单晶再结晶临界应力与涡轮叶片结构设计参数间的映射模型

以单晶涡轮叶片发生再结晶的榫头进气窗口为研究对象,基于镍基单晶合金再结晶临界应力模型,通过单晶叶片铸造热应力场仿真计算,建立了最大残余应力与结构参数和温度的关系模型;并在此基础上,以最大铸造残余应力不大于再结晶临界应力、冷气通道面积不变和满足强度为约束条件,求出了不发生再结晶条件下的临界应力与结构设计参数和热处理温度的映射模型。最后通过对实际叶片榫头进气窗口的优化设计和试验对比分析,验证了本文方法的有效性。结果表明,优化后榫头进气窗口最大铸造残余应力下降30%以上,原有的再结晶现象消除。     

Hover performance of helicopter main and tail rotors with swirl velocities

It is important to quickly predict the hover performance of main and tail rotors with sufficient precision for helicopter design. To investigate the effects of swirl velocities on the hover performance of main and tail rotors, and give a better prediction for the hover performance, a flight performance model was derived and a swirl velocity model was coupled into it. The test data of the UH-60A helicopter were used for validation. When the blade loading coefficient of the main rotor was higher than 005, the effects of the swirl velocities on the main rotor power became significant. The swirl velocities increased the profile torque of the main rotor. The increased torque required the tail rotor to produce more thrust with more power consumption. At a higher blade loading coefficient of the main rotor of 012, the swirl velocities increased the main rotor power, tail rotor power and total power by 380%, 524% and 508%, respectively. The profile power increase of the main rotor caused by the profile swirl velocity was less than that of the induced swirl velocity, but the power increase was higher at high rotor blade loadings. Considering the swirl velocities in the main rotor can improve the prediction precision of the hover performance, especially at high blade loadings      

非等直径柱肋阵列的冷却特性

为优化柱肋阵列冷却效果,通过缩小柱肋阵列中局部柱肋直径得到3种非等直径柱肋阵列通道。采用瞬态液晶测试技术和数值模拟方法研究了其传热和流阻特性。结果表明:保持奇数排柱肋直径的大小,仅减小偶数排的直径,能在传热减弱不多的情况下,使通道的流动阻力大幅降低。适当调整奇/偶数排柱肋的直径,雷诺数为10 000~50 000,奇偶数排柱肋直径比为1.4的非等直径柱肋阵列通道,其平均传热系数仅减小了约6%,而阻力系数则减小了约21%。      

某型航空发动机叶片逆向工程方法研究

以某航空发动机叶片为研究对象,结合叶片的曲面特征,使用三坐标测量机逆向工程采集点云数据;提出了适合于叶片曲面的最小二乘滤波降噪算法,应用滤波算法对点云数据进行降噪处理,并使用ImageWare软件完成数据的曲线曲面重构;最后从曲面质量和拟合精度两方面,分析和评价了叶片逆向工程的精度可靠性。     

基于自由尾迹方法的自转旋翼气动特性研究

为研究自转旋翼的气动特性,建立了自转旋翼的自由尾迹方法计算模型,并耦合桨叶挥舞运动模型和自转旋翼配平模型,建立了一种分析自转旋翼气动特性的方法。以某试验自转旋翼为算例对该方法进行了验证并运用该方法研究了自转旋翼的尾迹几何形状和桨盘诱导入流分布特性。研究结果表明:建立的自由尾迹方法计算模型可以满足自转旋翼气动特性分析的需求,相比传统的近似入流模型,该自由尾迹方法模型精度更高;前飞时自转旋翼尾迹随时间推移自桨盘处向桨盘后上方运动,水平面内自转旋翼尾迹畸变略小于驱转旋翼;自转旋翼桨盘诱导入流呈非均匀分布,从桨盘前缘到后缘,下洗入流大致呈不断增加趋势,在相同拉力水平下,自转旋翼90°方位角附近及桨盘后缘的诱导入流小于驱转旋翼。     

叶片三维轮廓测量点云数据高精度多角度融合

针对高精度多角度点云数据融合叶片测量难题,设计了一种基于相位测量轮廓方法的多角度点云数据融合的机械装置.通过设计对参考平面数据旋转的算法,实现叶片三维轮廓的高精度数据合成,精度达到(0.06±0.01)mm.这种装置的方法、结构简单实用,测量效率和精度高,可以多个叶片同时测量,是一种可以取代三坐标测量的实用方法.      

含裂纹叶片的轴流式压气机整体叶盘振动特性分析

某型轴流式压气机性能试验过程中出现转子叶片裂纹故障.结合该型压气机结构特点,分析了振动响应的时域信号、频域信号以及高频成分出现的频率波动现象,总结了含裂纹叶片的轴流式压气机整体叶盘振动特性.分析结果显示:含裂纹叶片的整体叶盘使得轴流压气机振动响应呈现非线性特性;振动频谱中出现共振峰分离现象,表明叶片裂纹引起轴流压气机1级转子叶盘出现结构失谐;随转速升高,两个共振峰对应频率均出现波动现象(波动周期分别约为8s和9.2s),叶片裂纹不断扩展且数量增加,整体叶盘失谐程度不断加深,整体叶盘系统出现低阶模态局部化现象.      

A new localization theory of adaptive machining of near-net-shape blades

In the fabrication of aero-engine blades, a great deal is gained when massive material removal is avoided at the end of the process, and as little as possible material is left on the blade billet. Due to the uncertainty of pre-process, the billet shapes are inconsistent. Sometimes, the near-net-shape billet doesn’t cover the blade design surface to be cut. Therefore, blade localization is necessary for these billets before the machining. In conventional localization methods, the design surface’s location focused on guaranteeing enough material to be cut. However, because the to-be-cut surface is in near-net and free-form shape, it is difficult to find a valid localized surface model to generate the tool path. Different from the localized surface is taken as rigid in previous investigation, it is allowed to deviate from the design surface no more than the tolerance band. In term of this principle, the tolerance band is utilized to promote localization ability. A series of optimization models with different priorities is established to avoid the abandonment expensive blade billet. Finally, with the experiments performed on the near-net-shape blades, the blade localization theory and the promotion of localization ability are verified.     

压气机静子非轴对称端壁优化设计及实验

为了探索多级压气机环境下非轴对称端壁优化设计方法,通过数值仿真优化和实验测试方法对某中间级静子的机匣端壁和轮毂端壁进行了非轴对称端壁造型研究,提出了在优化时将目标函数选择为近端壁的局部叶高总压损失系数。结果表明:相较于传统的全叶高总压损失系数作为目标函数的优化方法,该优化方法可以在较少的优化步数（400步）内使得静子总压损失系数下降更多,这表明该方法可以有效降低优化耗时,为多级压气机中进行非轴对称端壁优化设计的工程应用奠定基础。      

截断肋排布方式对内冷通道换热性能的影响

在给定通道雷诺数的条件下,实验研究了矩形内冷通道中截断肋片在6种不同排布方式下的换热特性,并结合三维数值模拟方法,基于流动特征深入分析了其中的对流换热机理.研究表明:6种不同排布方式下,结构2?3?5?9通道的换热性能最好,结构2?5?3?9通道的换热性能最差;结构2?3?5?9通道的压力损失最大,结构2?5?9?3通...