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1
Chen, Zi Xi, Neha Marathe et Siva Parameswaran. « CFD Study of Wake Interaction of Two Wind Turbines ». Advanced Materials Research 472-475 (février 2012) : 2726–30. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2726.
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Understanding the wake behavior properly would help in designing proper layouts of wind farms to obtain maximum power and improved turbine life. This research aims at studying the impact of power of a turbine that is in the wake of another turbine under uniform inflow condition. Computational Fluid Dynamics (CFD) simulations are carried out to represent the velocity deficit behind two turbines in-line with the wind using the Virtual Blade Model (VBM). Power loss of the second wind turbine located at different distance downstream is also calculated.
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Kurniawati, Diniar Mungil. « Investigasi Performa Turbin Angin Crossflow Dengan Simulasi Numerik 2D ». JTT (Jurnal Teknologi Terpadu) 8, no 1 (27 avril 2020) : 7–12. http://dx.doi.org/10.32487/jtt.v8i1.762.
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Wind turbine is a solution to harness of renewable energy because it requires wind as the main energy. Wind turbine work by extracting wind energy into electrical energy. Crossflow wind turbine is one of the wind turbines that are developed because it does not need wind direction to produce maximum efficiency. Crossflow wind turbines work with the concept of multiple interactions, namely in the first interaction the wind hits the first level of turbine blades, then the interaction of the two winds, the remainder of the first interaction enters the second level blades before leaving the wind turbine. In the design of crossflow wind turbine the diameter ratio and slope angle are important factors that influence to determine of performance in crossflow wind turbine. In this study varied the angle of slope 90 ° and variations in diameter ratio of 0.6 and 0.7. The study aimed to analyze the effect of diameter ratio and slope angle in performance of the crossflow wind turbine. This research was conducted with numerical simulation through 2D CFD modeling. The results showed that the best performance of crossflow wind turbine occurred at diameter ratio variation 0.7 in TSR 0.3 with the best CP value 0.34.
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Attene, Federico, Francesco Balduzzi, Alessandro Bianchini et M. Sergio Campobasso. « Using Experimentally Validated Navier-Stokes CFD to Minimize Tidal Stream Turbine Power Losses Due to Wake/Turbine Interactions ». Sustainability 12, no 21 (22 octobre 2020) : 8768. http://dx.doi.org/10.3390/su12218768.
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Tidal stream turbines fixed on the seabed can harness the power of tides at locations where the bathymetry and/or coastal geography result in high kinetic energy levels of the flood and/or neap currents. In large turbine arrays, however, avoiding interactions between upstream turbine wakes and downstream turbine rotors may be hard or impossible, and, therefore, tidal array layouts have to be designed to minimize the power losses caused by these interactions. For the first time, using Navier-Stokes computational fluid dynamics simulations which model the turbines with generalized actuator disks, two sets of flume tank experiments of an isolated turbine and arrays of up to four turbines are analyzed in a thorough and comprehensive fashion to investigate these interactions and the power losses they induce. Very good agreement of simulations and experiments is found in most cases. The key novel finding of this study is the evidence that the flow acceleration between the wakes of two adjacent turbines can be exploited not only to increase the kinetic energy available to a turbine working further downstream in the accelerated flow corridor, but also to reduce the power losses of said turbine due to its rotor interaction with the wake produced by a fourth turbine further upstream. By making use of periodic array simulations, it is also found that there exists an optimal lateral spacing of the two adjacent turbines, which maximizes the power of the downstream turbine with respect to when the two adjacent turbines are absent or further apart. This is accomplished by trading off the amount of flow acceleration between the wakes of the lateral turbines, and the losses due to shear and mixing of the front turbine wake and the wakes of the two lateral turbines.
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Danaila, Sterian, Dragoș Isvoranu et Constantin Leventiu. « Preliminary Simulation of a 3D Turbine Stage with In Situ Combustion ». Applied Mechanics and Materials 772 (juillet 2015) : 103–7. http://dx.doi.org/10.4028/www.scientific.net/amm.772.103.
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This paper presents the preliminary results of the numerical simulation of flow and combustion in a one stage turbine combustor (turbine stage in situ combustion). The main purpose of the simulation is to assess the stability of the in situ combustion with respect to the unsteadiness induced by the rotor-stator interaction. Apart from previous attempts, the salient feature of this CFD approach is the new fuel injection concept that consisting of a perforated pipe placed at mid-pitch in the stator row passage. The flow and combustion are modelled by the Reynolds-averaged Navier-Stokes equations coupled with the species transport equations. The chemistry model used herein is a two-step, global, finite rate combustion model while the turbulence model is the shear stress transport model. The chemistry turbulence interaction is described in terms of eddy dissipation concept.
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Mao, Zhaoyong, Guangyong Yang, Tianqi Zhang et Wenlong Tian. « Aerodynamic Performance Analysis of a Building-Integrated Savonius Turbine ». Energies 13, no 10 (21 mai 2020) : 2636. http://dx.doi.org/10.3390/en13102636.
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The building-integrated wind turbine is a new technology for the utilization of wind energy in cities. Previous studies mainly focused on the wind turbines mounted on the roofs of buildings. This paper discusses the performance of Savonius wind turbines which are mounted on the edges of a high-rise building. A transient CFD method is used to investigate the performance of the turbine and the interaction flows between the turbine and the building. The influence of three main parameters, including the turbine gap, wind angle, and adjacent turbines, are considered. The variations of the turbine torque and power under different operating conditions are evaluated and explained in depth. It is found that the edge-mounted Savonius turbine has a higher coefficient of power than that operating in uniform flows; the average Cp of the turbine under 360-degree wind angles is 92.5% higher than the turbine operating in uniform flows. It is also found that the flow around the building has a great impact on turbine performance, especially when the turbine is located downwind of the building.
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Badshah, Mujahid, Saeed Badshah et Kushsairy Kadir. « Fluid Structure Interaction Modelling of Tidal Turbine Performance and Structural Loads in a Velocity Shear Environment ». Energies 11, no 7 (13 juillet 2018) : 1837. http://dx.doi.org/10.3390/en11071837.
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Tidal Current Turbine (TCT) blades are highly flexible and undergo considerable deflection due to fluid interactions. Unlike Computational Fluid Dynamic (CFD) models Fluid Structure Interaction (FSI) models are able to model this hydroelastic behavior. In this work a coupled modular FSI approach was adopted to develop an FSI model for the performance evaluation and structural load characterization of a TCT under uniform and profiled flow. Results indicate that for a uniform flow case the FSI model predicted the turbine power coefficient CP with an error of 4.8% when compared with experimental data. For the rigid blade Reynolds Averaged Navier Stokes (RANS) CFD model this error was 9.8%. The turbine blades were subjected to uniform stress and deformation during the rotation of the turbine in a uniform flow. However, for a profiled flow the stress and deformation at the turbine blades varied with the angular position of turbine blade, resulting in a 22.1% variation in stress during a rotation cycle. This variation in stress is quite significant and can have serious implications for the fatigue life of turbine blades.
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Wiśniewski, Jan, Krzysztof Rogowski, Konrad Gumowski et Jacek Szumbarski. « Wind tunnel comparison of four VAWT configurations to test load-limiting concept and CFD validation ». Wind Energy Science 6, no 1 (24 février 2021) : 287–94. http://dx.doi.org/10.5194/wes-6-287-2021.
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Abstract. The article describes results of experimental wind tunnel testing of four different straight-bladed vertical axis wind turbine model configurations. The experiment tested a novel concept of vertically dividing and azimuthally shifting a turbine rotor into two parts with a specific uneven height division in order to limit cycle amplitudes and average cycle values of bending moments at the bottom of the turbine shaft to increase product lifetime, especially for industrial-scale turbines. Testing reduction effects of simultaneously including a vertical gap between turbine rotor levels, increasing shaft length but also reducing aerodynamic interaction between rotor levels, has also been performed. Experiment results have shown very significant decreases of bending moment cycle amplitudes and average cycle values, for a wide range of measured wind speeds, for dual-level turbine configurations as compared to a single-level turbine configuration. The vertical spacing between levels equal to a blade's single chord length has proven to be sufficient, on laboratory scale, to limit interaction between turbine levels in order to achieve optimal reductions of tested parameters through an operating cycle shift between two position-locked rotor levels during a turbine's expected lifetime. CFD validation of maintaining the effect on industrial scale has been conducted, confirming the initial conclusions.
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Benim, Ali Cemal, Sohail Iqbal, Franz Joos et Alexander Wiedermann. « Numerical Analysis of Turbulent Combustion in a Model Swirl Gas Turbine Combustor ». Journal of Combustion 2016 (2016) : 1–12. http://dx.doi.org/10.1155/2016/2572035.
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Turbulent reacting flows in a generic swirl gas turbine combustor are investigated numerically. Turbulence is modelled by a URANS formulation in combination with the SST turbulence model, as the basic modelling approach. For comparison, URANS is applied also in combination with the RSM turbulence model to one of the investigated cases. For this case, LES is also used for turbulence modelling. For modelling turbulence-chemistry interaction, a laminar flamelet model is used, which is based on the mixture fraction and the reaction progress variable. This model is implemented in the open source CFD code OpenFOAM, which has been used as the basis for the present investigation. For validation purposes, predictions are compared with the measurements for a natural gas flame with external flue gas recirculation. A good agreement with the experimental data is observed. Subsequently, the numerical study is extended to syngas, for comparing its combustion behavior with that of natural gas. Here, the analysis is carried out for cases without external flue gas recirculation. The computational model is observed to provide a fair prediction of the experimental data and predict the increased flashback propensity of syngas.
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Levick, T., A. Neubert, D. Friggo, P. Downes, R. Ruisi et J. Bleeg. « Validating the next generation of turbine interaction models ». Journal of Physics : Conference Series 2257, no 1 (1 avril 2022) : 012010. http://dx.doi.org/10.1088/1742-6596/2257/1/012010.
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Abstract It is important to validate turbine interaction models to understand the uncertainties and biases inherent when we model wind farm power output for future wind farms. We present here a repeatable and model-agnostic methodology developed for validating wind farm production models. Power data from the Supervisory Control and Data Acquisition systems of wake-free turbines are used with turbine power curves to generate inlet wind speeds representative of average conditions on the front row of a wind farm. These wind speeds are used, with other model inputs, to run models and predict a modelled power time series for each turbine. The modelled and measured power time series are compared to derive mean bias error metrics. The methodology is applied at 6 offshore wind farms to test established and novel turbine interaction models. We compare the distributions errors predicting power at turbines across models and wind farms. We find that the new models, CFD. ML and the Stratified Eddy Viscosity model, perform well with respect to the established WindFarmer Eddy Viscosity model, and see increased errors for the largest wind farms. We discuss methodological uncertainties in the input wind speed derivation that may cause biases in the overall distributions at windspeeds near the turbine low wind speed cut-in and rated power, and make suggestions for future methodological refinements.
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Amerini, Alberto, Simone Paccati et Antonio Andreini. « Computational Optimization of a Loosely-Coupled Strategy for Scale-Resolving CHT CFD Simulation of Gas Turbine Combustors ». Energies 16, no 4 (7 février 2023) : 1664. http://dx.doi.org/10.3390/en16041664.
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The accurate prediction of heat fluxes and, thus, metal wall temperatures of gas turbine (GT) combustor liners is a complicated and numerically expensive task. Computational Fluid Dynamics (CFD) support for the design of cooling systems is essential to ensure safe and proper operation of the entire gas turbine engine. Indeed, it is well known how complicated, and, at the same time, expensive it is to carry out experimental campaigns inside combustors operating under working conditions, and, therefore, pressurized and having high temperatures. The correct prediction of thermal fluxes in a CFD simulation depends on the proper modeling of all the involved phenomena and their interactions with each other. For this reason, Conjugate Heat Transfer (CHT) simulations are mandatory in gas turbine cooling system applications. Multiphysics and multiscale simulations, based on loosely-coupled approaches, have emerged as extremely effective numerical tools, providing enormous computational time savings, as compared with standard CHT simulations. The fundamental advantage of such approaches is based on the fact that each heat transfer mechanism is solved with the most suitable numerical setup, which leads to the use of spatial and temporal resolutions following the characteristic time scales of each phenomenon to be solved. For industrial applications, where the availability of numerical resources is limited and, at the same time, the timelines with which to obtain results are rather tight, having robust and easy-to-use loosely-coupled solutions available for the design of combustion chamber cooling systems would be extremely valuable. In this context, the objective of this work was to perform an initial optimization step for the multiphysics and multiscale tool, U-THERM3D, developed at the University of Florence to revise the coupling strategy workflow with a view to making the numerical tool faster and easier to use. The revised methodology was applied to the RSM gas turbine combustor model test case developed with cooperation between the Universities of Darmstadt, Heidelberg, Karlsruhe, and the DLR. In particular, all experimental tests were conducted by the Institute of Reactive Flows and Diagnostics (Reaktive Strömungen und Messtechnik) of the Department of Mechanical Engineering at TU Darmstadt, from which the gas turbine combustor model takes its name. The newly obtained results were compared and analyzed, both qualitatively and in terms of computational time savings, with those previously achieved with the current version of the U-THERM3D tool already studied by the authors and available in the literature. Moreover, an analysis of computing times was carried out relative to the super- computing center used for the different adopted methodologies.
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Gautam, Saroj, Sailesh Chitrakar, Hari Prasad Neopane, W. Bjørn Solemslie et Ole Gunnar Dahlhaug. « Numerical investigation of a Pelton turbine at several operating conditions ». IOP Conference Series : Earth and Environmental Science 1037, no 1 (1 juin 2022) : 012053. http://dx.doi.org/10.1088/1755-1315/1037/1/012053.
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Abstract The use of Computational Fluid Dynamics (CFD) for predicting the flow behaviour in Pelton turbines is limited by the complex nature of the flow, interaction between the jets and interference of the water after the impact on the buckets. Besides, validation of the numerical results in such turbines is usually challenging due to the unsteadiness of the flow properties. Hence, time-dependent analysis with multi-phase models is required for obtaining such solutions. This paper conducts a CFD analysis on a Pelton turbine using RANS based Eulerian scheme. The fluid domain consists of three successive buckets placed in their corresponding circumferential locations, along with a spear valve, which is adjusted for various operating conditions. Such a domain assumes that the interaction of the jet on the buckets takes place for a maximum of three buckets at any particular time. The results of the CFD analysis are compared with the experimental results for all the studied opening conditions. The objective of this work is to build a suitable numerical model that can be applied to any Pelton turbines, such that a complete performance curve of the turbine can be generated. The flow pattern between entry and exit of the bucket obtained from CFD is compared with images taken from a high speed camera in rotating frame of reference. The results of the numerical analysis are found to be in a good agreement with the experimental data.
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Giezendanner, R., P. Weigand, X. R. Duan, W. Meier, U. Meier, M. Aigner et B. Lehmann. « Laser-Based Investigations of Periodic Combustion Instabilities in a Gas Turbine Model Combustor ». Journal of Engineering for Gas Turbines and Power 127, no 3 (24 juin 2005) : 492–96. http://dx.doi.org/10.1115/1.1850498.
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The driving mechanism of pulsations in gas turbine combustors depends on a complex interaction between flow field, chemistry, heat release, and acoustics. Experimental data on all these factors are therefore required to obtain insight into the coupling mechanisms during a pulsation period. In order to develop a comprehensive experimental database to support a phenomenological understanding and to provide validation data for numerical simulation, a standard burner for optical investigations was established that exhibits strong self-excited oscillations. The burner was a swirl-stabilized nonpremixed model combustor designed for gas turbine applications and operated using methane as fuel at atmospheric pressure. It was mounted in a combustion chamber, which provides almost unobstructed optical access. The periodic combustion instabilities were studied by a variety of phase-resolved laser-based diagnostic techniques, locked to the frequency of the dominant pressure oscillation. Measurement techniques used were LDV for velocity measurements, planar laser-induced fluorescence for imaging of CH and OH radicals, and laser Raman scattering for the determination of the major species concentrations, temperature, and mixture fraction. The phase-resolved measurements revealed significant variations of all measured quantities in the vicinity of the nozzle exit, which trailed off quickly with increasing distance. A strong correlation of the heat release rate and axial velocity at the nozzle was observed, while the mean mixture fraction as well as the temperature in the periphery of the flame is phase shifted with respect to axial velocity oscillations. A qualitative interpretation of the experimental observations is given, which will help to form a better understanding of the interaction between flow field, mixing, heat release, and temperature in pulsating reacting flows, particularly when accompanied by corresponding CFD simulations that are currently underway.
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Patel, Yogesh Ramesh. « FSI in Wind Turbines : A Review ». International Journal of Recent Contributions from Engineering, Science & ; IT (iJES) 8, no 3 (30 septembre 2020) : 37. http://dx.doi.org/10.3991/ijes.v8i3.16595.
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This paper provides a brief overview of the research in the field of Fluid-structure interaction in Wind Turbines. Fluid-Structure Interaction (FSI) is the interplay of some movable or deformable structure with an internal or surrounding fluid flow. Flow brought about vibrations of two airfoils used in wind turbine blades are investigated by using a strong coupled fluid shape interplay approach. The approach is based totally on a regularly occurring Computational Fluid Dynamics (CFD) code that solves the Navier-Stokes equations defined in Arbitrary Lagrangian-Eulerian (ALE) coordinates by way of a finite extent method. The need for the FSI in the wind Turbine system is studied and comprehensively presented.
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Simisiroglou, Nikolaos, Simon-Philippe Breton et Stefan Ivanell. « Validation of the actuator disc approach using small-scale model wind turbines ». Wind Energy Science 2, no 2 (24 novembre 2017) : 587–601. http://dx.doi.org/10.5194/wes-2-587-2017.
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Abstract. The aim of the present study is the validation of the implementation of an actuator disc (ACD) model in the computational fluid dynamics (CFD) code PHOENICS. The flow behaviour for three wind turbine cases is investigated numerically and compared to wind tunnel measurements: (A) the flow around a single model wind turbine, (B) the wake interaction between two in-line model wind turbines for a uniform inflow of low turbulence intensity and (C) the wake interaction between two in-line model wind turbines at different separation distances in a uniform or sheared inflow of high turbulence intensity. This is carried out using Reynolds-averaged Navier–Stokes (RANS) simulations and an ACD technique in the CFD code PHOENICS. The computations are conducted for the design condition of the rotors using four different turbulence closure models and five different thrust distributions. The computed axial velocity field as well as the turbulence kinetic energy are compared with hot-wire anemometry (HWA) measurements. For the cases with two in-line wind turbines, the thrust coefficient is also computed and compared with measurements. The results show that for different inflow conditions and wind turbine spacings the proposed method is able to predict the overall behaviour of the flow with low computational effort. When using the k-ε and Kato–Launder k-ε turbulence models the results are generally in closer agreement with the measurements.
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Castorrini, A., L. Tieghi, V. F. Barnabei, S. Gentile, A. Bonfiglioli, A. Corsini et F. Rispoli. « Wake interaction in offshore wind farms with mesoscale derived inflow condition and sea waves ». IOP Conference Series : Earth and Environmental Science 1073, no 1 (1 septembre 2022) : 012009. http://dx.doi.org/10.1088/1755-1315/1073/1/012009.
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Abstract Numerical simulation is an indispensable tool for the design and optimization of wind farms layout and control strategies for energy loss reduction. Achieving consistent simulation results is strongly related to the definition of reliable weather and sea conditions, as well as the use of accurate computational fluid dynamics (CFD) models for the simulation of the wind turbines and wakes. Thus, we present a case study aiming to evaluate the wake-rotor interaction between offshore multi-MW wind turbines modelled using the Actuator Line Model (ALM) and realistic wind inflow conditions. In particular, the interaction between two DTU10 wind turbines is studied for two orientations of the upstream turbine rotor, simulating the use of a yaw-based wake control strategy. Realistic wind inflow conditions are obtained using a multi-scale approach, where the wind field is firstly computed using mesoscale numerical weather prediction (NWP). Then, the mesoscale vertical wind profile is used to define the wind velocity and turbulence boundary conditions for the high-fidelity CFD simulations. Sea waves motion is also imposed using a dynamic mesh approach to investigate the interaction between sea waves, surface boundary layer, and wind turbine wakes and loads.
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Tolpadi, A. K., I. Z. Hu, S. M. Correa et D. L. Burrus. « Coupled Lagrangian Monte Carlo PDF–CFD Computation of Gas Turbine Combustor Flowfields With Finite-Rate Chemistry ». Journal of Engineering for Gas Turbines and Power 119, no 3 (1 juillet 1997) : 519–26. http://dx.doi.org/10.1115/1.2817015.
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A coupled Lagrangian Monte Carlo Probability Density Function (PDF)-Eulerian Computational Fluid Dynamics (CFD) technique is presented for calculating steady three-dimensional turbulent reacting flow in a gas turbine combustor. PDF transport methods model turbulence-combustion interactions more accurately than conventional turbulence models with an assumed shape PDF. The PDF transport equation was solved using a Lagrangian particle tracking Monte Carlo (MC) method. The PDF modeled was over composition only. This MC module has been coupled with CONCERT, which is a fully elliptic three-dimensional body-fitted CFD code based on pressure correction techniques. In an earlier paper (Tolpadi et al., 1995), this computational approach was described, but only fast chemistry calculations were presented in a typical aircraft engine combustor. In the present paper, reduced chemistry schemes were incorporated into the MC module that enabled the modeling of finite rate effects in gas turbine flames and therefore the prediction of CO and NOx emissions. With the inclusion of these finite rate effects, the gas temperatures obtained were also more realistic. Initially, a two scalar scheme was implemented that allowed validation against Raman data taken in a recirculating bluff body stabilized CO/H2/N2-air flame. Good agreement of the temperature and major species were obtained. Next, finite rate computations were performed in a single annular aircraft engine combustor by incorporating a simple three scalar reduced chemistry scheme for Jet A fuel. This three scalar scheme was an extension of the two scalar scheme for CO/H2/N2 fuel. The solutions obtained using the present approach were compared with those obtained using the fast chemistry PDF transport approach (Tolpadi et al., 1995) as well as the presumed shape PDF method. The calculated exhaust gas temperature using the finite rate model showed the best agreement with measurements made by a thermocouple rake. In addition, the CO and NOx emission indices were also computed and compared with corresponding data.
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Abutunis, Abdulaziz, et Venkata Gireesh Menta. « Comprehensive Parametric Study of Blockage Effect on the Performance of Horizontal Axis Hydrokinetic Turbines ». Energies 15, no 7 (1 avril 2022) : 2585. http://dx.doi.org/10.3390/en15072585.
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When a hydrokinetic turbine operates in a confined flow, blockage effects are introduced, altering the flow at and downstream of the rotor. Blockage effects have a significant effect on the loading and performance of turbines. As a result, understanding them is critical for hydrokinetic turbine design and performance prediction. The current study examines the main and interaction effects of solidity (σ), tip speed ratio (TSR), blockage ratio (ε), and pitch angle (θ) on how the blockage influences the performance (CP) of a three-bladed, untwisted, untapered horizontal axis hydrokinetic turbine. The investigation is based on validated 3D computational fluid dynamics (CFD), design of experiments (DOE), and the analysis of variance (ANOVA) approaches. A total number of 36 CFD models were developed and meshed. A total of 108 CFD cases were performed as part of the analysis. Results indicated that the effect of varying θ was only noticeable at the high TSR. Additionally, the rate of increment of CP with respect to ε was found proportional to both TSR and σ. The power and thrust coefficients were affected the most by σ, followed by ε, TSR, and then θ.
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Adami, P., et F. Martelli. « Three-dimensional unsteady investigation of HP turbine stages ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 220, no 2 (1 mars 2006) : 155–67. http://dx.doi.org/10.1243/095765005x69189.
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This article deals with a three-dimensional unsteady numerical simulation of the unsteady rotor—stator interaction in a HP turbine stage. The numerical approach consists of a computational fluid dynamics (CFD) parallel code, based on an upwind total variation diminishing finite volume approach. The computation has been carried out using a sliding plane approach with hybrid unstructured meshes and a two-equation turbulent closure. The turbine rig under investigation is representative of the first stage of aeronautic gas turbine engines. A brief description of the cascade, the experimental setup, and the measuring technique is provided. Time accurate CFD computations of pressure fluctuations and Nusselt number are discussed against the experimental data.
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Cao, Cheng, Yaping Gao, Shaolin Wang, Fuqiang Liu, Cunxi Liu, Yong Mu, Deqing Mei et Gang Xu. « Numerical Investigation on Mechanism of Swirling Flow of the Prefilming Air-Blast Fuel Injector ». Energies 16, no 2 (5 janvier 2023) : 650. http://dx.doi.org/10.3390/en16020650.
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Prefilming air-blast atomizers are widely used in modern gas turbine combustors. Due to insufficient awareness of the coupling mechanism of multi-stage swirling flow in gas turbines, there is a lack of effective methods for flow field optimization in combustor. In this study, the effect of some critical parameters on the flow field of a prefilming air-blast atomizer was analyzed with CFD. The parameters include the angle and number of the first swirler blades, the angle of the second swirler blades and the angle of sleeve. Furthermore, the coupling mechanism of two-stage swirling airflows of prefilming air-blast atomizer was discussed. Moreover, the influence of the interaction between two-stage counter swirling airflows on the characteristics of flow field was explained. The results show that with the increase in SNi, the axial length of the primary recirculation zone decreased, while the radial width increased. The starting position of primary recirculation zone (PRZ) moves forward with the increase in SNo. Reducing the sleeve angle β helps to form the primary recirculation zone. The results indicate that it is the transition of tangential velocity of airflow to radial velocity that promotes the formation of the PRZ. These results provide theoretical support for optimization of the flow field in swirl combustor.
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Shkara, Yasir, Martin Cardaun, Ralf Schelenz et Georg Jacobs. « Aeroelastic response of a multi-megawatt upwind horizontal axis wind turbine (HAWT) based on fluid–structure interaction simulation ». Wind Energy Science 5, no 1 (28 janvier 2020) : 141–54. http://dx.doi.org/10.5194/wes-5-141-2020.
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Abstract. With the increasing demand for greener, sustainable, and economical energy sources, wind energy has proven to be a potential sustainable source of energy. The trend development of wind turbines tends to increase rotor diameter and tower height to capture more energy. The bigger, lighter, and more flexible structure is more sensitive to smaller excitations. To make sure that the dynamic behavior of the wind turbine structure will not influence the stability of the system and to further optimize the structure, a fully detailed analysis of the entire wind turbine structure is crucial. Since the fatigue and the excitation of the structure are highly depending on the aerodynamic forces, it is important to take blade–tower interactions into consideration in the design of large-scale wind turbines. In this work, an aeroelastic model that describes the interaction between the blade and the tower of a horizontal axis wind turbine (HAWT) is presented. The high-fidelity fluid–structure interaction (FSI) model is developed by coupling a computational fluid dynamics (CFD) solver with a finite element (FE) solver to investigate the response of a multi-megawatt wind turbine structure. The results of the computational simulation showed that the dynamic response of the tower is highly dependent on the rotor azimuthal position. Furthermore, rotation of the blades in front of the tower causes not only aerodynamic forces on the blades but also a sudden reduction in the rotor aerodynamic torque by 2.3 % three times per revolution.
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Marchewka, Emil, Krzysztof Sobczak, Piotr Reorowicz, Damian Obidowski et Krzysztof Jóźwik. « Influence of Tip Speed Ratio on the efficiency of Savonius wind turbine with deformable blades ». Journal of Physics : Conference Series 2367, no 1 (1 novembre 2022) : 012003. http://dx.doi.org/10.1088/1742-6596/2367/1/012003.
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Abstract Improving machines efficiency and searching for their new applications are the main topics in the development of the renewable energy industry. In the case of Savonius type wind turbines, the works aim at the improvement of aerodynamic performance. The CFD simulations of a turbine equipped with deformable blades showed a significant positive impact of this enhancement on the machine aerodynamic efficiency. Previously, the investigation was carried out for a TSR (Tip Speed Ratio) equal to 0.8, typically recognized as the point of maximal efficiency for conventional Savonius wind turbines with rigid blades. However, the continuously altering shape of blades during their rotation can influence the optimal TSR. Therefore, the efficiency of the deformable blade turbine was investigated in a wide range of TSR. In this paper, the previously developed quasi-2D model with a two-way Fluid-Structure Interaction method was employed to obtain turbine efficiency characteristics as a function of TSR. The maximum power coefficient Cp was achieved at TSR = 0.9. Obtained characteristic was compared with data for a conventional rigid blades turbine, gathered with a comparable sliding mesh model.
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Kolovratník, Michal, Gukchol Jun et Ondřej Bartoš. « CFD analysis of optical probe interaction with wet steam flow field ». EPJ Web of Conferences 180 (2018) : 02045. http://dx.doi.org/10.1051/epjconf/201818002045.
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In the frame of the measurement feasibility study of the liquid phase size distribution structure in steam turbines at intermediate and high pressures, on CTU the interaction of optical probes with the wet steam flow field is investigated. In order to validate and refine the existing knowledge, a new series of CFD simulations were performed, considering turbine flow geometry, water steam characteristics according to IAPWS97 formulation, and improved boundary conditions and quality of the computing mesh. This paper briefly presents the newly obtained results
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Klein, Levin, Jonas Gude, Florian Wenz, Thorsten Lutz et Ewald Krämer. « Advanced computational fluid dynamics (CFD)–multi-body simulation (MBS) coupling to assess low-frequency emissions from wind turbines ». Wind Energy Science 3, no 2 (17 octobre 2018) : 713–28. http://dx.doi.org/10.5194/wes-3-713-2018.
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Abstract. The low-frequency emissions from a generic 5 MW wind turbine are investigated numerically. In order to regard airborne noise and structure-borne noise simultaneously, a process chain is developed. It considers fluid–structure coupling (FSC) of a computational fluid dynamics (CFD) solver and a multi-body simulations (MBSs) solver as well as a Ffowcs-Williams–Hawkings (FW-H) acoustic solver. The approach is applied to a generic 5 MW turbine to get more insight into the sources and mechanisms of low-frequency emissions from wind turbines. For this purpose simulations with increasing complexity in terms of considered components in the CFD model, degrees of freedom in the structural model and inflow in the CFD model are conducted. Consistent with the literature, it is found that aeroacoustic low-frequency emission is dominated by the blade-passing frequency harmonics. In the spectra of the tower base loads, which excite seismic emission, the structural eigenfrequencies become more prominent with increasing complexity of the model. The main source of low-frequency aeroacoustic emissions is the blade–tower interaction, and the contribution of the tower as an acoustic emitter is stronger than the contribution of the rotor. Aerodynamic tower loads also significantly contribute to the external excitation acting on the structure of the wind turbine.
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Suhri, G. E., A. Rahman, L. Dass et K. Rajendran. « The influence of tidal turbine arrangement on the wake interaction in shallow water ». Journal of Physics : Conference Series 2051, no 1 (1 octobre 2021) : 012058. http://dx.doi.org/10.1088/1742-6596/2051/1/012058.
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Abstract The arrangement of tidal turbines in the tidal farm is known to be complicated due to the resistance to the tidal flow which causes the flow to be channeled around the individual devices. To successfully implement the tidal turbine, the wake interaction between the device and its implication needs to be fully understood. Typically, the wake interaction in the array depends on the arrangement and spacing between the device in the array. In this study, a numerical analysis is conducted through the use of Computational Fluid Dynamic (CFD) approach to investigate the influence of the array setup in shallow water application and to propose a suitable array layout for possible application in Malaysia. The numerical analysis is carried out with 2 combination sets of lateral and longitudinal spacing covering 15 turbines in staggered and squared array layout. Hypothetical ‘actuator’ disk and ‘actuator’ cylinder model are used to represent the Horizontal axis turbine (HATT) and Vertical axis turbine (VATT) respectively. The results showed that the VATT model has faster wake recovery and obeys the definition of the far wake. Staggered arrays with bigger spacing are preferable for application in shallow water due to the low probability of wake merging between the rows.
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Cao, C., J. W. Chew, P. R. Millington et S. I. Hogg. « Interaction of Rim Seal and Annulus Flows in an Axial Flow Turbine ». Journal of Engineering for Gas Turbines and Power 126, no 4 (1 octobre 2004) : 786–93. http://dx.doi.org/10.1115/1.1772408.
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A combined computational fluid dynamics (CFD) and experimental study of interaction of main gas path and rim sealing flow is reported. The experiments were conducted on a two stage axial turbine and included pressure measurements for the cavity formed between the stage 2 rotor disk and the upstream diaphragm for two values of the diaphragm-to-rotor axial clearance. The pressure measurements indicate that ingestion of the highly swirling annulus flow leads to increased vortex strength within the cavity. This effect is particularly strong for the larger axial clearance. Results from a number of steady and unsteady CFD models have been compared to the measured results. Good agreement between measurement and calculation for time-averaged pressures was obtained using unsteady CFD models, which predicted previously unknown unsteady flow features. This led to fast response pressure transducer measurements being made on the rig, and these confirmed the CFD prediction.
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Ng, Shu Kai, et Akihiko Nakayama. « Investigation of the Configuration of Small Hydropower using a Novel Smoothed Particle Hydrodynamics Method ». IOP Conference Series : Earth and Environmental Science 945, no 1 (1 décembre 2021) : 012039. http://dx.doi.org/10.1088/1755-1315/945/1/012039.
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Abstract A novel Computational Fluid Dynamics (CFD) method utilizing Smoothed Particle Hydrodynamics (SPH) has been developed and applied to a simulation of flows in small hydropower systems. The simulation of the flow through a gravitational vortex turbine (GVT) small hydropower system where the flow is directed to a circular basin with a vertical-axis turbine, harnessing the rotational energy of the vortex formed to drive the turbine. Two modes of Fluid-Structure Interactions (FSI) were tested with identical flow conditions to evaluate the potential of this method to simulate complex FSI scenarios. It was found that simulation results for both one-way and two-way interactions produced reasonable results. The two-way interaction result proved to reflect more accurate FSI scenarios, but more studies are needed to provide validation.
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Suhri, Gisrina Elin, Anas Abdul Rahman, Lakshuman Dass, Kumaran Rajendran et Ayu Abdul Rahman. « INTERACTIONS BETWEEN TIDAL TURBINE WAKES : NUMERICAL STUDY FOR SHALLOW WATER APPLICATION ». Jurnal Teknologi 84, no 4 (30 mai 2022) : 91–101. http://dx.doi.org/10.11113/jurnalteknologi.v84.17731.
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The placement of tidal turbines in a tidal farm is challenging owing to the flow resistance caused by individual devices. To successfully deploy tidal turbines, the wake interaction between devices, often determined by the array's layout and spacing, must be understood. In this study, the impact of array configuration for shallow water application is examined numerically using computational fluid dynamics (CFD). This is to propose a suitable array structure for possible implementation in Malaysia. This numerical study uses 15 turbines in a staggered and squared array with two sets of lateral and longitudinal spacing combinations. The horizontal axis tidal turbine (HATT) and vertical axis tidal turbine (VATT) are represented using disc and cylindrical models, respectively. The VATT with staggered setup and greater spacing model demonstrates faster wake recovery (between 10% to 21%), compared to the squared arrangement. This meets the far wake criteria and reduces the chance of wake mixing. It is also suitable for shallow depth implementation.
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Kozak, Nikita, Fei Xu, Manoj R. Rajanna, Luis Bravo, Muthuvel Murugan, Anindya Ghoshal, Yuri Bazilevs et Ming-Chen Hsu. « High-Fidelity Finite Element Modeling and Analysis of Adaptive Gas Turbine Stator-Rotor Flow Interaction at Off-Design Conditions ». Journal of Mechanics 36, no 5 (10 août 2020) : 595–606. http://dx.doi.org/10.1017/jmech.2020.28.
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ABSTRACTThe objective of this work is to computationally investigate the impact of an incidence-tolerant rotor blade concept on gas turbine engine performance under off-design conditions. When a gas turbine operates at an off-design condition such as hover flight or takeoff, large-scale flow separation can occur around turbine blades, which causes performance degradation, excessive noise, and critical loss of operability. To alleviate this shortcoming, a novel concept which articulates the rotating turbine blades simultaneous with the stator vanes is explored. We use a finite-element-based moving-domain computational fluid dynamics (CFD) framework to model a single high-pressure turbine stage. The rotor speeds investigated range from 100% down to 50% of the designed condition of 44,700 rpm. This study explores the limits of rotor blade articulation angles and determines the maximal performance benefits in terms of turbine output power and adiabatic efficiency. The results show articulating rotor blades can achieve an efficiency gain of 10% at off-design conditions thereby providing critical leap-ahead design capabilities for the U.S. Army Future Vertical Lift (FVL) program.
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Valladares, Aitor Vega, Manuel Garcia Díaz, Bruno Pereiras et José Gonzalez Pérez. « Influence of the blade leaning angle on the performance of a radial impulse turbine for OWC converters ». Journal of Physics : Conference Series 2217, no 1 (1 avril 2022) : 012072. http://dx.doi.org/10.1088/1742-6596/2217/1/012072.
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Abstract Oscillating Water Column systems (OWC) have been in the spotlight in the last 20 years since these devices are considered one of the most promising devices among wave energy technology. These systems produce electricity by means a generator driven by a turbine, which takes advantage of the bidirectional flow created by the OWC itself. Among these turbines suitable for bidirectional flows, it is possible to find radial impulse turbines, which are the focus of this work. Traditionally, the radial impulse turbines have shown lower efficiencies than their competitors. However, the radial turbines present interesting mechanical features and, recently, some research show that the difference has been reduced. Following this thread, this work deals with another modification in the radial impulse turbine looking for a further improvement. By using a validated CFD model, it has been analysed the influence of the lean angle of the blade. Until now, all the turbines present in the literature are leaned zero degrees, leading to a strong interaction between the guide vanes and the blades. This work shows results of the same turbine, equipped with blades leaning from -5deg to 25deg, in order to determine the influence such a modification on the maximum total-to-static efficiency. Results have revealed a slight improvement in the maximum efficiency for positive leaning angles, whereas negative angles drive the turbine to worse performance.
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Zhang, Yuan, Xin Cai, Shifa Lin, Yazhou Wang et Xingwen Guo. « CFD Simulation of Co-Planar Multi-Rotor Wind Turbine Aerodynamic Performance Based on ALM Method ». Energies 15, no 17 (2 septembre 2022) : 6422. http://dx.doi.org/10.3390/en15176422.
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Considering requirements such as enhanced unit capacity, the geometric size of wind turbine blades has been increasing; this, in turn, results in a rapid increase in manufacturing costs. To this end, in this paper, we examine the aerodynamics of co-planar multi-rotor wind turbines to achieve higher unit capacity at a lower blade length. The multiple wind rotors are in the same plane with no overlaps. The ALM-LES method is used to investigate the interaction effect of the blade tip vortices, by revealing the regulation of aerodynamic performance and flow field characteristics of the multi-rotor wind turbines. The simulated results suggest an observable reduction in the blade tip vortices generated by blades located closely together, due to the breaking and absorption of the blade tip vortices by the two rotors. This results in increased aerodynamic performance and loads on the multi-rotor wind turbine. The influence between the blade tip vortex is mainly located in the range of 0.2 R from the blade tip, with this range leading to a significant increase in the lift coefficient. Thus, when the wind rotor spacing is 0.2 R, the interaction between the blade tip vortices is low.
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Zhangaskanov, Dinmukhamed, Sagidolla Batay, Bagdaulet Kamalov, Yong Zhao, Xiaohui Su et Eddie Yin Kwee Ng. « High-Fidelity 2-Way FSI Simulation of a Wind Turbine Using Fully Structured Multiblock Meshes in OpenFoam for Accurate Aero-Elastic Analysis ». Fluids 7, no 5 (11 mai 2022) : 169. http://dx.doi.org/10.3390/fluids7050169.
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With increased interest in renewable energy, the power capacity of wind turbines is constantly increasing, which leads to increased rotor sizes. With ever larger rotor diameters, the complex and non-linear fluid-structure interaction (FSI) effects on wind turbine aerodynamic performances become significant, which can be fully studied using hi-fidelity 2-way FSI simulation. In this study, a two-way FSI model is developed and implemented in Openfoam to investigate the FSI effects on the NREL Phase VI wind turbine. The fully structured multiblock (MB) mesh method is used for the fluid and solid domains to achieve good accuracy. A coupling method based on the ALE is developed to ensure rotation and deformation can happen simultaneously and smoothly. The simulation results show that hi-fidelity CFD (Computational Fluid Dynamics) and CSD (Computational Structural Dynamics) -based 2-way FSI simulation provides high accurate results for wind turbine simulation and multi-disciplinary design optimization (MDO).
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Yi, Jin-Hak, Sang-Ho Oh, Jin-Soon Park, Kwang-Soo Lee et Sang-Yeol Lee. « Flow-Turbine Interaction CFD Analysis for Performance Evaluation of Vertical Axis Tidal Current Turbines (I) ». Journal of Ocean Engineering and Technology 27, no 3 (30 juin 2013) : 67–72. http://dx.doi.org/10.5574/ksoe.2013.27.3.067.
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Yi, Jin-Hak, Sang-Ho Oh, Jin-Soon Park, Kwang-Soo Lee et Sang-Yeol Lee. « Flow-Turbine Interaction CFD Analysis for Performance Evaluation of Vertical Axis Tidal Current Turbines (II) ». Journal of Ocean Engineering and Technology 27, no 3 (30 juin 2013) : 73–78. http://dx.doi.org/10.5574/ksoe.2013.27.3.073.
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Cheng, Tai Hong, et Il Kwon Oh. « Fluid-Structure Coupled Analyses of Composite Wind Turbine Blades ». Advanced Materials Research 26-28 (octobre 2007) : 41–44. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.41.
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The composite rotor blades have been widely used as an important part of the wind power generation systems because the strength, stiffness, durability and vibration of composite materials are all excellent. In composite laminated blades, the static and dynamic aeroelasticity tailoring can be performed by controlling laminate angle or stacking sequence. In this paper, the fluid-structure coupled analyses of 10kW wind turbine blades has been performed by means of the full coupling between CFD and CSD based finite element methods. Fiber enforced composites fabricated with three types of stacking sequences were also studied. First the centrifugal force was considered for the nonlinear static analyses of the wind turbine so as to predict the deformation of tip point in the length direction and maximum stress in the root of a wind turbine. And then, the aeroelastic static deformation was taken into account with fluid-structure interaction analysis of the wind turbine. The Arbitrary Lagrangian Eulerian Coordinate was used to compute fluid structure interaction analysis of the wind turbine by using ADINA program. The displacement and stress increased apparently with the increment of aerodynamic force, but under the condition of maximum rotation speed 140RPM of the wind turbine, the displacement and stress were in the range of safety.
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Perpignan, André A. V., Stella Grazia Tomasello et Arvind Gangoli Rao. « Evolution of Emission Species in an Aero-Engine Turbine Stator ». Aerospace 8, no 1 (4 janvier 2021) : 11. http://dx.doi.org/10.3390/aerospace8010011.
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Future energy and transport scenarios will still rely on gas turbines for energy conversion and propulsion. Gas turbines will play a major role in energy transition and therefore gas turbine performance should be improved, and their pollutant emissions decreased. Consequently, designers must have accurate performance and emission prediction tools. Usually, pollutant emission prediction is limited to the combustion chamber as the composition at its outlet is considered to be “chemically frozen”. However, this assumption is not necessarily valid, especially with the increasing turbine inlet temperatures and operating pressures that benefit engine performance. In this work, Computational Fluid Dynamics (CFD) and Chemical Reactor Network (CRN) simulations were performed to analyse the progress of NOx and CO species through the high-pressure turbine stator. Simulations considering turbulence-chemistry interaction were performed and compared with the finite-rate chemistry approach. The results show that progression of some relevant reactions continues to take place within the turbine stator. For an estimated cruise condition, both NO and CO concentrations are predicted to increase along the stator, while for the take-off condition, NO increases and CO decreases within the stator vanes. Reaction rates and concentrations are correlated with the flow structure for the cruise condition, especially in the near-wall flow field and the blade wakes. However, at the higher operating pressure and temperature encountered during take-off, reactions seem to be dependent on the residence time rather than on the flow structures. The inclusion of turbulence-chemistry interaction significantly changes the results, while heat transfer on the blade walls is shown to have minor effects.
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Aurahs, L., C. Kasper, M. Kürner, M. G. Rose, S. Staudacher et J. Gier. « Water flow model turbine flow visualization study of the unsteady interaction of secondary flow vortices with the downstream rotor ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 223, no 6 (21 juillet 2009) : 677–86. http://dx.doi.org/10.1243/09576509jpe841.
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This article presents detailed flow visualization photographs, root mean square processed photography, and computational fluid dynamics (CFD) results of the interaction of the vane passage vortex and horseshoe vortex with the rotor of an axial flow turbine model. Different modes of vortex breakdown behaviour have been experimentally observed inside the rotating passage of the turbine blade. These are spiral vortex mode and bubble mode breakdown. The breakdown mode changes as the vortices are influenced by the periodic pressure field of the rotor. The measurements were taken in a vertical water channel with ink injection for flow visualization. Unsteady CFD analyses have been made with some success in prediction of the unsteady flow structures. In particular, the pre-instability behaviour of the passage vortex in the experiments matches the results of the numerical investigations.
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Guma, Giorgia, Philipp Bucher, Patrick Letzgus, Thorsten Lutz et Roland Wüchner. « High-fidelity aeroelastic analyses of wind turbines in complex terrain : fluid–structure interaction and aerodynamic modeling ». Wind Energy Science 7, no 4 (13 juillet 2022) : 1421–39. http://dx.doi.org/10.5194/wes-7-1421-2022.
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Abstract. This paper shows high-fidelity fluid–structure interaction (FSI) studies applied to the research wind turbine of the WINSENT (Wind Science and Engineering in Complex Terrain) project. In this project, two research wind turbines are going to be erected in the south of Germany in the WindForS complex-terrain test field. The FSI is obtained by coupling the CFD URANS–DES code FLOWer and the multiphysics FEM solver Kratos Multiphysics, in which both beam and shell structural elements can be chosen to model the turbine. The two codes are coupled in both an explicit and an implicit way. The different modeling approaches strongly differ with respect to computational resources, and therefore the advantages of their higher accuracy must be correlated with the respective additional computational costs. The presented FSI coupling method has been applied firstly to a single-blade model of the turbine under standard uniform inflow conditions. It could be concluded that for such a small turbine, in uniform conditions a beam model is sufficient to correctly build the blade deformations. Afterwards, the aerodynamic complexity has been increased considering the full turbine with turbulent inflow conditions generated from real field data, in both flat and complex terrains. It is shown that in these cases a higher structural fidelity is necessary. The effects of aeroelasticity are then shown on the phase-averaged blade loads, showing that using the same inflow turbulence, a flat terrain is mostly influenced by the shear, while the complex terrain is mostly affected by low-velocity structures generated by the forest. Finally, the impact of aeroelasticity and turbulence on the damage equivalent loading (DEL) is discussed, showing that flexibility reduces the DEL in the case of turbulent inflow, acting as a damper that breaks larger cycles into smaller ones.
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Javiya, Umesh, John Chew, Nick Hills et Timothy Scanlon. « Coupled FE–CFD thermal analysis for a cooled turbine disk ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 229, no 18 (18 février 2015) : 3417–32. http://dx.doi.org/10.1177/0954406215572430.
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This paper presents transient aero-thermal analysis for a gas turbine disk and the surrounding air flows through a transient slam acceleration/deceleration “square cycle” engine test, and compares predictions with engine measurements. The transient solid–fluid interaction calculations were performed with an innovative coupled finite element (FE) and computational fluid dynamics (CFD) approach. The computer model includes an aero-engine high pressure turbine (HPT) disk, adjacent structure, and the surrounding internal air system cavities. The model was validated through comparison with the engine temperature measurements and is also compared with industry standard standalone FE modelling. Numerical calculations using a 2D FE model with axisymmetric and 3D CFD solutions are presented and compared. Strong coupling between CFD solutions for different air system cavities and the FE solid model led to some numerical difficulties. These were addressed through improvement of the coupling algorithm. Overall performance of the coupled approach is very encouraging giving temperature predictions as good as a traditional model that had been calibrated against engine measurements.
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Alshroof, Osama N., Gareth L. Forbes, Nader Sawalhi, Robert B. Randall et Guan H. Yeoh. « Computational Fluid Dynamic Analysis of a Vibrating Turbine Blade ». International Journal of Rotating Machinery 2012 (2012) : 1–15. http://dx.doi.org/10.1155/2012/246031.
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This study presents the numerical fluid-structure interaction (FSI) modelling of a vibrating turbine blade using the commercial software ANSYS-12.1. The study has two major aims: (i) discussion of the current state of the art of modelling FSI in gas turbine engines and (ii) development of a “tuned” one-way FSI model of a vibrating turbine blade to investigate the correlation between the pressure at the turbine casing surface and the vibrating blade motion. Firstly, the feasibility of the complete FSI coupled two-way, three-dimensional modelling of a turbine blade undergoing vibration using current commercial software is discussed. Various modelling simplifications, which reduce the full coupling between the fluid and structural domains, are then presented. The one-way FSI model of the vibrating turbine blade is introduced, which has the computational efficiency of a moving boundary CFD model. This one-way FSI model includes the corrected motion of the vibrating turbine blade under given engine flow conditions. This one-way FSI model is used to interrogate the pressure around a vibrating gas turbine blade. The results obtained show that the pressure distribution at the casing surface does not differ significantly, in its general form, from the pressure at the vibrating rotor blade tip.
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Amin, E. M., G. E. Andrews, M. Pourkashnian, A. Williams et R. A. Yetter. « A Computational Study of Pressure Effects on Pollutant Generation in Gas Turbine Combustors ». Journal of Engineering for Gas Turbines and Power 119, no 1 (1 janvier 1997) : 76–83. http://dx.doi.org/10.1115/1.2815565.
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A numerical study of the effect of pressure on the formation of NOx and soot in an axisymmetric 30 deg counterrotating axial swirler lean low-NOx gas turbine combustor has been conducted. This has previously been studied experimentally and this CFD investigation was undertaken to explain the higher than expected NOx emissions. The combustion conditions selected for the present study were 300 K inlet air, 0.4 overall equivalence ratio, and pressures of 1 and 10 bar. The numerical model used here involved the solution of time-averaged governing equations using an elliptic flow-field solver. The turbulence was modeled using algebraic stress modeling (ASM). The thermochemical model was based on the laminar flame let formulation. The conserved scalar/assumed pdf approach was used to model the turbulence chemistry interaction. The study was for two pressure cases at 1 and 10 bar. The turbulence–chemistry interaction is closed by assumption of a clipped Gaussian function form for the fluctuations in the mixture fraction. The kinetic calculations were done separately from the flowfield solver using an opposed laminar diffusion flame code of SANDIA. The temperature and species profiles were made available to the computations through look-up tables. The pollutants studied in this work were soot and NO for which three more additional transport equations are required, namely: averaged soot mass fraction, averaged soot particle number density, and finally averaged NO mass fraction. Soot oxidation was modeled using molecular oxygen only and a strong influence of pressure was predicted. Pressure was shown to have a major effect on soot formation.
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Gao, Yanjing, Hongwei Liu, Yonggang Lin, Yajing Gu et Yiming Ni. « Hydrodynamic Analysis of Tidal Current Turbine under Water-Sediment Conditions ». Journal of Marine Science and Engineering 10, no 4 (8 avril 2022) : 515. http://dx.doi.org/10.3390/jmse10040515.
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The rivers connecting oceans generally carry sediment due to water and soil losses in China. Additionally, the maximum sediment concentration is 300 g/L, which is much higher than that of other countries. It is unknown whether seawater with sand particles will affect the power of tidal current turbine blades. It is therefore necessary to study the capture power of tidal current turbines in the water-sediment environment. In this study, the blade was divided into a number of transversal airfoil elements based on the blade element theory. The CFD-DPM model was employed to study the lift and drag coefficients of airfoil under multiphase flow, and the fluid–particle interaction was considered. The accuracy of this presented model was assessed using the experimental data of a 120 kW tidal current turbine in a water-sediment environment. Good agreement between the predictions and experimental data was observed. The effect of particle properties on the lift coefficient and the drag coefficient of airfoil were investigated in detail. Furthermore, the 120 kW tidal current turbine power was calculated based on the Blade Element Momentum theory under different particle concentrations. The results show that small diameter particles can improve the tidal current turbine power and the large diameter particle can reduce the power.
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Malael, Ion, et Ioana Octavia Bucur. « Numerical Evaluation of the Flow around a New Vertical Axis Wind Turbine Concept ». Sustainability 13, no 16 (12 août 2021) : 9012. http://dx.doi.org/10.3390/su13169012.
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In order to develop a sustainable economy based on the efficient use of green energy resources, it is necessary to research and innovate systems such as wind turbines. In this paper, a new configuration for vertical axis wind turbines was proposed and numerically analyzed using CFD methods. The concept is based on solving the starting problem of lift-based vertical axis wind turbines. The new concept consists of three blades with different chords, arranged at different radii so that the interaction between the blades is reduced and the operation in the vortex wake is minimal, thus reducing the losses. Through comparing a classic case of an H-Darrieus wind turbine with the new concept, not only were satisfying results regarding the blade-to-blade interaction presented, but an increased efficiency of up to 10% was also observed. Among the presented results is the variation of the vorticity magnitude at different positions of the blades, thus, the concept’s blade-to-blade interaction is reduced. Conclusions drawn after the investigation are in favor of the proposed geometry and the concept should be pursued further.
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Panagiotopoulos, A., A. Židonis, G. A. Aggidis, J. S. Anagnostopoulos et D. E. Papantonis. « Flow Modeling in Pelton Turbines by an Accurate Eulerian and a Fast Lagrangian Evaluation Method ». International Journal of Rotating Machinery 2015 (2015) : 1–13. http://dx.doi.org/10.1155/2015/679576.
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The recent development of CFD has allowed the flow modeling in impulse hydro turbines that includes complex phenomena like free surface flow, multifluid interaction, and unsteady, time dependent flow. Some commercial and open-source CFD codes, which implement Eulerian methods, have been validated against experimental results showing satisfactory accuracy. Nevertheless, further improvement of accuracy is still a challenge, while the computational cost is very high and unaffordable for multiparametric design optimization of the turbine’s runner. In the present work a CFD Eulerian approach is applied at first, in order to simulate the flow in the runner of a Pelton turbine model installed at the laboratory. Then, a particulate method, the Fast Lagrangian Simulation (FLS), is used for the same case, which is much faster and hence potentially suitable for numerical design optimization, providing that it can achieve adequate accuracy. The results of both methods for various turbine operation conditions, as also for modified runner and bucket designs, are presented and discussed in the paper. In all examined cases the FLS method shows very good accuracy in predicting the hydraulic efficiency of the runner, although the computed flow evolution and the torque curve exhibit some systematic differences from the Eulerian results.
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Song, Haiqin, Jinfeng Zhang, Ping Huang, Haikun Cai, Puyu Cao et Bo Hu. « Analysis of Rotor-Stator Interaction of a Pump-Turbine with Splitter Blades in a Pump Mode ». Mathematics 8, no 9 (1 septembre 2020) : 1465. http://dx.doi.org/10.3390/math8091465.
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The pump-turbine is the core component of a pumped storage power station. This paper considers an in-depth analysis of the rotor-stator interaction characteristics under computational fluid dynamics (CFD) and experimental measurements of pump-turbine with splitter blades used in a domestic pumped storage power station. The results show that as the guide blade opening increases, the rotor-stator interaction of the pump-turbine intensifies and the magnitude of the runner radial force and its pulsation amplitude as well as the magnitude of the guide blade water moment and its pulsation amplitude also increase. In addition, when the opening degree increases from 9.8° to 17.5°, the influence on the main frequency is mainly reflected in the phase change. While the opening degree increases from 17.5° to 24.8°, the influence on the main frequency is mainly reflected in the amplitude change. Moreover, the amplitude of 5fn at opening 9.8° and opening 24.8° is greater than the optimal opening 17.5°, indicating that deviation from the optimal opening will aggravate the difference of rotor-stator interaction between splitter blades and guide blades. In the paper, the influence of guide blade openings on the rotor-stator interaction between the splitter guide blade is studied, which provides a theoretical reference for the stable operation of the pump-turbine.
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Kumar, K. Ramesh, et M. Selvaraj. « Review on Energy Enhancement Techniques of Wind Turbine System ». Advances in Science and Technology 106 (mai 2021) : 121–30. http://dx.doi.org/10.4028/www.scientific.net/ast.106.121.
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Wind energy is the quickest growing sustainable energy resource in present energy crisis scenario. It has been considered as one of the most viable sources of environmental friendly energy. Starting investment cost of the wind turbine plant is exorbitant. Moreover, production cost of the wind turbine blade is about 20% of the wind turbine plant cost. It is fundamental to decrease the life-cycle cost of wind turbine plant by efficient utilization available wind speed. Optimized diffuser (Convergent divergent type and Convergent type) has been developed with highest possible pressure difference between inlet and exit of shroud, Area Ratio of inlet to exit section, wall length, incident angle and various flow qualities to enhance the available wind velocity considerably. The suitable tiny riblets on external layer of turbine blade have been introduced to lessen the skin friction drag force. Moreover, dual rotor blade with various rotor sizes for primary and secondary rotor, direction of rotor rotation, separation distance between them has been studied to augment wind turbine power generation and improvement in cut-in-speed. Moreover, comparative study will be conducted with standard (bare) wind turbine. Based on the above features, available wind speed increased significantly. In addition, various experiments and CFD analysis work still to be done to assess Diffuser based Wind Turbine model which is much closer to realistic product with available interaction. Due to the above additional features of the turbine system, the utilization of wind speed gets augmented with greater power production.
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Chen, Funan, Huili Bi, Soo-Hwang Ahn, Zhongyu Mao, Yongyao Luo et Zhengwei Wang. « Investigation on Dynamic Stresses of Pump-Turbine Runner during Start Up in Turbine Mode ». Processes 9, no 3 (10 mars 2021) : 499. http://dx.doi.org/10.3390/pr9030499.
Texte intégralRésumé :
The startup process occurs frequently for pumped storage units. During this process, the rotating rate that changes rapidly and unsteady flow in runner cause the complex dynamic response of runner, sometimes even resonance. The sharp rise of stress and the large-amplitude dynamic stresses of runner will greatly shorten the fatigue life. Thus, the study of start-up process in turbine mode is critical to the safety operation. This paper introduced a method of coupling one dimensional (1D) pipeline calculation and three-dimensional computational dynamics (3D CFD) simulation to analyze transient unsteady flow in units and to obtain more accurate and reliable dynamic stresses results during start up process. According to the results, stress of the ring near fixed support increased quickly as rotating rate rose and became larger than at fillets of leading edge and band in the later stages of start-up. In addition, it was found that dynamic response can be caused by rotor stator interaction (RSI), but also could even be generated by the severe pressure fluctuation in clearance, which can also be a leading factor of dynamic stresses. This study will facilitate further estimation of dynamic stresses in complex flow and changing rotating rate cases, as well as fatigue analysis of runner during transient operation.
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Guha, A. « Computation, analysis and theory of two-phase flows ». Aeronautical Journal 102, no 1012 (février 1998) : 71–82. http://dx.doi.org/10.1017/s0001924000065556.
Texte intégralRésumé :
AbstractThe non-equilibrium fluid mechanics and thermodynamics of two-phase vapour-droplet and gas-particle flow are considered. The formation of the droplets as well as their subsequent interaction with the vapour are discussed. Five topics have been given particular attention: (i) CFD application to unsteady condensation waves, (ii) CFD application to shock waves moving through a vapour-droplet mixture, (iii) a new theory of nucleation of water droplets in steam turbines based on Monte Carlo simulation (steam turbines are responsible for 80% of global electricity production and the presence of moisture significantly reduces the turbine efficiency costing £50m per annum in the UK alone), (iv) a unified theory for the interpretation of total pressure and total temperature in two-phase flows and, (v) a unified theory of particle transport in a turbulent flowfield.
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Gupta, B., T. Hoshi et H. Yoshizawa. « High durability variable geometry turbine for commercial vehicle turbochargers ». Journal of Physics : Conference Series 2217, no 1 (1 avril 2022) : 012080. http://dx.doi.org/10.1088/1742-6596/2217/1/012080.
Texte intégralRésumé :
Abstract Transportation sector constitutes a major portion in the Green House Gas (GHG) emissions of the world. Reduction of GHG emission requires the development of highly efficient Internal Combustion Engines (ICE) which are downsized using turbochargers that provide compressed air for cleaner combustion. Variable Geometry (VG) turbochargers are widely accepted for this application because of the ability of VG turbine to function at wider flow range. This ensures the supply of compressed air at low engine speeds also. However, the interaction between stator vanes and turbine rotor has been a major issue in terms of High Cycle Fatigue (HCF) of such a turbocharger. Till now, a conservative design approach constrained the maximum rotation speed to below resonance speed for vibration mode 2. But, to achieve further downsizing it would be necessary to challenge higher rotation speeds. This paper will firstly introduce the tip-timing experiment and CFD-FEA simulations used to evaluate the HCF of VG turbine, and secondly it discusses the results of new VG turbine system which achieved safe operability even at vibration mode 3, both on simulation and experiment. The tip-timing experiment was conducted at 680°C on hot gas stand test bench with optical sensors installed circumferentially around the rotor tip. These measurements have been verified and validated with the safety factor calculated from blade surface pressure data obtained from transient rotor CFD simulations.
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Gad-el-Hak, Ibrahim. « Fluid–Structure Interaction for Biomimetic Design of an Innovative Lightweight Turboexpander ». Biomimetics 4, no 1 (22 mars 2019) : 27. http://dx.doi.org/10.3390/biomimetics4010027.
Texte intégralRésumé :
Inspired by bird feather structures that enable the resistance of powerful aerodynamic forces in addition to their lower weight to provide stable flight, a biomimetic composite turbine blade was proposed for a low-temperature organic Rankine cycle (ORC) turboexpander that is capable of producing lower weight expanders than that of stainless steel expanders, in addition to reduce its manufacturing cost, and hence it may contribute in spreading ORC across nonconventional power systems. For that purpose, the fluid–structure interaction (FSI) was numerically investigated for a composite turbine blade with bird-inspired fiber orientations. The aerodynamic forces were evaluated by computational fluid dynamics (CFD) using the commercial package ANSYS-CFX (version 16.0) and then these aerodynamic forces were transferred to the solid model of the proposed blade. The structural integrity of the bird-mimetic composite blade was investigated by performing finite element analysis (FEA) of composite materials with different fiber orientations using ANSYS Composite PrepPost (ACP). Furthermore, the obtained mechanical performance of the composite turbine blades was compared with that of the stainless steel turbine blades. The obtained results indicated that fiber orientation has a greater effect on the deformation of the rotor blades and the minimum value can be achieved by the same barb angle inspired from the flight feather. In addition to a significant effect in the weight reduction of 80% was obtained by using composite rotor blades instead of stainless steel rotor blades.
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Kosiak, Pavlo, Jindřich Hála, Martin Luxa et Jaromír Příhoda. « CFD Simulation of Transonic Flow Through the Tip-Section Turbine Blade Cascade Intended for the Long Turbine Blade ». MATEC Web of Conferences 369 (2022) : 01004. http://dx.doi.org/10.1051/matecconf/202236901004.
Texte intégralRésumé :
The paper deals with numerical simulations of transonic flow through the turbine blade cascade consisting of flat profiles. The cascade is one of variants of the tip section of ultra-long blades, which were designed for the last stage of the steam turbine. CFD simulations were realized by means of the ANSYS CFX commercial software using the γ-Reθ bypass transition model completed by the two-equation SST turbulence model. Some simulations were made only by the SST turbulence model for comparison. Numerical results were compared with experimental data. Calculations performed for two nominal regimes and two computational domains. In addition to the standard computational domain, the calculation was performed for a domain with an extended output part for the suppression of reflected shock waves. The interaction of the inner branch of the exit shock wave with the boundary layer on the blade suction side leads in the both flow regimes to the flow separation followed by the transition to turbulence. The flow structure in the blade cascade obtained for the extended domain corresponds well to experimental results.