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