Working range optimization for turbine and compressor blading

A partially reduced SQP algorithm for a multiple setpoint industrial design optimization problem is presented. It is highlighted that the modularity of this concept has made it possible to apply it to problems as complex as working range optimization in high-temperature gas turbine and compressor blade design. Further emphasis is drawn on parallelization aspects and practical experiences in engineering practice.     

Measurements of Tip Vortex Characteristics and the Effect of an Anti-Cavitation Lip on a Model Kaplan Turbine Blade

Motivated by the problem of cavitation erosion, the position and strength of the roll-up vortex on the suction side of a Kaplan-type turbine blade with various endings is investigated. Measurements are made on different models with simplified two-dimensional geometries using mainly particle image velocimetry. It is found that the greatest danger of cavitation erosion exists when the casing of the turbine is of the “semi-spherical” type, so that there is a large and closing clearance gap at the leading edge of the blade. Furthermore, the anti-cavitation lip used in this study is shown to be ineffective at increasing the distance of the vortex from the blade, although it does reduce the circulation of the vortex and presumably the danger of cavitation. Our measurements are found to be in good agreement with existing models for the position of the vortex when appropriately interpreted. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dynamic Study of a Structure with Flexion-Torsion Coupling in the Presence of Dry Friction

In aero engines, blade vibrations are frequently reduced by centrifugal flyweights, which exert a dry friction force per unit length under blade platforms. The response of this system to a periodic load has been analysed experimentally and theoretically. From a model having mode shapes similar to those of a blade, and a dry friction link per unit length, we show that the presence of the dry friction link is very effective in reducing vibrations for a range of excitation loads. The theoretical analysis is based on the Craig and Bampton mode synthesis, the rigid movement of the platform in its plane and the replacing of the linear dry friction link by several discrete parallel systems. Direct integration of the equations of motion is carried out by using the Newmark method. The comparison with experimental results is good. This method can easily be extended to more complex structures and shows that the dry friction link is effective when stick-slip occurs in the contact zone by limiting the energy provided to the system.     

基于动态网格的旋翼流场计算

基于无限插值理论,将旋翼按桨叶数分为几个子块,然后在桨叶连续公共界面上对接各子块,形成绕整个旋翼流场的三维多块网格。各桨叶子块的流场信息直接通过连续公共界面相互交换,利用非定常欧拉方程求解出整个旋翼流场。发展的动态网格在前飞流场计算中取得了成功。     

大间隙环流中偏心转子动特性系数的数值分析方法

基于作者用整体流动理论和Moody壁面摩擦系数方程建立的大间隙环流中转子动特性系数数值计算模型,应用摄动方法推导了大间隙环流流场非线性控制方程组的一阶摄动方程,提出了求解大间隙环流中偏心转子动力学特性系数的数值分析方法。用该方法得到的数值结果与已有的解析解和实验结果具有较好的一致性。     

关于Krain实验叶轮几何型线及其流道二次流旋涡结构的讨论

Krain关于高速离心式压缩机叶轮内部流畅的LDA实验测量不仅对认识这种特定的复杂流动有重要意义,而且亦为验证正在迅速发展的CFD软件提供了比较依据。但是作者发现,Krain公开发表的实验叶轮的几何型线缺少叶轮出口附近区域的型线坐标,直接用其进行数值计算分析将引起误差。为此,本文根据Krain在不同文献中所提供的有关实验叶轮的资料,重新构造补全了实验叶轮出口区域的型线坐标。然后,利用一多功能CFD软件对该实验叶轮进行了计算分析,较详细、深入地探讨了叶轮流道内二次流旋涡结构的形成和发展过程。     

计及Re数影响的气动—声学性能实验及优化设计

实验和计算都发现高Ｒｅ数（自模化区）风机的宽频噪声占有大部分频域,而低Ｒｅ数（非 自模化区）下离散噪声占主导地位。优化设计结果表明对低Ｒｅ数的动叶必须进行修正,低Ｒｅ数 弯掠动叶与高Ｒｅ数相比,需要更大的弯角和掠角才能达到气动—声学性能的最佳值。     

A New Expression for Nuclear Rotational Spectra

A new formula, which is derived from a deformed rotor model for describing nuclear rotational spectra, is analyzed. The ground band of most even-even rare-earth and actinide nuclei are accurately reproduced using a damped nonlinear least-square fitting procedure for determining parameters of the theory. The results show that energy spectra obtained from a deformed rotor model are more accurate than those from a three-parameter formula based on perturbation theory.     

可倾瓦径向滑动轴承支承的转子系统瞬态响应计算

研究了可倾瓦径向滑动轴承支承的转子系统瞬态响应的计算方法,提出了可倾瓦径向滑动轴承非线性滑膜力计算的数据库方法,将可倾瓦与轴颈的结构和运动参数归结到三个参数中,建立了起可倾瓦的非线性油膜力数据库,通过精确插值到每一运动参数组合下轴承提代的油力和轴瓦上所受的油膜力矩。     

On the finite displacement problem of a hollow cylinder under internal and external pressures

Using the method of successive approximations we find of this boundary-value problem the first-and second-order solutions. And then we obtain the formulae in the second approximation for the displacement, strain, and stress fields. Also, our results show that after deformation (i) a cross-section of the cylinder must be displaced into a plane section perpendicular to the central axis of the cylinder; and (ii) neither the sum of the strain components E _RR ⁽²⁾ and E ⁽²⁾ nor the sum of the stress components E _RR ⁽¹⁾ and E ⁽¹⁾ maintains contant throughout the cylinder. The latter effect, which is absent from classical elasticity, bears respensibility for the presence of the E _ZZ ⁽¹⁾ . Moreover, there exhibits a linear relation between E _ZZ ⁽¹⁾ and (E _RR ⁽²⁾ +E _OO ⁽¹⁾ ), with the proportionality coefficients depending only on the material of the cylinder.