Combustion Flow Field And Stability Analysis Of High Temperature Rising Combustor

Lean premixed combustion as a new type of combustion technology has been widely used in modern aviation engines,which can effectively reduce pollutants.But lean premixed combustion technology usually decrease combustion stability because of the coupling effect between pressure pulsation and flame heat release rate.The strong pressure vibration cause the huge combustion noise and even result in the phenomenon of the backfire,the flameout,and the mechanical vibration,and even the damage of combustion chamber structure in severe cases.Therefore,it is very meaningful to study the characteristics and the influencing factors of oscillating combustion.In this paper,numerical simulation was applied to analyze steady state flow field.And experiment methods were applied to observe oscillation combustion in high temperature rise.Then,transient combustion flow field was researched by numerical simulation in order to discuss evolutionary process of the oscillating combustion.Research content in this paper is as follows:Firstly,reasonable simulation model and calculation method are used to calculate the hightemperature rising combustion chamber,The simulation results show that: 1)The fuel atomization position changes significantly when the flight conditions change.2)The area of the high temperature area in the combustion chamber gradually retracts toward the outlet of the swirler as the fuel supply of the auxiliary oil circuit decreases.Secondly,high-speed camera and high-frequency pressure sensor are used to measure the oscillatory combustion in the high-temperature combustion chamber to study the influence of different fuel distribution and incoming flow conditions on the oscillating combustion.The test results show that: 1)Intermittent combustion oscillations appear in the combustion chamber,and the intermittent combustion oscillations are affected by the incoming flow conditions.2)With the increase of the oil supply in the main oil circuit,the area with the higher amplitude of the heat release pulsation in the combustion chamber moves downstream.3)The combustion flow field is divided into an angular recirculation zone and a central recirculation zone.The angular recirculation zone is ignited when burning vigorously and extinguished during slow combustion;Thirdly,on the basis of the foregoing,a transient numerical analysis of key operating conditions is carried out and focusing on the study of the characteristics of oscillating combustion in the flame tube.The simulation results show that: 1)Periodically moving recirculation zone is the main cause of oscillating combustion in the flame tube;2)The oscillating combustion in the flame tube gradually approaches the limit cycle oscillation with the change of the incoming flow conditions.