Three Dimensional Stability Analysis of a Liquid Propellant Combustor

A theoretical study analyzing ihrec-dimensicnuil combustion acoustic instabilities in a liquid propellant rocket engine comliustor has been conducted. A linear theory based on CrocCO 8 pressure sensitive time lag model 1S used. To apply this theory, the combustor is diuuied into two main components, incl-uding the combustion chamber and the conuerquu; part of ilu: nozzle, The assumption of concentrated cornlnistioti zone is used and the goveT1l:ing perturbatior: equations describing oscillations offiowum iablcs are considered, To solve these equations appropriate hourulari; conditions at both ends of the coinlnistion chamber are required. Combustion zone boutularu condition at one end and the nozzle admittance relation at other end are used, To obtein the nozzle admittance the three dimensional flow periurbuiioti equations are solved m the converging part of the nozzle, This approach i8 capable of predictitu; acoustic stability teluioicn of a combustor at a wide ranqe of Mach. numbers and frequencies, Also, this analysis enables the rocket cnqiru: designer to observe the effects of different partutieiers such. as nozzle eutrouce !vlach number, chamber qeouietru. nozzle geometry. atui gas properties on stability choracteristics of an engine combusior, In case oflnstahility observation: one can. predict the acoustic mode which causes the instability and achieve an optimiim design before cotuiuciuui an)! expensive and time consuming ecperiruetital tests, This paper presents the stability anll.lysis results and 0. parametric stndy of the effect of dcsign parameters on stahility characteristics of a. typical combustor.