Regarding the perturbed operating process of DB propellant rocket motor at extreme initial grain temperatures

• Main Authors: Ioan ION, Titica VASILE, Doru SAFTA
• Format: Article
• Language: English
• Published: National Institute for Aerospace Research “Elie Carafoli” - INCAS 2012-03-01
• Series: INCAS Bulletin
• Subjects: thermodynamics of rocket propulsion; steady and unsteady flows; unsteady combustion; ccombustion instability; pressure-coupled response function; flight dynamics
• Online Access: http://bulletin.incas.ro/files/safta__vasile_ion__v4_iss_1_full.pdf
• ISSN: 2066-8201; 2247-4528

Despite many decades of study, the combustion instability of several DB propellants is still of particular concern, especially at extreme grain temperature conditions of rocket motor operating. The purpose of the first part of the paper is to give an overview of our main experimental results on combustion instabilities and pressure oscillations in DB propellant segmented grain rocket motors (SPRM-01, large L/D ratio), working at extreme initial grain temperatures. Thus, we recorded some particular pressure-time traces with significant perturbed pressure signal that was FFT analysed. An updated mathematical model incorporating transient frequency-dependent combustion response, in conjunction with pressure-dependent burning, is applied to investigate and predict the DB propellant combustion instability phenomenon. The susceptibility of the tested motor SPRM-01 with DB propellant to get a perturbed working and to go unstable with pressure was evidenced and this risk has to be evaluated. In the last part of our paper we evaluated the influence of recorded perturbed thrust on the rocket behaviour on the trajectory. The study revealed that at firing-table initial conditions, this kind of perturbed motor operating may not lead to an unstable rocket flight, but the ballistic parameters would be influenced in an unacceptable manner.