Effect of Number of Blades on Performance of Ceiling Fans

Adeeb, Ehsan; Maqsood, Adnan; Mushtaq, Ammar

doi:10.1051/matecconf/20152802002

Cited by 10 publications

(5 citation statements)

References 14 publications

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“…Further, recent literature highlights that furniture, partitions, and openings change the flow field initially explored for an empty chamber [24][25][26][27][28]. These characteristics combined may affect the resulting flow field and the expected efficiency to deliver thermal comfort [29][30][31]. Ceiling fans create a highly turbulent air motion with toroid shape flowing downwards in the environment; for enhancing a better thermal comfort sensation, buildings occupants should be under this turbulent flow [10].…”

Section: Air Speed (M/s)mentioning

confidence: 99%

Prediction of the Impact of Air Speed Produced by a Mechanical Fan and Operative Temperature on the Thermal Sensation

et al. 2022

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Natural ventilation associated with a mechanical fan is a feasible strategy to enhance thermal acceptability in warm weather. The ASHRAE-55 provides the increase for operative temperature proportional to the increase in air speed while maintaining thermal comfort. Conversely, the range of informed values is limited and little guidance for mechanical fans is provided. This work explores the relationship between operative temperature and air speed produced by ceiling fans, and the effectiveness to deliver thermal comfort for a wider range of values. The research method comprises transient computer fluid dynamics simulations coupled with a thermal sensation model and is divided into two stages: a calibration exercise and a parametrical investigation. Three matrices are presented for a range of operative temperatures (21.0–36.0 °C) and air speeds (0–2.5 m/s) for: Dynamic Thermal Sensation (DTS) (a computer-based seven-point index), Predicted Percentage of Dissatisfied, and potential Cooling Effect. When compared to the Predicted Mean Vote, the DTS overestimates thermal comfort for temperatures under 28.0 °C with increased air speed and overestimates discomfort for temperatures above 31.0 °C, even with increased air speed. Agreement is found between both scales for 28.0–31.0 °C, defining a range for the effective use of ceiling fans to provide thermal comfort under warm weather conditions.

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Section: Air Speed (M/s)mentioning

confidence: 99%

Prediction of the Impact of Air Speed Produced by a Mechanical Fan and Operative Temperature on the Thermal Sensation

et al. 2022

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“…Many prior studies focus on the airflow through a ceiling fan and show that blade geometry and number of blades affect airflow and efficiency [31,35,[39][40][41][42][43][44]. However, these don't focus on the air speed distribution within the room.…”

Section: Review Of Prior Studies Investigating Ceiling-fan Driven Airmentioning

confidence: 99%

Ceiling fans: Predicting indoor air speeds based on full scale laboratory measurements

Raftery

Fizer²,

Chen

et al. 2019

Building and Environment

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We measured indoor air speeds generated by ceiling fans in 78 full-scale laboratory tests. The factors were the room size, fan diameter, type, speed, direction (up or down), blade height, and mount distance (i.e. blade to ceiling height). We demonstrated the influence o f t hese f actors, s howing t hat t he m ost s ignificant ar e speed, diameter and direction. With other factors fixed, t he average r oom a ir s peed i n t he o ccupied z one increases proportionally with fan air speed and diameter. Blowing fans upwards yields lower but far more uniform air speeds than downwards. We show that for the same fan diameter and airflow, f an type h as l ittle effect on the air speed distribution in the region outside the fan blades. We developed several new dimensionless representations and demonstrate that they are appropriate for comparisons over a wide range of fan and room characteristics. Dimensionless linear models predict the lowest, average, and highest air speeds in a room with a median (and 90 th percentile) absolute error of 0.03 (0.08), 0.05 (0.13), and 0.12 (0.26) m/s respectively over all 56 downwards tests, representing common applications. These models allow designers to quickly and easily estimate the air speeds they can expect for a given fan and room. We include all measured data and analysis code in this paper. Highlights:• Measured air speed distribution in 78 full-scale laboratory tests • Average air speeds increase in direct proportion to fan rotational speed and diameter • Blowing fans upwards yields lower but more uniform air speeds than downwards • At equal diameter and airflow, fan type doesn't affect air speeds in most of the room • Developed easily applied models to predict indoor air speeds with ceiling fans Graphical Abstract 2

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“…Araştırıcılar, Standart k-ε modeline göre dönüş akışlarının modellenmesinde daha iyi sonuçlar göstermesi nedeniyle Reliazable k-ε türbülans modelini simülasyonlarda kullanmıştır. Adeeb et al (2015), farklı sayıda fan kanatların etkisi üzerinde çalışmalar gerçekleştirmişlerdir. Chen et al (2018), 3 kanatlı 1.5 m çapındaki tavan vantilatörü ile ilişkili iç mekan hava dağılımını ortaya koymak için farklı fan dönüş hızı, kanat geometrisi, fan-tavan arası mesafe için ölçümler ve Standart k-ε türbülans modeli kullanarak HAD ile simülasyon gerçekleştirmiştir.…”

Section: Tarımda Kullanılan Büyük çAplı Tavan Tipi Vantilatörde Hava ...unclassified

Tarımda kullanılan büyük çaplı tavan tipi vantilatörde hava akışının hesaplamalı akışkanlar dinamiği ile incelenmesi

Demir

Günhan

BİLGEN

2022

Ege Üniversitesi Ziraat Fakültesi Dergisi

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Bu çalışmada iki farklı dönme dairesi çapına sahip tavan tipi vantilatörün hava hareketlerinin Hesaplamalı Akışkanlar Dinamiği (HAD) yöntemiyle ortaya konulması ve en uygun türbülans modelinin belirlenmesi amaçlanmıştır.Materyal ve Yöntem: İlk aşamada, tavan tipi vantilatörlerin fan merkezinden belirli uzaklıklardaki eksenel yöndeki hava hızı değişimleri ölçülmüştür. Bu amaçla zeminden iki farklı yükseklik (1.0 ve 1.5 m) dikkate alınmıştır. İkinci aşamada farklı türbülans modelleri ile hesaplamalı akışkanlar dinamiği analiz yöntemiyle hesaplanan değerler, ölçüm değerleri ile karşılaştırılmıştır.Araştırma Bulguları: Sonuçlar istatistiksel olarak değerlendirildiğinde, en düşük MAE ve NRMSD değerleri 4 m dönme dairesi çapı için Spalart Allmaras ve SST k-ω modellerinde, 5 m dönme dairesi çapı için SST k-ω modelinde bulunmuştur. Grafik karşılaştırmalar incelendiğinde SST k-ω modelinin diğer modellere göre az da olsa daha iyi tahminlemeyi gerçekleştirdiği görülmektedir.Sonuç: HAD simülasyon modellerinin çözüm yaklaşımları birbirine oldukça yakın bulunmuştur. Türbülans modelinin uygun seçimi ve iyi yapılandırılmış ağ yapısı ile zeminden belirli yükseklikteki noktalarda HAD simülasyonu ile deneysel verilere çok yakın tahminlerin elde edilebileceği ortaya konulmuştur.

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Effect of Number of Blades on Performance of Ceiling Fans

Cited by 10 publications

References 14 publications

Prediction of the Impact of Air Speed Produced by a Mechanical Fan and Operative Temperature on the Thermal Sensation

Prediction of the Impact of Air Speed Produced by a Mechanical Fan and Operative Temperature on the Thermal Sensation

Ceiling fans: Predicting indoor air speeds based on full scale laboratory measurements

Tarımda kullanılan büyük çaplı tavan tipi vantilatörde hava akışının hesaplamalı akışkanlar dinamiği ile incelenmesi

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