高压喷水设备在空心叶片脱芯工艺中的应用

研究了内腔形状比较复杂的涡轮叶片铸件脱芯方法，结果表明：在化学腐蚀法脱芯的基础上辅之以高压喷水设备，可以较有效的清除叶片内通道的残芯，通过试验得出了合适的工艺参数。     

Numerical and experimental investigation of axial fan with trailing edge self-induced blowing

Axial fans often show adverse flow conditions at the fan hub and at the tip of the blades. In the present paper, a modification of conventional axial fan blades with numerical and experimental investigation is presented. Hollow blades were manufactured from the hub to the trailing edge at the tip of the blades. They enable the formation of self-induced internal flow through internal passages. The internal flow enters the internal radial flow passages of the hollow blades through the openings near the fan hub and exits through the trailing edge slots at the tip of the blade. The study of the influence of internal flow on the flow field of axial fan and the modifications of aerodynamic characteristics of the axial fan have been made. The numerical and experimental results show a comparison of integral and local characteristics of the axial fan with the internal flow, compared to characteristics of a geometrically equivalent fan without internal flow. The experimental results of local characteristics were performed with a five-hole probe and computer-aided visualization. A reduction of adverse flow conditions near the trailing edge at the tip of the blade was achieved, as well as boundary layer reduction on the blade suction side and the reduction of flow separation. The introduction of self-induced blowing led to the preservation of the direction of external flow, defined by blade geometry, and enabled maximal local energy conversion. The integral characteristic reached higher degree of efficiency.     

Solidification Simulation of Investment Castings of Single Crystal Hollow Turbine Blade

The three-dimensional solidification simulation of the investment castings of single crystal hollow turbine blade at the withdrawal rates of 2 mm/min, 4.5 mm/min and 7 mm/min has been performed with the finite element thermal analysis. The calculated results are in accordance with the experimental ones. The results show that with the increase of withdrawal rate the concave curvature of the liquidus isotherm is larger and larger, and the temperature gradients of the blades increase. No effects of withdrawal rate on the distribution of the temperature gradients of the starter and helical grain selector of the blades are observed at withdrawal rates of 2 mm/min, 4.5 mm/min and 7 mm/min. The relatively high temperature gradient between 500℃/cm and 1000℃/cm in the starter and helical grain selector is obtained at three withdrawal rates.     

Review of main manufacturing processes of complex hollow turbine blades

In view of their development at present, the advanced manufacturing processes of hollow turbine blades are reviewed thoroughly. There are several kinds of manufacturing technologies, including investment casting, laser metal direct forming and integrated manufacturing of ceramic cores shell, for hollow turbine blades, and their advantages and disadvantages are contrastively analysed. The development direction and the problems to be solved are put forward for manufacturing the hollow turbine blades to fulfil the increasing requirements of the high performance engine and energy conservation in the future.     

玻璃钢/复合材料叶片结构优化设计

本文讨论玻璃钢/复合材料叶片结构动力优化设计。设计变量为截面单向层壁厚,目标函数为叶片最轻重量,约束条件为应力和频率约束,并考虑了工艺和构造对壁厚的要求。应力约束采用满应力准则来处理,频率约束采用非线性规则中的Kuhu—Tucker条件来处理。文中给出了两个算例,表明本文介绍的方法对于叶片结构动力优化设计是有效的。     

Fatigue strength of working blades of turbines and compressors repaired by welding

A method of determining the welding repair zones of working blades of gas turbine engines is proposed based on the principle of equal strength of the component using the fatigue strength criterion. The method takes into account the difference of the mechanical properties of the deposit and the parent metal. Investigations were carried out on new and repaired working blades of turbines and compressors of different gas-pumping systems. The experimental results are used to prepare recommendations for repairing the working blades subjected to pilot-plant service conditions.Translated from Problemy Prochnosti, No. 11, pp. 20–25, November, 1994.     

A simple method for potential flow simulation of cascades

A simple method using a combination of conformal mapping and vortex panel method to simulate potential flow in cascades is presented. The cascade is first transformed to a single body using a conformal mapping, and the potential flow over this body is solved using a simple higher order vortex panel method. The advantage of this method over existing methodologies is that it enables the use of higher order panel methods, as are used to solve flow past an isolated airfoil, to solve the cascade problem without the need for any numerical integrations or iterations. The fluid loading on the blades, such as the normal force and pitching moment, may be easily calculated from the resultant velocity field. The coefficient of pressure on cascade blades calculated with this methodology shows good agreement with previous numerical and experimental results.     

Experimental crack propagation and failure analysis of the first stage compressor blade subjected to vibration

This paper presents results of experimental vibration tests of the helicopter turbo-engine compressor blades. The blades used in investigation were retired from maintenance under technical inspection of engine. Investigations were conducted for selected undamaged blades, without existence of preliminary cracks or corrosion pits. The blades during experiment were entered into transverse vibration. The crack propagation process was conducted in resonance condition. During the fatigue test, the growth of crack was monitored. In the second part of work, a nonlinear finite element method was utilized to determine the stress state of the blade during vibration. In this analysis a first mode of transverse vibration were considered. High maximum principal stress zone was found at the region of blade where the crack occurred.     

DZ125定向凝固涡轮叶片合金研究

ＤＺ１２５定向凝固高温合金是为新航空发动机研制的涡轮叶片材料，。它具有高的中，高温强度和延性，特别是具有良好的可铸性和小的薄壁效应，可铸成内腔十分复杂的薄壁空心叶片。     

Accelerated LCF‐creep experimental methodology for durability life evaluation of turbine blade

This paper proposes an accelerated low cycle fatigue (LCF)‐creep experimental methodology in laboratory to investigate the durability life of turbine blades. A typical mission profile of the turbine blade was obtained by means of rain flow counting method, considering both the actual flight condition and ground test data. Finite element analysis (FEA) was conducted to obtain the stress and temperature fields of turbine blade. A test system was constructed to conduct LCF‐creep experiments of turbine blades, simulating the stress and temperature distributions of critical section properly. LCF‐creep experiments of full‐scale turbine blades were performed under a trapezoidal loading spectrum. Experiment results showed that the durability life of turbine blade based on numerical method was longer than that based on this experimental methodology, even an order of magnitude. Furthermore, this experimental methodology helped to extend the service life of this blade safely, and its validity was verified in actual service condition.     

铕掺杂的TiO2空心微球的制备及光催化性能

通过溶胶-凝胶法制备未掺杂和铕掺杂的TiO₂空心微球, 采用XRD、SEM、TEM、HRTEM、BET和XPS等技术对样品进行表征, 以亚甲基蓝的光催化降解为目标反应, 评价其光催化活性。结果表明, 钛酸四丁酯(TBOT)的加入量对微球的形貌影响较大, 当滴加1.5 mL的TBOT时, 可得结构清晰、分散性良好的TiO₂空心微球。XRD分析表明, 400℃煅烧的纳米TiO₂空心微球为锐钛矿, 掺铕可抑制TiO₂的晶相转变。光催化实验表明, 铕掺杂能显著提高TiO₂空心微球的活性。当铕掺量为0.7%时, 所得样品粒径和孔径最小, 比表面积最大, 光催化活性最高。     

煅烧温度对TiO_2中空微球光催化性能的影响

以分散聚合法制得的单分散阳离子聚苯乙烯（PS）微球为模板,钛酸丁酯为前驱体,采用溶胶-凝胶法在模板表面包覆TiO2壳层,并在不同煅烧温度下制备了晶相结构不同的微米级中空TiO2微球。采用TEM、SEM、FT-IR、XRD、UV-Vis DRS对样品的微观结构、相态组成及光催化性能进行了表征。结果表明TiO2中空微球平均粒径达到1.23μm,壳层厚度约为30nm;随着煅烧温度增加,锐钛矿晶粒尺寸会增加,并在700℃时出现混晶结构;在500℃煅烧得到的TiO2中空微球对甲基橙（MO）降解表现出比P25更好的光催化性能及光催化稳定性。     

Development of a High‐fidelity Experimental Substructure Test Rig for Grid‐scored Sandwich Panels in Wind Turbine Blades

This paper outlines high‐fidelity experimental substructure testing of sandwich panels which constitute the aerodynamic outer shell of modern wind turbine blades. A full‐scale structural experimental and numerical characterisation of a composite wind turbine blade has been conducted. The development of a full‐scale numerical model is detailed, and the necessary experimental set‐up is described. Further, the numerical and experimental results obtained are compared, and an idealised set of boundary conditions for a chosen blade substructure is presented. From this, the development of a test rig suitable for representing the established loading and boundary conditions is presented, and some preliminary experimental results are discussed. The work provides a road map for developing high‐fidelity experimental substructure tests, which in more generic terms are applicable to similar developments of substructure tests for composite wind turbine blades. Furthermore, recommendations on the use of grid‐scored sandwich structures in wind turbine blades are presented, which outline the sensitivity in terms of quasi‐static strength to the established loading conditions.     

One-pot synthesis of hierarchical fluorapatite hollow microparticles

Hierarchical fluorapatite (FHAp) microparticles with hollow interiors were prepared by a one-pot hydrothermal method using Na₂EDTA/citric acid (CA) as additive. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results showed that the resultant hollow FHAp microparticles with uniform shape and size are hierarchically constructed by many small FHAp crystallites building units. Time-dependent experimental results indicated that Ostwald ripening process could be used to explain the formation mechanism for the hollow FHAp microparticles.     

冲击混响法溶洞探测初步试验

提供一种区别于通常地矿应用的测声时差的新的溶洞声学测试方法一冲击混响法。通过有无溶洞两个模型的声学试验,对测量数据进行时域分析和时频分析,得到混响衰减系数和混响持续时间两个参数,结果表明：两个模型的混响衰减系数和混响持续时间都存在明显差异,空心模型的混响衰减系数较实心模型小．而混响持续时间则比实心模型大。因而为方便快捷地判断有无溶洞的冲击混响法提供了试验依据。     

轻质碳酸钙干燥设备选型

对轻质碳酸钙的干燥及其有关设备的概况作了介绍，选用空心桨叶加旋转闪蒸相组合的形式作为轻质碳酸钙的干燥设备，具有热效率高、能耗低、产品质量好、干燥均匀、操作工况稳定等特点。是一种较为理想的干燥设备。     

快速铸造收缩-扩张形气膜孔空心涡轮叶片

本文将光固化成形技术和凝胶注模成形技术集成在一起,间接自由成形了带有收缩-扩张形气膜孔空心涡轮叶片整体式陶瓷铸型.通过建立收缩-扩张形气膜孔型芯干燥收缩受阻模型,推导了临界干燥收缩率计算公式,实验研究了凝胶注模成型坯体冻干特性.结果表明:冻干收缩率随着失水程度增加而增大,在失去约50%水分之后,干燥收缩停止;预冻温度越...     

低周往复荷载下空心矩形墩抗震性能试验研究

为了研究空心矩形薄壁墩柱的抗震性能,对五根钢筋混凝土空心墩柱进行了低周往复加载的拟静力试验。从构件与截面两个层面评价了墩柱试件的整体抗震性能,并分析了配筋率、剪跨比对桥墩承载能力、延性、耗能等抗震性能的影响,最后用试验数据对日本规范中残余位移的计算公式进行了修正。研究发现: 钢筋混凝土空心矩形薄壁墩抗震性能良好,提高配箍率、降低剪跨比能在一定程度上提高墩柱延性变形能力。本文研究结果对空心矩形薄壁墩柱的抗震设计有参考意义,对其理论研究有重要的借鉴价值。     

Fatigue strength of gas turbine compressor blades

An experimental procedure has been developed for the investigation of fatigue and crack growth resistance of materials and real compressor blades. Methods for the determination of stress intensity factors in specimens and in blades with cracks have been justified. Investigations have been performed into the influence of manufacturing residual stresses and surface defects in the form of simulators of dents, corrosion pits, and nonmetallic inclusions on fatigue strength of steels and a titanium alloy. The characteristics of the material crack growth resistance have been studied considering the effect of the medium (sea water) and stress ratio in a cycle, as well as fatigue strength of newly-manufactured blades and those after being in operation. Specific features of fatigue crack propagation in blades have been considered and a method for predicting the life of blades with cracks has been justified.     

混流式水轮机转轮叶片流激振动分析

结合小变形弹性理论和不可压缩粘性流体的最大功率耗散原理构造流体-叶片系统的功率泛函,通过广义变分原理建立了混流式水轮机转轮叶片在非定常湍流场中考虑流体-结构相互作用(FSI)的有限元模型,计算叶片在FSI情况下的流激振动。数值计算采用分离迭代格式,流动用大涡模拟(LES),叶片振动用直接积分法。试验模型以某型水轮机为原型设计制作,在一片叶片的正面和负面上分别装有5只Kulite的压力传感器,在另一片叶片上装有3只微加速度传感器。计算得到的叶片自振频率、频谱曲线以及加速度时程与试验实测结果是吻合的。