چكيده لاتين :
A theoretical study analyzing ihrec-dimensicnuil combustion acoustic instabilities
in a liquid propellant rocket engine comliustor has been conducted. A linear
theory based on CrocCOי8 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 offiowumיiablcs 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.
