湍流预混燃烧器燃烧自激振动的数值研究

Numerical investigation of self-excited oscillation of turbulent premixed combustion

对湍流预混燃烧器的燃烧不稳定现象应用湍流燃烧CFD的方法进行了数值研究。计算模拟了Krueger等人的实验研究,并着重对自激振动的频率和火焰动态特性进行了分析。计算表明,非稳态雷诺平均Navier Stokes(URANS)方法和基于重整化群的RNGk-ε湍流模型以及有限速率/涡漩耗散(FR/EDM)燃烧模型是适用的。将预测结果与实验结果进行比较可以看出,数值计算得到的燃烧室内压力振动的频率和幅值与实验很好地吻合,自激振动过程中火焰的动态行为也被计算很好地捕捉到,可以在计算的流动域的图像中看到整个激励循环的火焰前锋的变形和分离过程。同时从计算结果中还可以看出热释放的波动与压力波动的频率是一致的,这也进一步验证了瑞利准则。所得结果为进一步深入研究燃烧不稳定性产生的驱动机理和对燃烧不稳定的控制奠定了基础。

Turbulent premixed combustion instability is investigated using turbulent combustion CFD. The calculations simulate the experimental investigations by Krueger,and focus on the frequency and dynamic behavior of the flame when self- excited oscillation occurs.Tbe calculation results indicate that the unsteady Reynolds- averaged Navier Stokes（UR.ANS） approach and RNG k -~ turbulence model and Finite- Rate/ Eddy - Dissipation combustion model are appropriate. The predictions of frequency and amplitude of pressure are in very good agreement with the experimental results, and the dynamic behaviors of flame under the self- excited oscillation are also captured by the calculations, the peri- odical distortion and separation of the flame front are observed. Furthermore the frequencies of heat release and pressure fluctuations are accor- dant,which can validate the Rayleigh rule again.It is shown that the present method will be beneficial to further research on mechanisms and suppressions of combustion instabilities.