论文部分内容阅读
为了探究单边扩张超声速燃烧室在不同当量比下出现的多种模态及其内在机理,通过实验和数值模拟,对该构型燃烧室在并联凹腔对称喷注的工况下进行了系统研究。实验中,隔离段来流入口马赫数为3.46,来流总温为1486K;采用乙烯作为燃料,当量比范围从0.26到0.51。结果表明:燃烧室工况随着当量比的上升而改变,且可分为三个模态。当量比较低时(0.26),形成只有剪切层内有火焰的对称燃烧。当量比较高时(0.51),形成上凹腔为凹腔内燃烧、下凹腔为剪切层燃烧的非对称燃烧。当量比适中时(0.4),火焰在上下凹腔间来回震荡。在非稳态过程中,预燃激波串沿燃烧室轴向做周期性往复运动,定量分析表明火焰震荡的频率约为170Hz。燃烧震荡来源于分离区喷注与燃烧的耦合效应,震荡机制与涡无关,可能是由声振机制引起的凹腔自激震荡。
In order to explore the various modalities and their intrinsic mechanisms of uniaxial expansion supersonic combustor at different equivalence ratios, the system was carried out through experiments and numerical simulations under the symmetrical injection of parallel concavities in this configuration chamber the study. In the experiment, the Mach number of inflow port in isolated section was 3.46, and the total temperature of incoming stream was 1486K; using ethylene as fuel, the equivalence ratio ranged from 0.26 to 0.51. The results show that the combustion chamber operating conditions change with the increase of equivalence ratio and can be divided into three modes. When the equivalent weight is relatively low (0.26), a symmetrical combustion with flame only in the shear layer is formed. When the equivalent ratio is high (0.51), the upper cavity is formed as the combustion cavity, the lower cavity is the asymmetric combustion of shear layer combustion. When the equivalence ratio is moderate (0.4), the flame oscillates back and forth between the upper and lower cavities. In the unsteady process, the pre-deflagration wave train periodically reciprocates along the axial direction of the combustion chamber. The quantitative analysis shows that the frequency of flame turbulence is about 170Hz. Combustion oscillation comes from the coupling effect of injection and combustion in the separation zone. The oscillation mechanism has nothing to do with the vortex, which may be the self-oscillation of the cavity caused by the vibration mechanism.