二维风洞侧壁干扰修正准则的改进

ON THE MODIFICATION OF THE CORRECTION RULE FOR SIDEWALL INTERFERENCE IN TWO-DIMENSIONAL WIND TUNNELS

Barnwell二维风洞侧壁干扰修正准则未计及壁面摩擦影响,理论上是不完善的。本文对此作了改进。用Karman-Pohlhausen方法对侧壁边界层进行了处理;将壁面摩擦项用速度梯度适当表示出来,从而克服了因考虑摩擦项带来的困难。建立了修正准则的新形式。在改进的准则中摩擦影响是通过Pohlhausen型边界层参数Λ表示的,Λ绝对值越小摩擦影响越大。此外,文中对修正中有关参数,如δ~*的选取以及湍流情况作了简单讨论。

Owing to failing to take the friction on the side wall into account, Barnwell's correction rule for sidewall interference in two-dimensional wind tunnel is, in therotician view, imperfect. To improve this, a corresponding modification on the Barnwell's rule has been made in this study; in which the sidewall boundary layer is reconsidered by means of the Karman-Pohlhausen method; the wall friction is represented in terms of the velocity gradient and therefore, the troubles faced in the correction with the friction are overcome. Based on this, a noval correction rule is formulated. The influence of the friction is reflected by the Pohlhausen parameter A of the boundary layer. The less the absolute value of A is, the greater the influence of the friction is. In addition, choice of the relevant parameter, such as δ , in the correction and turbulent case are briefly discussed.