Low Density Boundary Layer Control by Liquid Hydrogen Cryopumping

Abstract

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High Temperature, Low Density Boundary-Layer Control by Cryogenic Pumping

“…Similar data were presented for a stagnation temperature of 300°K in Ref. 2, where it was also shown that the flat plate boundary-layer approximation was accurate to within ±15 percent for a large number of low density nozzles. Within this approximation, then, referring to Fig.…”

“…8 of Ref. 2. Such a mode of operation appeared to offer a significant increase in core size over the normal mode of operation with suction, which incorporated a water-cooled throat insert.…”

“…The feasibility of predicting boundary-layer thicknesses within a 15-percent accuracy in low density hypersonic nozzles by use of simple flat plate theory was discussed in Ref. 2. The feasibility of this method, of course, results from the fact that the velocity gradient over the greatest part of the diverging section of a hypersonic nozzle is negligible.…”

“…In Ref. 2, results were given for a combination of liquid hydrogen as the refrigerant and nitrogen as the test gas in a 1-ft-diam hypersonic nozzle. Extensive Mach number calibrations and flow profiles were given for a stagnation temperature of 300°K, and it was shown that the attainable degree of rarefaction in the nozzle, Kn cm , was increased by at least an order of magnitude by the use of the cryogenic BLC.…”