Ferhat KARAKAŞ, Onur PAÇA, Cihad KÖSE, Onur SON, Berk ZALOĞLU, İDİL FENERCİOĞLU AYDIN, Okşan ÇETİNER

Çırpan kanatta kanat profilinin etkisi

Mikro hava araçlarının (MHA) tasarımı ve pratikteki uygulamaları için yapılan çalışmalar, düşük Reynolds sayılı akışlarıdaki araştırmaların önemini arttırmıştır. Su canlıları, kuşlar ve böceklerin etrafındaki akışlardan biyolojik esinlenme ile yaratılabilen itki kuvveti, bu tür hareket mekanizmalarının havacılıkta kullanılabilecek tahrik sistemlerinin uygulama olanakları açısından gittikçe artan şekilde ilgi çekmektedir. Çırpan kanatlar, halihazırda kullanılmakta olan sabit ve döner kanatlı küçük-boyutlu hava araçlarının performansını arttırmada gelecek vaad etmektedir. Daha önce, SD7003 profiline sahip, çift taraftan sonlandırılarak iki boyutlu incelemeye tabii tutulmuş, yunuslama ve ötelenme yapan bir çırpan kanatta, değişik hareket parametrelerinde oluşan vorteks yapıları sınıflandırılmıştır. Bu çalışmada ise vorteks yapılarına dayanarak niteliksel olarak itki veya sürükleme oluşturduğu belirlenen hareketlerde, dört değişik kanat profiline sahip model (SD7003, NACA0012, t/c=0.05 yuvarlak kenarlı ve t/c=0.05 keskin kenarlı düz levhalar) için üç boyutlu durumda (AR=4) kuvvet ölçümleri yapılmıştır. Çalışma deneysel olarak su kanalında 2,000 < Re < 15,000 arası değerlerde, DPIV (Digital Particle Image Velocimetry – Dijital Parçacık Görüntüleyerek Hız Belirleme) sistemi ve kuvvet/moment duyargası kullanılarak gerçekleştirilmiştir. Niceliksel akım görüntüleme sonuçları kanat açıklığı boyunca üç değişik düzlemde elde edilmiştir. Sonuçlar çırpan kanadın yakın iz bölgesinde oluşan vorteks yapıları ile kanada etkiyen kuvvet değerleri arasındaki ilişkiyi zamana bağlı olarak ortaya koymaktadır. Ayrıca çalışmada, sonlu kanat için değişik kanat profilleri kullanımının vorteks oluşumları ile itki/sürükleme elde edilmesinde oluşturduğu farklılıklar incelenmiştir.

Effect of cross sectional shape variation for an oscillating wing

Investigations on the design and applications for Micro Air Vehicles (MAV) attract increasing attention to the fields of study on low Reynolds number flows. Generation of thrust and locomotion mechanism of swimming and flying animals may improve the design and development of engineered systems that take advantage of similar unsteady aerodynamic mechanisms. Biological inspiration offers a means to enhance the performance of the next generation of small-scale air vehicles over existing fixed and rotary wing systems. A 2D oscillating wing with SD7003 airfoil profile undergoing pitching and plunging motions was investigated in a previous study and the vortical structures were categorized for various flapping parameters. In this study, three-dimensional models (AR=4) with four different airfoil profiles (SD7003, NACA0012, t/c=0.05 rounded edge and t/c=0.05 sharp edge flat plates) are used for the cases where thrust or drag production was qualitatively defined based on flow structures. The study is performed in a water channel at the Reynolds number range of 2,000 < Re < 15,000 using the DPIV (Digital Particle Image Velocimetry) technique and a Force/Torque sensor. Quantitative flow visualization results are obtained for three different planes along the span of the test models. The results reveal the time dependent relation between the vortical structures and the forces acting on the test models. The effect of using various airfoil profiles on the vortical structures and thrust/drag production is also investigated.

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