空燃比对燃气轮机燃烧室燃烧不稳定性影响的数值研究

Numerical Study on Influences of Air-fuel Ratio on Combustion Instability in Gas Turbine Combustor

针对某型燃气轮机旋流燃烧室,建立了全尺寸三维燃烧室数值模型,数值研究了空燃比对其扩散和预混燃烧稳定性的影响.结果表明,扩散燃烧模式下,保持燃烧室入口燃气总流量不变,空燃比变化对燃烧室压力脉动主频及燃烧稳定性影响较小.预混燃烧模式下,保持燃烧室入口燃气总流量不变,调整空燃比,燃烧室压力脉动振幅相对稳定;但空燃比增大,燃烧室压力脉动主频减小,燃烧不稳定增长时间缩短,燃烧稳定性相对变差;而空燃比降低,燃烧室压力脉动主频增加,燃烧不稳定增长时间增加,燃烧稳定性相对增强.

Based on one type of gas turbine swirl combustor,a full-size three-dimensional numerical model of combustor is established,and the influences of air-fuel ratio on the diffusion and premixed combustion stability are studied numerically.Results show that in the diffusion combustion mode,the adjustment of air-fuel ratio has less influences on the main frequency of pressure fluctuation in the combustor and the combustion stability when the total gas flow at the combustor inlet is kept constant.In the premixed combustion mode,as the air-fuel ratio varies,the amplitude of pressure fluctuation in the combustor changes slightly when the total gas flow at the combustor inlet is kept constant.However,as the air-fuel ratio increases,the main frequency of pressure fluctuation in the combustor is reduced,the combustion instability growth time is shortened,and the combustion stability weakens relatively.As the air fuel ratio decreases,the main frequency of pressure fluctuation in the combustor increases,its combustion instability growth time also increases,and the combustion stability is relatively strengthened.