铍青铜簧片的热处理变形控制

铍青铜簧片类弹性弯曲零件热处理时效后,产生翘曲、扭曲、变形等热处理质量问题.通过分析铍青铜簧片原材料状态、机械制造成形应力和时效过程中的应力转变,研究其翘曲、扭曲、变形机理.根据铍青铜的时效特性进行相应的热处理工艺试验,通过手工校正、装模时效等方法得出铍青铜簧片弯曲角度与时效变形之间的对应关系.最后提出了新的工艺方法,将簧片弯曲角度手工校正到特定角度后装模时效,有效控制了铍青铜簧片热处理时效变形,极大提高了零件合格率.     

定向凝固合金涡轮叶片的低周疲劳寿命研究

对某发动机DZ4定向凝固高温合金涡轮叶片进行了有限元应力分析，应力分析中考虑了发动机实际工作过程中的离心载荷和不均匀温度引起的热负荷。利用应力分析结果和该材料的疲劳特性计算了1次飞行起落过程造成的发动机低循环疲劳损伤和900h飞行的总损伤，根据损伤等效原理，确定了试验规定条件下与900h飞行等效的试验谱以及试验寿命折算为飞行小时寿命的计算公式。     

基于参数法和贝塞尔曲线的涡轮叶片造型及其优化

为实现涡轮叶片的优化设计,采用参数造型法和贝塞尔曲线进行叶片初步造型,结合N-S方程流场模拟,并利用多目标遗传算法和序列二次算法组合优化算法,通过调节吸力面和压力面的关键控制点参数对其压力损失和转折角进行优化.结果表明该方案切实可行.     

Extracting sectional contours from scanned point clouds via adaptive surface projection

This paper presents a new and fully automatic method to extract cross-sectional contour profiles of a physical object from the point cloud data scanned from its surface. Correctly extracting the sectional contours is of particular importance in the quality inspection of airfoil blades as the tolerances specified on a manufactured aero-engine blade are generally imposed at specific blade sections. The collected point cloud via 3D laser scanning is, however, distributed all over the blade surface rather than at the desired specific sections. In fact, no point in the point cloud is located exactly on the sectional planes. The desired sectional data have to be extracted from the nearby data points. If the underlying smooth surface geometry of the point cloud in the vicinity of a nearby data point can be approximated by a mathematical function, the approximated local surface formulation can be used to project the nearby point onto the desired sectional plane along a curvilinear trajectory. This is achieved in this work by fitting a local quadric surface to the neighbouring points of the point of interest. A systematic approach to establish a balanced set of neighbouring points is employed to avoid bias in fitting the local quadric surface as well as to guide the selection of points to be projected onto the sectional plane. The projected points are then used to construct the desired sectional contour profile. Implementation results have demonstrated the superior performance of the proposed fully automatic method in comparison with the existing methods.     

曲线螺旋叶片冷拉伸修复技术在粗颗粒分离机的应用

分析介绍在韶钢第三炼钢厂水处理污泥粗颗粒分离机螺旋叶片上应用的快速成功修复技术及取得的良好应用效果。经现场安装、调试运行证明,此修复技术可靠、可行,为公司节约了高额的设备采购费用。     

Deformation of antisymmetric laminate under centrifugal force and/or thermal load

A smart blade conception has been proposed by the authors. With stretching–twisting coupling effect, the blade is twisted by centrifugal load or ambient temperature change. In this paper, the blade, simplified as a cantilevered antisymmetric laminate, is investigated by classic plate theory. An analytical scheme based on Rayleigh–Ritz (RR) method is proposed to calculate plate's deformation behavior. RR's analytical results are compared with FEM's to check the present scheme's numerical accuracy. Influence of the fiber orientation angle is discussed and the angle at which the blade twists most is found. Further analysis focusing on plate's nonlinear behavior is performed. The nonlinearity, originated with large out-plane deflection, influences the plate in two aspects: large-strain and follower force. These aspects are discussed separately in the analysis, by introducing quadric terms into strain and virtual work expressions. It is shown that for the present model, nonlinear influence must be considered at 10,000 rpm rotation speed loading, but is negligible at temperature-load below 120 K.     

Numerical Experiment of the Solid Particle Erosion of Bionic Configuration Blade of Centrifugal Fan

In this paper, a bionic method was presented to improve the erosion resistance of blade of the centrifugal fan. A numerical investigation of the solid particle erosion on the standard and bionic configuration blade of 4-72N10C centrifugal fan was presented. The numerical study employs computational fluid dynamics (CFD) software, based on a finite volume method, in which the discrete phase model was used to modele the solid particles flow, and the Eulerian conservation equation was adopt to simulate the continuous phase. Moreover, user-defined function was used to define wear equation. The various diameters of the particles were taken into account. The positions of collision of standard and bionic fan blades were discussed, and two kinds of centrifugal fan blade wear were compared. The results show that the particles from the incident source with different positions have different processes of turning and movement when enter into the impeller. The trajectories of flow in the fan channel are significantly different for the particles with different diameters. Bionic fan blade have lower erosion rate than the standard fan blade when the particle size is 20 μm. The anti-erosion mechanism of the bionic fan blade was discussed.     

涡轮叶片型线结构对叶栅流场的影响研究

涡轮叶片型线影响涡轮液流压降变化和速度变化的平稳程度,从而影响涡轮水力能量转化效率。分析了涡轮叶片的结构参数,据此绘制出五圆弧叶型及三次多项式叶型涡轮的叶片型线,在此基础上,利用Fluent软件对常用的五圆弧叶型和三次多项式叶型的涡轮叶栅流场压力、速度变化进行了模拟分析。分析结果表明,三次多项式叶型涡轮的液流压降变化和速度变化比五圆弧叶型涡轮更平稳,因此前者的水力损失比后者更小,水力效率更高。建议涡轮钻具叶片型线设计时尽量采用三次多项式。     

离心泵叶片缝隙对声场特性影响的研究

为进一步研究离心泵的声场特性，对离心泵叶轮叶片尾缘进行开缝测试。考虑开缝径向直径D_k和缝隙宽度B，设计了18组正交试验来探究叶片尾缘缝隙对声场的影响。针对离心泵噪声的发生机理，采用重整化群k-ε（Re Normalization Group，RNG k-ε）模型对离心泵进行全流场非定常数值模拟，并根据FW-H方程提取蜗壳壁面的湍流脉动作为偶极子声源，基于声学边界元法进行离心泵声场计算，将声学计算结果与流场压力脉动结果进行综合分析。研究结果表明：压力脉动可在一定程度上反映声压级的大小，隔舌区压力脉动波动剧烈，此处是噪声的主要发生源。开缝叶片可以有效改善叶轮出口的不均匀流动，对内外声场噪声的降低有一定的积极作用，且在径向开缝位置γ=0.90时降噪效果最佳。     

Experimental investigation of energy loss in straight and bowed cascades with aft‐loaded profiles

An experimental investigation was carried in a low speed annular wind tunnel. The energy loss evolution from upstream to downstream in the blade cascade channel with aft‐loaded profiles was measured in detail. The results of the present study showed that energy loss was generated mainly in places near the leading and the trailing edges. Therefore, measurements were taken to improve the cascade performance by choosing the appropriate leading edge diameter, to provide a good match between the affecting length and the magnitude of adverse pressure gradient on suction surface, and to improve the static pressure distribution along the span height. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(2): 108–119, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20044