The precessing vortex core (PVC) and symmetric coherent structures in partly confined swirling flows of gas turbine combustors are investigated numerically. The computational combustor features a sidewall in the circumferential direction, and the ratio between the sidewall length (L) and dome height (H) is specified as 0, 0.27, 0.68, and 1 to construct various confinements. Then a large eddy simulation is performed under the isothermal condition to investigate the effect of different L/H values on dominant coherent structures in combustors. The time-averaged flowfields exhibit different shapes of the inner recirculation zone (IRZ) with increasing L/H. Proper orthogonal decomposition is used to extract coherent structures from the turbulence; the single helical structure referred to as the PVC, and the symmetric vortices that shed and are amplified in the shear layer, are found to dominate the evolution of the flow in all cases. Relevant phase-averaged velocity fields show that the PVC synchronizes with the IRZ rotating around the centerline of the combustor while the symmetric coherent structure causes the deformation of the IRZ. By examining the azimuthal wave related to the PVC, it is shown that the PVC is suppressed in the partly confined swirling flow, and its strength is enhanced as L/H increases. Changes in shear layer thickness are suggested as being responsible for the suppression of the PVC under the partly confined condition.

数值研究了燃气轮机燃烧室部分旋流中的旋进涡核（PVC）和对称相干结构。计算燃烧器在圆周方向上具有侧壁，并且侧壁长度（L）与圆顶高度（H）之间的比率被指定为0、0.27、0.68和1以构造各种限制。然后在等温条件下进行大涡模拟，以研究不同的L / H值对燃烧室中主要相干结构的影响。时间平均流场随L / H的增加显示出内部再循环区（IRZ）的不同形状。适当的正交分解用于从湍流中提取相干结构。单个螺旋结构称为PVC，在所有情况下，都发现了在剪切层中脱落并放大的对称涡流占主导地位。相关的相位平均速度场表明，PVC与绕着燃烧器中心线旋转的IRZ同步，而对称的相干结构导致IRZ变形。通过检查与PVC相关的方位角波，可以看出PVC在部分受限的旋流中受到抑制，并且随着L / H的增加其强度得​​到增强。剪切层厚度的变化被认为是部分限制条件下抑制PVC的原因。相关的相位平均速度场表明，PVC与绕着燃烧器中心线旋转的IRZ同步，而对称的相干结构导致IRZ变形。通过检查与PVC相关的方位角波，可以看出PVC在部分受限的旋流中受到抑制，并且随着L / H的增加其强度得​​到增强。剪切层厚度的变化被认为是部分限制条件下抑制PVC的原因。相关的相位平均速度场表明，PVC与绕着燃烧器中心线旋转的IRZ同步，而对称的相干结构导致IRZ变形。通过检查与PVC相关的方位角波，可以看出PVC在部分受限的旋流中受到抑制，并且随着L / H的增加其强度得​​到增强。剪切层厚度的变化被认为是部分限制条件下抑制PVC的原因。