Three Dimensional Stability Analysis of a Liquid Propellant Combustor

A theoretical study analyzing ihrec-dimensicnuil combustion acoustic instabilitiesin a liquid propellant rocket engine comliustor has been conducted. a lineartheory based on crocco'8 pressure sensitive time lag model 1s used. to applythis theory, the combustor is diuuied into two main components, incl-uding thecombustion chamber and the conuerquu; part of ilu: nozzle, the assumption ofconcentrated cornlnistioti zone is used and the govet1l:ing perturbatior: equationsdescribing oscillations offiowum'iablcs are considered, to solve these equationsappropriate hourulari; conditions at both ends of the coinlnistion chamber arerequired. combustion zone boutularu condition at one end and the nozzleadmittance relation at other end are used, to obtein the nozzle admittancethe three dimensional flow periurbuiioti equations are solved m the convergingpart of the nozzle, this approach i8 capable of predictitu; acoustic stabilityteluioicn of a combustor at a wide ranqe of mach. numbers and frequencies,also, this analysis enables the rocket cnqiru: designer to observe the effects ofdifferent partutieiers such. as nozzle eutrouce !vlach number, chamber qeouietru.nozzle geometry. atui gas properties on stability choracteristics of an enginecombusior, in case oflnstahility observation: one can. predict the acoustic modewhich causes the instability and achieve an optimiim design before cotuiuciuuian)! expensive and time consuming ecperiruetital tests, this paper presentsthe stability anll.lysis results and 0. parametric stndy of the effect of dcsignparameters on stahility characteristics of a. typical combustor.