Düz bir yüzeye çarpan halkasal ve sentetik jetin ısı transferi karakteristiğinin parametrik olarak incelenmesi
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Dosyalar
Tarih
2023
Yazarlar
Dergi Başlığı
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Yayıncı
Aksaray Üniversitesi Fen Bilimleri Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu çalışmada, sabit ısı akısıyla ısıtılmış düz bir yüzey üzerinde türbülanslı halkasal bir jet çarpmasından kaynaklanan ısı transferi performansı deneysel ve sayısal olarak incelenmiştir. Halkasal çarpan jetler, ısı transferini arttırır ve dairesel çarpan jete kıyasla çarpma yüzeyi üzerinde akışı daha üniform bir şekilde yayar ve bir ters durgunluk akışı oluşturma gibi kayda değer bir özelliğe sahiptir. İncelemelerde, hedef yüzey ile jet çıkışı arasındaki mesafe (H/D), jet Reynolds sayısı (Rej), Sentetik jetin genliği (Ao) ve frekansı (Wo) değiştirilirken, Prandtl sayısı (Pr) ve geometrik parametreler sabit tutulmuş ve ısı transferi üzerinde bu parametrelerin etkileri analiz edilmiştir. Deneyler, belirlenen Reynolds sayılarında, dört farklı çarpma mesafesi, dört farklı genlik ve altı farklı frekans için yapılmıştır. Aktif ısı transferi iyileştirme yöntemi olarak kullanılan sentetik ve halkasal jet için imal edilen deney düzeneği üzerinde ayrıntılı olarak sıcaklık ölçümleri yapılmış ve ölçülen sıcaklıklar yardımıyla Nusselt sayıları hesaplanmıştır. Deneysel parametrelere uygun olarak sayısal modellemede yapılmış olup, akış yapısı hakkında detaylı değerlendirmeler yapılabilmiştir. Elde edilen sonuçlar, boyutsuz sayılarla ifade edilmiş olup, sonuçlar dairesel jet çarpması sonucu oluşan ısı transferi sonuçlarıyla karşılaştırılmıştır. Deneysel sonuçlar, ısı transferi iyileştirmede dairesel jete göre halkasal sentetik jetin önemli bir etkiye sahip olduğunu göstermiştir.
In this study, heat transfer performance from a turbulent annular jet impingement on a constant heat flux heated flat surface was investigated experimentally and numerically. Annular impinging jets enhance the heat transfer and spread the flow more uniformly over the impingement surface compared to the round impinging jet, and have one noteworthy characteristic of forming a reverse stagnation flow. In the investigations, the distance between the target surface and the jet exit (H/D), the jet Reynolds number (Rej), the amplitude (Ao) and frequency (Wo) of the synthetic jet were changed, while the Prandtl number (Pr) and geometric parameters were kept constant, and the effects of these parameters on heat transfer were analyzed. Experiments were carried out for three different impact distances, four different amplitudes and six different frequencies at the determined Reynolds number. The synthetic jet is used as an active heat transfer enhancement method, temperature measurements were made in detail on the experimental setup and Nusselt numbers were calculated with the based on measured temperatures. Numerical modeling was carried out in accordance with the experimental parameters, and detailed evaluations were made about the flow structure. The obtained results are expressed as a function of dimensionless numbers, and the results are compared with the heat transfer results of continuous (circular) jet impingement. Experimental results showed that the annular synthetic jet has a significant effect on heat transfer enhancement. It was observed that the annular synthetic jet significantly increased the heat transfer compared to the continuous jets.
In this study, heat transfer performance from a turbulent annular jet impingement on a constant heat flux heated flat surface was investigated experimentally and numerically. Annular impinging jets enhance the heat transfer and spread the flow more uniformly over the impingement surface compared to the round impinging jet, and have one noteworthy characteristic of forming a reverse stagnation flow. In the investigations, the distance between the target surface and the jet exit (H/D), the jet Reynolds number (Rej), the amplitude (Ao) and frequency (Wo) of the synthetic jet were changed, while the Prandtl number (Pr) and geometric parameters were kept constant, and the effects of these parameters on heat transfer were analyzed. Experiments were carried out for three different impact distances, four different amplitudes and six different frequencies at the determined Reynolds number. The synthetic jet is used as an active heat transfer enhancement method, temperature measurements were made in detail on the experimental setup and Nusselt numbers were calculated with the based on measured temperatures. Numerical modeling was carried out in accordance with the experimental parameters, and detailed evaluations were made about the flow structure. The obtained results are expressed as a function of dimensionless numbers, and the results are compared with the heat transfer results of continuous (circular) jet impingement. Experimental results showed that the annular synthetic jet has a significant effect on heat transfer enhancement. It was observed that the annular synthetic jet significantly increased the heat transfer compared to the continuous jets.
Açıklama
Anahtar Kelimeler
Halkasal Çarpan Jet, Sentetik Jet, Isı Transferi, Yüzey Soğutma, Annular Jet Impingement, Synthetic Jet, Heat Transfer, Surface Cooling
