PASİF VE AKTİF KONTROL YÖNTEMLERİ OLARAK HEM BİR AYIRICI PLAKA HEMDE PLAZMA AKTÜATÖRLER KULLANILMASIYLA DAİRESEL BİR SİLİNDİR ETRAFINDA ETKİLİ AKIŞ KONTROLÜNÜN SAĞLANMASI

Bu çalışmada, pasif ve aktif akış kontrol metotları birlikte kullanılarak bir dairesel silindir etrafındaki akış manipüle edilmiştir. Deneyler dairesel silindirin çapına bağlı (D) Reynolds sayısının 4000 ve 10000 olduğu değerlerde rüzgâr tünelinde gerçekleştirilmiştir. Pasif akış kontrol metodu olarak 3.75D uzunluğa sahip ayırıcı plaka seçilmiştir. Aktif akış kontrol metodu elemanı olarak ise plazma aktüatörler seçilmiştir ve dairesel silindirin ±90° konumuna yerleştirilmiştir. Aktif ve pasif akış kontrol yöntemleri birlikte kullanılarak, bu yöntemleri ayrı ayrı kullanılmasına göre daha büyük bir azalma elde edilmiştir. Reynolds sayısının 5000 ve 10000 olduğu değerler için hibrit yöntem, sürükleme katsayısında sırasıyla %48 ve %45 azalma sağlamıştır. Hız ölçümleri kızgın tel anemometresi kullanılarak yapılmıştır ve iz bölgesindeki hız profilleri elde edilmiştir. Akış, duman-tel yöntemi kullanılarak görselleştirilmiştir. Plazma aktüatörlü ve ayırıcı plakalı dairesel silindirin iz bölgesinin sade silindire ve ayırıcı plaka kullanılan silindirin iz bölgesine kıyasla daha dar bir genişliğe sahip olduğu sonuçlarla ortaya koyulmuştur. Ayrıca, spektral analizden, hibrit akış kontrol yöntemi kullanılarak girdap kopma frekansının önemli ölçüde baskılandığı gözlemlenmiştir.

Anahtar Kelimeler:

Dairesel silindir, Plazma aktüatör, Ayırıcı plaka, Hibrit akış kontrol, Girdap kopma frekansı

EFFECTIVE FLOW CONTROL AROUND A CIRCULAR CYLINDER BY USING BOTH A SPLITTER PLATE AND PLASMA ACTUATORS AS PASSIVE AND ACTIVE CONTROL METHODS

In this study, passive and active flow control methods were used together to manipulate the flow around a circular cylinder. The experiments were conducted in a wind tunnel for the Reynolds number range of 4000 and 10000 based on the diameter of the circular cylinder (D). A splitter plate was used as passive flow control device and its length was chosen to be about 3.75D. Plasma actuators were placed on the circular cylinder at a position of ±90° as an active flow control device. Combining the active and passive flow control methods, a greater reduction of the drag coefficient was achieved compared to that of the cases when using these methods separately. For Reynolds numbers of 5000 and 10000, the hybrid method gives a reduction in drag of 48% and 45%, respectively. The velocity measurements were carried out by using the hot-wire anemometry and velocity profiles were obtained in the wake region. The flow was visualized by using a smoke wire method. The results revealed that the wake region of the circular cylinder with plasma actuator and splitter plate has a narrower width than the plain cylinder and with splitter plate. Also, it can be seen from spectral analysis that the vortex shedding frequency was suppressed significantly by usage of the hybrid flow control method was used.

Keywords:

Circular cylinder, Plasma actuator, Splitter plate, Hybrid flow control, Vortex shedding frequency,

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