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Khan, Mubashar Ahmed
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Publications (2 of 2) Show all publications
Sandberg, M., Mattsson, M., Wigö, H., Hayati, A., Claesson, L., Linden, E. & Khan, M. (2015). Viewpoints on wind and air infiltration phenomena at buildings illustrated by field and model studies. Building and Environment, 92, 504-517
Open this publication in new window or tab >>Viewpoints on wind and air infiltration phenomena at buildings illustrated by field and model studies
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2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 92, p. 504-517Article in journal (Refereed) Published
Abstract [en]

Ventilation and infiltration caused by wind are difficult to predict because they are non-local phenomena: driving factors depend on the surrounding terrain and neighbouring buildings and on the building orientation with respect to the wind direction. Wind-driven flow through an opening is complex because wind can flow through the opening or around the building, in contrast to buoyancy driven flow. We explored wind and air infiltration phenomena in terms of pressure distributions on and around buildings, stagnation points, flow along façades, drag forces, and air flow through openings. Field trials were conducted at a 19th-century church, and wind tunnel tests were conducted using a 1:200 scale model of the church and other models with openings.

 

The locations of stagnation points on the church model were determined using particle image velocimetry measurements. Multiple stagnation points occurred. The forces exerted on the church model by winds in various directions were measured using a load cell. The projected areas affected by winds in various directions were calculated using a CAD model of the church. The area-averaged pressure difference across the church was assessed. A fairly large region of influence on the ground, caused by blockage of the wind, was revealed by testing the scale model in the wind tunnel and recording the static pressure on the ground at many points. The findings of this study are summarized as a number of steps that we suggest to be taken to improve analysis and predictions of wind driven flow in buildings.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Infiltration, Wind, Particle Image Velocimetry, Openings, Stagnation points, Drag force
National Category
Building Technologies
Identifiers
urn:nbn:se:hig:diva-19278 (URN)10.1016/j.buildenv.2015.05.001 (DOI)000358807800046 ()2-s2.0-84930645066 (Scopus ID)
Projects
Church project
Funder
Swedish Energy Agency, 34964-1
Available from: 2015-05-04 Created: 2015-05-04 Last updated: 2018-12-03Bibliographically approved
Khan, M. A., Fransson, J. H. M. & Sandberg, M. (2013). On the wake pressure footprint and its potential application for wake flow analysis. In: European Wind Energy Conference and Exhibition, EWEC 2013: . Paper presented at European Wind Energy Conference and Exhibition, EWEC 2013, 4-7 February 2013, Vienna (pp. 939-945).
Open this publication in new window or tab >>On the wake pressure footprint and its potential application for wake flow analysis
2013 (English)In: European Wind Energy Conference and Exhibition, EWEC 2013, 2013, p. 939-945Conference paper, Published paper (Refereed)
Abstract [en]

This paper introduces a new wake analysis technique behind wind turbines, called pressure footprint (p-f) method, as a simple technique for wind tunnel experiments as well as for field measurements. It is based on the assumption that the pressure at ground is related to the total pressure at the hub height, which in turn can be correlated to the velocity deficit of the wake. The p-f method requires that the static pressure can be measured on the ground and for this purpose we here use a pressure plate with 400 pressure taps. A single wind turbine model was positioned in the middle of the plate and the pressures were measured using a scani-valve. The static and total pressures at hub height were also measured. The effect on the wake pressure footprint when varying the hub height was studied, and by an appropriate definition of the applied pressure coefficient the variation of the footprint size vanishes, which is an important first step in relating the footprint area to the velocity deficit in the wake. We also show the interaction of two wind turbine models, located on the same centre line, with varying reciprocal streamwise distance. With the current method the relative size between the upstream and the downstream pressure footprint remains constant with a factor of two. Next, we will investigate the correlation between the pressure footprint and the velocity deficit in the wake by performing particle image velocimetry measurements in the same setup.

Keywords
Wind power, Wind turbines, Applied pressure, Downstream pressure, Field measurement, Particle image velocimetry measurement, Static pressure, Velocity deficits, Wind tunnel experiment, Wind turbine modeling, Wakes
National Category
Environmental Engineering
Identifiers
urn:nbn:se:hig:diva-19485 (URN)2-s2.0-84903432947 (Scopus ID)9781632663146 (ISBN)
Conference
European Wind Energy Conference and Exhibition, EWEC 2013, 4-7 February 2013, Vienna
Available from: 2015-06-07 Created: 2015-06-07 Last updated: 2018-03-13Bibliographically approved
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