Vind- och snösimulering kring byggnader genom modellstudier i strömmande vatten
Wind and snow could have negative effects on buildings in densely populated areas, farm yards, single buildings or even on details of the building. Farm related problems are for example that the wind blows up doors, that the natural ventilation fails with too high airspeeds in the animal residence area, huge amounts of snow deposits inside open buildings, formation of snow-drifts in front of doors or on roads. In Sweden the interest for open, natural ventilated buildings has increased since the beginning of the 1990's. Many such buildings have also been built. With increased knowledge of the manners of snow and wind many problems could be avoided before the buildings are built. Knowledge is also necessary for actions in existing buildings and farmsteads. The advantage of using models for predetermining air and snow patterns has been recognised since many years. In model studies you could choose to investigate the wind and snow situation at different scales from densely populated areas, farm yards, single buildings to specific details of the building. Tests were made on the categories of building environment that are of most interest for farm buildings namely farm yards and single buildings. The first study aimed at finding the best location of a single-floor building with an open ridge next to a higher building with regard to avoid snow blowing into the ridge. The results show that the best location is depending on the main direction of the wind. The first part of the ridge from the short sides should be covered. The length of the covered ridge should be adjusted to the local situation. Experiments were made on a section of single-sloped open-front building to compare the influence of different rear opening design on the air patterns inside. Two different opening designs with identical vent areas were tested. The air patterns changed both in its magnitude and directions between the models. The placement of the centre for the slot influence air patterns. Experiments were made on a single-sloped open-front building to investigate if the problem with snow accumulation at the front of the building, when wind is blowing from behind the building, could be solved with a slot-opening at the top of the rear wall, This action had a positive effect on the amount of snow that drifts back into the building. The same building without a rear slot has been tested in a field study in Canada. The results were compared showing the quantitative results of the model study were not 100 % correct but there was a qualitative correlation between the model and the field study. The final conclusions are that the water flume is an excellent tool to investigate and show the air patterns in and around buildings. Regarding snow, the water flume could be used to compare results between models. There is some correspondence between snow accumulation in the water flume and in nature. Unfortunately it was not possible to simulate two phases of snow drift i.e. Saltation and Suspension because of a too low velocity of the water (0,09 m/s) in the flume. The required velocity for simulating those two phases of snow drifting is 0,77 m/s.
strömningsbord; snödrift; stall; simulering; modell; luftrörelser; vatten
Rapport - Sveriges lantbruksuniversitet, Institutionen för lantbruksteknik
Publisher: Institutionen för lantbruksteknik, Sveriges lantbruksuniversitet
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