有关昆塔条件（Kutta condition） 求解释！

cyliqh

求解释：昆塔条件
我不是学流体的，但是最近有很涉及空气动力学的内容。有很多不懂得问题，想请各位替我解释一下。

昆塔条件（Kutta condition）

文献中是这样写
Under completely inviscid conditions, one would expect the
fluid to deflect only minimally by the presence of an airfoil,
thereby generating a flow field around the wing similar to the
one described in Fig.·2A. Under such conditions, the rear
stagnation point (where velocity is zero) would be present not
at the tip of the trailing edge but on the upper surface of the
wing. However, to maintain this flow profile, the fluid must
turn sharply around the trailing edge causing a singularity or
‘kink’ in the flow at the trailing edge. Such a flow profile
necessitates a high gradient in velocity at the trailing edge,
thereby causing high viscous forces due to shear. The viscous
forces in turn will eventually eradicate this singularity. Thus,
the presence of even the slightest viscosity in the fluid
functions to smooth out sharp gradients in flow. This
phenomenon may be incorporated into an otherwise inviscid
formulation by adding a circulatory component to the flow field
(Fig.·2B). At a unique value of the additional circulation, the
stagnation point is stationed exactly at the trailing edge. When
this condition is met, the fluid stream over the plate meets the
fluid stream under the plate smoothly and tangentially at the
trailing edge (Fig.·2C). This phenomenon is called the ‘Kutta
condition’, which ensures that the slopes of the fluid streams
above and below the wing surface are equal, and thus the
vorticity (i.e. curl of the velocity) at the trailing edge is zero.
In addition, when satisfied, the Kutta condition ensures that the
inclined plate imparts a downward momentum to the fluid.
This, in essence, is the classic Kutta–Jukowski theory of thin
airfoils (Kuethe and Chow, 1998).】

图见附件！

求解释！谢谢！！！~~

cyliqh

有哪位能烦心给解释下么？

cyliqh

比如说图中B的环量怎么来？  C中流型有什么好处？ 满足这个昆塔条件有什么用？

通流

这个跟有什么好处没有关系。当时，因为大家发现，如果使用这个库塔条件，计算出来的结果与实际比较接近。后来有了边界层理论后，明白其实是与粘性有关。

cyliqh

原帖由 通流 于 2010-11-15 20:51 发表

                               
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这个跟有什么好处没有关系。当时，因为大家发现，如果使用这个库塔条件，计算出来的结果与实际比较接近。后来有了边界层理论后，明白其实是与粘性有关。

原来如此！~~谢谢哦~！~

cyliqh

原帖由 通流 于 2010-11-15 20:51 发表

                               
登录/注册后可看大图

这个跟有什么好处没有关系。当时，因为大家发现，如果使用这个库塔条件，计算出来的结果与实际比较接近。后来有了边界层理论后，明白其实是与粘性有关。

那请问这个又是如何计算的呢？ 根据这个条件是可以得出环量的大小的吧。是不是根据驻点的条件？