A thermographic method to evaluate laminar bubble phenomena on airfoil operating at low Reynolds number

Cesini, G.; Ricci, R. A.; Montelpare, Sergio; Silvi, E.

doi:10.21611/qirt.2002.011

Cited by 5 publications

(2 citation statements)

References 6 publications

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“…9) is carried out on the basis of literature information [5] and fluid dynamic considerations [6][7]. The bubble presence, with a boundary condition of fixed heat flow and a forced convective heat exchange, generates a temperature distribution that shows a local increase in coincidence with the laminar bubble; this because the re-circulating flow inside the local boundary layer separation has a low convective heat transfer coefficient h and so there is not a good thermal exchange.…”

Section: T I J T I J T I J T I J T I Jmentioning

confidence: 99%

Thermographic Analysis of Acoustic Distourbance Effects on Laminar Separation Bubble

Ricci¹,

Angeletti²,

Montelpare³

et al. 2006

Proceedings of the 2006 International Conference on Quantitative InfraRed Thermography

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This research is aimed to evaluate the possibility to destabilize the boundary layer in order to reduce the Laminar Bubble phenomenon; this is carried out by means of acoustic or mechanical perturbations of the flow field. The analyses are performed in a low speed wind tunnel for an Eppler 205 airfoil typically subjected to the laminar separation bubble phenomenon at low Reynolds. The effects of the acoustic perturbations on the flow pattern are revealed by means of an infrared camera and the heated thin foil technique; instead, at the present work stage, the results of the mechanical perturbations are observed by using the pressure distribution analysis.The experimental results show, as expected, a frequency and amplitude influence on the bubble reduction. These effects are not constant varying the angle of attack for the tested airfoil neither modifying the chord based Reynolds number.

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Section: T I J T I J T I J T I J T I Jmentioning

confidence: 99%

Thermographic Analysis of Acoustic Distourbance Effects on Laminar Separation Bubble

Ricci¹,

Angeletti²,

Montelpare³

et al. 2006

Proceedings of the 2006 International Conference on Quantitative InfraRed Thermography

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“…It was concluded that the LSB negatively exhibited major role on aerodynamic performance. It was seen that LSB effected the performance by not only increasing drag and reducing lift [8,9] but also producing noise and vibration [10,11]. In order to diminish the negative effects of LSB, some researchers used membrane to observe the impact of flexibility [12,13].…”

Section: Introductionmentioning

confidence: 99%

Rüzgar Türbini Kanadı Üzerindeki Yüzey Pürüzlülüğü Etkisinin Deneysel İncelenmesi

Koca¹,

Genç²,

Açıkel³

2016

Çukurova Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi

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The present study ensures an experimental investigation of NACA4412 wind turbine blade airfoil prepared with the sandpaper as a roughness device in order to control its flow. The smoke-wire and hotwire experiments were carried out at low Reynolds number ranging from 25000 to 75000 and angle of attack of 8°. As geometrical parameters, height of sandpaper and it location over the airfoil were conducted. It was positioned 15%-25% chord length. Height of sandpaper was selected 0.5 mm. The experimental results revealed that the flow over NACA4412 was affected when sandpaper was utilized because either amount of lift apparently increased or the location and size of laminar separation bubble (LSB) were changed. As a result, it was shown that the use of sandpaper provided passive flow control and it was an effective way in terms of delay or suppress separation over NACA4412 airfoil.Keywords: Low reynolds number, Laminar separation bubble, Surface roughness, Passive flow control Rüzgar Türbini Kanadı Üzerindeki Yüzey Pürüzlülüğü Etkisinin Deneysel İncelenmesi ÖzMevcut çalışma, akış kontrolü sağlamak için pürüzlülük elemanı olan zımpara kağıdı ile hazırlanmış NACA4412 rüzgar türbini kanadının deneysel çalışmasını sağlamaktadır. Duman teli ve Sıcak-tel anemometresi deneyleri 8° hücum açısında ve 25000 ile 75000 arasında değişen hücum açılarında gerçekleştirilmiştir. Geometrik parametre olarak, kanat üzerindeki pürüzlülüğün yeri ve yüksekliği ele alınmıştır. Pürüzlülük %15-25 kord boyuna yerleştirilmiştir. Zımpara kağıdı yüksekliği 0,5 mm olarak seçilmiştir. Önceden deneysel çalışmalar NACA4412 kanat profilinin aerodinamik performansı açısından iyi sonuçlar gösterecek mi şeklinde düşünülmüştü. Gerçekten, deneysel sonuçlar zımpara kağıdı kullanıldığı zaman NACA4412 kanat profili üzerindeki akışın etkilendiğini ortaya çıkardı, çünkü ya kanadın kaldırma miktarında belli bir artış vardı ya da laminer ayrılma kabarcığının konumu değiştirilmişti. Sonuç olarak, zımparanın kullanılması pasif akış kontrolü sağladığını ve NACA4412 kanat profili üzerindeki akış ayrılmasını ertelediği ya da yok ettiğini göstermektedir.

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Study of acoustic disturbances effect on laminar separation bubble by IR thermography

Ricci

Montelpare

Silvi

2007

Experimental Thermal and Fluid Science

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A thermographic method to evaluate laminar bubble phenomena on airfoil operating at low Reynolds number

Cited by 5 publications

References 6 publications

Thermographic Analysis of Acoustic Distourbance Effects on Laminar Separation Bubble

Thermographic Analysis of Acoustic Distourbance Effects on Laminar Separation Bubble

Rüzgar Türbini Kanadı Üzerindeki Yüzey Pürüzlülüğü Etkisinin Deneysel İncelenmesi

Study of acoustic disturbances effect on laminar separation bubble by IR thermography

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