Study of the Effects of Materials Selection for the Closeout Structure on the Service Life of a Liquid Rocket Engine Thr
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JMEPEG https://doi.org/10.1007/s11665-019-03896-5
Study of the Effects of Materials Selection for the Closeout Structure on the Service Life of a Liquid Rocket Engine Thrust Chamber M. Ferraiuolo and A. Riccio (Submitted July 30, 2018; in revised form December 6, 2018) The external structure of rocket engines thrust chambers for aerospace applications should be designed in order to provide adequate stiffness to the thrust chamber; however, it affects in a significant way the engine service life since it acts as a structural bound for the internal structure which is subjected to very high temperature values. The adoption of thin closeout structures allows to have lighter structures and to significantly increase the service life of the thrust chamber. The aim of the present work is to perform numerical investigations on the influence of the closeout geometry and materials on the number of cycles to failure of the thrust chamber. Furthermore, a study on the impact of creep phenomenon on the service life is illustrated. In particular, the present paper is focused on the thermomechanical study of the closeout structure, in terms of material choice, thickness, joining process with the inner liner, etc. Transient thermal and static structural nonlinear analyses are conducted by means of a commercial finite element code (ANSYS), in order to evaluate the number of cycles to failure for the investigated configurations. Viscoplastic models are adopted in order to simulate the highly nonlinear and rate-dependent phenomena occurring in the inner liner structure. Keywords
regenerative cooling, service life, thermal ratcheting, thrust chamber
1. Introduction The aim of the Hyprob project, financed by MIUR (Italian Ministry of University and Research) and leaded by CIRA (Italian Aerospace Research Centre), is to design, manufacture and test a 30 kN thrust chamber based on a regenerative cooling system which adopts liquid methane as refrigerant. The adoption of regeneratively cooled thrust chambers for aerospace applications is necessary when high heat fluxes coming from the combustion chamber are detected. In fact, in order to avoid high temperatures and stresses in the liner, the fuel, that is, usually liquid hydrogen or liquid methane, flows in the thrust chamber cooling channels and, then, is introduced in the thrust chamber where it is burnt (see Fig. 1). One of the major technological challenges when manufacturing the thrust chamber is to connect the inner liner with the closeout structure ensuring an appropriate service life. A This article is an invited submission to JMEP selected from presentations at the International Symposium on Dynamic Response and Failure of Composite Materials (Draf2018) held June 12-15, 2018, on the Island of Ischia, Italy, and has been expanded from the original presentation. M. Ferraiuolo, Structures and Materials Department, Italian Aerospace Research Center (CIRA), Capua, Italy; and A. Riccio, Department of Industrial and Information Engineering, Universita` degli studi della Campania ‘‘Luigi Vanvite
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