The Discharge Coefficient of a Centre-Pivot Roof Window

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Abstract

Accuracy in estimation of airflow through windows is the key parameter for modelling and designing of naturally ventilated buildings. The flow through windows is usually described by the orifice flow plate equation. This equation involves the discharge coefficient. In practice, often a constant value of discharge coefficient is used. The constant value of discharge coefficient leads to deceptive airflow estimation in the cases of centre-pivot roof windows. The object of this paper is to study and evaluate the discharge coefficient of the centre pivot roof window. Focus is given on unidirectional flows i.e. inflow and outflow. CFD techniques are used to predict the airflow through the modelled window. Analytical orifice flow equation is used to calculate the discharge coefficient. Results are compared with experimental results. It is concluded that the single value of the discharge coefficient leads to ambiguous estimation of airflow rates. The discharge coefficient decreases with increase in flap opening area. The discharge coefficient also depends upon the flow direction.
Original languageEnglish
Title of host publication33rd AIVC and 2nd TightVent Conference : Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort: Proceedings
Number of pages4
Place of PublicationCopenhagen
PublisherAIVC
Publication date2012
Pages 270-273
Publication statusPublished - 2012
Event33rd AIVC and 2nd TightVent Conference: Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort - Axelborg, København, Denmark
Duration: 10 Oct 201211 Oct 2012

Conference

Conference33rd AIVC and 2nd TightVent Conference
LocationAxelborg
CountryDenmark
CityKøbenhavn
Period10/10/201211/10/2012

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Roofs
Orifices
Computational fluid dynamics

Bibliographical note

Proceedings is handed out at the conference in print

Keywords

  • Centre pivot roof window
  • Discharge Coefficient
  • CFD

Cite this

Iqbal, A., Afshari, A., Nielsen, P. V., & Heiselberg, P. (2012). The Discharge Coefficient of a Centre-Pivot Roof Window. In 33rd AIVC and 2nd TightVent Conference: Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort: Proceedings (pp. 270-273). Copenhagen: AIVC.
Iqbal, Ahsan ; Afshari, Alireza ; Nielsen, Peter V. ; Heiselberg, Per. / The Discharge Coefficient of a Centre-Pivot Roof Window. 33rd AIVC and 2nd TightVent Conference: Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort: Proceedings. Copenhagen : AIVC, 2012. pp. 270-273
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abstract = "Accuracy in estimation of airflow through windows is the key parameter for modelling and designing of naturally ventilated buildings. The flow through windows is usually described by the orifice flow plate equation. This equation involves the discharge coefficient. In practice, often a constant value of discharge coefficient is used. The constant value of discharge coefficient leads to deceptive airflow estimation in the cases of centre-pivot roof windows. The object of this paper is to study and evaluate the discharge coefficient of the centre pivot roof window. Focus is given on unidirectional flows i.e. inflow and outflow. CFD techniques are used to predict the airflow through the modelled window. Analytical orifice flow equation is used to calculate the discharge coefficient. Results are compared with experimental results. It is concluded that the single value of the discharge coefficient leads to ambiguous estimation of airflow rates. The discharge coefficient decreases with increase in flap opening area. The discharge coefficient also depends upon the flow direction.",
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Iqbal, A, Afshari, A, Nielsen, PV & Heiselberg, P 2012, The Discharge Coefficient of a Centre-Pivot Roof Window. in 33rd AIVC and 2nd TightVent Conference: Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort: Proceedings. AIVC, Copenhagen, pp. 270-273, København, Denmark, 10/10/2012.

The Discharge Coefficient of a Centre-Pivot Roof Window. / Iqbal, Ahsan; Afshari, Alireza; Nielsen, Peter V.; Heiselberg, Per.

33rd AIVC and 2nd TightVent Conference: Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort: Proceedings. Copenhagen : AIVC, 2012. p. 270-273.

Research output: Contribution to book/anthology/report/conference proceedingArticle in proceedingResearchpeer-review

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Iqbal A, Afshari A, Nielsen PV, Heiselberg P. The Discharge Coefficient of a Centre-Pivot Roof Window. In 33rd AIVC and 2nd TightVent Conference: Optimising ventilative cooling and airtightness for (nearly) zero-energy buildings, IAQ and comfort: Proceedings. Copenhagen: AIVC. 2012. p. 270-273