1,720,991 research outputs found
Progetto ottimale Integrato del velivolo e della strategia di missione per un lanciatore SSTO a propulsione composita a decollo orizzontale
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Modeling of Flowfield Features During Ignition Transient of Solid Rocket Motor
No full textAIAA Paper 2002-375
Modeling of Solid Motor Start-Up
No full textAn unsteady quasi- ID numerical simulation model has been developed in order to predict the behavior of large solid motors during the ignition transient. In particular, this model is finalized to be used as a numerical tool during the preliminary design phase, when no information about the future behavior of the motor is available. An Euler flow model has been adopted coupled with suitable semi-empirical models that take into account the main phenomena affecting the ignition transient. Special attention has been devoted to simulate the effects of the impingement of the igniter jets on the grain propellant surface (heating, ignition and combustion of the impingement region). A radiation model is also proposed. The simulation model has been extensively tested and the numerical results have been compared with the experimental results obtained for largely different motor concepts and configurations. Significant information about the role of some phenomena affecting the ignition transient has been also deduced from the critical analysis of these results. © 2001 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved
3D Numerical Simulation of Ignition Transient in SRM
No full textThis paper presents a three dimensional numerical code for the analysis of Solid Rocket Motor (SRM) pre-ignition transient. For motors with a 3D star-shaped "finocyl" region and high energy igniter, like the first three stages of the new European launcher "Vega", experimental results and preliminary quasi-1D and axisymmetric simulations show that this operative phase can be characterized by strong unsteady phenomena with the possible presence of nocive pressure oscillations inside the combustion chamber. Therefore in order to accurately design such kink of SRM the prediction capabilities of these pressure fluctuations has to be improved. A three dimensional (both cylindrical and rectangular coordinates), inviscid, compressible and multicomponent solver (named EoS) has been developed. It is based on a finite-volume Godunov-like scheme and adopts a cartesian structured grid. The code is written in Fortran 95 with Object Oriented style to ensure flexibility and easy maintenance/improvement (adding sub-models, parallelization etc). Some validation tests are presented. Also a preliminary analysis of Pre-Ignition Transient of a SRM, with a comparison between the experimental head-end pressure time-history and the numerical one, is presented
Lessons learnt during the development of VEGA launcher solid rocket motors
No full textVEGA is the new launcher developed by European Space Agency and qualified with its maiden flight on February, 13rd 2012. During the launcher development, a total of nine static firing tests (SFTs) have been performed for the 3 solid stages which compose the launcher: the 1 st stage P80, the 2 nd stage Zefiro 23 and the 3rd stage Zefiro 9A. Tailored for small payloads and low earth orbit missions, VEGA is a single-body four-staged launcher (three solid rocket motors – SRMs and one liquid upper stage), which completes the family of the European launchers, beside Soyuz and Ariane 5. This paper discusses and summarizes the activities performed during the last decade, for the development of the VEGA launcher SRMs, from the SPqR (Space Propulsion quasi Research) team at Sapienza University of Rome, as scientific consultant of the ESA ESRIN – VEGA Integrated Project Team. The paper will be focused, in particular, upon all the ”lessons learnt” during the solid stages development, describing the contributions given from the work-group to the launch vehicle: from Zefiro16, prototype of the VEGA family SRMs, to Zefiro9A, ”last born” of the solid stages, and flight version of the third stage. The research activities spanned all the relevant aspects in SRMs internal ballistics, from the SRM ignition to burn-out, as well as the external aerodynamic of the entire launch vehicle. Firstly, the use of the helium as pressurizing gas in order to reduce the pressure oscillations during the ignition transient (IT) of all the SRMs will be discussed from both ”historically”, during the project evolution, and technical point of views, from Zefiro 16 to P80 (DM fired with helium and QM, with nitrogen). Afterwards, the analyses performed during the design of Zefiro 9A, concerning the first phase of the ignition transient of the SRM, will be described, giving a description of the reasons behind the subsequent design modifications of Zefiro 9A with respect to the Zefiro 9 configuration. The description of the applied research activities performed will, then, consider the prediction and reconstruction methods and the consequent results, achieved in the analysis of all the VEGA SFTs: 0D post-static firing tests reconstruction, Q1D simulations of the internal ballistics and reconstruction of the P80 pressure oscillations. Finally, an analysis on the external aerodynamic of the complete launcher, performed in its full and detailed configuration (all protrusions included) will be resumed in its essential aspects. All these activities have been carried out with a series of numerical and analysis tools developed ”in-house” at Sapienza University of Rome – Propulsion Area of the Dept. of Mechanical and Aerospace Engineering, spanning from a 0D quasi-steady model of SRMs internal ballistics, to a full 3D unsteady CFD model of SRMs internal ballistics and launcher external aerodynamics
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