Forcing of Separation Bubbles by Main Flow Unsteadiness or Pulsed Vortex Generating Jets—A Comparison
Forcing of Separation Bubbles by Main Flow Unsteadiness or Pulsed Vortex Generating Jets—A Comparison
复制标题
主流不稳定性或脉冲涡流产生喷射对分离气泡的强制比较
DOI：
10.1115/1.4025214
复制
发表时间：
2014
影响因子：
1.7
通讯作者：
Peitsch
中科院分区：
文献类型：
--
作者：
Dähnert;Peitsch
低压涡轮机通常在低雷诺数状态下操作。取决于叶片的载荷，它们可能表现出分离流，并在吸力面后部出现相关的再附着。此外，由于旋转和静止叶片排的顺序，流动高度依赖于时间。本文介绍的工作包括详细调查这种类型的流的实验努力。选择典型的低压涡轮机流动条件作为实验工作的基线。在低速风洞中，用仿形上壁在平板上产生了压力分布。该分布与Pak-B翼型的分布相匹配。然后以两种方式叠加不稳定性：通过在试验段下游使用旋转襟翼（RF）来产生特定的不稳定性。这导致几乎正弦的周期性非定常流穿过板，模拟涡轮机级的定子和转子之间的相互作用。此外，在吸力峰的上游采用旋涡发生射流（VGJ）脉冲吹气来影响分离泡的转捩过程和发展。测量已与热线风速仪进行。实验结果进行了比较两种强迫机制。在正弦非定常主流中，通过剪切层不稳定性的破坏自然发生过渡，这受到总雷诺数的周期性变化以及压力梯度的影响。相反，VGJ的主动流动控制（AFC）通过向边界层中注入脉冲和涡量来触发过渡过程，同时保持恒定的雷诺数。流场比较使用相平均的速度和湍流强度的数据以及边界层参数，即形状因子和动量厚度雷诺数。最后，一个模型来描述的时间平均磁通量分布进行了改进，以适应数据。
Low pressure turbines typically operate in the low Reynolds number regime. Depending on the loading of the blade, they may exhibit detached flow with associated reattachment in the rear part of the suction surface. Additionally, the flow is highly time-dependent due to the sequence of rotating and stationary blade rows. The work presented in this paper covers experimental efforts taken to investigate this type of flow in detail. Typical low pressure turbine flow conditions have been chosen as baseline for the experimental work. A pressure distribution has been created on a flat plate by means of a contoured upper wall in a low speed wind tunnel. The distribution matches the one of the Pak-B airfoil. Unsteadiness is then superimposed in two ways: A specific unsteadiness was created by using a rotating flap (RF) downstream of the test section. This results in almost sinusoidal periodic unsteady flow across the plate, simulating the interaction between stator and rotor of a turbine stage. Furthermore, pulsed blowing by vortex generating jets (VGJ) upstream of the suction peak was used to influence the transition process and development of the separation bubble. Measurements have been performed with hot-wire anemometry. Experimental results are presented to compare both forcing mechanisms. In sinusoidal unsteady main flow, the transition occurs naturally by the breakdown of the shear layer instability, which is affected by periodic changes in the overall Reynolds number and thus pressure gradient. In opposition, active flow control (AFC) by VGJ triggers the transition process by impulse and vorticity injection into the boundary layer, while maintaining a constant Reynolds number. The flow fields are compared using phase averaged data of velocity und turbulence intensity as well as boundary layer parameters, namely shape factor and momentum thickness Reynolds number. Finally, a model to describe the time mean intermittency distribution is refined to fit the data.
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DOI：
--
发表时间：
1996
期刊：
影响因子：
--
作者：
J. Gostelow;G. Walker;W. J. Solomon;G. Hong;N. Melwani
通讯作者：
N. Melwani
采用脉冲流量控制的低压涡轮叶片上的分离流量过渡
DOI：
--
发表时间：
2008
期刊：
影响因子：
--
作者：
J. Bons;Daniela Reimann;Matthew J. Bloxham
通讯作者：
Matthew J. Bloxham
边界层外部间歇区域的一些湍流/非湍流特性
影响因子：
3.7
作者：
Thomas B. Hedleyt;J. Keffer
通讯作者：
J. Keffer
影响因子：
1.5
作者：
Y. Chew;D. A. Shah;J. Wan
通讯作者：
Y. Chew;D. A. Shah;J. Wan
DOI：
--
发表时间：
1986
期刊：
影响因子：
--
作者：
J. Hourmouziadis;F. Buckl;P. Bergmann
通讯作者：
P. Bergmann