Gas flow control system for sub-sonic divergent diffusers

Claim 1

IN A DIVERGENT PASSAGE FOR SUB-SONIC GAS FLOW, GAS FLOW CONTROL MEANS COMPRISING A SERIES OF FLAT PREFORATED PLATES OF THIN CROSS-SECTION COMPARED TO THE TRANSVERSE DIMENSIONS OF SAID PASSAGE, SAID PLATES BEING NON-BUCKLING DURING GAS FLOW AND MOUNTED IN THE DIVERGENT PASSAGE WITH THE FLAT FACES THEREOF POSITIONED GENERALLY NORMAL TO THE FLOW OF GAS IN THE PASSAGE, THE PERFORATIONS IN EACH OF THE PLATES BEING DISCRETE, CIRCULAR IN CROSS-SECTION AND OF A UNIFORM DIAMETER, AND COMPRISING FROM ABOUT 30 TO ABOUT 60% OF THE AREA OF EACH OF SAID PLATES, THE RADIO OF THE PERFORATION DIAMETER TO THE MINIMUM DIMENSION OF THE OUTLET END OF THE DIVERGENT PASSAGE BEING 1 TO FROM ABOUT 80 TOL ABOUT 130, THE FIRST OF SAID SERIES OF PLATES BEING POSITIONED AT THE DOWNSTREAM END OF THE DIVERGENT PASSAGE, AND EACH PRECEDING PLATE OF THE SERIES BEING SPACED UPSTREAM OF ITS ADJACENT DOWNSTREAM PLATE AT A DISTANCE FROM ABOUT 15 TO ABOUT 20 TIMES THE DIAMETER OF THE PERFORATIONS IN THE PLATES.