旋流非预混火焰长度的实验研究与理论预测

An Experimental and Theoretical Investigation on Flame Length of a Swirl Nonpremixed Combustion

在旋流非预混燃烧条件下,测量了变燃料量和变燃烧室压力工况下的火焰长度。采用基于直喷射流火焰建立的Fr模型、Fr_f模型及无量纲热释放率Q~*模型对火焰长度进行预测,将预测结果进行旋流修正后与实验结果进行比较。结果表明:随着燃料量的增大,火焰长度增大,这是由于形成火焰表面所需的空气卷吸增强所致;而随着压力的增大,火焰长度减小。3个模型的旋流修正结果均准确地预测了火焰长度的变化趋势,其预测值均高于实验值,预测值分别是实验值的1.2倍、1.7倍及1.3倍。基于3种模型,将实验数据进行拟合,得到新的关联式,提出了一种基于雷诺数的计算方法。

In order to investigate the influencing factors on the flame length of a swirl nonpremixed combustion,an experimental investigation and theoretical analysis were performed and the flame length was measured under various fuel flow rate and combustor pressure.Three models based on jet flame,including Fr model,Fr_f model and dimensionless heat release rate Q~*model,were used to calculate flame length,the prediction results were modified by swirl effect,and then compared with experimental results.It was concluded that,flame length increased with the increment of fuel mass flow rate because of the enhancement of air entrainment for generating flame surface,but it decreased as combustor pressure increased.All three models correctly predicted the variation trends of flame length,and the prediction results were larger than experimental ones by a factor of 1.2,1.7 and 1.3,respectively.Meanwhile,the measured data was fitted,and new correlations were obtained.Lastly,a new method based on Re number was proposed.