Computational Fluid Dynamics Turbulence Models Research Articles

Comparative analysis of different CFD turbulence models for a diesel pool combustion event in an underground mine: a case study

ABSTRACT Underground mine fires are dangerous, consume resources, and emit pollutants. Therefore, acquiring in-mine data for fire research is hazardous and expensive due to unsteady temperature changes and toxic gas emissions. Computational fluid dynamics (CFD) models are often developed to mimic airflows and combustion-associated heat transfer. However, research on the performance evaluation of the CFD turbulence models to mimic fire events is limited. This paper summarises the modelling results for a diesel pool fire event in an experimental underground mine that uses an exhaust ventilation system. A fire dynamics simulator (FDS) model was developed to show the spatio-temporal temperature evolution. Reynolds-Averaged Navier-Stokes and large eddy simulation (LES) models were developed using ANSYS Fluent to model species transportation in the transient-state combustion event. LES models showed the closest agreement with the experiments but required the most computing resources. Similar exercises will assist the mine operators in emergency preparedness and in training their safety teams.

Impact of High-Pressure-Turbine Purge Flow on the Evolution of Turbulence in a Turbine Vane Frame

Abstract This paper describes the measurement and postprocessing of turbulence data. The experiments were carried out in a two-stage, two-spool transonic turbine test rig at the Institute for Thermal Turbomachinery and Machine Dynamics at the Graz University of Technology, which includes relevant purge and turbine rotor tip leakage flows. The test setup consists of a high-pressure turbine (HPT) stage, a turbine vane frame (TVF) with turning struts and splitters, and a counter-rotating low-pressure turbine (LPT) to allow engine realistic measurements. Time-resolved area traverse measurements have been performed for three different operating conditions in three measurement planes downstream of the HPT rotor, which enable the measurement of the turbulence quantities at the TVF inlet and outlet as well as the LPT outlet. The turbulence quantities are evaluated using triaxial- and single hot-film probes by means of Constant-Temperature-Anemometry, and their results were validated with five-hole probe (FHP) measurements. Ensemble- and time-averaging, as well as Fourier transforms, were applied for data reduction. It is shown how the turbulence intensity and integral length scale vary over different purge flowrates (PFR). The acquired measurement data illustrate that the interaction of the ejected purge flow with mean flow enhances the turbulent mixing in the secondary flow structures at the TVF inlet and TVF outlet, respectively. Furthermore, the flow downstream of the LPT rotor is affected by TVF and LPT rotor secondary flow structures, which are identified as high turbulence regions. These regions strongly depend on the purge flowrate. These results acquired under engine realistic rig flow conditions enable a deeper understanding of the relationship between loss and turbulence quantities and will help improve the application of computational fluid dynamics turbulence models to turbomachinery modeling.

Assessment of the three-dimensional flow field in the reactor pressure vessel in Hualong One nuclear power plants

This study uses computational fluid dynamics (CFD) to investigate the three-dimensional flow field under normal operating conditions in the reactor pressure vessel (RPV) in the Hualong One nuclear power plants (NPPs). With a particular focus on the flowrate distribution at the core inlet, the numerical framework is validated against the integral hydraulic experiment in a 1:4-scaled RPV of CNP1000, the prototype of the Hualong One reactor. The simulation results of the normalized flowrate at the core inlet agree reasonably well with the measured data. Based on the experimental data, several methods of calibrating the CFD turbulence model coefficients are suggested by introducing the concepts of data assimilation and machine learning. The flow field in a realistic RPV for Hualong One is predicted using the validated numerical framework, showing that the flowrate distribution at the core inlet is nearly homogeneous and that the turbulent intensity is acceptably low for each fuel assembly. It can provide essential information for the reactor core thermal–hydraulic design and the fuel assembly mechanical assessment.

Temperature and Pressure Drop Analysis of Automobile Minichannel Condenser using CFD

Refrigeration and air conditioning plays a vital role in domestic and industrial heating, cooling, refrigerating and ventilation but they are contributing to ozone layer depletion and global warming due to unfriendly refrigerants and consume 33% of the world energy. The condenser is an important component of the vapor compression system which contained 30% of the refrigerant charge. The versatile one ton of refrigeration system is designed, developed for testing minichannel condenser for different condenser temperature and pressure by providing artificial condenser compartment with three air heaters of 2.2 kW capacity each with a multispeed condenser fan for controlling air velocity. Thus, the condensation temperature is reduced by 2 to 3°C due to its special geometry, passes provided, efficient cooling and the coefficient of performance increased by 10 to 15% for condensation temperature varying from 40 to 55°C whereas evaporation temperature varies from -10 to +15°C. Computational Fluid Dynamics (CFD) simulation for different sections of the minichannel condenser such as a single minichannel, single tube with 10 minichannels, first, second, third, fourth passes with varying tubes and entire condenser with all four passes for different inlet and exit temperature are performed using ANSYS FLUENT-20 CFD turbulence models and validated with the experimental results. The pressure and temperature counters for all the sections are studied and plotted. It is found that the temperature difference between experimental and CFD results are within ±15% for all the simulations along the condenser.

Computational Fluid Dynamics Turbulence Model and Experimental Study for a Fontan Cavopulmonary Assist Device.

Head-flow HQ curves for a Fontan cavopulmonary assist device (CPAD) were measured using a blood surrogate in a mock circulatory loop and simulated with various computational fluid dynamics (CFD) models. The tests benchmarked the CFD tools for further enhancement of the CPAD design. Recommended Reynolds-Averaged Navier-Stokes (RANS) CFD approaches for the development of conventional ventricular assist devices (VAD) were found to have shortcomings when applied to the Fontan CPAD, which is designed to neutralize off-condition obstruction risks that could contribute to a major adverse event. The no-obstruction condition is achieved with a von Karman pump, utilizing large clearances and small blade heights, which challenge conventional VAD RANS-based CFD hemodynamic simulations. High-fidelity large eddy simulation (LES) is always recommended; however, this may be cost-inhibitive for optimization studies in commercial settings, thus the reliance on RANS models. This study compares head and power predictions of various RANS turbulence models, employing experimental measurements and LES results as a basis for comparison. The models include standard k-ϵ, re-normalization group k-ϵ, realizable k-ϵ, shear stress transport (SST) k-ω, SST with transitional turbulence, and Generalized k-ω. For the pressure head predictions, it was observed that the standard k-ϵ model provided far better agreement with experiment. For the rotor torque, k-ϵ predictions were 30% lower than LES, while the SST and LES torque values were near identical. For the Fontan CPAD, the findings support using LES for the final design simulations, k-ϵ model for head and general flow simulation, and SST for power, shear stress, hemolysis, and thrombogenicity predictions.

CFD simulations of the refueling of long horizontal H2 tanks with tilted injector

With the recent development of Hydrogen Refueling Stations (HRS), the refueling of hydrogen composite tanks is an important issue for the safe handling of hydrogen. In particular, an appropriate protocol is needed to avoid tank overheating during refueling. To model the temperature distribution everywhere inside the tank during these processes, CFD (Computational Fluid Dynamics) simulations have been performed under cases where thermal stratification occurs. The performances of several CFD turbulence models are benchmarked through a comparison with experimental data. Two injector configurations are considered in this work: a straight one and another tilted upwards. The U-RANS (Unsteady-Reynolds Averaged Navier-Stokes) - Reynolds Stress Model (RSM) is found to be the most reliable turbulence model for both configurations.

Comparison of turbulence models for solving problems of swirling jet flows

There are several turbulence models that can be used to solve the swirling jet problems, which are typical turbulence problems. A comparison of these models allows us to determine which one is better suited for a given task. When comparing turbulence models for the swirling jet problem, the most important criteria are the accuracy and stability of the solution. Accuracy is assessed by comparison with experimental data or other numerical methods, and stability is assessed by the absence of oscillations and convergence of the solution. In addition, it is also important to consider the computational complexity of each model and its applicability to a specific problem. The swirling flow in a nozzle is studied in the article using various turbulence models (SA, k-ε, k-ω, L-VEL, v2-f, yPlus, SST). To evaluate the performance of different CFD (Computational Fluid Dynamics) turbulence models, their numerical results for velocity profiles are compared with known experimental data.

Evaluation of CFD URANS Turbulence Models for the Building under Environmental Wind Flow with Experimental Validation

Wind flow on and around buildings attains more importance among architectures, builders, urban planners, structural engineers, and wind engineers. Wind tunnel experiments and wind flow assessments of full-scale buildings are expensive and complex in varied terrain conditions. Hence, wind flows are extensively assessed using Computational Fluid Dynamics (CFD). By following the turbulence parameters, CFD turbulence models create the wind tunnel and atmospheric environments. No literature has till elucidated which CFD turbulence model is more suitable for predicting the terrain wind flow on and around high-rise buildings. The efficiency of the CFD models, their performance, and their accuracy must be validated with experimental results, which is indispensable before using the turbulence model in practice. Therefore, this investigation aims to validate the Unsteady Reynolds–Averaged Navier-Stokes (URANS) simulations for a setback tall building under open terrain wind conditions enclosed within the wind tunnel dimensions. The URANS simulation is accompanied with Standard k– ε, Realizable k-ε, RNG k-ε, Standard k–ω, k–ω SST and RSM. The k –ω SST and RSM turbulence models have reproduced the wind pressure coefficients observed from the wind tunnel. However, all turbulence models failed to produce the same velocity profiles at downstream recirculation, as they vary with sampling time. The transient feature, RMS (Root Mean Square), is better reproduced by RSM and k–ω SST models, while the most unsteady features like across wind spectra and eddies were captured by Realizable, RSM and SST using iso-surface. k–ω SST and RSM models predict similar results with the experiment. Where less computational time was required for the SST, it is promising that this model provides both mean pressure and unsteady feature, encouraging more accurate simulation around the buildings.

Study on Accuracy of CFD Simulations of Wind Environment around High-Rise Buildings: A Comparative Study of k-ε Turbulence Models Based on Polyhedral Meshes and Wind Tunnel Experiments

It is important to create a comfortable wind environment around high-rise buildings for outdoor activities. To predict the wind environment, Computational Fluid Dynamics (CFD) has been widely used by designers and engineers. However, the simulation results of different CFD turbulence models might significantly vary. This paper researched the wind environment around a typical high-rise building and verified the accuracy of the CFD simulations based on polyhedral meshes. The differences between the simulation results of the k-ε turbulence models and those of the wind tunnel experiments were compared from the perspectives of wind speed and turbulence energy. The results show that the modified k-ε models could still not perfectly match the wind tunnel experiment results. Specifically, in the low-wind-speed areas, the simulation results of the Realizable Two-Layer K-Epsilon (RTLKE) model were the closest to the experimental results of the wind tunnels, while in the high-wind-speed areas the simulation results of the Standard Two-Layer K-Epsilon (STLKE) model were the closest to the experimental results of the wind tunnels. Therefore, it is recommended that these two k-ε turbulence models are applied under different conditions—the RTLKE model should be used to simulate low-wind areas around high-rise buildings (e.g., defining the size of the static-wind area around high-rise buildings, predicting the diffusion time of pollutants around high-rise buildings, etc.); STLKE should be used to simulate high-wind-speed areas around high-rise buildings (e.g., the high speed wind area around high-rise buildings during a typhoon, the maximum wind speed area around high-rise buildings, etc.). It is expected that findings from this research study supplement some existing high-rise building design guidance.

Numerical simulation and optimization of a cold model of a flat membrane bioreactor air scouring for membrane fouling control

Aeration scouring is currently the most common membrane fouling control technology. The optimization of aeration parameters, such as the aeration aperture, aeration pore spacing, and aerator layout height, can improve the efficiency of aeration and reduce the energy consumption of aeration. However, the simulation results cannot guide engineering practices well due to the limitations in the model precision of computational fluid dynamics. On this basis, the study compared and selected the computational fluid dynamics turbulence model. The DES model was used to study the influence of aeration parameters on membrane fouling control. The study showed that the DES turbulence model had a higher precision and accuracy in predicting the average shear force and the instantaneous shear force distribution on the membrane surface than the k-ε turbulence model. The average error of the DES turbulence model simulation of a bubble height was only 1.33%, which was 14.33% lower than the 15.66% of k-ε. An aeration pore spacing of 20 mm, a height of 100 mm, and an aeration aperture of 2.0 mm were the best layout parameters. The degree of influence of the aeration aperture, the aeration pore spacing, and the height of the aerator layout on the shear force of the membrane surface decreased sequentially. The influence of each interaction on the average shear force of the membrane surface was negligible. Among these parameters, the main reason for the membrane surface shear force was the change in the flow velocity caused by aeration. By calculating the fitting equation and the critical value of the shear force, the critical value of the liquid velocity on the membrane surface that could remove membrane fouling was 0.232 m/s. Although the numerical simulation and optimization of a flat membrane bioreactor air scouring for membrane fouling control were carried out with pure water, it still plays a significant impact on the actual membrane fouling control. These results could guide the optimization design of aeration parameters for flat membrane bioreactors and provide a reference for the analysis of aeration scour control membrane pollution control research.

Effect of turbulence, dispersion, and stratification on Escherichia coli disinfection in a subtropical maturation pond

Sunlight disinfection is important for treatment of wastewater within maturation ponds. This study analyses the movement of Escherichi coli within a slice of a maturation pond, being affected by stratification, sunlight attenuation and mixing driven by wind shear and natural convection using computational fluid dynamics (CFD). Since the exposure to ultraviolet light is most effective in the near-surface region of the pond, natural convective mixing mechanisms to transport the pathogens from the lower parts of the pond are critical for disinfection efficacy. Different turbulence models are considered for closure of the momentum conservation equations and compared with a laminar flow simulation and a completely stirred tank reactor (CSTR) model. The effect of turbulence and stratification is shown to be significant for thermal and velocity distributions, and predictions of E. coli die-off. Greater volume-averaged E. coli die-off was predicted by the computationally convenient CSTR model than the CFD turbulence and laminar models. The simulation results are compared with experimental data and show that complete vertical mixing occurs in a diurnal pattern aiding die-off in sunlight-attenuating water. Practical applications of the model can assist in management strategies for maturation ponds such as off-take locations/times and evaluating seasonal variations in sunlight disinfection.

Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

Role of CFD based in silico modelling in establishing an in vitro-in vivo correlation of aerosol deposition in the respiratory tract.

Effective evaluation and prediction of aerosol transport deposition in the human respiratory tracts are critical to aerosol drug delivery and evaluation of inhalation products. Establishment of an in vitro-in vivo correlation (IVIVC) requires the understanding of flow and aerosol behaviour and underlying mechanisms at the microscopic scale. The achievement of the aim can be facilitated via computational fluid dynamics (CFD) based in silico modelling which treats the aerosol delivery as a two-phase flow. CFD modelling research, in particular coupling with discrete phase model (DPM) and discrete element method (DEM) approaches, has been rapidly developed in the past two decades. This paper reviews the recent development in this area. The paper covers the following aspects: geometric models of the respiratory tract, CFD turbulence models for gas phase and its coupling with DPM/DEM for aerosols, and CFD investigation of the effects of key factors associated with geometric variations, flow and powder characteristics. The review showed that in silico study based on CFD models can effectively evaluate and predict aerosol deposition pattern in human respiratory tracts. The review concludes with recommendations on future research to improve in silico prediction to achieve better IVIVC.

Internal flow analysis of a porous burner via CFD

Purpose This study aims to introduce a metal porous burner design. Literature is surveyed in a comprehensive manner to relate the current design with ongoing research. A demonstrative computational fluid dynamics (CFD) analysis is presented with projected flow conditions by means of a common commercial CFD code and turbulence model to show the flow-related features of the proposed burner. The porous metal burner has a novel design, and it is not commercially available. Design/methodology/approach Based on the field experience about porous burners, a metal, cylindrical, two-staged, homogenous porous burner was designed. Literature was surveyed to lay out research aspects for the porous burners and porous media. Three dimensional solid computer model of the burner was created. The flow domain was extracted from the solid model to use in CFD analysis. A commercial computational fluid dynamics code was utilized to analyze the flow domain. Projected flow conditions for the burner were applied to the CFD code. Results were evaluated in terms of homogenous flow distribution at the outer surface and flow mixing. Quantitative results are gathered and are presented in the present report by means of contour maps. Findings There aren’t any flow sourced anomalies in the flow domain which would cause an inefficient combustion for the application. An accumulation of gas is evident around the top flange of the burner leading to higher static pressure. Generally, very low pressure drop throughout the proposed burner geometry is found which is regarded as an advantage for burners. About 0.63 Pa static pressure increase is realized on the flange surface due to the accumulation of the gas. The passage between inner and outer volumes has a high impact on the total pressure and leads to about 0.5 Pa pressure drop. About 0.03 J/kg turbulent kinetic energy can be viewed as the highest amount. Together with the increase in total enthalpy, total amount of energy drawn from the flow is 0.05 J/kg. More than half of it spent through turbulence and remaining is dissipated as heat. Outflow from burner surface can be regarded homogenous though the top part has slightly higher outflow. This can be changed by gradually increasing pore sizes toward inlet direction. Research limitations/implications Combustion via a porous medium is a complex phenomenon since it involves multiple phases, combustion chemistry, complex pore geometries and fast transient responses. Therefore, experimentation is used mostly. To do a precise computational analysis, strong computational power, parallelizing, elaborate solid modeling, very fine meshes and small time steps and multiple models are required. Practical implications Findings in the present work imply that a homogenous gas outflow can be attained through the burner surfaces while very small pressure drop occurs leading to less pumping power requirement which is regarded as an advantage. Flow mixing is realizable since turbulent kinetic energy is distinguished at the interface surface between inner and outer volumes. The porous metal matrix burner offers fluid mixing and therefore better combustion efficiency. The proposed dimensions are found appropriate for real-world application. Originality/value Conducted analysis is for a novel burner design. There are opportunities both for scientific and commercial fields.

Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

PTV/PIV measurements of turbulent flows in interior subchannels of a 61-pin wire-wrapped hexagonal fuel bundle

This study summarizes the experimental effort to characterize the flow fields of various interior subchannels in a 61-pin wire-wrapped hexagonal fuel bundle prototypical for a sodium fast reactor. The objective was to generate high spatiotemporal velocity field data for computational fluid dynamics turbulence model validation. The experimental facility employed the matched-index-of-refraction and modern laser-based optical measurement techniques. It is the largest transparent hexagonal test fuel assembly. Measurements were performed in two planes parallel to the axial flow, Interior-1 and Center-2. The Interior-1 location captured fluid interactions in four narrower subchannels formed by the exterior row of pins near the hexagonal duct wall. The Center-2 location captured fluid interactions in two wider subchannels spanning from the center pin out to the hexagonal duct wall. All measurements have been performed at a Reynolds number of 19,000. Results include discussion about statistical convergence of the dataset, along with flow statistics such as ensemble-averaged velocity, root-mean-square fluctuating velocity, Reynolds stress, and integral length scales.

Integrated probabilistic modeling method for transient opening height prediction of check valves in oil-gas multiphase pumps

To ensure the reliability of oil-gas multiphase pumps, it is necessary to model the relationship between the transient opening height of the check valve and multiphase transportation conditions. However, the choice of a suitable turbulence model is not straightforward for the widely used computational fluid dynamics (CFD) method. Additionally, the CFD models are still not easy to be validated experimentally because the transient opening motion is difficult to be accurately measured for its quick and nonlinear characteristics. In this work, an integrated probabilistic modeling (IPM) method is proposed to predict the transient opening height of the check valve in oil-gas multiphase pumps. First, candidate CFD transient models with different turbulence models are adopted to provide initial training data for several Gaussian process regression (GPR) models. Then, a probabilistic index of the trained GPR models is formulated to assess their reliability. Consequently, without knowing the actual values, a suitable GPR model is chosen from the candidates for online prediction of a new condition. Moreover, instead of the time-consuming CFD design process, a better CFD turbulence model can be selected efficiently. The superiority of IPM is demonstrated using simulation and experiments.

Evaluation of CFD turbulence models for simulating external airflow around varied building roof with wind tunnel experiment

Detailed airflow information around a building can be crucial for the design of naturally ventilated systems and for exhaust air dispersion practices in agricultural buildings like greenhouses and livestock buildings. Full-scale measurements are cost-intensive and difficult to achieve due to varied wind conditions. A common method to gain insight of flow field under different wind conditions is the numerical simulation by using computational fluid dynamics (CFD). Still, evaluation of a CFD models’ performance and validation of its predictions with high quality experimental data is necessary before the model is used in practice. In this research three types of common agricultural buildings, arched-type, pitched-type and flat-type roof, were examined by conducting experiments in a wind tunnel with controlled airflow conditions, in order to validate different 3D turbulence models for predicting airflow patterns. The focus of this work was the detailed description of the external airflow field over the varied roof geometries and especially the velocity distribution and turbulent kinetic energy in the wake of each building. Experimental measurements of velocity were performed with a Laser Doppler Anemometer (LDA) and were compared with 3D RANS turbulence models’ simulation results. A reasonable agreement was found between experimental and simulation results concerning the velocity and the turbulence kinetic energy with CFD models slightly underestimating these magnitudes. The k-e series turbulence models and especially the standard k-e, RNG k-e and Realizable k-e models presented good agreement concerning velocity contours; however, high prediction error occurred over the roof of the buildings compared to the average values.

Investigating ventilation system performance in large space building: A nozzle primary air supply with secondary airflow-relay system

In large space buildings, nozzle is usually used for ventilation and air conditioning. A secondary airflow-relay system is proposed for situations that building span is larger than the primary jet flow range. A field measurement was conducted to investigate the performance of primary airflow nozzle and secondary jet fan system; a computational fluid dynamics model was built up to research the secondary airflow velocity and relative location of primary and secondary terminal on the ventilation performance. The performance of different computational fluid dynamics turbulence models in predicting the primary jet trajectory path was evaluated by comparing predicted result with field measurements. The temperature field predicted by computational fluid dynamics method was also validated by experimentally measured vertical temperature distribution data in certain measurement points. Various indices including Air Diffusion Performance Index, percentage dissatisfied, and coefficient of variation of temperature and velocity at breathing level were used to quantitatively evaluate the ventilation performance of different configurations. It is found that re-normalization group k-ϵ turbulence model gives the best overall prediction on the primary air nozzle jet trajectory path and field temperature distribution. In a certain large space building utilizing secondary airflow system, the relative location of primary and secondary equipment and air velocity should be properly specified in order to improve the ventilation performance of a large space building. The secondary airflow-relay may potentially increase the cooling energy consumption as indicated by computational fluid dynamics result.

XFOIL vs CFD performance predictions for high lift low Reynolds number airfoils

Blade Element Momentum (BEM) theory is an extensively used technique for calculation of propeller aerodynamic performance. With this method, the airfoil data needs to be as accurate as possible. At the same time, Computational Fluid Dynamics (CFD) is becoming increasingly popular in the design and optimization of devices that depend on aerodynamics. For fixed and rotary wing applications, the airfoil lift over drag coefficient is the dominant airfoil performance parameter. Selecting a suitable computational tool is crucial for the successful design and optimization of this ratio. The XFOIL code, the Shear Stress Transport k−ω turbulence model and a refurbished version of k−kl−ω transition model were used to predict the airfoil aerodynamic performance at low Reynolds numbers (around 2.0×105). It has been shown that the XFOIL code gives the overall best prediction results. Also, it is not clear that CFD turbulence models, even with boundary layer transition detection capability, can compute better airfoil performance predictions data.