A special CAD/CAM software for electro-discharge machining of shrouded turbine blisks

In this paper, a special-purpose CAD/CAM software package, BliskCad/Cam, based on a commercial CAD/CAM software Unigraphics is developed to reduce difficulties in CNC-EDM of the shrouded turbine blisks. The software package consists of five modules such as electrode design, path searching, and machining simulation module. Functions of BliskCad/Cam include parametrical reconstruction of 3-D model of the blisk, intelligent design of complex shaped electrode, automatic generation of NC codes, search of interference-free tool path for multi-axis NC-EDM and machining simulation, etc. Experimental verification is conducted by using BliskCad/Cam and the results show that it satisfies the requirements, and can realize precision machining and reduce accessorial time remarkably.

Deep learning-based modeling method for probabilistic LCF life prediction of turbine blisk

Turbine blisk is one of the typical components of gas turbine engines.The fatigue life of turbine blisk directly affects the reliability and safety of both turbine blisk and aeroengine whole-body.To monitor the performance degradation of an aeroengine,an efficient deep learning-based modeling method called convolutional-deep neural network(C-DNN)method is proposed by absorbing the advantages of both convolutional neural network(CNN)and deep neural network(DNN),to perform the probabilistic low cycle fatigue(LCF)life prediction of turbine blisk regarding uncertain influencing parameters.In the C-DNN method,the CNN method is used to extract the useful features of LCF life data by adopting two convolutional layers,to ensure the precision of C-DNN modeling.The two close-connected layers in DNN are employed for the regression modeling of aeroengine turbine blisk LCF life,to keep the ac-curacy of LCF life prediction.Through the probabilistic analysis of turbine blisk and the com-parison of methods(ANN,CNN,DNN and C-DNN),it is revealed that the proposed C-DNN method is an effective mean for turbine blisk LCF life prediction and major factors affecting the LCF life were gained,and the method holds high efficiency and accuracy in regression modeling and simulations.This study provides a promising LCF life prediction method for complex structures,which contribute to monitor health status for aeroengines operation.

Effects of swirl and hot streak on thermal performances of a high-pressure turbine

Advanced civil aero-engines tend to adopt lean burn combustors to meet emission requirements.The exit of a lean burn combustor experiences highly non-uniformities in both temperature(Hot Streak,HS)and flow(swirl).This paper presents a numerical investigation on the behaviors of a High-Pressure(HP)turbine under a combined effect of swirl and hot streak.The investigation was conducted on a GE-E3 HP turbine with unsteady numerical simulations,which considered the realistic clocking position of the HP Nozzle Guide Vane(NGV)relative to the combustor.The influences of swirl orientations on the HS migration and thermal performances on the blade surface were examined.Results indicate that,inside the NGV passage,the swirl’s induced incidence angle effect dominates the HS radial migration.The transversal movement of HS follows the cross flow and thus makes itself approach the Suction Side(SS)and keep away from the Pressure Side(PS)as passing through the NGV,so that HS near the SS is more influenced by the incidence angle effect than that near the PS.As for the heat transfer,swirl affects the Heat Transfer Coefficient(HTC)on the NGV’s PS and SS mainly through the incidence angle effect.Different from the NGV,the inlet swirl and HS have limited effect on the HTC on the rotor blade’s PS,while on the rotor blade’s SS,the original vortex system dominates;therefore,the inlet non-uniformities merely enhance the HTC on the SS rather than alter its distribution characteristics.

3D modeling of transformation of gaseous pollutants in the high-pressure turbine of an aircraft engine

Aircraft emissions contribute to global climate change and regional air pollution near airports.Understanding the formation and the transformation of emissions in the aircraft engine is essential to properly quantify the environmental impact and air pollution.However,precise investigation of chemical process in the turbine is challenging because of the complexity of the transformation process in the complex flow relating to the moving blade at high temperature and high pressure.We present here,the first published model study of 3D chemical formations inside a high-pressure turbine and first time to compare three numerical solutions(1D,2D and 3D calculations)of transformation of trace species inside an aircraft engine.The model has simulated the evolution of principal precursor pollutant gases(NOx and SOx)and other species(hydrogen,oxygen species and carbon oxides).Our results also indicated strong dissimilarities in chemical transformations of 3D calculations.In comparing the three solutions,the results obtained showed that the difference of mole fractions of species can be under predicted by 75%between 1D and 2D calculations and in the comparison of 2D and 3D calculation,the under predicted difference may be 90%.

Advanced multiple response surface method of sensitivity analysis for turbine blisk reliability with multi-physics coupling

To reasonably implement the reliability analysis and describe the significance of influencing parameters for the multi-failure modes of turbine blisk, advanced multiple response surface method (AMRSM) was proposed for multi-failure mode sensitivity analysis for reliability. The mathematical model of AMRSM was established and the basic principle of multi-failure mode sensitivity analysis for reliability with AMRSM was given. The important parameters of turbine blisk failures are obtained by the multi-failure mode sensitivity analysis of turbine blisk. Through the reliability sensitivity analyses of multiple failure modes (deformation, stress and strain) with the proposed method considering fluid-thermal-solid interaction, it is shown that the comprehensive reliability of turbine blisk is 0.9931 when the allowable deformation, stress and strain are 3.7 x 10(-3) m, 1.0023 x 10(9) Pa and 1.05 x 10(-2) m/m, respectively; the main impact factors of turbine blisk failure are gas velocity, gas temperature and rotational speed. As demonstrated in the comparison of methods (Monte Carlo (MC) method, traditional response surface method (RSM), multiple response surface method (MRSM) and AMRSM), the proposed AMRSM improves computational efficiency with acceptable computational accuracy. The efforts of this study provide the AMRSM with high precision and efficiency for multi-failure mode reliability analysis, and offer a useful insight for the reliability optimization design of multi-failure mode structure. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.

一种航空发动机涡轮叶盘预制体工艺设计方法

概述了当前涡轮叶盘预制体的结构类型,得出2D叠层极性编织结构具有力学性能优良和成型难度低的优势。预制体的结构设计对复合材料的性能有显著影响,当前涡轮叶盘预制体研究的相关文献还很少,尤其是体积分数设计方面。为此,提出了一种极性编织结构涡轮叶盘预制体的结构设计方法,推导出能满足体积分数设计要求的结构参数关系式,并通过一个实例对该关系式进行说明验证。研究表明:该种航空发动机涡轮叶盘预制体的工艺设计方法具有实用性。

基于Solidworks平台的涡轮盘专用CAD/CAM系统开发

带冠整体涡轮盘具有高效率、高可靠性等许多优点,其流体通道属半封闭结构,叶片弯扭,叶盆和叶背均是自由曲面,难以加工制造。针对整体涡轮盘的电火花加工方法存在的问题,对Solidworks进行二次开发,建立了一套整体涡轮盘专用CAD/CAM系统,实现了计算机辅助涡轮盘三维重构、电极设计与制造、加工轨迹优化搜索和加工仿真等功能。通过典型零件的加工实例,验证了整体涡轮盘专用CAD/CAM系统的应用性能。

基于智能双重响应面法的涡轮叶盘可靠性灵敏度分析

为了合理进行整体叶盘多失效模式可靠性分析和准确描述各影响参数的重要程度,将智能算法与双重响应面方法相结合提出可靠性灵敏度分析的智能双重响应面方法 (Intelligent Dual Response Surface Method,IDRSM)。首先,建立IDRSM的数学模型,给出基于IDRSM的可靠性灵敏度分析的流程。然后,考虑流场和温度场作用,基于IDRSM对整体叶盘径向变形和应力两种失效模式进行可靠性分析和灵敏度分析。可靠性分析显示:当许用径向变形、许用应力的均值和标准差分别取3.8mm和76μm,690MPa和14MPa时,叶盘综合可靠度为0.9926。灵敏度分析显示:整体叶盘综合失效概率的主要影响因素为流速和转速,占叶盘总失效的92%。通过蒙特卡洛法、响应面法、极值响应面法、智能响应面法等四种方法比较显示:IDRSM能在保证计算精度的前提下提高计算效率。实例分析表明该方法在多失效模式综合可靠性灵敏度分析中的可行性和有效性,也为结构多失效模式可靠性优化开辟了有效途径。

带冠涡轮叶盘弯扭通道中复杂电极的进给轨迹

整体涡轮叶盘精加工是决定叶盘最终几何精度的关键技术 ,电火花加工 (EDM)则是涡轮叶盘精加工的有力手段。在涡轮叶盘EDM精加工中电极的设计的基础上 ,进行了电极在带冠叶盘弯扭狭窄通道中无干涉进给轨迹的搜索 ,其中的核心问题是电极运动约束条件的确定。

整体涡轮叶盘五坐标数控电火花加工编程

大扭曲叶型带冠整体涡轮叶盘结构复杂,五坐标数控电火花加工中成型电极与加工工件极易发生干涉,成型电极进给轨迹复杂.针对上述问题,采用逆向搜索算法搜索成型电极进给轨迹.利用通道内相邻叶盆曲面、叶背曲面设计成型电极,由逆向搜索算法平移和旋转成型电极,再进行干涉检测;若无法得到合理加工轨迹,可减小成型电极厚度,重复该过程,直至成型电极安全退出,同时得到成型电极最优厚度.控制成型电极平移及旋转步长,生成密度合理的NC加工轨迹.系统验证表明,生成的NC加工轨迹优化、密度合理,成型电极厚度优化.

大栅距带叶冠涡轮盘电火花加工工艺优化设计

以大栅距带叶冠涡轮盘电火花加工工艺设计为例,分析了数控电火花加工的电极设计方案,给出了提高加工效率的工艺方法。通过采用整体式成组电极的方法,实现了工艺的再优化设计,达到了再次提高加工效率的目的。

整体叶盘铣削数控编程与加工技术

整体叶盘有良好的结构完整性、轻质化、装配环节少、装配精度高等优点,已被广泛应用于航空发动机中。根据整体叶盘的切削加工特征,将其简化为整体叶盘基准件,从数控编程和加工技术两方面实现整体叶盘的高质量加工。首先,利用Hyper MILL软件对整体叶盘基准件进行数控编程,优化获得理想的刀具路径,保证高效高质量的零件加工。然后,利用DMU-70V五轴加工中心对钛合金TC4整体叶盘基准件进行切削加工,在整体叶盘基准件叶片和流道几何特征的精加工时,选用不同型号的立铣刀,并监测加工过程中的切削力。最后,对加工后叶片和流道加工表面形貌进行测试分析,并结合切削力对比分析国产刀具和进口刀具对钛合金整体叶盘的切削加工性能。

某高压涡轮整体叶盘破裂转速计算方法及试验验证

轮盘的一个重要设计准则是防止其破裂。本文介绍了某高压涡轮整体叶盘破裂转速的计算方法和试验验证。根据试验结果对整体叶盘破裂转速的计算方法进行了验证,反推并验证了该高压涡轮整体叶盘的材料利用系数。该研究成果可供工程设计人员参考。

大栅距带叶冠涡轮盘电火花加工电极优化设计

以大栅距带叶冠涡轮盘电火花加工电极设计为例,分析了数控电火花加工的电极设计思路与方法,给出了新的电极设计方法,同时分析了简化的加工轨迹搜索方法,实现了大栅距带叶冠涡轮盘的快速电极设计与加工轨迹搜索,大大缩短了电极工艺设计时间。

基于压缩Voxel模型的整体涡轮叶盘五坐标数控电火花加工仿真验证

提出了基于压缩Voxel模型的整体涡轮叶盘五坐标数控电火花加工仿真、验证新方法.该方法首先构造整体涡轮叶盘仿真工件、成型电极压缩Voxel模型,再根据数控加工轨迹构造成型电极扫描体,最后在三维虚拟空间完成加工过程仿真.利用Marching Cubes方法提取仿真工件表面三角网格,增强了仿真工件显示质量和速度.通过仿真工件压缩Voxel模型与标准CAD模型的三维对比实现了仿真结果分析验证.该方法在某航天火箭发动机整体涡轮叶盘五坐标数控电火花加工编程仿真与验证中得到了应用,效果良好.

整体叶盘约束状态对叶片模态影响程度的研究

研究了某型发动机整体叶盘在不同约束状态下叶片模态参数的变化情况。利用有限元软件对整体叶盘进行了振动特性分析,并基于变截面伯努利梁的模态分析揭示出叶片模态随盘体刚度变化的规律;同时,就盘体自由和中心固定两种状态对叶片完成了模态试验。试验结果与仿真分析相符,说明了该型发动机整体叶盘盘体约束状态的变化对叶片模态参数的影响甚微。同时指出,当整体叶盘盘体刚度比叶片大到一定倍数时,叶片的模态即可认为是相对独立的。

基于双重响应面法的涡轮叶盘蠕变可靠性分析

为了精确有效地解决高温蠕变状态下多种失效模式共存时的综合可靠性分析的问题,运用双重响应面法(Dual Response Surface Method, DRSM)对航空发动机涡轮叶盘进行了可靠性分析。通过蠕变试验数据确定材料特征参数;将叶盘结构的燃气温度、材料密度、弹性模量和工作转速作为输入变量,基于建立的叶盘有限元模型,结合有限元法对其进行热-结构耦合分析得到叶盘应力和应变;利用拉丁超立方抽样技术小批量抽取样本,建立涡轮叶盘的应力和应变双重响应面数学模型;运用蒙特卡罗联动抽样技术对双重响应面数学模型进行大批量抽样,完成叶盘结构的综合可靠性分析。分析结果表明:涡轮叶盘高温蠕变综合可靠度为0.985 6;方法比较显示:双重响应面法在保证计算精度的同时明显提高了计算速度。

大栅距等锥形带叶冠涡轮盘电火花加工电极优化设计

以某型号大栅距等锥形带叶冠涡轮盘电火花加工电极设计为例,分析了原电极设计的不足并进行了改进,给出了简化的加工轨迹搜索方法,实现了电极优化设计与加工轨迹快速搜索,大大缩短了电极设计的时间。

遄达XWB发动机发展与设计特点

遄达XWB发动机是RR公司遄达系列发动机的第6个也是最新的型号。该发动机在风扇支承结构、带冠高压涡轮工作叶片与中压涡轮级数上突破了RR公司的传统设计,各部件采用了21世纪初开发和验证的一些新技术。通过概述遄达XWB发动机的发展背景和研制进展,重点分析了总体结构及各部件结构设计的特点,得出该发动机在性能、经济性、排放特性、噪声特性、维修成本等方面具有良好的综合性能。

先进涡轮盘结构强度对比分析

为减小航空发动机涡轮盘应力,减轻质量,提高发动机推重比,介绍了3种先进涡轮盘,即纤维增强涡轮盘、双辐板涡轮盘和整体涡轮叶盘的结构特点和工艺难点,提出其未来的研制设想;应用有限元分析软件对传统涡轮盘与3种先进涡轮盘进行了强度对比分析和质量计算。结果表明:3种先进涡轮盘在强度和质量方面较传统涡轮盘具有优势,突破相应的关键技术后,可应用于未来高推重比发动机中。