四角燃烧器射流向火侧相干结构涡的研究

COHERENT STRUCTURE VORTICES ON THE FIRE-FACING SIDE OF FOUR BURNER JETS

利用IFA300恒温式热线风速仪和六线涡量探针及其定位坐标系统,测量了HG-2008/18.2-YM2型切向炉等温模型燃烧器区的涡量场,判别了涡量探针所测炉内空间点涡矢量的大小和方向,采用条件采样技术,研究了4股燃烧器射流向火侧形成的相干结构涡。研究发现:对于单股射流,引射(卷吸)主要发生在射流两侧,从而在两侧造成负压并出现旋转方向相反的旋涡;对于两股相交射流,射流偏转,出现了射流向火侧的剪切涡,以及由于横向射流干涉,在射流背部的尾迹涡。当四角燃烧器同时投运,燃烧器射流偏转且贴壁运行,射流向火侧有大的剪切涡出现,该涡即为相干结构涡;涡量场研究结果,也表明了最大的涡矢量在燃烧器射流的向火侧。相干结构涡的研究目的一为探讨涡中NOx的初生形态;二为研究涡对上炉膛内烟温偏差的影响提供理论依据。

A IFA300 constant temperature hot wire anemometer and a six-sensor hot-wire probe located on a 3D movable frame for coordinate setting are firstly used to measure the vorticity field in the burner zone of HG-2008/18.2-YM2 tangentially fired furnace (TFF) which is isothermal model. It is discriminated that the value and direction of vorticity measured by the six-sensor hot-wire probe in the TFF Coherent structure vortices on the fire-facing side of four burner jets are studied by conditional sampling. It is discovered that a pair of opposite-direction vortices appears bilaterally to the jet in the horizontal plane of the central section of the burner zone, directed toward only one turbulent jet. Injection and entrainment phenomena mainly appear in both sides of the jet so that there is negative pressure in them. For two cross-turbulent jets, one of the jets will deflect and the shear vortex on the fire-facing side of the jet. and the vortex in the wake of the jet should appear because of interference of lateral jet. When the four jets operate at the same time, all the jets deflect and are attached to the walls, and only shear vortices appear on the fire-facing side of the jets. It is regarded as coherent structure vortices. And also the maximum vector of vorticity exists in the fire-facing side of the jets. Studies on the coherent structure vortices are aimed at inquiring into the formation of initial stage NOx in the coherent structure vortex and vortices influence on thermal imbalance in the TFF..