Search

Impact of the local flexible membrane (LFM) on aerodynamic phenomena including the formation of a laminar separation bubble (LSB) and transition to turbulence was experimentally investigated over the suction surface of a Clark-Y airfoil first time in literature. The experiments such as aerodynamic force measurement, smoke-wire flow visualization and hot-film tests were carried out at the free-stream velocity of U infinity = 3.2 m/s, U infinity = 6.4 m/s, U infinity = 9.6 m/s, U infinity = 12.8 m/s, and Reynolds number based upon on the chord length was Rec = 3.5 x 104, Rec = 7.0 x 104, Rec = 1.05 x 105 and Rec = 1.4 x 105, respectively. The experimental angle of attack was set at 0 degrees = alpha

Energy consumption which is the most critical input in daily life is increasing constantly because of the growth of the world population and development of the devices. The transportation industry which is responsible for almost half of all worldwide emissions is switching to innovative devices run on renewable energy. Renewable-powered charging stations are important for reducing the environmental impact of vehicles. The objective of the study was to determine the best hydrogen charge station locations and rates which are supplied by coupled solar power plants. The GIS-based assessment was carried out with proper data from data sources such as Copernicus Land Monitoring (CLC 2018), and Global Solar Atlas (GSA). For the determination of suitable regions for solar power plants, eight sub-criteria were assessed under technical (C1), accessibility (C2), and environmental (C3) main criteria. Afterward, the obtained result map layer and suitability of the six determined water bodies, located in the study region, were investigated by assuming the buffer zone value. Results showed that the study area had suitable regions of 38.1km2indicating that %22.4 of it was convenient for the solar power plant investments. While Cihanbeyli Lake does not have the highest suitable region, the biggest suitable area inside the buffer zone of lakes was determined as the Ağcaşayar Dam. The maximum annual solar production level is obtained as 1,919 MWh/year in the Ağcaşayar Dam, with a hydrogen production of 34,933 tons/year. Consequently, the Ağcaşayar Dam is the best suitable destination for a hydrogen fuel station in Kayseri.

This study ensures experimental and numerical investigation of different airfoils to observe and understand how camber ratio affects the flow characteristics over surface of different airfoils. Experimental results in the previous studies were used while the numerical study was performed for present investigation. Reynolds numbers based on the airfoil chords were 1x105 and the angle of attack of 8°. Instantaneous voltage output data were used in order to detect transition location for NACA 4412, oil surface visualization experiments were presented for NACA 2415. In the numerical analysis, values of u/U∞ and turbulent kinetic energy were presented for NACA 4415 airfoil. The experimental results denoted that the change of camber ratio and thickness significantly affected the flow phenomenon such as boundary layer separation or formation and progress of the laminar separation bubble. The long bubble was clearly observed with accumulation of pigments at oil-flow measurement experiment. By increasing the camber ratio with the use of NACA 4412 airfoil, the long bubble turned into the short bubble. Briefly, not only the progress and formation of laminar separation bubble was being affected, but also the onset of transition point was obviously influenced by changing of camber ratio.

A passive flow control device with a local flexible membrane material over the suction surface was experimentally investigated with a smoke-wire experiment and time-dependent force measurement in this study. The experiments were performed on both the uncontrolled and the controlled FX 84-W-150 wind turbine airfoils applying the local flexible membrane at different locations first in the literature. The smoke-wire result for the uncontrolled airfoil indicated that a laminar separation bubble formed over the suction surface and the increasing incidence caused the short bubble at lower angles of attack to turn into the long bubble at moderate angles of attack by shifting upstream. After the experiment for the uncontrolled airfoil, six different locations of local flexibility were considered on the suction surface. All tests showed that applying the local flexibility especially at the leading edge ensured better aerodynamic performance. Additionally, it was observed that the lift coefficient was negatively affected when the length of local flexibility increased. As a result of these findings, employing the local flexibility between x/c = 0.2 and x/c = 0.4 over the suction surface was determined as the best optimum location and length. With employing this configuration, the laminar separation bubble was not only suppressed and eliminated but the fluctuations of the lift and the drag curves especially at moderate incidences were also decreased, resulting in increasing in aerodynamic performance as well as having less vibration and more stable on wind turbine airfoil. Apart from the studies regarding wind turbine airfoils with the local flexible material in the literature, our results bear witness that mounting this passive flow controller close to the leading edge and keeping it shorter was more influential in terms of the power output of wind turbine blades. (c) 2021 Elsevier Ltd. All rights reserved.

This study was conducted to determine the milk yield and reproduction characteristics, genetic trend, and breeding values of Holstein cattle reared in Teke region (Antalya, Burdur, Denizli, and Isparta provinces) of Turkey. In this study, 9844 lactation and reproductive records of Holstein Friesian dairy cattle for the period of 2010 to 2017 were used. For this purpose, variance components and the heritability were calculated based on calving interval (CI) and number of inseminations per conception (NIC) from fertility characteristics and lactation length (LL), 305-day milk yield (305 DMY), and dry period (DP). It was determined that CI, NIC, LL, 305 DMY, and DP were 0.11, 0.10, 0.11, 0.33, and 0.01, respectively. The genetic trend of 305 DMY was 111.5 kg/year. The average breeding value was negative between 2005 and 2009 and positive between 2010 and 2015. In conclusion, the fact that especially 305 DMY heritability was generally higher in this study than the values reported by other studies conducted in Turkey and the genetic trend for 305 DMY was positive and high indicates that breeding value of Holstein cattle in the Teke region is high. Therefore, it can be recommended to continue the pedigree breeding of Holstein cattle in this region, keep pedigree and yield records meticulously, estimate breeding values for selecting animals with superior yield characteristics and using them in future generations, and include current biotechnological methods in breeding program to increase the efficiency in selection. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.

Günümüzde rüzgar enerjisinden daha fazla faydalanabilmek için, düşey eksenli türbinlerin yaygınlaşması gerekmekte ve kırsal veya şehiriçi her türlü alanda kullanılması gerekmektedir. Dikey eksenli türbin uygulamaları için Savonius ve Darrieus tipi türbinler yoğun bir şekilde kullanılmakta olup, performanslarını arttırmak için Savonius-Darrieus rüzgar türbinleri birlikte kullanım örnekleri görülmektedir. Bu sebeple yapılan çalışmalara göre tek başına kullanılan Savonius veya Darrieus rüzgar türbinlerine kıyasla birlikte kullanımının daha etkili performans sonucunu verdiği araştırmalarda görülmüştür. Dikey eksenli türbinlerin şehiriçi uygulamaları için uygulanabilirliği düşünüldüğünde bu türbinler üzerine daha fazla çalışma yapılması gerekmekte olup ayrıca yeni tasarım araştırma ve geliştirme çalışmaları yapılmalıdır.

Bu çalışmada, Kırşehir ili Damızlık Sığır Yetiştiricileri Birliği’ne üye 389 işletmedeki Siyah Alaca sığırlara ait 2007-2017 yılları arasında tutulan 4589 adet süt verim kaydı kullanılmıştır. Süt verimi özelliklerinden 305 gün süt verimi (305 GSV), laktasyon süresi (LS) ve kuruda kalma süresine (KKS) ve bunlar üzerine buzağılama yılı, laktasyon sırası, buzağılama mevsimi, işletme faktörünü ve buzağılama yaşının etkileri belirlenmiştir. Çalışmada 305 GSV, LS ve KKS ortalamaları sırasıyla 7350,5±30,70 kg, 398,2±1,61 gün ve 62,5±17,02 gün olarak hesaplanmıştır. Buzağılama yılı, laktasyon sırası, buzağılama mevsimi ve işletme büyüklüğünün 305 GSV ve LS üzerine etkileri istatistik olarak önemlidir (p0,05) olarak tespit edilmiştir. Çalışmada doğum yıllarına göre 305 GSV’nin fenotipik yönelim 62,6 kg olarak bulunmuştur. Sonuç olarak bu çalışma ile Kırşehir ilinde yetiştirilen Siyah Alaca sığırların süt verim özellikleri belirlenmiştir. Yıllar itibari ile 305 GSV bakımından istatistik olarak önemli farklılıklar olduğu tespit edilmiştir.

In the Ottoman cities, stores constitute the main element of socioeconomic and commercial life. The stores located in market places, covered bazaars, neighbourhoods, piers/harbours, inns and caravansaries are the places in which various branches of tradesmen make production and sales. Besides, stores were also used as an inn room or cellar. Moreover, some shops i.e. barbershops incurred the wrath of political power at times as they served as gathering places for the people. These shops which a master and a journeymanor an apprenticework in together, are the basic constituents of the Ottoman tradesmen organization. There are various studies carriedout on tradesmen, whiche valuate a number of numerical data on th organization of bazaars, tradesmen branches and shops. However, there is extremely limited information regarding the content of shops as the places where tradesmen branches were active. The purpose of this study is to focus on shops belonging to various tradesmen branches in Beşiktaş town. Among those; herbalist, barber, coffeehouse, vegetable-seller, round cake-maker, gözlemeci, leblebici, kebab-maker and picle maker etc. shops shall be taken as sample. Inaccordance with the sesamples which are selecte damong tradesmen branches that both produce and sale foods as well as located in the service industry, the tools and commodity in shops will be identified and thus an envision for the shops shall be presented. The main source to examine these shops are the Beşiktaş Kadi registers (shariah sicilis).

In the presented study, a thermal analysis of a lithium-ion battery was carried. The battery consists of 6 Series 2 parallel, 12 lithium-ion (NCA 18650) batteries. Liquid water was used as a refrigerant in the thermal analysis of the battery. After designing in SOLIDWORKS computer-aided design program, performance of the battery module was investigated with the help of SIEMENS FloEFD program which is a computational fluid dynamics program. The simulations were performed under steady-state conditions by using the k-epsilon turbulence model. The results bring out that the highest temperatures were occurred at the busbars and the liquid cooled batteries can operate efficiently at a temperature of 27-28°C.

Offshore wind energy resources are not fully exploited renewable energy resources until now and could play a crucial role in mitigating the impacts of climate change by the generation of renewable electricity. Planning processes such as technical, social, environmental, various agents, and political concerns are necessary for the development of offshore wind energy projects. The objective of this study was to assess the comprehensive feasibility of a desired offshore wind power plant applying Geographical Information Systems (GIS) and Multi-Criteria Decision-Making (MCDM) guidance for the coastal area of Turkey. Furthermore, EMODnet (the European Marine Observation and Data Network) was employed for data acquisition to unlock fragmented and hidden marine data resources and to facilitate investment in sustainable coastal and offshore activities. For the determination of potential site with Multi-Criteria Decision Maker Method, 3 main criteria Technical (C1), Environmental (C2), and Social (C3), and 13 sub-criteria were determined. Based on these criteria, the suitability map was created by using all criteria map layers with their buffer zones. The final map indicated that %1.38 (3294.8 km(2)) of Turkey Seas was suitable for offshore wind farms. The most suitable region was determined in the Marmara Sea with 1194 km(2). The Aegean Sea, the Black Sea, and the Mediterranean Sea were following the Marmara Sea in terms of the huge suitable regions respectively. It was apparent that the growth of offshore wind farms in Turkey would increase if the supporting mechanism and the necessary legislation were ensured.

Purpose Wind turbines are one of the best candidates to solve the problem of increasing energy demand in the world. The aim of this paper is to apply a multi-objective structural optimization study to a Phase II wind turbine blade produced by the National Renewable Energy Laboratory to obtain a more efficient small-scale wind turbine. Design/methodology/approach To solve this structural optimization problem, a new Non-Dominated Sorting Genetic Algorithm (NSGA-II) was performed. In the optimization study, the objective function was on minimization of mass and cost of the blade, and design parameters were composite material type and spar cap layer number. Design constraints were deformation, strain, stress, natural frequency and failure criteria. ANSYS Composite PrepPost (ACP) module was used to model the composite materials of the blade. Moreover, fluid–structure interaction (FSI) model in ANSYS was used to carry out flow and structural analysis on the blade. Findings As a result, a new original blade was designed using the multi-objective structural optimization study which has been adapted for aerodynamic optimization, the NSGA-II algorithm and FSI. The mass of three selected optimized blades using carbon composite decreased as much as 6.6%, 11.9% and 14.3%, respectively, while their costs increased by 23.1%, 29.9% and 38.3%. This multi-objective structural optimization-based study indicates that the composite configuration of the blade could be altered to reach the desired weight and cost for production. Originality/value ACP module is a novel and advanced composite modeling technique. This study is a novel study to present the NSGA-II algorithm, which has been adapted for aerodynamic optimization, together with the FSI. Unlike other studies, complex composite layup, fiber directions and layer orientations were defined by using the ACP module, and the composite blade analyzed both aerodynamic pressure and structural design using ACP and FSI modules together.

Renewable and sustainable energy sources such as wind, biomass, geothermal and solar are defined as a less harmfully to environment than other fossil fuels reserves. At the last decade, the demand of energy because of the rising of industrialization and population is increasing in Turkey. Thus, investments on renewable energy sources especially wind and solar energy systems are increasing rapidly because of unlicensed energy production legislation published by Turkish Ministry of Energy and Natural Sources. Although Turkey has high solar and wind capacity, there has not been develop a tool to determine the suitable regions for hybrid energy systems. In this study, geographical information systems (GIS) and Multi-criteria-base method (MCDM) are used to determine the suitable regions for wind-solar hybrid energy systems of Kayseri Province under potential and environmental impacts. The results shows (2.080 km2) %12.3 of Kayseri is suitable for hybrid energy system investment.

In this research work the aerodynamic performance of two novel vertical axis wind turbine was numerically investigated using Siemens FloEFD code. The STS-VAWT configuration performance is compared with the combined helical-STS-VAWT. The Κ-e turbulence model was selected to establish the analysis. The same airfoil (NACA0015) was employed in the design of the two wind turbine blades. The rotational region grid was refined comparing to the grid of the static region which was designed specially to minimize the effects of blockage. The obtained contours, flow trajectories , iso-surfaces of the velocity magnitude and pressure plots around the VAWT s showed a high turbulence flow inside the rotation region and the wake region of the combined configuration helical-STS-VAWT comparing to the conventional STS-VAWT.

Rüzgar enerjisi çevre dostu, karlı ve yenilenebilir bir enerji kaynağıdır. Rüzgar enerjisi yayılımı son yirmi yılda artmaktadır. Bu çalışmada, deniz üstü rüzgar yayılımı potansiyeli olan Bandırma körfezi içindeki en uygun alanın belirlenmesi için çalışılmış ve sonuç olarak buradaki potansiyel deniz üstü güç kapasitesi tahmin dilmiştir. Bu çalışma, görsel ve hızlı analiz sonuçlarını elde etmek için Coğrafi Bilgi Sistemi ve Çok-Kriterli-Karar-Verme Metodolojisi metodlarını birlikte kullanmaktadır. Bu kapsamda rüzgar hızı, deniz derinliği, kuş göç hatları gibi sekiz standart kriter uygulanarak detaylı bir şekilde Coğrafi Bilgi Sistemi kullanılarak incelenmektedir. Bandırma'nın deniz trafiği yoğunluğunun yüksek olması nedeniyle uygun bölge seçiminde gemi rotaları önemli ölçüde rol oynarken, askeri bölgelere, haberleşme kablolarına ve turistik alanlara yakınlık uygun bölge seçiminde sonucu etkileyecek derecede değildir. Sonuç olarak, denizüstü rüzgar santrali kurulumu için iki konum uygun olarak bulunmuştur; biri kuzeybatıda, diğeri ise Bandırma körfezininkuzey doğusunda, sırasıyla 72 MW ve 48 MW kapasitelidir., Wind energy is an environmentally friendly, profitable, and renewable energy resource. Wind energy eployment is increasing in the last two decades. In this paper, Bandırma bay which has a potential for offshore wind deployment is studied to determine the most suitable area in it and eventually potential offshore power capacity of the location is estimated. This study combines applications of Geographical Information System and Multi-Criteria- Decision-Making Methodology to obtain fast results supported with visual documentation. In this scope, eight standard criteria such as wind speed, water depth, bird migration lines are applied and nvestigated in detail by using Geographical Information System. It is found that there is sufficient wind speed t the shallow level of the sea. Consequently, two locations are found to be suitable; one is on the northwest and the other one is on the north east of Bandırma, with capacities of 72 MW and 48 MW, respectively.

Purpose The purpose of this exhaustive experimental study is to investigate the fluid-structure interaction in the flexible membrane wings over a range of angles of attack for various Reynolds numbers. Design/methodology/approach In this paper, an experimental study on fluid-structure interaction of flexible membrane wings was presented at Reynolds numbers of 2.5 × 104, 5 × 104 and 7.5 × 104. In the experimental studies, flow visualization, velocity and deformation measurements for flexible membrane wings were performed by the smoke-wire technique, multichannel constant temperature anemometer and digital image correlation system, respectively. All experimental results were combined and fluid-structure interaction was discussed. Findings In the flexible wings with the higher aspect ratio, higher vibration modes were noticed because the leading-edge separation was dominant at lower angles of attack. As both Reynolds number and the aspect ratio increased, the maximum membrane deformations increased and the vibrations became visible, secondary vibration modes were observed with growing the leading-edge vortices at moderate angles of attack. Moreover, in the graphs of the spectral analysis of the membrane displacement and the velocity; the dominant frequencies coincided because of the interaction of the flow over the wings and the membrane deformations. Originality/value Unlike available literature, obtained results were presented comparatively using the sketches of the smoke-wire photographs with deformation measurement or turbulence statistics from the velocity measurements. In this study, fluid-structure interaction and leading-edge vortices of membrane wings were investigated in detail with increasing both Reynolds number and the aspect ratio.

In this study, to analyze the mtDNA D-loop region and the origin of the maternal lineages of 16 different donkey populations, and to assess the domestication of Turkish indigenous donkeys in seven geographical regions, we investigated the DNA sequences of the D-loop region of 315 indigenous donkeys from Turkey. A total of 54 haplotypes, resulting from 35 polymorphic regions (27 parsimoniously informative and 6 singleton sites), were defined. Twenty-eight of these haplotypes are unique (51.85%), and 26 are shared among different Turkish indigenous donkey populations. The most frequent haplotype was Hap 1 (45.71%), followed by two haplotypes (Hap 4, 15.55% and Hap 7, 5.39%). The breed genetic diversity, evaluated by the haplotype diversity (HD) and nucleotide diversity (&pi, D), for the Turkish donkey populations ranged from 0.533 &plusmn, 0.180 (Tekirdağ&ndash, Malkara, MAL) to 0.933 &plusmn, 0.122 (Aydin, AYD), and from 0.01196 &plusmn, 0.0026 (Antalya, ANT) to 0.02101 &plusmn, 0.0041 (Aydin, AYD), respectively. We observed moderate-to-high levels of haplotype diversity and moderate nucleotide diversity, indicating plentiful genetic diversity in all of the Turkish indigenous donkey populations. Phylogenetic analysis (NJT) and median-joining network analysis established that all haplotypes were distinctly grouped into two major haplogroups. The results of AMOVA analyses, based on geographic structuring of Turkish native donkey populations, highlighted that the majority of the observed variance is due to differences among samples within populations. The observed differences between groups were found to be statistically significant. Comparison among Turkish indigenous donkey mtDNA D-loop regions and haplotypes, and different countries&rsquo, donkey breeds and wild asses, identified two clades and which is named Somali (Clade IV) and Nubian (Clade V) lineages. The results can be used to understand the origin of Turkish donkey populations clearly, and to resolve the phylogenetic relationship among all of the different regions.

A detailed experimental investigation on the mapping of the LSB formation over a turbine blade with different airfoils, and their vibration effects were considered first in this study. Wind tunnel experiments were performed on FX 84-W-150, SD7062, Clark-Y and WASP airfoils at Re = 3.5 × 104, Re = 7 × 104 and various angles of attack. Experimental arrangements consisted of detailed instantaneous and time-dependent flow visualizations, quasi-wall shear stress measurements by means of a hot-film sensor, aerodynamic force measurements with an external force balance system. It was observed that there was a strong correlation between voltage signals obtained from the hot-film sensor and the smoke-wire results. Fluctuation amplitude started to increase within the LSB especially at the aft portion due to the transition induced trapped roll-up vortices. Then, fluctuations peaked upstream of the reattachment point. It was observed that the airfoil with different thickness and camber caused the LSB (either short or long) to form, resulting in variation of aerodynamic forces with the time. This could trigger the stochastic vibrations such as flap-wise and edge-wise vibrations at the blade, causing the stochastic fatigue loads and limiting the lifespan of turbine blades.

This study proposes a new design idea to measure wind speed and direction using drag force. For this aim, load cells which are get aligned with the geographical directions were used. A prototype was built and tested in a wind tunnel located at WEAR Laboratory in Erciyes University. The tests were performed for the direction of 225 between 5 m/s and 25.2 m/s and the outputs were compared with reference velocities. The results were shown that the mean measurement errors of the new design were less than 3% and the mean direction errors were less than 3 respectively, which provided WMO accuracy requirements. (C) 2017 Elsevier Ltd. All rights reserved.

Fluid-structure interaction phenomena on NACA 4412 airfoil having membrane material which was partially mounted on both its suction and pressure surfaces were experimentally investigated in wind tunnel measurements. Different experiments including Digital Image Correlation, smoke-wire, force measurement, and hot-wire systems were conducted at varying angles of attack, α (0° to 24°), and different Reynolds numbers (Re = 2.5 × 104, 5 × 104and 7.5 × 104). The controlled case gave benefits of up to 2 times in lift coefficient at lower angles of attack (α = 0° − 10°), at the same time drag coefficient decreased. Moreover, the partially flexible airfoil presented high power efficiencies at the pre-stall angles of attack (α = 0° − 10°). Using the flexibility caused the shear layer to approach, laminar separation bubble to suppress, and the wake region to shrunk, indicating the high lift force and less drag force production. The membrane vibrated and deformed due to the flow over the airfoil. Then, the membrane vibration caused the flow to trigger, which caused fluid–structure interaction to perform and the laminar separation bubble to shrink. The transition to turbulence formed earlier and these two flow phenomena moved towards upstream, resulting in having fewer flow fluctuations and increasing the flow stability. This ensures important advantages such as enhancement of aerodynamic performance, power efficiency, and decreasing vibration and noise for wind turbine blades.

Over the past years, the installations of Shallow Geothermal Energy (SGE) systems are increasing throughout Europe, and it is indicating that a specific and detailed legal framework is necessary. Towards this direction, this paper consists of an overview of legislation issues on SGE at European level, based on concise reviews from fourteen countries, i.e., Croatia, Cyprus, France, Greece, Italy, Latvia, Lithuania, Poland, Portugal, Serbia, Slovenia, Spain, Sweden, and Turkey. Said reviews discuss key national legislation as well as experts’ experience in the procedure of SGE integration. Legal and technical issues are also critically discussed for all involved countries, both individually and collectively. Findings show that high diversity exists on legislation provisions as well as on regulations, standards, and institutional support amongst European countries. The latter acts as an effective barrier for the further development of the SGE market ; therefore indicating the need for a common approach. Increase of awareness, need for standardization, improvement of legal framework, and administration procedures and permitting, are essential steps in moving forward and supporting the effectiveness of design, construction, maintenance, and operation of SGE systems.

Humpback whales have very special fins, which reduce the friction force by the projections on the fins and enhance the lift force with increasing angle of attack. Thus, it has opportunity to move with less energy. In this study, the tubular structure was formed and adapted to the NACA0012 airfoil profile. Numerical modelling of tubercle wing was performed in ANSYS FLUENT. In numerical modelling, k-ω SST and Transition SST turbulence models were used to investigate tubercle wing performance. The tubercle structure on the wing provided to canalize the flow in the tubercle cavities, thus flow separation decreased. Consequently, it was observed that the aerodynamic performance of the wing increased when the sinusoidal protrusions known as tubercle structure were applied to the leading edge of the wing.

The proposal of this paper is clear to reveal and understand the unsteady flow characteristics over the surface of chambered airfoil operating especially at low Reynolds numbers by detecting boundary layer separation and laminar separation bubble (LSB). Experiments including smoke-wire technique for flow visualization, velocity measurement via hot-wire sensor and quasi-wall shear stress measurement by means of the hot-film sensor have been performed over the suction surface of NACA 4412 airfoil at Reynolds number of 5x104 and angle of attack of 14°. Experiments indicate that the airfoil at a stall angle exhibits the bistable characteristics over the suction surface because of the unsteady bubble bursting at low Reynolds numbers. That is, either laminar flow separates from the leading-edge of the airfoil owing to a dominant adverse pressure gradient (APG) or it does not separate along downstream. It is also noted that unsteady boundary layer formation may affect the flow characteristics by changing airfoil’s stability appreciably, causing the periodic fluctuations with the occurring bubble bursting and the leading edge and trailing edge vortex merging. This may conclude undesirable problems such as noise, vibration and flutter for the flight vehicles and wind turbines.

In this experimental study, flow over NACA 4412 airfoil with flexible membrane mounted both on suction surface and pressure surface was investigated at Reynolds number of 5x104 and different angles of attack. The smoke-wire visualization method was used for flow visualization to demonstrate flow phenomena as laminar separation bubble (LSB), leading edge separation and tip vortices. A constant temperature anemometer (CTA) was used for measuring flow over the partially flexible airfoil. Concerning the flow visualization, smoke-wire experiment was been conducted at z/c=0.1 and z/c=0.4. Besides, hot-wire experiment by means of CTA was employed to measure flow properties including values of velocity, turbulence statistics and Reynold stress over both uncontrolled and controlled airfoil. The results showed that partially flexible airfoil had several benefits compared with the uncontrolled airfoil. The results for this partially flexible airfoil were mainly lower size of LSB, higher stall angle of attack, ensuring more stable flow characteristics and more aerodynamic performance.

In the current study, the aerodynamic performance of NACA 4412 airfoil with sandpaper which was used as an alternative control device instead of vortex generators was investigated. It was especially considered how the sandpaper affected the growth of the separation bubble. Regarding the flow visualization, the smoke-wire experiment was done at different angles of attack and Reynolds numbers. Moreover, the hot-wire experiment was employed to measure velocity as well as the values of the turbulence statistics over and near wake of the airfoil. Besides the mentioned experiments, the force measurement was performed to obtain aerodynamic forces, and quasi-wall shear stress was measured by means of a hot-film sensor. With the roughness, the instability in the long transition region at low Reynolds number was bypassed. Flow momentum was increased in the boundary layer on the airfoil surface, and the flow over the roughened airfoil exhibited more resistance against adverse pressure gradients. The flow triggered by the roughness element suppressed the bubble, which meant pre-stall flow control carried out with resulting CL increment and CD reduction. Finally, using the sandpaper over the airfoil provided prominent benefits in terms of postponing of the stall and enhancement of aerodynamic performance for wind turbine blades.

Mevcut calisma, akis kontrolu saglamak icin puruzluluk elemani olan zimpara kagidi ile hazirlanmis NACA4412 ruzgar turbini kanadinin deneysel calismasini saglamaktadir. Duman teli ve Sicak-tel anemometresi deneyleri 8° hucum acisinda ve 25000 ile 75000 arasinda degisen hucum acilarinda gerceklestirilmistir. Geometrik parametre olarak, kanat uzerindeki puruzlulugun yeri ve yuksekligi ele alinmistir. Puruzluluk %15-25 kord boyuna yerlestirilmistir. Zimpara kagidi yuksekligi 0,5 mm olarak secilmistir. Onceden deneysel calismalar NACA4412 kanat profilinin aerodinamik performansi acisindan iyi sonuclar gosterecek mi seklinde dusunulmustu. Gercekten, deneysel sonuclar zimpara kagidi kullanildigi zaman NACA4412 kanat profili uzerindeki akisin etkilendigini ortaya cikardi, cunku ya kanadin kaldirma miktarinda belli bir artis vardi ya da laminer ayrilma kabarciginin konumu degistirilmisti. Sonuc olarak, zimparanin kullanilmasi pasif akis kontrolu sagladigini ve NACA4412 kanat profili uzerindeki akis ayrilmasini erteledigi ya da yok ettigini gostermektedir.