7. Experience of Development and Use of Generator Pressurization System for Tanks of Launch Vehicles on High-Temperature Propellants

Annotation: Long-term experience in development, development testing and use of generating systems of fuel tanks pressurization for rockets powered by nitrogen tetroxide and unsymmetrical dimethylhydrazine is summarized. Replacement of gas bottle pressurization systems with generating ones on such launch vehicles as 15A14, 15A15, 11K68 (8K67), 15A18M substantially simplified operation, reduced the pneumohydraulic feed system mass at least twice and its cost – by five times. Typical stages of development and introduction of the pressurization generating systems are shown: development of generators, their development testing, study of the composition and parameters of gas. The important steps were the development of methodology for pressurization system parameters calculation, which enabled achievement of the substantial improvements of their characteristics, appearance of the high-performance hightemperature (up to ~ 1000o C) unsymmetrical dimethylhydrazine tank pressurization system, study of the degree of impact of each of the pressurization system parameters on the tank pressure. Accounting of the correlation between the flow rate and the generator gas temperature improved the output performance, as well as simplified and reduced the amount of development testing of the pressurization system. Important role of the gas sprayer design in pressurization system parametric configuration is described, and the advanced versions are shown taking into account g-loads, changes in temperature, pressure and propellant level inside the tank. Significant phase in the development of the generating pressurization system was the effective use of the high-temperature pressurization of the fuel tank with submerged propulsion system. Besides for the first time the effect of mechanical temperature destratification of the propellant in the tanks was observed, which occurs during the propulsion systems shutdown. Due to this effect, the Dnepr LV payload capability enhanced. Successful engineering solutions in the design of the pressurization system were defended by ~80 copyright certificates and patents of invention, ~40 of which were successfully implemented.