某型发动机高涡叶片掉块故障分析与排故

某型航空发动机在台架试车过程中出现振动值急剧上升问题,停车后孔探仪检查发现发动机高涡叶片掉块烧蚀,对故障件进行质量复查、强度复查、冶金及断口分析,并对高涡转子叶片相关机件进行系统分析,最终找到故障原因,同时制定了后续排故措施。

单晶高涡叶片高温振动疲劳试验研究

单晶叶片在常温和高温下的疲劳性能存在较大的差异。针对某发动机高涡叶片高循环疲劳失效故障,进行了高温振动疲劳性能试验研究。试验依据高频感应加热原理,研究了单晶材料高涡叶片高温振动疲劳试验的加温方式,介绍了高温振动疲劳试验的试验方法。通过一种试验夹具定位装置和闭环温度控制系统确保了应力场及温度场的精度和有效性。根据某高涡叶片前期的试验研究和故障定位,确定了叶片的试验温度和加温位置。试验获取了单晶高涡叶片在450℃下的疲劳极限,并探索了叶片在900℃下的疲劳强度。结果表明,该单晶高涡叶片在450℃下的疲劳极限较常温条件有明显提升,在900℃条件下的疲劳性能较450℃有所下降。

××机Ⅱ涡叶片的阻尼块试验研究

在排除××机三齿Ⅱ级涡轮叶片裂纹故障的攻关工件中，我们开展了在叶片缘板下加装阻尼块的研究。在该机这种无中间叶根的叶片下加装阻尼块尚未见有报道。为确定阴尼块的阴尼效果及最佳阴尼块质量，在振动台上进行了阴尼效果对比试验及在发动机台架上进行了阻尼块效果动测试验。试验结果表明，在发动机处于较低转速下（包括最关注的9700r/min），整体式阻尼块对Ⅱ涡叶片的一弯振动有较明显的减振效果显示，振动台的试验结果与动测数据在一定可信度范围内趋势一致。虽然加装阻尼块尚未在××机Ⅱ涡叶片防振措施中采用，但该试验工作及采用的研究方法对今后的设计研究工作仍有较大的参考价值。建议这方面的研究工作在条件许可下可以继续深化，取得充分可靠的数据，以能在具体结构中（包括Ⅱ涡叶片）起到作用。

一种“全可控涡”三元叶轮设计叶片涡的给定方法

针对“全可控涡”三元叶轮设计方法中叶片涡的给定环节 ,在考虑气动力学条件的基础上 ,介绍了一种确定叶片涡在子午流面分布的数学模型 ,编制了计算机程序 ,提供了一种快速确定子午流面叶片涡分布的方法。

背掠式离心转子设计中叶片涡分布对其性能影响的研究

基于“全可控涡”的思想 ,对小型高转速离心式压气机S2流面通流的气动设计计算方法进行了较深入的研究与分析 ,通过背掠式转子算例 ,将验算结果同原始数据作对比分析 ,验证了该方法的有效性 ;在此基础上 ,通过给定不同的叶片涡分布 ,计算分析了叶片涡对叶片相对速度的影响 ,以及对背掠式转子性能的影响 ,为通过叶片涡分布来比较好地控制叶片通道内子午面速度分布提供了一种有效的技术途径 ,可为进一步设计高性能背掠式转子提供参考依据。

粒子分离器涡形叶片金属块撞击损伤研究

研究粒子分离器涡形叶片受外物冲击损伤的规律,提高粒子分离器抗外物损伤设计能力,降低外物对航空涡轮轴发动机安全运行的影响。以冲击动力学为基础,通过冲击损伤试验方法,研究了金属块撞击粒子分离器涡形叶片的过程。采用瞬态响应测试系统,得到了金属块撞击涡形叶片的应变——时间历程;利用三坐标测量仪,获得了涡形叶片金属块撞击后的变形。对金属块撞击粒子分离器涡形叶片进行了数值仿真,对比分析了金属块撞击涡形叶片的试验结果与数值仿真结果。金属块(M6和M8螺栓)以0.2 Ma速度撞击涡形叶片时,涡形叶片的变形较小。

某型发动机Ⅰ级涡轮叶片断裂原因分析

通过对材料、制造工艺 ,以及用宏观和SME对断裂叶片进行分析 ,认为 :Ⅰ级涡轮叶片是由于叶冠间隙偏大 ,使叶片在工作时振幅增大引起的疲劳断裂。

Determination of wax pattern die profile for investment casting of turbine blades

In order to conform to dimensional tolerances, an efficient numerical method, displacement iterative compensation method, based on finite element methodology （FEM） was presented for the wax pattern die profile design of turbine blades. Casting shrinkages at different positions of the blade which was considered nonlinear thermo-mechanical casting deformations were calculated. Based on the displacement iterative compensation method proposed, the optimized wax pattern die profile can be established. For a A356 alloy blade, substantial reduction in dimensional and shape tolerances was achieved with the developed die shape optimization system. Numerical simulation result obtained by the proposed method shows a good agreement with the result measured experimentally. After four times iterations, compared with the CAD model of turbine blade, the total form error decreases to 0.001 978 mm from the orevious 0.515 815 mm.

翼型桨叶片尾涡结构的PIV实测与LES模拟研究

在塔径383mm、高径比为1的翼型桨搅拌反应器内,采用粒子图像测速(PIV)技术和大涡模拟(LES)研究了一种翼型桨的叶片尾涡结构.对比二维PIV技术测定的翼型桨搅拌反应器平均速度场数据,验证了LES方法的可靠性.并通过叶片端的速度矢量场、叶片区内的涡量大小及湍动能分布清楚地识别了翼型桨叶片尾涡结构.发现该叶片尾涡为单涡结构,其尾涡轴心轨迹几乎就在桨叶尖划过的圆柱面上.此外,还探讨了叶片尾涡对湍动能分布、湍流特性等的影响,表明最大无因次湍动能k/Vtip2约为0.04～0.06,其位置约在0.5<Z/DT<0.67和0.3<r/R<0.4处,可优化混合过程.

GE公司汽轮机通流技术的进展

本文叙述ＧＥ公司在改进汽轮机性能方面的一系列新的通流设计的特点。讨论了这些新特点对新机组和现有机组改造所带来的好处。此外，本文还讨论了用开发新设计概念的最近产生的三维粘性ＣＦＤ分析规范：叙述了为验证ＣＦＤ规程及用新设计特点后对效率收益所作的预测而进行的实验室试验规划。最后，讨论了ＧＥ公司为使先进的气动设计显著缩短周期而开发的新的独特的现代化通流设计自动化和优化工具。

Parametric Modeling System for Cooling Turbine Blade Based on Feature Design

Based on feature modeling and mathematical analysis methods,a process-oriented and modular parametric design system for advanced turbine cooling blade is developed with UG API,aiming at the structural complexity and high design difficulty of aero-engine cooling turbine blade.The relationship between the external and internal body features,the body attached feature is analyzed as viewed from the feature and parameter terms.The parametric design processes and design examples of the external body shape,tenon,platform and internal body shape,ribs,pin fins are introduced.The system improves the design efficiency of cooling turbine blade and establishes the foundation of multidisciplinary design optimization procedure for it.

CFD Prediction of Mean Flow Field and Impeller Capacity for Pitched Blade Turbine

This work focused on exploring a computational fluid dynamics(CFD)method to predict the macromixing characteristics including the mean flow field and impeller capacity for a 45° down-pumping pitched blade turbine(PBT)in stirred tanks. Firstly, the three typical mean flow fields were investigated by virtue of three components of liquid velocity. Then the effects of impeller diameter(D)and off-bottom clearance(C)on both the mean flow field and three global macro-mixing parameters concerning impeller capacity were studied in detail. The changes of flow patterns with increasing C/D were predicted from these effects. The simulation results are consistent with the experimental results in published literature.

Vibrations measurements for shrouded blades of steam turbines based oneddy current sensors with high frequency response

With the development of power plants towards high power and intelligent operation direction,the vibrations or failures of blades,especially the last stage blades in steam turbines,happen more frequently due to the unstable operating conditions brought by flexible operation.A vibration measuring method for the shrouded blades of a steam turbine based on eddy current sensors with high frequency response is proposed,meeting the requirements of non-contact heath monitoring.The eddy current sensors produce the signals which are related to the area changing of every blade’s shroud resulting from the rotation of stator.Then an improved blade tip timing(BTT)technique is proposed to detect the vibrations of shrouded blades by measuring the arrival time of each area changing signal.A structure of eddy current sensors is developed in steam turbines and an amplitude modulation/demodulation circuit is designed to improve the response bandwidth up to 250 kHz.Vibration tests for the last stage blades of a steam turbine were carried out and the results validate the efficiency of the improved BTT technique and the high frequency response of the eddy current sensors presented.

Parametric geometry representations for wind turbine blade shapes

Based on the Joukowsky transformation and Theodorsen method, a novel parametric function （shape function） for wind turbine airfoils has been developed. The airfoil design space and shape control equations also have been studied. Results of the analysis of a typical wind turbine airfoil are shown to illustrate the evaluation process and to demonstrate the rate of convergence of the geometric characteristics. The coordinates and aerodynamic performance of approximate airfoils is rapidly close to the baseline airfoil corresponding to increasing orders of polynomial. Comparison of the RFOIL prediction and experimental results for the baseline airfoil generally show good agreement. A universal method for three-dimensional blade integration-＂ Shape function/Distribution function＂ is presented. By changing the parameters of shape function and distribution functions, a three dimensional blade can be designed and then transformed into the physical space in which the actual geometry is defined. Application of this method to a wind turbine blade is presented and the differences of power performance between the represented blade and original one are less than 0. 5%. This method is particularly simple and convenient for bodies of streamline forms.

Effects of stator bending on pressure field and loss of transonic turbine stage

To study effects of the upstream flow field changing on the downstream flow field of transonic turbine, different three-dimensional bowed blades, which are the stator blades of transonic turbine stage, were designed in this paper. And then numerical calculations were carried out. The effects on downstream flow field were studied and analyzed in detail. Results show that, at the middle of stator blades, although the increasing Maeh number causes the increase of shock-wave strength and friction, the middle flow field of downstream rotors is improved obviously. It is an important change in transonic condition. This causes the loss of the rotor＇ s middle part decreased greatly. Correspondingly, efficiency of the whole transonic stage can be increased.

Study and innovation of a flexible blade turbine,a new type of tidal current generating device

Utilization of tidal current is becoming a focus of marine energy research and development field. In this paper, a new type of tidal current power generating device which was called flexible blade turbine was put forward. A scale model testing was carried out, and results show that the models performed as expected with good hydrodynamic characteristics. Based on analysis of the results, a scale model turbine with a rated power of 5 kW was constructed, which was an optimal scheme of the flexible blade turbine having higher coefficient of power and power generation capacity. Sea trials were carried out in the Zhaitang Island Channel to evaluate the performance of the turbine. Results show that the turbine performed well, generating the power predicted.

Performance Analysis and Design of Vertical Axis Tidal Stream Turbine

This study numerically analyzes the unsteady flow around the Darrieus-type turbine by using FLUENT and deals with the application to the design of blades. Two kinds of blade sections were used in this study. Unsteady RANS equation and the turbulence model, either k-e or k-co model, which are appropriate for each blade section, were employed. First for the NACA 634-021 blade that the experimental data is available, the 2-dimensional and 3-dimensional numerical analyses have been performed and compared with the experimental result. For the optimization of the turbine, the parametric study has been performed to check the performance in accordance with the changes in the number of blades, solidity and camber. It is demonstrated that the present approach could draw the turbine characteristics better in performance than the existing turbine. Next for the NACA 653-018 blade with the high lift-drag ratio from the purpose of developing highly-efficient turbine, this study has also tried to get the highly efficient turbine specifications by analyzing the performance while using 2-dimensional and 3-dimensional numerical analyses and the result was verified through the experiment. According to the present study, it is concluded that the 3-dimensional numerical analysis has simulated the experimental values relatively well and also, the 2-dimensional analysis can be a useful tool in the parametric study for the turbine design.

Flow-induced Noise and Vibration Analysis of a Piping Elbow with/without a Guide Vane

The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×10^5 to 6.81×10^5, and the position of guide vane is determined by publications. The turbulent flow in the piping elbow is simulated with large eddy simulation （LES）. Following this, a hybrid method of combining LES and Lighthill＇s acoustic analogy theory is used to simulate the hydrodynamic noise and sound sources are solved as volume sources in code Actran. In addition, the flow-induced vibration of the piping elbow is investigated based on a fluid-structure interaction （FSI） code. The LES results indicate that the range of vortex zone in the elbow without the guide vane is larger than the case with the guide vane, and the guide vane is effective in reducing flow-induced noise and vibration in the 90° piping elbow at different Reynolds numbers.

Effects of the Blade Shape on the Trailing Vortices in Liquid Flow Generated by Disc Turbines

Particle image velocimetry technique was used to analyze the trailing vortices and elucidate their rela-tionship with turbulence properties in a stirred tank of 0.48 m diameter,agitated by four different disc turbines,in-cluding Rushton turbine,concaved blade disk turbine,half elliptical blade disk turbine,and parabolic blade disk turbine.Phase-averaged and phase-resolved flow fields near the impeller blades were measured and the structure of trailing vortices was studied in detail.The location,size and strength of vortices were determined by the simplified λ2-criterion and the results showed that the blade shape had great effect on the trailing vortex characteristics.The larger curvature resulted in longer residence time of the vortex at the impeller tip,bigger distance between the upper and lower vortices and longer vortex life,also leads to smaller and stronger vortices.In addition,the turbulent ki-netic energy and turbulent energy dissipation in the discharge flow were determined and discussed.High turbulent kinetic energy and turbulent energy dissipation regions were located between the upper and lower vortices and moved along with them.Although restricted to single phase flow,the presented results are essential for reliable de-sign and scale-up of stirred tank with disc turbines.