贫油预混燃烧室燃烧稳定性的数值研究

Numerical Study on Combustion Instability in a Lean Premixed Combustor

对工业燃气轮机所使用的典型贫油预混燃烧室内的不稳定燃烧特性进行了数值研究.应用非定常N-S方程,基于重整化群的RNGk-ε紊流模型及甲烷与空气的单步反应模型,数值模拟了某典型燃烧装置内2种条件下(空气入口速度分别为30和60 m/s)的气流流动和压力振荡特性.在2种情况下分别可观察到稳定燃烧和不稳定燃烧,数值再现了由于当量比的扰动产生的不稳定振荡燃烧,所得结果同实验结果吻合很好.在模拟的2种情况下,燃烧可以是稳定的或非稳定的,取决于燃料喷注位置到火焰前沿的迟滞时间.通过改变燃料喷注位置,可使得振荡情况发生变化.所得结果为振荡燃烧的进一步分析和有效控制提供了研究基础.

Combustion instability in a lean premixed combustor typically used in industrial gas turbines was studied with computational fluid dynamics technology. Transient N-S equations were applied with the RNG k-ε turbulence model and one-step reaction rate equation for methane and air to obtain the flow characters in the combustor. Combustion instability induced by disturbance of equivalence ratio can be confirmed. Detailed results such as frequencies and amplitudes of pressure and velocity were achieved in two cases with an inlet air velocity of 30 m/s and 60 m/s respectively. The results agree well with that of experimental measurements. Both stable and unstable combustion can be seen in these two cases, depending on the time lag associated with the flow time from the fuel injection location to the flame front. It is shown that the present method will be beneficial to further research on analysis and suppression of combustion instabilities.