THE EFFECT OF DOMINANT OPENINGS AND POROSITY ON INTERNAL-PRESSURES

This paper describes a parametric wind funnel study carried out in the BRE boundary layer wind tunnel to investigate the effects of porosity and dominant openings on both steady and unsteady internal pressures. The propagation of pressures through single and multi-cell models was studied to determine the effects of location and size of single and t win orifices (orifices on opposite walls). The area of the orifices wa s variable between 1% and 25% of the wall area. The results show that for a single dominant opening the mean internal pressure is generally similar to the external pressure at the opening. The peak internal pre ssures tend to be more variable. For the case of twin dominant opening s, large differences were observed between measured internal pressures and steady state predictions due to the influence of both the magnitu de and correlation between fluctuating external pressures at the openi ngs.