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Öğe Artificial Frame Filling Using Adaptive Neural Fuzzy Inference System for Particle Image Velocimetry Dataset(SPIE-INT SOC OPTICAL ENGINEERING, 2015) Akdemir, Bayram; Dogan, Sercan; Aksoy, Muharrem Hilmi; Canli, Eyup; Ozgoren, MuammerLiquid behaviors are very important for many areas especially for Mechanical Engineering. Fast camera is a way to observe and search the liquid behaviors. Camera traces the dust or colored markers travelling in the liquid and takes many pictures in a second as possible as. Every image has large data structure due to resolution. For fast liquid velocity, there is not easy to evaluate or make a fluent frame after the taken images. Artificial intelligence has much popularity in science to solve the nonlinear problems. Adaptive neural fuzzy inference system is a common artificial intelligence in literature. Any particle velocity in a liquid has two dimension speed and its derivatives. Adaptive Neural Fuzzy Inference System has been used to create an artificial frame between previous and post frames as offline. Adaptive neural fuzzy inference system uses velocities and vorticities to create a crossing point vector between previous and post points. In this study, Adaptive Neural Fuzzy Inference System has been used to fill virtual frames among the real frames in order to improve image continuity. So this evaluation makes the images much understandable at chaotic or vorticity points. After executed adaptive neural fuzzy inference system, the image dataset increase two times and has a sequence as virtual and real, respectively. The obtained success is evaluated using R-2 testing and mean squared error. R2 testing has a statistical importance about similarity and 0.82, 0.81, 0.85 and 0.8 were obtained for velocities and derivatives, respectively.Öğe AN ASSESSMENT OF WIND ENERGY POTENTIAL TO MEET ELECTRICITY DEMAND AND ECONOMIC FEASIBILITY IN KONYA, TURKEY(TAYLOR & FRANCIS INC, 2014) Kose, Faruk; Aksoy, Muharrem Hilmi; Ozgoren, MuammerIn this study, wind energy potential of Selcuk University campus region was investigated by means of wind data, which were obtained locally from a special observation station. The wind data were collected during the year 2005 at three different heights and were statistically analyzed with the help of MS office, Alwin, Wasp, and Witerm software. It is obtained that yearly averaged wind velocities of the region in 2005 at 10, 20, and 40 m of the mass height were found to be 5.36, 5.40, and 6.05 m/s, respectively. The power density of the region at 40 m was in the range of 260-308 W/m(2) with a medium level. For consideration of the calculation, wind speed frequency histogram, Rayleigh and Weibull distributions, wind direction, and temperature data were also used. The obtained results were used for evaluating electricity production of a 6 MW capacity wind farm composed of 1.0, 1.5, and 2.0 MW wind turbines. In addition, the planned wind farm was economically evaluated by means of the basic payback, the net present value, and the internal rate of return methods. The minimum basic payback period was found to be 6.44 years. The results were discussed and interpreted to encourage the investors for establishing wind farm in the region.Öğe Comparison of flow characteristics around an equilateral triangular cylinder via PIV and Large Eddy Simulation methods(ELSEVIER SCI LTD, 2017) Yagmur, Sercan; Dogan, Sercan; Aksoy, Muharrem Hilmi; Goktepeli, Ilker; Ozgoren, MuammerThe flow structures around an equilateral triangular Cylinder, which is commonly used as a vortex shedder in the vortex flowmeter, were investigated experimentally and numerically. Flow characteristics such as voracity contours, patterns of sectional streamlines, velocity vectors, velocity fields, Reynolds stress correlations, Strouhal numbers and drag coefficients were examined using the Particle Image Velocimetry (PIV) technique and the Large Eddy Simulation (LES) turbulence model. Experimental studies were performed in an open water channel for Re= 2.9 x 10(3), Re= 5.8 x 10(3) and Re = 1.16 x 10(4) based on the equilateral triangle edge. A sharp-tip corner of the cylinder with a triangle cross-section was exposed to the upstream side while the other two sharp -tip corners were placed on the downstream side. Numerical studies were also completed at Reynolds numbers in the range of 2.9 x 103 <= Re <= 1.16 x 10(5) to obtain the changes in the Strouhal numbers and drag coefficients. When the results of PIV and LES are considered in the same interval of Reynolds numbers, the maximum and minimum values of each flow pattern were nearly the same. The time -averaged patterns had considerable symmetry with respect to the axis line passing through the sharp -tip corner of the cross-section of the triangular cylinder. The Strouhal number was independent of the Reynolds number and was found to be approximately 0.22. The drag coefficient decreased with increasing Reynolds numbers while increasing the Power Spectral Density (PSD) and the vortex shedding frequency. For the same Reynolds numbers, the experimental and numerical results were in good agreement. Therefore, the LES turbulence model is recommended for applications of flow around this type of bluff body that is generally used in the design of vortex flowmeters to generate vortex shedding.Öğe Comparison of Flow Characteristics of Different Sphere Geometries Under the Free Surface Effect(E D P SCIENCES, 2013) Özgören, Muammer; Doğan, Sercan; Okbaz, Abdulkerim; Aksoy, Muharrem Hilmi; Şahin, Beşir; Akıllı, HakanComparison of the experimental results of turbulent flow structures between a smooth sphere and a sphere with a vent hole, roughened, and o-ring is presented in the presence of a free-surface. Dye visualization and particle image velocimetry (PIV) techniques were performed to examine effects of passive control methods on the sphere wake for Reynolds number Re = 5000 based on the sphere diameter with a 42.5mm in an open water channel. Instantaneous and time-averaged flow patterns in the wake region of the sphere were examined from point of flow physics for the different sphere locations in the range of 0 <= h/D <= 2.0 where h was the space between the top point of the sphere and the free surface. The ratio of ventilation hole to sphere diameter was 0.15, o-ring was located at 55 degrees with a 2 mm from front stagnation point of the sphere and roughened surface was formed by means of totally 410 circular holes with a 3 mm diameter and around 2 mm depth in an equilateral triangle arrangement. The flow characteristics of instantaneous velocity vectors, vorticity contours, time-averaged streamline patterns, Reynolds stress correlations and streamwise and cross-stream velocity fluctuations for both the smooth and passively controlled sphere were interpreted.Öğe The Effect of Balance Holes to Centrifugal Pump Performance(AMER INST PHYSICS, 2017) Babayiğit, Osman; Özgören, Muammer; Aksoy, Muharrem Hilmi; Kocaaslan, OsmanThe aim of this study is to analyze of a centrifugal pump with and without balance holes by using ANSYSFluent software. The pump used in the study is a commercial centrifugal pump consisting of two stages that is a model of Sempa Pump Company. Firstly, models of impeller, diffuser, suction and discharge sections of the centrifugal pump were separately drawn using Ansys and Solidworks software. Later, grid structures were generated on the flow volume of the pump. Turbulent flow volume was numerically solved by realizable k-. turbulence model. The flow analyses were focused on the centrifugal pump performance and the flow characteristics under different operational conditions with/ without balance holes. Distributions of flow characteristics such as velocity and pressure distributions in the flow volume were also determined, numerically. The results of Computational Fluid Dynamics (CFD) with/without balance holes for the pump head and hydraulic efficiency on the design flow rate of 80 m(3)/h were found to be 81.5/91.3 m and 51.9/65.3%, respectively.Öğe EFFECTS OF DIFFERENT BINDING MATERIALS ON THE PROPERTIES OF BIOFUEL PELLETS PRODUCED FROM MDF AND PINE WOOD SAWDUST WASTE(UNIV MINHO, 2015) Kose, Faruk; Kaya, Mehmet Numan; Aksoy, Muharrem Hilmi; Tuplek, AliImportance of biofuels has increased in recent years in Turkey as well as in the World. Million tones of biomaterials such as wood are used in woody industries and significant amount of wood waste is obtained. It is possible to make use of wood waste as fuel by pelletizing them. In this study, samples of pine wood sawdust (PWS) and medium density fiber (MDF) sawdust pellets have been obtained. After carrying out chemical analyses on these samples; the ratio of volatile matter, upper calorific value, lower calorific value, ash, total humidity rate and sulfur rates have been identified. The emission values of the exhaust gases (CO, CO2, SO2, NO, NOx) forming as a result of the combustion process of pellet samples in laboratory conditions have been measured. The effects of addition of zeolite, cane molasses (CM), starch in pellet samples on the emission values have been studied. In addition, in order to identify the combustion velocities of the pellet samples, a fixed-bed experimental singeing machine has been devised. As a conclusion, PWS pellet has been found to be a cleaner and more efficient alternative to coal of lignite type. The calorific value of MDF dust pellet samples has reached a value of 3.857 cal/gr as a result of the fire retardant materials in it. The lowest emission values have been observed in PWS pellets which contains 9% zeolite as a binding material. It has been found out that PWS burning with zeolite reduces the combustion velocity and thus increasing the efficiency and also reducing the stack gas emission.Öğe Experimental and CFD investigation of a multistage centrifugal pump including leakages and balance holes(DESALINATION PUBL, 2017) Babayigit, Osman; Ozgoren, Muammer; Aksoy, Muharrem Hilmi; Kocaaslan, OsmanThe aim of this study is to analyze numerically a multistage pump with some new approaches and compare the results with experimental data. A centrifugal pump, consisting of six backward curved blades, ten vane diffusers and two stages, was used. First, models of an impeller, a diffuser, suction and discharge sections of the centrifugal pump were separately designed by empirical equations. The flow volume of the pump was numerically solved by different turbulence models. Thus, the most accurate results in comparison with experimental data were obtained for the realizable k-epsilon turbulence model. For the purposes of this study, the effect of balance holes and leakages (clearances) on the performance was scrutinized. In most studies, it is not taken into consideration in computational fluid dynamics (CFD) analyses due to the difficulty of meshing these regions. The experimental studies were performed at a computer controlled pump test rig that was established according to the standard TS EN ISO 9906. The results of CFD/experimental analyses for the pump head, hydraulic efficiency and hydraulic power on the design point, having the flow rate of 80 m(3)/h and the revolution of 2,975 rpm, were found to be 81.47/80.70 m, 51.98%/51.42% and 17.94/17.77 kW, respectively. The obtained CFD and experimental results were found to be close agreement for the design flow rate as well as for all tested flow rates. Other characteristics of the pump such as velocity, static pressure, streamline patterns and turbulence kinetic energy were also investigated. In addition, the leakages and balance holes have significantly affected the pump characteristics, which must be considered in CFD analyses in order to find more precise results for true-to-life simulations.Öğe Experimental and Numerical Investigation of Coating Effect on Pump Impeller and Volute(ISFAHAN UNIV TECHNOLOGY, 2016) Kocaaslan, Osman; Özgören, Muammer; Aksoy, Muharrem Hilmi; Babayiğit, OsmanIn this study, an impeller and volute of a centrifugal pump were designed and numerically analyzed in order to improve the pump efficiency. Before design, experimental and theoretical studies were performed on a centrifugal water pump taken as Model Pump (MP). Design parameters were taken as 100 m(3)/h for volume flow rate, 18m for head and 1480 rpm for rotating speed. After the inspection of the flow field in the MP, some geometrical modifications such as impeller inlet and outlet diameters, blade inlet and exit angles, blade wrap angle, blade thickness, blade inletand exit widthswere realized to design a new pump. Numerical analyses were performed for 8 different volume flow rates overlapping with experimental operation points by Ansys-Fluent Software. In numerical studies, k-epsilon turbulence model and standard wall function were utilized. The experimental and computational results were compared with the model pump. According to the analysis results at design flow rate, hydraulic torque value is decreased from 56.62 Nm to 51.05 Nm, while hydraulic efficiency is increased from 55.98% to 63.09%. In addition, in order to see the roughness effect and increase the pump efficiency, the wetted surfaces of the impeller and volute were coated with a polyurethane dye material. Later, performance curves of the coated and uncoated pumps were experimentally obtained which showed that the shaft power of the pump for the coated case was decreased around 10% and the hydraulic efficiency of the pump was increased approximately 18%. According to the economic analysis by basic payback period of the polyurethane coating is less than one year and the internal income ratio for ten-year life-cycle period is around %114.Öğe Experimental and Numerical Investigation of Flow Structures around Cylindrical Bluff Bodies(E D P SCIENCES, 2015) Yağmur, Sercan; Doğan, Sercan; Aksoy, Muharrem Hilmi; Canlı, Eyüb; Özgören, MuammerThe understanding and quantitative prediction of velocity and pressure fluctuations in turbulent flows around such bluff bodies have been evolving over the years. The main aim of the present work is to investigate experimentally and numerically the flow field in the wake region of different bluff bodies such as circular, square and triangle cross section cylinders placed horizontally perpendicular to the uniform flow. The experimental studies were performed by Particle Image Velocimetry (PIV) method in an open water channel at Reynolds numbers 5000 and 10000 defined according to the characteristic lengths of the cylinders in the facilities of Selcuk University of Advanced Technology Research and Application Center in Turkey. The experimental results are compared to the numerical results obtained by means of transient simulation with LES turbulence model of ANSYS-Fluent Software. It is shown that the numerical and experimental results have a good agreement in respect of the instantaneous and time-averaged flow field patterns of vorticity, velocity component streamwise direction and streamline topology. In addition, drag coefficient of the geometries were also numerically calculated. For all geometries the wake length in x and y directions and size of the foci of the streamlines are decreasing by increasing Reynolds numbers in time-averaged results. The time-averaged flow patterns of both experimental and numerical results have considerable symmetry with respect to the centerline of each cylinder. Contours of the time-averaged stream wise velocity for Re=10000 demonstrate that the stagnation point around the symmetry plane moves further upstream for all cylinders in accordance with Re=5000. The maximum drag coefficient value was yielded for the square cross-section cylinder as 1.78 due to the sharp-edged geometry.Öğe Experimental Performance Investigation of Photovoltaic/Thermal (PV-T) System(E D P SCIENCES, 2013) Özgören, Muammer; Aksoy, Muharrem Hilmi; Bakır, C.; Doğan, SercanPhotovoltaic solar cells convert light energy from the sun into electricity. Photovoltaic cells are produced by semi-conducting materials to convert the energy into electricity and during this process heat is absorbed by the solar radiation. This heat causes a loss of electricity generation efficiencies. In this study, an experimental setup was designed and established to test two separate photovoltaic panel systems with alone PV and with water cooling system PV/T to examine the heat effect on PV systems. The absorbed heat energy behind the photovoltaic cell's surface in insulated ambient was removed by means of a water cooling system and the tests for both systems were simultaneously performed along the July 2011. It is found that without active water cooling, the temperature of the PV module was higher during day time and solar cells could only achieve around 8% conversion efficiency. On the other hand, when the PV module was operated with active water cooling condition, the temperature dropped significantly, leading to an increase in the efficiency of solar cells as much as 13.6%. Gained from absorbed solar heat and maximum thermal conversion efficiencies of the system are determined as 49% and 51% for two different mass flow rates. It is observed that water flow rate is effective on the increasing the conversion efficiency as well as absorption and transition rates of cover glass in PV/T (PV-Thermal) collector, the insulation material and cell efficiency. As a conclusion, the conversion efficiency of the PV system with water cooling might be improved on average about 10%. Therefore, it is recommended that PV system should be designed with most efficient type cooling system to enhance the efficiency and to decrease the payback period.Öğe An experimental, computational and flow visualization study on the air-side thermal and hydraulic performance of louvered fin and round tube heat exchangers(PERGAMON-ELSEVIER SCIENCE LTD, 2018) Okbaz, Abdulkerim; Pinarbasi, Ali; Olcay, Ali Bahadir; Aksoy, Muharrem HilmiThe aim of this study is to determine heat transfer and pressure drop characteristics in different louvered fin geometries for manufacturing of commercial louvered fin and round tube heat exchangers. Numerical simulations were carried out for various louver angles, louver lengths (pitches), fin pitches and frontal air velocities. The heat transfer and pressure drop characteristics of the louvered fin and round tube heat exchangers, Colburn and friction factors, were respectively normalized with Colburn and friction factors of the flat plate fin and round tube heat exchangers operating under the same conditions and they were presented as the relative Colburn factor j* and the relative friction factor f*. Thermal & hydraulic performance was presented as JF*. Temperature and local Nusselt number contours, and streamline patterns were provided to reveal the mechanisms behind the heat transfer enhancement. Among different heat exchangers for which heat transfer and pressure drop characteristics were obtained, one was chosen to manufacture a real size heat exchanger. Flow visualization studies were also conducted with a PIV system in an open water channel to determine whether the flow structure is louvered directed or not. The louvered fin heat exchanger tested in the PIV system was a five times scaled up model of the real size louvered fin heat exchanger and made from a transparent plexiglas material. PIV results were presented and evaluated based on streamlines and velocity vectors. Furthermore, a numerical analysis was performed using exactly the same dimensions and conditions of the model tested in the PIV system. The comparison between numerical and experimental results was done to validate the numerical model. Consequently, the performance of the fabricated real size heat exchanger was tested at different air velocities in a wind tunnel in a conditioned room. The experimental results were compared with numerical analyses and found to be compatible with each other. Finally, thermal and hydraulic performance of the louvered fin and round tube heat exchanger was compared with a wavy fin and round tube heat exchanger with identical size and specifications. It was found that the thermal and hydraulic performance of the louvered fin and round tube heat exchanger is higher than that of the wavy fin and round tube heat exchanger. The Colburn factor j, friction factor f and JF of the louvered fin and round tube heat exchanger are higher about 16.8-7%, 19.9-8.2% and 10-4.3% than that of the wavy fin and round tube heat exchanger depending on the Reynolds number, respectively. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Güneş ve rüzgâr enerjisi ile çalışan su pompalama sisteminin deneysel incelenmesi(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2011-08-11) Aksoy, Muharrem Hilmi; Özgören, Muammer; Köse, FarukÜlkemizde tarımda kullanılan birçok arazinin yakınından geçen ulaşılabilir bir elektrik hattı olmaması sebebi ile sulama kuyulardan, akarsulardan ya da sulama kanallarından dizel jeneratörler yardımıyla yapılmaktadır. Bu durumda sulama sırasında oldukça fazla miktarda enerji harcanmakta ve ürün maliyetleri artmaktadır. Bu çalışmada, güneş ve rüzgâr enerjisinden oluşan hibrit sistem ile elektrik üretimi yapan bir yenilenebilir enerji sisteminin tarımsal sulama amaçlı teorik ve deneysel araştırması yapılmıştır. Selçuk Üniversitesi Konya Teknokent bahçesine kurulan 1500 W kapasiteli rüzgâr türbini ve toplam 480 W kapasiteli 4 adet fotovoltaik panelden üretilen elektrik enerjisi, şarj kontrol cihazlarında regüle edilerek kapasiteleri 12V 200Ah olan toplam 4 aküde depolanmıştır. 24 Volt DC olarak tasarlanan sistemden üretilen elektrik enerjisi ile 2,5 m yeraltında bulunan sulama deposuna kurulan 300 W kapasiteli DC sürücülü dalgıç pompa tahrik edilmiştir. Deney süresince fotovoltaik panellerden ve rüzgâr türbininden üretilen elektrik enerjisi ile pompa tarafından tüketilen elektrik enerjisi değerleri kayıt edilmiştir. Ayrıca, rüzgâr hızı ve güneş ışınım şiddeti, pompalanan su miktarı ve pompa çıkış basıncı da anlık olarak ölçülerek ortalamalar halinde kaydedilmiştir. Türbin direği ile aynı yükseklikte 10,5 metrede anemometre ile ölçülen rüzgâr hızı Mayıs ayında 3,49 m/s, Haziran ayında 3,76 m/s, Temmuz ayında ise 4,66 m/s olarak gerçekleşmiştir. Temmuz ayında rüzgâr türbininden 3805 Wh elektrik enerjisi üretilmiştir. Yatayla 12° açı ile ve 0° güneye yönlendirilmiş piranometre ile günlük toplam ışınım değeri Haziran ayında 6480 W/m2gün, Temmuz ayında ise 7737 W/m2gün olarak ölçülmüştür. Fotovoltaik panellerden Haziran ayında günlük ortalama 2413 Wh, Temmuz ayında ise 2841 Wh elektrik enerjisi elde edilmiştir. Yapılan analizlerle, hibrit sistemle yıl boyunca rüzgâr türbininden 635 kWh, PV panellerinden ise 738 kWh elektrik üretilebileceği hesaplanmıştır. Ölçüm süresince rüzgâr türbini verimi ortalama %33,3, fotovoltaik panellerin hücre verimi %10,07 olarak bulunmuştur. Üretilen elektrik enerjisi ile DC pompa vasıtası ile Temmuz ayında günlük ortalama 44,1 m3, ay boyunca toplam 1368 m3/gün su yaklaşık 2,5 m kot farkı oluşturacak şekilde pompalanmıştır. Ayrıca üretilen 24 V DC elektrik enerjisi, invertörde 220 V AC'ye dönüştürülerek ölçümlerin kaydedilmesinde kullanılan 90 W gücündeki dizüstü bilgisayarda ölçüm süresince kullanılmıştır. Hibrit sistem ile pompalanan su doğal sulamaya ek olarak damla sulama yöntemi ile 12,4 da (dekar) şeker pancarı, 13,0 da patates, 13,6 da mısır, 31,4 da kavun tarlası için yetebilecek miktardadır.Öğe Hourly cooling load prediction of a vehicle in the southern region of Turkey by Artificial Neural Network(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Solmaz, Ozgur; Ozgoren, Muammer; Aksoy, Muharrem HilmiIn this study, Artificial Neural Networks (ANNs) method for prediction hourly cooling load of a vehicle was implemented. The cooling load of the vehicle was calculated along the cooling season (1 May-30 September) for Antalya, Konya, Mersin, Mugla and Sanliurfa provinces in Turkey. For ANN model, seven neurons determinated as input signals of latitude, longitude, altitude, day of the year, hour of the day, hourly mean ambient air temperature and hourly solar radiation were used for the input layer of the network. One neuron producing an output signal of the hourly cooling load was utilized in the output layer. All data were divided into two categories for training and testing of the ANN. The 80% of the data was reserved to training and the remaining was used for testing of the model. Neuron numbers in the hidden layer from 7 to 40 were tested step by step to find the best matching ANN structure. The obtained results for different numbers of neurons were compared in terms of root mean squared error (RMSE), coefficient of determination (R-2) and mean absolute error (MAE). The best matching results for the training and testing were obtained as 8 neurons for the minimum testing RMSE value for the prediction of cooling load by the ANN model on the 23rd day of each month along the cooling season. For the model with 8 neurons RMSE, R-2 and MAE (Training/Testing) were found to be 0.0128/0.0259, 0.9959/0.9818 and 78.81/174.71 W/m(2), respectively. It is shown that the cooling load of a vehicle can be successfully predicted by means of the ANNs from geographical characteristics and meteorological data. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Investigation of Absorption Cooling Application Powered by Solar Energy in the South Coast Region of Turkey(E D P SCIENCES, 2013) Babayiğit, Osman; Aksoy, Muharrem Hilmi; Özgören, Muammer; Solmaz, ÖzgürIn this study, an absorption system using ammonia-water (NH3-H2O) solution has been theoretically examined in order to meet the cooling need of a detached building having 150 m(2) floor area for Antalya, Mersin and Mugla provinces in Turkey. Hourly dynamic cooling load capacities of the building were determined by using Radiant Time Series (RTS) method in the chosen cities. For the analysis, hourly average meteorological data such as atmospheric air temperature and solar radiation belonging to the years 1998-2008 are used for performance prediction of the proposed system. Thermodynamic relations for each component of absorption cooling system is explained and coefficients of performance of the system are calculated. The maximum daily total radiation data were calculated as 7173 W/m(2)day on July 15, 7277 W/m(2) day on July 19 and 7231 W/m(2)day on July 19 for Mersin, Antalya and Mugla, respectively on the 23 toward to south oriented panels from horizontal surface. The generator operating temperatures are considered between 90-130 degrees C and the best result for 110 degrees C is found the optimum degree for maximum coefficient of performance (COP) values at the highest solar radiation occurred time during the considered days for each province. The COP values varies between 0.521 and 0.530 for the provinces. In addition, absorber and condenser capacities and thermal efficiency for the absorption cooling system were calculated. The necessary evacuated tube collector area for the different provinces were found in the range of 45 m(2) to 47 m(2). It is shown that although the initial investment cost is higher for the proposed absorption cooling system, it is economically feasible because of its lower annual operation costs and can successfully be operated for the considered provinces.Öğe Numerical identification of blade exit angle effect on the performance for a multistage centrifugal pump impeller(E D P SCIENCES, 2015) Babayigit, Osman; Kocaaslan, Osman; Aksoy, Muharrem Hilmi; Guleren, Kursad Melih; Ozgoren, MuammerNowadays, single and multistage centrifugal pumps are widely used in industrial and mining enterprises. One of the most important components of a centrifugal pump is the impeller. The performance characteristics are related to the pump comprising the head and the overall efficiency rely a great deal on the impeller geometry. In this work, effects of blade exit angle change on hydraulic efficiency of a multi stage pump impeller are investigated via Ansys-Fluent computational fluid dynamics software for constant width impeller entrance and exit gates, blade numbers and blade thickness. Firstly, the flow volume of a centrifugal pump impeller is generated and then mesh structure is formed for the full impeller flow volume. Secondly, rotational periodic flow model are adopted in order to examine the effect of periodic flow assumption on the performance predictions. Corresponding to the available experimental data, inlet mass flow rate, outlet static pressure and rotation of impeller are taken as 0.02m(3)s(-1), 450 kPa and 2950 rpm, respectively for the water fluid. No slip boundary condition is exposed to all solid of surface in the flow volume. The continuity and Navier-Stokes equations with the k-epsilon turbulence model and the standard wall functions are used. During the study, numerical analyses are conducted for the blade exit angle values of 18 degrees, 20 degrees, 25 degrees, 30 degrees and 35 degrees. In consequence of the performed analyses, it is determined that hydraulic efficiency of the pump impeller value is changed between 81.0-84.6%. The most convenient blade exit angle that yields 84.6% hydraulic efficiency at is 18 degrees. The obtained results show that the blade exit angle range has an impact on the centrifugal pump performance describing the pump head and the hydraulic efficiency.Öğe Numerical Investigation of the Effect of Number of Blades on Centrifugal Pump Performance(AMER INST PHYSICS, 2017) Kocaaslan, Osman; Özgören, Muammer; Babayiğit, Osman; Aksoy, Muharrem HilmiIn this study, the flow structure in a centrifugal pump was numerically investigated for the different blade numbers in the impeller between 5 and 9. The pump used in the study is a single-stage horizontal shafted centrifugal pump. The original pump impeller was designed as 7 blades for the parameters of flow rate Q=100 m(3)/h, head Hm=180 kPa and revolution n=1480 rpm. First, models of impellers with the different blade numbers between 5 and 9 and the volute section of the centrifugal pump were separately drawn using Solidworks software. Later, grid structures were generated on the flow volume of the pump. Last, the flow analyses were performed and the flow characteristics under different operational conditions were determined numerically. In the numerical analyses, k-e turbulence model and standard wall functions were used to solve turbulent flow. Balance holes and surface roughness, which adversely affect the hydraulic efficiency of pumps, were also considered. The obtained results of the analyses show that the hydraulic torque and head values have increased with the application of higher number of the impeller blades. For the impellers with 5 and 9 blades on the design flow rate of 100 m(3)/h (Q/Qd=1), the hydraulic torque and head were found 49/59.1 Nm and 153.1/184.4 kPa, respectively. Subsequently the hydraulic efficiencies of each pump were calculated. As a result, the highest hydraulic efficiency on the design flow rate was calculated as 54.16% for the pump impeller having 8 blades.Öğe Santrifüj pompa çarkındaki akış karakteristiklerinin HAD ve PIV Yöntemi ile incelenmesi(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2018-04-13) Aksoy, Muharrem Hilmi; Köse, FarukPompa verimlerini azaltan problemlerin üstesinden gelmek ve yeni tasarımlar yapmak için pompa çarkı içerisindeki karmaşık akış yapılarını daha iyi anlamak ve incelemek gerekmektedir. Bu nedenle, bu tez çalışmasında özel olarak tasarlanan ve kurulan bir test düzeneğinde, pompa çarkı içerisinde, iki kanat arasındaki akış yapısı, çark çıkış genişliğinin tam ortasında deneysel olarak Parçacık Görüntülemeli Hız Ölçme (PIV) yöntemi ile belirlenmiştir. Çalışmada, tasarım parametreleri 2850 d/d, 12.5m3/h debi ve 40 metre basma yüksekliğine sahip 3 kademeli santrifüj pompa, tasarım devri yanında, 1900 d/d çalışma şartlarında da denenmiştir. Her bir devir değeri için tasarım debisinin 0.85Qd-1.0Qd ve 1.15 Qd değerlerinde olmak üzere 3 farklı debi oranında deneyler yapılmıştır. Sayısal çalışmalar aynı sınır şartlarında yapılmış, Hesaplamalı Akışkanlar Dinamiği (HAD) ile elde edilen akış yapısı deneysel elde edilen PIV sonuçları ile karşılaştırılmıştır. Deneysel ve sayısal çalışmalar orijinal pompa çarkı olan 6 kanatlı (çark 1) ara kanat ilaveli 4 kanatlı (çark 2), ara kanat ilavesiz 4 kanatlı (çark 3) olmak üzere 3 farklı pompa çarkı kullanılarak yapılmıştır. PIV çalışmalarında çarkın aynı pozisyonda olduğu durağan halde faz ortalamalı 500 görüntü alınmış ve akış özellikleri mutlak hız vektörü, bağıl hız vektörü, mutlak hız konturu, bağıl hız konturu ve Türbülans Kinetik Enerji (TKE) değerleri ile incelenmiştir. Ayrıca çark ve difüzör etkileşimini daha iyi incelemek için 5 farklı çark-difüzör pozisyonunda da çark içerisindeki akış yapısı incelenmiştir. Pompa çarkı içerisinde oluşturulan 16 farklı nokta ile elde edilen PIV-HAD sonuçları arasındaki bağıl fark %5.7-21.2 arasında olduğu bulunmuştur. 12.5 m³/h debide yapılan deneysel ve HAD çalışmalarında en yüksek pompa genel verimi çark 1 için sırası ile %56.0 ve %56.6 olarak elde edilirken, en yüksek basma yüksekliği çark 2 ile sırasıyla 46.0 m ve 44.2 m olarak bulunmuştur. Çark 3 ise verim değeri bu debide %55.8 olmasına rağmen basma yüksekliği 37.8 m'de kalmıştır. Deneysel çalışmalarda çark 2'nin kullanımı ile orijinal çark olan çark 1'e göre basma yüksekliği %9.7 artış ile 40.3 m'den 44.2 m ye çıkarılırken, genel verim %56'dan %53.7'ye % 4.7 düşüşte kalmıştır. Bunun yanında HAD ve deneysel çalışmalarda elde edilen pompa karakteristik değerleri arasındaki fark %1-9 aralığında olduğu bulunmuştur. Özellikle az kanat sayısına sahip ve PIV ölçümlerine uygun olan çark 2'de mutlak hız değerlerinin PIV ve HAD sonuçları ile uyum içerisinde olduğu görülmüştür.Öğe Wake structures of two side by side spheres in a tripped boundary layer flow(E D P SCIENCES, 2014) Canlı, Eyüb; Özgören, Muammer; Doğan, Sercan; Aksoy, Muharrem Hilmi; Akıllı, HüseyinTwo independent spheres were placed in a side by side arrangement and flow structure in the wake region of the spheres was investigated with a Particle Image Velocimetry (PIV) system when the spheres were in a boundary layer over a flat plate as a special case. Reynolds number was 5000 based on the sphere diameter which was 42.5 mm. Boundary layer was tripped 8mm away from the leading edge of the flat plate with a 5 mm trip wire. The thickness of the hydrodynamically developed boundary layer was determined as 63mm which was larger than the sphere diameter of D=42.5mm. Wake region of the spheres was examined from point of flow physics for the different sphere locations in the ranges of 0 <= G/D <= 1.5 and 0 <= S/D <= 1.5 where G and S were the distance between the spheres and the distance between the bottom point of the spheres and the flat plate surface, respectively. Depending on the different sphere locations, instantaneous and time averaged vorticity data, scalar values of time-averaged velocity components and their root mean square (rms) values and time averaged vorticity data are presented in the study for the evaluation of wake region of the spheres. It is demonstrated that the gap between the two spheres and the interaction between the gap and the boundary layer greatly affects flow pattern, especially when spheres are located near to the flat plate surface, i.e. S/D=0.1 for 0 <= G/D <= 1.5. Different distances between the spheres resulted in various flow patterns as the spheres were approached to the flat plate. The distance S/D=0.1 for all gap values has the strongest effect on the wake structures. Beyond G/D=1.0, the sphere wakes tend to be similar to single sphere case. The instantaneous vorticity fields of the side by side arrangements comprised wavy structures in higher level comparing to an individual sphere case. The gap flow intensifies the occurrence of small scale eddies in the wake region. The submersion rate of the spheres actually determines the characteristics of the wake region and is affected from boundary layer flow in a gradually decreasing manner.