强旋-V型钝体组合燃烧装置绕流实验研究

Experimental Study on Flow around a V-Type Bluff BodyFlame Stabilizer Coupled with Strong Swirling Flow

关键词:  旋流  钝体绕流  旋涡脱落  回流区  火焰稳定器

Key words:  Swirling flow  Flow around a bluff body  Vortex shedding  Recirculation zone  Flame Stabilizer

摘要:

为了探明强旋流对钝体绕流旋涡脱落规律的影响，利用PIV速度场仪和高频动态压力传感器等测量仪器研究了强旋-V型钝体组合稳燃装置中旋流器出口安装位置对旋涡脱落频率和尾流流场的影响规律。实验结果表明，当旋流器出口位置安装在钝体内部时，可获得较小的旋涡脱落频率。随着旋流器安装位置向钝体出口方向逐渐移动时，旋涡脱落频率增大。当旋流器出口置于钝体外部时，将破坏钝体剪切旋涡的几何特征，从而导致钝体旋涡脱落机制的改变。另外，当旋流体积流量控制在一定范围(0～1m3/h)内，增大旋流流量有助于减小钝体绕流剪切旋涡的脱落频率，对比无旋流时的V型钝体绕流，当旋流流量为1m3/h时，旋流器出口位置位于钝体尾缘内部1倍开口直径处的V型钝体绕流St数下降幅度最大，约为34.96% 。一定范围内的旋流同样有利于扩大回流区，在旋流流量为0.5m3/h时回流区长度达到最大，约为钝体开口直径的2.3倍。但当旋流体积流量过大时，将导致下游流动恶化，钝体的火焰稳定性能可能会急剧下降。

Abstract:

In order to explore the effects of strongly swirling flow on the vortex shedding patterns around the V-type bluff body，the effects of the installation position of the swirler outlet in the combined flame stabilizer on the vortex shedding frequency and the wake flow field are studied by using the PIV velocimetry and the high frequency dynamic pressure sensor. Compared with the V-type bluff body without swirling flow，the experimental results show that the vortex shedding frequency can be decreased when swirling is added. With the installation position of the swirler outlet moves toward the outlet position of the blunt body，the shearing vortex shedding frequency of the V-type bluff body increases gradually. When the swirler outlet is located outside of the bluff body，the geometrical characteristics of the shear vortex will be destroyed，which will lead to the change of the vortex shedding mechanism. Moreover，when the swirling volume flow rate is controlled within a certain range(0～1m3/h)，increasing the swirl flow rate can reduce the shedding frequency of the shearing vortex around the bluff body. Compared with the case of V-type bluff body without swirling flow，the largest drop of the St number，about 34.96% ，occures in the case under the 1m3/h swirling volume flow rate condition when the swirler outlet is located 1 time of the opening diameter at the trailing edge in the bluff body. A certain range of swirl flow is also helpful to expand the recirculation zone. When the swirl flow rate is 0.5m3/h，the length of the recirculation zone reaches the maximum，which is about 2.3 times of the opening diameter. However，when the swirling volume flow rate is beyond a certain range，the wake flow field becomes deterioration，which is possible to influence the flame stability of the combined flame stabilizer.