In {TAIL ~ one preferred embodiment}, {HEAD ~ an air blast} is directed through the porosity created by tensioning the fabric to impinge upon the underlying layer of fabric 
In
In { TAIL ~ one preferred embodiment } , { HEAD ~ an air blast } is directed through the porosity created by tensioning the fabric to impinge upon the underlying layer of fabric
REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH