a plurality of {HEAD ~ air inlets} 32 at the lower periphery of {TAIL ~ the inner tube} 30, and 
a plurality of { HEAD ~ air inlets } 32 at the lower periphery of { TAIL ~ the inner tube } 30 , and
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH