. In this study, the updated CS conductor and coil design are presented. A CFX simulation carried out to check the pressure drop condition and a thermo-hydraulic analysis is performed.

Comparison of airfoil performance for 120 cm diameter of LLBC-Based Low Speed Wind Turbine

The development of wind turbine attracts more attention as a renewable energy. Layer Laminated Bamboo Composite (LLBC) is a prospective material for rotor blades of low speed wind turbine. Airfoil S834 is commonly used for blade of low speed wind turbine. But there are other airfoils that can be considered, namely S835, S809 and NACA 0012. This research addresses which airfoil shows the best performance for low speed wind turbine. The blade material for wind turbine is LLBC (Laminated Layer Bamboo Composite) which is combination of Gombong Bamboo and Standard Resin. The blade has incidence angle 16° and twist angle 16°, respectively. The four blade configurations were compared with the standard blade using ANSYS CFX simulation. The simulation was carried out with 7,9 million elements, frozen rotor as model for interface between static mesh and rotated mesh. The simulations resulted that S834 airfoil showed the best performance as indicated by the highest power generated.

3D CFD SIMULATION AND EXPERIMENTAL STUDY OF A WATER JET IMPINGEMENT

To investigate the reaction forces produced by the change in momentum of a water jet, an experimental and computational fluid dynamics (CFD) study are carried out. In the experiment, the water jet forces on a test horizontal hemispherical cup are measured. ANSYS CFX simulation code is used to provide a 3D CFD simulation of a circular cross section water jet released from a nozzle and moves upward in the air before striking a horizontal hemispherical cup and a flat plate. The progress in the CFD simulation within the last decade make it possible to analyze and visualize the flow pattern of complex multiphase free surface fluid flow. The simulated forces of the vertical water jet against a horizontal hemispherical cup using ANSYS CFX code are compared with the experimental forces generated by the water jet as it strikes a hemispherical cup. A good agreement is found in the CFD results compared with the experimental results. 21.649 % was the maximum percent difference recorded at 0.245 kg/sec flowrate and 0.484 % was the minimum percent difference at 0.368 kg/sec flowrate.

Indirect cooling experiment for magnetic alloy-loaded cavity

Indirect cooling method is an alternative scheme for magnetic alloy (MA)-loaded cavity because of the feasible structure and MA core treatment process. Stable and long-term operation is not possible without a powerful cooling system for the high-power MA cavity. The paper reports a method to evaluate the cooling efficiency of an indirect cooling structure for high-power-loss MA cavity. Two types of helix metallic cooling plate were designed and checked by CFX code considering the average power loss more than 0.13 W/cc. In order to enhance the heat-transfer efficiency between the non-flatness surface of the MA core and metallic cooling plate, a filling material with high thermal conductivity is needed. Different commercial filling materials were investigated, and a high-power test bench was developed to assess the cooling efficiency. A parametric fitting method was adopted to qualify the heat-transfer coefficient according to the temperature rising curve. The results indicate that the experimental data maintain good consistency with the CFX simulation results and the cooling structure meets the high-power-loss cooling requirement. The heat-transfer capability of the filling was influenced by the thickness of heat-transfer materials and the painting process. The heat-transfer performance of the thermal grease is better than that of the thermal gasket even though the latter has a higher thermal conductivity. The virtual thermal conductivity of the filling material was less than the product index and affirmed by the CFX transient simulation.

Design and CFD performance analysis of a novel impeller for double suction centrifugal pumps

Abstract Double suction centrifugal pumps are the main devices involved in the feedwater system of nuclear power plants and they are responsible for a significant share of their energy consumption (by affecting the balance of both the gross and net electrical energy production), hence even an efficiency increase of only a few percentage points could be substantial in their economy. Herein a novel impeller designed for low-medium specific speed double suction centrifugal pumps ( n q 60 ) is proposed showing an efficiency improvement with respect to conventional designs in the order of 1–2% associated to a slip factor increase, secondary losses reduction and impeller outflow homogeneity improvement. The novel double suction impeller is characterized by a new arrangement of its flow channels, which come up alternately on the same circumferential exit even if they start from the two different sides. The flow field through the impeller is investigated via numerical simulations run by means of the open source CFD code OpenFOAM and its performance is compared against experimental results. The CFD model set-up, in terms of grid size and discretization schemes, has been previously assessed against results of consolidated CFX simulations on a conventional centrifugal pump.

Combined CFX and Structural Simulation for Bow Thrusters Loading under Operating Conditions

The purpose of this paper is to simulate the bow thrusters loading under operating conditions installed onboard ships. The bow thrusters are specially designed to operate in seawater. In some cases the blades operate in difficult conditions like ice. The software analysis of the bow thrusters events associated to a jammed propeller blade is performed in operation conditions. As a result, it has been identified the forces acting on blades during operation in ice or jammed by objects. Also, we present a result for pressure and speeds acting on the propeller.

Experimental Studies of the Influence of Configuration of Regular Microrelief of Plunger Surface on Sucker-Rod Pump Delivery

The influence of configuration of regular microrelief on leakage of fluid pumped through plunger pair of sucker-rod pump is studied. An experimental unit developed to study fluid leakage through plunger pair is presented. The experimental data and the results of simulation in ANSYS CFX of leakage through plunger pairs with and without microrelief are given. Practical recommendations are offered on the choice of geometric parameters of plunger pair grooves for minimizing leakage.

Cavitating flow analysis and design optimization for a waterjet mixed flow pump

This research investigates cavitation flow simulation and design optimization for a waterjet mixed flow pump whose design flow coefficient is 0.183 and rotational speed is 1450 r/min. Both the hydraulic and cavitation characteristics are predicted and compared with model test. In order to improve the pump performance, an optimized impeller is obtained with the blade thickness reducing by 0.6 mm and adjusting the blade inlet angle. The cavitating flow in a waterjet mixed flow pump is simulated using the SST k-ω turbulence model and homogeneous cavitation model with a single blade-to-blade flow passage. Compared with the experimental results, the numerical data are in reasonable agreement for predicting hydraulic characteristics and show a similar trend in cavitation performance prediction. Future work will focus on improving the cavitation model for better accuracy of cavitation prediction. Based on the experimental test and commercial software CFX simulation, it can be concluded that reducing the blade thickness and inlet angle can have favorite effects on the hydraulic performance as well as cavitation performance.