Analysis of effects of shape and location of micro-turbulators on unsteady shockwave-boundary layer interactions in transonic flow
Analysis of effects of shape and location of micro-turbulators on unsteady shockwave-boundary layer interactions in transonic flow
复制标题
跨音速流中微湍流器形状和位置对非定常冲击波-边界层相互作用的影响分析
DOI：
10.5604/12314005.1213755
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
T. Kwiatkowski
中科院分区：
文献类型：
--
作者：
J. Sznajder;T. Kwiatkowski
采用ANSYS FLUENT求解器中的四变量Transition SST湍流模型作为封闭，通过求解非定常N-S方程，研究了跨声速层流翼型激波上游部分层流边界层的湍流解。该湍流模型具有解决层流-湍流转捩的能力，该转捩发生在未扰动流中以及在流量控制装置的影响下。这项工作的目的是研究在不利条件下改善未来运输机层流机翼空气动力特性的可能性，其特征是在层流-湍流过渡区出现激波，激波下层流分离。该课题对于层流技术在民用运输航空中的应用具有重要意义，由于减少了摩擦阻力，层流技术提供了经济和环境优势。在所研究的条件下，自然层流-湍流转变发生在激波脚下的“层流分离泡”的出现，并且所产生的激波是强烈的，并且容易发生非定常振荡，即“抖振”现象，限制了飞行参数的操作范围。为了抵消跨音速流中自然层流-湍流转捩的有害影响，研究了两种放置在激波上游的减阻器。其中一个由三角形涡流发生器组成，产生弦向涡流。另一个由矩形微叶片组成，垂直于气流和翼型表面，产生展向旋转轴的涡流。研究了这两种类型的减流器在不同高度和翼弦位置下的减流效果。这两种类型的减阻器都证明了它们在消除层流边界层方面的有效性。在洁净翼型上发生层流分离的区域，每种类型的扰流器的具体效果不同。结果表明，每种减阻器的升力和阻力的变化是不同的。
Solutions for turbulisation of a part of laminar boundary layer upstream of shockwave on laminar airfoil in transonic flow were investigated by means of solution of Unsteady Reynolds-Averagd Navier-Stokes equations using as a closure the four-variable Transition SST turbulence model of ANSYS FLUENT solver. This turbulence model has the capability of resolving laminar-turbulent transition occurring in undisturbed flow as well as under the influence of flow-control devices. The aim of the work was to investigate possibilities of improvement of aerodynamic characteristics of laminar wing of a prospective transport aircraft in adverse conditions characterised by occurrence of a shockwave over a laminar-turbulent transition region with separation of laminar flow under the shockwave. The subject is important for application of laminar flow technology, offering economic and environmental advantages due to decreased friction drag, into civil transport aviation. Natural laminar-turbulent transition in the investigated conditions takes place with occurrence of “laminar separation bubble” under the foot of a shockwave and the resulting shockwave is intensive and prone to unsteady oscillations, the “buffet” phenomenon, limiting operational range of flight parameters. In order to counteract the harmful effects of natural laminar-turbulent transition in transonic flow two types of turbulators, placed upstream of the shockwave, were investigated. One of them consisted of delta-shaped vortex generators, producing chordwise-oriented vortices. The other consisted of rectangular micro-vanes, perpendicular to flow and to airfoil surface producing vortices of rotation axes oriented spanwise. Effectiveness of both types of turbulators was investigated for varying height and their location on airfoil chord. Both types of turbulators have proved their effectiveness in tripping laminar boundary layer. The specific effects of the tutbulators, different for each type occurred in the region where laminar separation takes place on clean airfoil. As a result, the changes of lift and drag were different for each type of turbulators.