Surface pressure characteristics of elliptic cylinders of various thicknesses and orientations are investigated in steady flow regime. A stabilized finite-element method has been used to discretize the conservation equations of incompressible fluid flow in two dimensions. The Reynolds number, Re, is based on the major axis of cylinder and free-stream speed. Results have been presented for \(Re\le 40\) and \(0^\circ \le \alpha \le 90^\circ \), where \(\alpha \) is the angle of attack. Cylinder aspect ratios AR considered are 0.2 (thin), 0.5 and 0.8 (thick). It is found that a decrease in AR does not significantly alter the location of minimum surface pressure for \(\alpha = 90^\circ \), but the value of minimum pressure decreases sharply, resulting in severe adverse pressure gradient. In contrast, for \(\alpha = 0^\circ \), the location travels towards the base and the minimum pressure increases, leading to delayed flow separation. In general, the magnitude of forward stagnation pressure at low Re is smaller than the maximum pressure for \(AR\le 0.5\). The maximum pressure occurs at the forward stagnation point as the Re and AR increase. However, in most cases, the locations of forward stagnation and maximum pressure points differ even when the pressure coefficients are very close to each other. The forward stagnation and maximum pressure coefficients of an elliptic cylinder decrease monotonically with increasing \(\alpha \). The drag of a circular cylinder in most cases exceeds the ones obtained for elliptic cylinders. With increasing AR, the drag increases approximately linearly for small \(\alpha \), lift decreases approximately linearly and moment decreases non-linearly. For a thick cylinder, while the effect of Re on lift and moment is insignificant, the drag shows a strong dependence. Roughly \(\alpha = 20^\circ \) for \(Re = 40\) flow represents a critical angle of attack below which a cylinder of \(AR\le 0.5\) acts like a streamlined body and above, like a bluff body.

在稳态流态下研究了不同厚度和方向的椭圆圆柱体的表面压力特性。稳定有限元方法已被用于离散二维不可压缩流体流动的守恒方程。雷诺数Re基于汽缸的主轴和自由流速度。已经给出了\（Re \ le 40 \）和\（0 ^ \ circ \ le \ alpha \ le 90 ^ \ circ \）的结果，其中\（\ alpha \）是迎角。所考虑的圆柱体纵横比AR为0.2（薄），0.5和0.8（厚）。发现AR的降低不会显着改变最小表面压力的位置\（\ alpha = 90 ^ \ circ \），但是最小压力值急剧下降，从而导致严重的不利压力梯度。相反，对于\（\ alpha = 0 ^ \ circ \），该位置朝着基部行进，并且最小压力增加，从而导致流分离延迟。通常，低Re时的前向滞止压力的大小小于\（AR \ le 0.5 \）的最大压力。最大压力出现在前停滞点，即Re和AR增加。但是，在大多数情况下，即使压力系数彼此非常接近，前向停滞点和最大压力点的位置也会有所不同。椭圆圆柱的前向停滞和最大压力系数随着\（\ alpha \）的增加而单调减小。在大多数情况下，圆柱的阻力超过了椭圆形的阻力。随着AR的增加，阻力对于小\（\ alpha \）大约线性增加，升力大约线性减少，力矩非线性减小。对于较厚的圆柱体，尽管Re对升力和力矩的影响微不足道，但阻力表现出很强的依赖性。大致\（\阿尔法= 20 ^ \ CIRC \）为\（Re = 40 \）流量表示临界攻角，在该角度下，\（AR \ le 0.5 \）的圆柱体像流线型的实体，而上方像虚张声势的实体。