Autovibration of coax injector elements of O_2/H_2 staged combustion liquid rocket engines

摘要

Little literature is available on the study of combustion instability of staged combustion rocket engines, However as a result of professional exchanges with Design Bureaus in Russia, some of their fundamental work can now be published. This paper presents the results of an extensive investigation conducted by the Lyulka-Saturn Inc. in support of the development of the D-57 O_2/H_2 staged combustion high energy upper stage engine. Several O_2/H_2 main chamber injector elements were evaluated for combustion stability, and the auto vibration characteristics of these elements were defined as a function of design. The results of main chamber injector element optimization is presented for gas- liquid injection schemes. Analytical correlation of experimental results was accomplished using the dynamci pressure ratio at the element exits. Optimization of injector element design with respect to transverse acoustic instability is also discussed along with the display of experimental data with definition of operating boundaries in which stable and unstable operation was recorded. The design parameters which support instability are displayed with the design basis for their elimination.