The invention provides a back up supply, by putting {HEAD ~ the air} through {TAIL ~ a plenum chamber} and dividing it so that when cooling airflow is reduced, a further sealing air flow is provided in compensation therefore 
The invention provides a back up supply , by putting { HEAD ~ the air } through { TAIL ~ a plenum chamber } and dividing it so that when cooling airflow is reduced , a further sealing air flow is provided in compensation therefore
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH