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Published March 1961 | Reprint
Journal Article Open

Effect of scale size on a rocket engine with suddenly frozen nozzle flow

Watson, Ronald


Recent analytical work by Bray indicates that single element, chemically reacting systems, e.g., H_2 ⇋ 2H, may suddenly freeze their composition at some point in a high speed nozzle and then remain at fixed composition throughout the remainder of the expansion. This sudden freezing or "quenching" phenomenon was also apparent in some theoretical calculations reported by Hall et al. and has been verified experimentally by Wegener. It is the purpose of this note to show qualitatively how Bray's sudden-freezing criterion is related to engine size by the scale factor for geometrically similar engines having n on equilibrium nozzle flows and in which a propellant system is used for which Bray's analysis is valid.

Additional Information

© 1961, by the American Hocket Society, Inc. Received Sept. 29, 1960. This work was carried out in part under Air Force Contract AF 04(647)-309 at Space Technology Laboratories, Inc., Los Angeles, Calif. NSF Fellow, Daniel and Florence Guggenheim Jet Propulsion Center. Numbers in parentheses indicate References at end of paper. The "suddenness" of the freezing depends on both the reaction rate constants and geometry. In a personal communication Bray pointed out that for nozzles with very small expansion angles, the freezing stretches out over quite some length and is far from sudden.

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August 19, 2023
October 21, 2023