Method of preventing instabilities produced by combustion in a turbojet engine

A method of preventing instabilities due to combustion in a turbojet engine having a primary flow and secondary flow, and an afterburner into which an air-fuel mixture is injected in proportions measured in terms of primary richness and secondary richness from each of said flows and of overall richness, said method comprising the steps of:

• detecting experimentally vibration zones created during afterburn as a function of the operating conditions of said engine and as a function of an afterburn operating region, said vibration zones comprising a first zone of operation located between a minimum recorded value of idling of post-combustion and a maximum recorded value of post-combustion at full throttle and a second zone of operation located at full throttle post-combustion;
• and
• selecting operating points of post combustion for regulating the fuel richness from each of said primary and secondary flows to enable the detected vibration zones to be avoided wherein first and second groups of operating points for regulation of fuel richness mixtures for each flow are selected, said first group of operating points being an operating area of post-combustion located between idling and full throttle, and said second group of operating points being a functioning area of post-combustion located at full throttle.