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The variable-frequency operation of the coreless induction melting furnace (IMF) has been investigated in detail both theoretically and experimentally. The time variations of the operational impedance value of the IMF, owing to the time-varying resonance frequency and crucible conditions, have been derived for typical melting cycles by using a variable parallel RLC model derived from extensive field measurements. The work coil and its crucible are supplied at variable frequency from a multipulse rectifier and a current-fed load-resonant inverter cascade. Uncharacteristic current harmonics caused by cross-modulation phenomenon across the alternating current ac-dc-ac link have been derived theoretically and verified by field tests. These theoretical results and extensive field measurements on a sample IMF installation have shown the following: 1) The major power quality problem of an IMF as a load on the power system is the injection of various characteristic and uncharacteristic current harmonics to the grid; 2) line currents on the supply side are nearly balanced; 3) flicker contribution is below the limits specified in the standards; 4) reactive power demand is relatively low and the variations in the magnitude and rate of change of active power are not drastic; and 5) no voltage sag and swell phenomena arising from furnace operation occur.
This paper presents gas emissions from turbulent chemical flow inside a model combustor, for different blending ratios of hydrogen–methane composite fuels. Gas emissions such as CO and O2 from the combustion reaction were obtained using a gas analyzer. NOx emissions were measured with a NOx analyzer. The previously obtained flame temperature distributions were also presented. As the amount of hydrogen in the mixture increases, more hydrogen is involved in the combustion reaction, and more heat is released, and the higher temperature levels are resulted. The results have shown that the combustion efficiency increases and CO emission decreases when the hydrogen content is increased in blending fuel. It is also shown that the hydrogen–methane blending fuels are efficiently used without any important modification in the natural gas burner. Copyright © 2011 John Wiley & Sons, Ltd.
This paper presents the effect of swirl number on combustion characteristics such as temperature, velocity, gas concentrations in a natural gas diffusion flame. Numerial simulations carried out using the commercial computational fluid dynamics (CFD) code, Fluent by choosing appropriate model parameters. The combustion reaction scheme in the flame region was modeled using eddy dissipation model with one step global reaction scheme. A standard k-ε turbulence model for turbulent closure and P-I radiation model for flame radiation inside the combustor is used in the numerical simulations. In order to investigate the swirling effect on the combustion characteristics, seven different swirl numbers including 0; 0.1; 0.2; 0.3; 0.4; 0.5; and 0.6 are used in the study. Numerical results are validated and compared with the published experimental and simulation results. A good consistency is found between the present results and those published measurement and simulation results in the available literature. The results shown that the combustion characteristics such as the flame temperature, the gas concentrations including CO2, H2O, O2, and CH4 are strongly affected by the swirl number. Depending on the degree of swirl, the fluid dynamics behavior of natural gas diffusion flame including axial velocity distribution, central recirculation zone (CTRZ) and external recirculation zone (ETRZ) were also strongly affected.
The objective of this work is to investigate numerically the turbulent non-premixed hydrogen (H2) and hydrogen–hydrocarbon flames in a small burner. Numerical studies using Fluent code were carried out for air-staged and non-staged cases. The effects of fuel composition from pure hydrogen to natural gas (100%H2, 70%H2+30%CH4, 10%H2+90%CH4, and 100%CH4) were also investigated. The predictions are validated and compared against the experimental results previously obtained and results from the literature. Turbulent diffusion flames are investigated numerically using a finite volume method for the solution of the conservation equations and reaction equations governing the problem. Although, three different turbulence models were tested, the standard k–ε model was used for the modelling of the turbulence phenomena in the burner. The temperature and major pollutant concentrations (CO and NOx) distributions are in good agreement with the existing experimental results. Air staging causes rich and lean combustion regions thus lower NOx emissions through the combustor exit. Blending hydrogen with methane causes considerable reduction in temperature levels and thus NO emissions. Increasing the mixture ratio from stoichiometric to leaner mixtures also decreases the temperature and thus NO emissions. Hydrogen may be considered a good alternative fuel for burners, as its use reduces the emission of pollutants, and as it is a renewable synthetic fuel. Copyright © 2005 John Wiley & Sons, Ltd.
In this paper, the coreless medium-frequency induction melting furnace (IMF) system is represented by alternative field-data-based models, developed specifically for power quality studies. The IMF operation has been represented by a variable series RL circuit, to model the fundamental components of electrical quantities, and a shunt-connected current source, to model the generated harmonics and interharmonics over a typical melting cycle. Both the sinusoidal coding method applied to the major harmonics and interharmonics in the supply line currents obtained from field measurements and the raw data have been used in the developed models. It has been shown that the sinusoidal coding method can be used to satisfactorily represent the operation of the IMF system as seen from the supply terminals, with a minimum data storage requirement, and can be used to construct efficient IMF databases for power quality studies. The power quality problems of the IMF system, particularly the problematic time-varying interharmonic voltage distortion, and the interaction of those time-varying interharmonic currents with the passive shunt filter installations connected to the same bus have been investigated in detail, using the developed models.
This paper describes the design and field implementation of a hybrid active power filter (HAPF) system to suppress time-varying interharmonics injected into the grid by medium-frequency coreless induction melting furnaces (IMFs). In a sample steel melt shop, variable-frequency load-resonant inverters of works coils are supplied from the medium-voltage grid via 12- and 24-pulse thyristor rectifiers. The cross-modulation phenomenon in ac-dc-ac link of the medium-frequency coreless IMF installations produces interharmonics and characteristic and uncharacteristic harmonics in the grid-side line current waveforms. Furthermore, frequencies of dominant interharmonics are migrating in time inside a frequency window as the operating frequency of the load-resonant inverter varies in wide range during a melting cycle. The HAPF system developed for this application consists of nine HAPF units operating in parallel in current control mode and is connected to the grid via a coupling transformer. Current control is achieved by extracting high-order fixed frequency characteristic harmonic components from the reference current signal and defining a fixed hysteresis band for each HAPF unit. The input LC filter of the HAPF system is optimized in the design stage by taking into account the frequency range of prominent interharmonics. Theoretical findings are verified in a sample steel melt shop by extensive field measurements. Field test results have shown that the developed HAPF system suppresses successfully the dominant time-varying interharmonics and harmonics in the frequency range from 250 to 650 Hz.
The variable frequency operation of the coreless induction melting furnace has been investigated in detail both theoretically and experimentally. The time variations of the operational impedance value of the induction melting furnace, owing to the time-varying resonance frequency and crucible conditions, have been derived for typical melting cycles by using a variable, parallel RLC model derived from extensive field measurements. The work coil and its crucible is supplied at variable frequency from a multi-pulse rectifier and a current-fed, load resonant inverter cascade. Uncharacteristic current harmonics caused by cross modulation phenomenon across the AC-DC-AC link have been derived theoretically, and verified by field tests. These theoretical results and extensive field measurements on a sample induction melting furnace installation have shown that i. the major power quality problem of an induction melting furnace as a load on the power system, is the injection of various characteristic and uncharacteristic current harmonics to the grid, ii. line currents on the supply side are nearly balanced, iii. flicker contribution is below the limits specified in the standards, iv. reactive power demand is relatively low and the variations in the magnitude and rate of change of active power are not drastic, and v. no voltage sag and swell phenomena arising from furnace operation occur.
This study presents the relationship between exhaust gas temperature (EGT) and engine operational parameters at two different power settings, including maximum continuous and take-off, in the CFM56-7B turbofan engine. The ground measurements of engine operational parameters including net thrust, fuel flow, low rotational speed, core rotational speed, pressure ratio, air temperature at engine fan inlet, take-off margin temperature, and thrust-specific fuel consumption of 51 different CFM56-7B engines are used to find the relationship mentioned in the study. This engine type is selected due to its common use by the civil aviation sector. In accordance with the results of multiple linear regression analysis, it was shown that EGT is affected by the engine operational parameters in different rate. The relationship between EGT and the operational parameters used in the maximum continuous power setting is slightly stronger than that of take-off power setting, R 2 =0.73 and 0.69, respectively. The fuel flow, thrust-specific fuel consumption, and take-off margin temperature are determined to be the most significant operational parameters in the correlations used to predict the EGT of 51 CFM56-7B turbofan engines in maximum continuous and take-off power settings, R 2 =0.28, 0.23, and 0.35 and R 2 =0.27, 0.14, and 0.60, respectively. It is found that there are good agreements between the predicted and measured values of EGT in the study. It can be concluded that the proposed technique is an effective tool for the EGT estimation of the turbofan engine.
Ricci collineations of the Bianchi types I and III, and Kantowski–Sachs spacetimes are classified according to their Ricci collineation vector (RCV) field of the form (i)–(iv) one component of ξ a (x b ) is nonzero, (v)–(x) two components of ξ a (x b ) are nonzero, and (xi)–(xiv) three components of ξ a (x b ) are nonzero. Their relation with isometries of the spacetimes is established. In case (v), when det (R ab )=0, some metrics are found under the time transformation, in which some of these metrics are known, and the other ones new. Finally, the family of contracted Ricci collineations (CRC) are presented.
The current research has investigated the effects of magnetic fields on molecular structures, especially on flame formation, flame behavior and emission gases. This study particularly examines the phenomenon of combustion instability and emission characteristics of CH4 and CH4/H2 fuels under lean combustion conditions and under external acoustic forcing. Conducted within a combustor utilizing premixing and swirl techniques, experiments strategically generated magnetic fields in specific regions: the burner input, pre-mixer, and fuel supply lines. Trials maintained a constant magnetic field intensity of 3500 gauss, with a thermal output of 3 kW, swirl number of 1, and equivalency ratio of 0.7. Evaluation of acoustic resonance was performed at 95 Hz and 175 Hz frequencies within the combustion chamber. Findings suggest that applying a magnetic field positively impacts the combustion process, reducing instabilities in fuels like CH4 and CH4/H2, especially at a 95 Hz frequency. During pure methane combustion, CO emissions initially measured 4785 ppm but decreased to 4143 ppm under the magnetic field's influence. Introducing the magnetic field to the pre-mixer increased CO emissions to 4233 ppm, while its application to the fuel line reduced emissions to 4104 ppm. For the CH4/H2 fuel mix, CO emissions decreased from 2638 ppm to 1961 ppm with the magnetic field, indicating improved combustion and reduced pollutant gases, including CO and NOx. This study highlights the potential of magnetic fields to improve combustion efficiency and address environmental concerns.
A medium power Current Source Converter (CSC) based Active Power Filter (APF) system is designed and implemented to suppress the amplification of low order harmonics at the Medium Voltage (MV) interface bus between the distribution and transmission systems, owing to the presence of large shunt capacitor banks installed only for reactive power compensation. For this purpose, four CSC based APF units designed at 1.0 kV are operated in parallel, and connected to the 31.5 kV MV bus via a specially designed coupling transformer. In each APF module, a specially designed LC-type input filter eliminates the switching ripples, and active damping method embedded into the control software suppresses harmonic frequencies around the natural frequency of the input filter. The resulting system can operate at relatively high frequencies in the range from 2.0 to 3.0 kHz, depending upon which selected harmonics among 5th, 7th, 11th, and 13th are to be eliminated. Furthermore, in order to reduce the installed capacity of CSCs, Selective Harmonic Amplification Method (SHAM) is applied to the APF system described in the paper. MV APF system has been built as a mobile system for temporary connection to a problematic MV interface bus, until a permanent solution is found for that location in the distribution system.
In this study, we have focused on commonly used 14 different small wind turbine airfoils (A18, BW3, Clark Y, E387, FX77, NACA 2414, RG 15, S822, S823, S6062, S7012, SD6060, SD7032, SD7062). The main purpose of the study is to determine the lift, drag and lift/drag coefficients of these airfoils with numerical analysis and to verify 2 best airfoil\'s results with experimental analysis. Airfoils were determined from past studies on small wind turbines. Numerical analyzes of the airfoils were done with Ansys Fluent fluid dynamics program. Experimental analyzes were done at wind tunnel in Erciyes University, Turkey. Lift and drag coefficients of these airfoils were determined for 50,000-100,000-200,000 Reynolds numbers.
This study aimed to investigate the numerical modelling parameters that are in good agreement with experimental data for the temperature distribution of a non-premixed swirling methane flame. All numerical calculations have been performed with FLUENT, a computational fluid dynamics code. P-1 radiation model has been chosen for all numerical calculations. In addition, the swirl number has been taken 0.4 value to validate the results with respect to reference experimental data. All comparisons have been performed in axial and radial temperature distributions according to experimental data. Firstly, the number of swirl has been defined as a user-defined function. Thus, the effect of defining user-defined functions has been examined in the swirl number. Secondly, the model constant (A) of the eddy dissipation combustion model has been investigated to determine suitable value. After that, the eddy dissipation and PDF mixture fraction combustion models have been compared with each other. Finally, k-ε standard, realizable and RNG models have been analyzed to determine the proper turbulence model. The results showed that to define the swirl number as a user-defined function in the comparison tests has not been an important effect to obtain good agreement with the experimental temperature distribution data. It has been found that the value of one for the Eddy dissipation model constant is suitable for this model. It has also been found that the experimental results in both combustion models give approximate results, but the PDF model is particularly better at axial temperature distribution. Moreover, it has been seen that the k-ε realizable turbulence model is more suitable for this model.
Wind energy has an increased usage in last years. Its importance is because of the renewability and potential for usage with a low budget. In this study we focus on the small wind turbines which can easily usable by public and small operations with a small budget. 14 types of best small wind turbine airfoils (A18, BW3, Clark Y, E387, FX77, NACA 2414, RG 15, S822, S823, S6062, S7012, SD6060, SD7032, SD7062) determined from past studies and examined with Ansys Fluent fluid dynamics program. Their lift and drag coefficients determined for 50000 Reynolds number which is a function of Kayseri’s common wind speed and air density. As a result best suited small wind turbine airfoil type is determined for Kayseri usage.
Abstract In this study, the effect of swirl number, gas composition and CO 2 dilution on combustion and emission behaviour of CNG/H 2 /CO 2 gas mixtures was experimentally investigated in a laboratory scale combustor. Irrespective of the gas composition, thermal power of the combustor was kept constant (5 kW). All experiments were conducted at or near stoichiometric and the local atmospheric conditions of the city of Kayseri, Turkey. During experiments, swirl number was varied and the combustion performance of this combustor was analysed by means of centreline temperature distributions. On the other hand, emission behaviour was examined with respect to emitted CO, CO 2 and NO x levels. Dynamic flame behaviour was also evaluated by analysing instantaneous flame images. Results of this study revealed the great impact of swirl number and gas composition on combustion and emission behaviour of studied flames.
In this paper, the coreless, medium frequency induction melting furnace (IMF) system, has been represented by alternative field-data-based models, developed specifically for power quality studies. The IMF operation has been represented by a variable series RL circuit to model the fundamental components of electrical quantities, and a shunt-connected current source, to model the generated harmonics and interharmonics over a typical melting cycle. Both the sinusoidal coding method applied to the major harmonics and interharmonics in the supply line currents obtained from field measurements and also raw data, have been used in the developed models. It has been shown that the sinusoidal coding method can be used to satisfactorily represent the operation of the IMF system as seen from the supply terminals, with a minimum data storage requirement, and can be used to construct efficient IMF databases for power quality studies. The power quality problems of the IMF system, in particular the problematic time-varying interharmonic voltage distortion, and the interaction of those time-varying interharmonic currents with the passive shunt filter installations connected to the same bus have been investigated in detail, using the developed models.
Chemical composition of synthetic gas and concentration of its components depend on gasification process and feedstock. Synthetic gas mainly consists of hydrogen (H2) and carbon monoxide (CO), and may contain trace amounts of carbon dioxide (CO2) and methane (CH4). In this study, combustion and emission characteristics of H2/CO/CH4/CO2 blending syngas mixtures with high H2/CO ratio were experimentally investigated in a swirl-stabilized premixed combustor. Furthermore, stable operating ranges (flashback and blowout equivalence ratios) of such mixtures and flame response of 67.5%H2-22.5%CO-5%CO2-5%CH4 mixture to acoustic forcing were also detected. During the experiments, CH4 amount in tested gas mixtures varied between 5% and 20% by volume (at intervals of 5%), and H2/CO ratio and CO2 concentration were kept constant at the values of 3 and 5%, respectively. As a consequence, mixtures of 67.5%H2-22.5%CO-5%CO2-5%CH4, 63.75%H2-21.25%CO-5%CO2-10%CH4, 60%H2-20%CO-5%CO2-15%CH4 and 56.25%H2-18.75%CO-05%CO2-20%CH4 were derived and tested under the same boundary and physical conditions. All experiments were conducted at 0.4 equivalence ratio (Φ) and 0.2 geometric swirl number (SN). Preliminarily, stable operating ranges of respective gas mixtures were determined to find an equivalence ratio at which all gas mixtures could be tested without causing any flame instability and then, CH4 addition effects on combustion and emission characteristics of such mixtures were evaluated via utilizing axial and radial temperature, CO and O2 profiles. Lastly, flame behavior of 67.5%H2-22.5%CO-5%CO2-5%CH4 mixture was evaluated under externally modified acoustic conditions. Acoustic field in the combustor was mechanically altered by using side-mounted loudspeakers in the frequency range of 30–200 Hz. To identify flame instabilities and to evaluate the degree of coupling between heat release and pressure oscillations, pressure sensors and photodiodes installed on combustion chamber and burner were utilized. Results of this study showed that CH4 addition to synthetic gas mixtures improves rich flammability limits, and increases flame temperature, flame height and emissions. Under externally modified acoustic conditions, flame behavior slightly alters (flashback and blowout does not occur). Additionally, pollutant emissions improve in an environment-friendly manner under such conditions.
Using generalized building blocks for the design of power electronics converters is advantageous in terms of scalability, modularity, power density, and reliability. For the control of those power electronic converters composed of Power Electronics Building Blocks (PEBBs), an easily scalable and modular control system should also be integrated. In this paper, a hierarchical control system architecture is proposed for the first time for a modular Hybrid Active Power Filter (HAPF) system in order to suppress interharmonics, which their magnitudes and frequencies change dynamically in time, produced by Induction Melting Furnace (IMF). The proposed control system architecture is successfully implemented in the field on a 2.7-MVA modular HAPF system for a steel melting facility equipped with three IMFs. The performance of the HAPF system and the proposed control architecture is verified by the intensive field tests. The overall system has been working successfully in a steel melting facility since March, 2013.
In this study, combustion instabilities and flue gas emission changes under different dilutions of N2 (nitrogen) and Ar (argon) of a promising biogas mixture (70% CH4 - 30% CO2) in the fight against greenhouse gas emissions were investigated. In the experiments, additions were made from 0% to 50% at intervals of 10% for both gases. In order to detect the instability of the flame, external acoustic enforcements at different frequencies was applied through the speakers placed in the combustion chamber arms. The dynamic pressure fluctuation values were recorded. The results showed that low dilution ratios were effective in reducing flame instability for both inert gases. However, as the dilution ratio increased, the fuel/air mixture became leaner and blowoff occurred. In the case of comparing two different gases, it has been observed that the effect of argon gas on reducing dynamic pressure fluctuation is higher. Burner outlet temperature and brightness values of the flame decreased in both Ar and N2 dilution. CO and NOx emissions increased with increasing diluent volume for all dilution conditions. When the emissions of the two diluent gases are compared, the CO emission, which was 3134 ppm in the undiluted condition, increased up to 4949 ppm in 50% Ar dilution, while it increased to 4521 ppm in 50% N2 dilution.
In this paper, the medium frequency induction melting furnace (IMF) system, has been represented by field-data-based models, developed specifically for power quality studies. The IMF is an electrical furnace in which heat is applied by induction heating of the metal and its operation injects various time-varying harmonic and interharmonic currents to the power system, which should be analyzed in terms of power quality. In this research work, the IMF operation has been represented by a variable series RL circuit to model the fundamental components of electrical quantities, and a shunt-connected current source, to model the generated harmonics and interharmonics over a typical melting cycle. Based on the similarity between the spectrums of speech signals and that of the IMF current, sinusoidal coding method is applied to represent the major harmonics and interharmonics of the supply line currents obtained from field measurements of the IMFs. It has been shown that the sinusoidal coding method can be used to satisfactorily represent the operation of the IMF system as seen from the supply terminals, with a minimum data storage requirement, and can be used to construct efficient IMF databases for power quality studies. The power quality problems of the IMF system, in particular the problematic time-varying interharmonic voltage distortion have been investigated in detail, using the developed model.
Bu makalede; hava fazlalık katsayısının yanma verimi ve emisyonlara etkisinin belirlenmesi amaçlanmıştır. İki farklı yakıt, üç farklı sıvı yakıt kazanında yakılmış ve duman kanalından değişik radyal uzaklıklarda kazan yanma verimleri ve emisyon davranışları deneysel olarak incelenmiştir. Yapılan çalışmalar ile çok sayıda deneysel veriler elde edilmiştir. Hava fazlalık değeri arttıkça NOX emisyonunun genellikle azaldığı, SO2 emisyonun fazla değişmediği görülmüştür. Hava fazlalık değeri arttıkça CO emisyonunun ve ısıl verimin azaldığı görülmüştür. Ayrıca SO2 emisyonunun yakıttaki kükürt miktarına bağlı olarak değiştiği görülmüştür
Swirling flows increase combustion performance via favouring flame stability, pollutant emissions, and combustion intensity. The strength of a swirling flow is characterized by a parameter known as swirl number, which is highly related to the dh/do ratio. In this study, effects of the swirler dh/do ratio on combustion and emission characteristics of the synthetic gas flames of premixed 20%CNG/30%H2/30%CO/20%CO2 mixture were experimentally investigated in a laboratory-scale swirl stabilized combustor. For this purpose, twelve different swirl generators were designed and manufactured. dh/do ratios of these swirlers were set as 0.30 and 0.50, and the geometric swirl number was varied between the values of 0.4 and 1.4 (at 0.2 intervals). All experiments were conducted at a fuel-lean equivalence ratio (ϕ = 0.6), room temperature, and local atmospheric conditions of the city of Kayseri, Turkey. A data logger was utilized to plot axial and radial temperatures and NOx, CO, and CO2 profiles, which were exploited to assess combustion and emission performance. Results showed that the dh/do ratio had a non-monotonic effect on the behaviour of combustion and emission of the tested synthetic gas mixture. Depending on the swirl number, increments and decrements were observed in temperature and emission values.
In a combustion device, unsteady heat release causes acoustic energy to increase when acoustic damping (energy loss) is not that effective, and, as a result, thermo-acoustic flame instabilities occur. In this study, effects of the swirler dh/do ratio (at different swirl numbers) on dynamic flame behaviour of the premixed 20%CNG/30%H2/30%CO/20%CO2 mixture under externally altered acoustic boundary conditions and stability limits (flashback and blowout equivalence ratios) of such mixture were investigated in a laboratory-scale variable geometric swirl number combustor. Therefore, swirl generators with different dh/do ratios (0.3 and 0.5) and geometric swirl numbers (0.4, 0.6, 0.8, 1.0 1.2 and 1.4) were designed and manufactured. Acoustic boundary conditions in the combustion chamber were altered using loudspeakers, and flame response to these conditions was perceived using photodiodes and pressure sensors. Dynamic flame behaviour of respective mixture was evaluated using luminous intensity and pressure profiles. Results showed that the dh/do ratio has a minor impact on dynamic flame behaviour.
This study presents a numerical investigation of the momentum, heat transfer, and combustion mechanisms of a cylindrical combustion chamber's non-premixed swirling flame motion. Fluent, a commercial CFD software, has been used in calculations. Scenarios created with different turbulence models, combustion models, and reaction mechanisms have been compared with the experimental results. The realizable k-epsilon model in the turbulence modeling study and FR/EDM-4 step combination in the combustion modeling study has presented the most impressive results for reacting flow. The Realizable k-epsilon model is promising in that it is most compatible with the experimental results. The Finite Rate/Eddy Dissipation model employed with the 4-step reaction mechanism has provided much more reliable results than other scenarios, especially the Flamelet model used with a detailed chemical mechanism. Realizable k-epsilon and FR/EDM-4 step combination have increased the capacity to predict the reaction flow, resulting in better accuracy. In addition, the effect of radiation heat transfer on the temperature field has been investigated. As a result, the scenario with radiation conducted employing the Discrete Ordinates (DO) model has presented more realistic results than the scenario without radiation. Finally, the effects of different turbulent Scmidth numbers on velocity and temperature fields have been investigated. While the turbulent Schmidt number has not caused significant changes in the velocity field, it has proved critical for the temperature field, and processing it as 0.7 has demonstrated much more accurate results.
This study presents a numerical investigation of momentum, heat transfer, and combustion mechanisms ofnon-premixed swirling flame movement of a cylindrical combustion chamber. Fluent, a commercial CFDsoftware, has been used in calculations. Combinations created with different turbulence models, combustionmodels and reaction mechanisms have been compared with experimental results. Realizable k-epsilon andFR/EDM-4 step combination have increased capacity to predict reacting flow, resulting in better accuracy.FR/EDM-4 step has provided much more reliable results than other scenarios, especially the Flamelet modelused with a detailed chemical mechanism. In addition, the effect of radiation heat transfer on thetemperature field has been investigated. Considering radiation heat transfer causes an increase in heattransfer from the combustion chamber, which provides desired agreement with experimental results. Finally,the effects of different Schmidt numbers on temperature and velocity fields have been investigated. Schmidtnumber has not caused significant changes in the velocity field. Also, as the Schmidt number increases, ithas been observed that the flame temperatures decrease to a certain extent in the combustion chamber.
In this study, the aerodynamic performance of different wind turbine blades including FX 63-137, NACA 6415, NACA 63-415 has been investigated. XFLR5 has been employed to analyze the wind turbine blade at Reynolds numbers ranging from 1.5x105 to 1x106 and low angles of attack (00≤α≤200). The lift (CL), drag(CD), and pitch moment (CM) coefficients, and lift/drag coefficient ratio (CL/CD) of the wind turbine blades have been evaluated. Numerical lift coefficients obtained using XFLR5 and lift coefficients from the literature have beeen compared and it has been found that they have been compatible with each other. According to numerical analyzes, the highest lift coefficient-to-drag coefficient ratio, as called aerodynamic efficiency, was obtained as 109.14 with FX63-137 blade at Re number of 1x106, the lowest lift coefficient-to-drag coefficient ratio was obtained as 2.63 with NACA 63-415 blade. Also, the maximum lift coefficient-to-drag coefficient ratio with the NACA 63-415 blade profile was 104.28, while that for the NACA6415 blade profile was 102.11 at Re number of 1x106. The analysis results show that lift coefficient-to-drag coefficient increases with the increase in the angle of attack up to the stall angle, and then begins to decrease in all studied blades.
