Experimental study on flame characteristics of aeroengine combustor case burn-through
[Objective]With the development of airworthiness certification for domestic commercial aeroengines,research in domestic civil aviation has continued to deepen.As one of the core components of the aeroengine,the combustor case has been subjected to long-term testing using high-temperature and high-pressure flames.The safety of the aircraft would be compromised if the combustor case is burned-through.The Federal Aviation Administration(FAA)has included burn-through safety as one of the criteria for engine airworthiness certification in its regulations.From the perspective of simulation and experimentation,foreign scholars have conducted a series of studies on the combustor case burn-through phenomenon.However,few relevant studies have been conducted in China.[Methods]The development of a set of jet flame test bench systems is presented in this paper.The system is designed to simulate the emitted flame from the combustion hole after the combustor case is burned.The test bench system can meet the following specifications:First,the temperature of the generated jet flame at the nozzle should not be below 1 648 ℃.Second,the internal pressure of the burner must be 0.74 MPa based on the standard operating conditions.The effects of the nozzle aperture,oil-gas mass ratio,outer air velocity,and internal pressure on the axial temperature and heat flux distribution of the jet fire are studied using the system through the single variable method.[Results]Experimental results are as follows:(1)The jet flame takes on a concentrated form,revealing a rapid decrease in the temperature and heat flow in the axial direction.(2)The oil-gas mass ratio notably affects flame temperature and heat flux,demonstrating a positive correlation.Specifically,at distances of 127 mm,the increases in temperature of 18.6％and heat flux of 13.0％are observed when the oil-gas mass ratio increases from 0.035 to 0.050.(3)The flame temperature and heat flux are also affected by the outside air flow rate.The temperature and heat flux have a considerable impact at distances of 254 to 508 mm and 127 to 254 mm,respectively.(4)The internal pressure of the burner considerably influences the flame temperature and heat flux.However,the data changes cannot be observed due to the limitations of the test bench system.(5)The size of the nozzle aperture has a significant impact on the shape and temperature of the flame.The flame concentration increases when the aperture is small.At distances of 127 to 381 mm,the temperature initially increases with aperture size but eventually declines.However,at distances of 508 to 762 mm,a high temperature at the corresponding position is observed under a large aperture.The trend of heat flux follows the same pattern as that of temperature.[Conclusions]To prevent the hazards of possible combustor case burn-through,aeroengine design should focus on the provision of a fire barrier within 254 mm outside the normal direction of the weak point of the combustor case.
combustor case burn-throughjet firetemperatureheat flux densityflame
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