超低压量程下的可燃气体燃烧特性研究

Study on Combustion Characteristics of Combustible Gas at An Ultra-Low Pressure Range

试验研究了超低压环境对甲烷层流扩散火焰特性的影响。试验基于3 m×2 m×2 m变气压变氧浓度试验舱完成,试验舱的压力以恒定速率从标准大气压101.6 kPa降低到设定压力13 kPa,通过线性变化的不同降压、升压速率两个阶段,研究甲烷燃料在匀速动态的不同环境压力下的扩散火焰燃烧特性(如火焰温度、热辐射通量、火焰形状)。实验发现,浮力羽流区温度ΔT_(0)与环境压力P_(∞)^(-2/3)呈显著的正相关,但不适用于30 kPa~13 kPa的超低压量程。火焰形态(颜色和高度)与甲烷流量及环境压力变化关系密切。此外,在动态的压力变化下,甲烷火焰的热辐射通量与环境压力呈正相关变化。在降压阶段,随着甲烷流量增大,火焰高度先增后减再增,最后为持续增加;升压阶段情形则与之相反。

The effect of ultra-low pressure environment on the flame properties of methane laminar fire experimental has been studied.This test is based on the 3 m×2 m×2 m variable pressure and oxygen concentration test chamber.The pressure of the test chamber can be reduced from standard atmospheric pressure 101.6 kPa to the set pressure 13 kPa with a constant rate,and the linear change of the ambient pressure can be controlled by changing at two stages(the step-down and pressure-boost rates).The combustion characteristics(flame temperature,heat radiation flux and flame shape)of methane fire are studied under different ambient pressures at uniform various velocity.It is found that the temperature ΔT_(0) in the buoyant plume region is positively correlated with the ambient pressure P_(∞)^(-2/3),but it is not suitable for the ultra-low pressure range of 30 kPa~13 kPa.Flame morphology(color and height)is closely related to methane flow and ambient pressure.In addition,the heat radiation flux of methane flame is positively correlated with the ambient pressure by dynamic pressure changing.Finally,In the depressurization stage,with the increase of methane flow,the flame height increases first,then decreases and then increases,and then continues to increase.That in the booster phase is opposite.