面向叶片型面的五轴联动柔性数控砂带抛光技术

针对叶片型面抛光,在分析五轴联动数控砂带抛光可行性的基础上,设计并开发了五轴联动柔性数控砂带抛光机。提出了接触轮与叶片型面有效贴合的概念,并通过改善抛光工具、采用柔性抛光技术和控制抛光轴矢量来实现砂带与叶片型面的有效贴合。抛光轴矢量由抛光位点处法矢和接触轮进给矢量计算获得,既实现了砂带与叶片型面的有效贴合,而且满足抛光轮接触压力方向与柔性机构收缩方向基本一致的要求。抛光轨迹规划采用等参数线法,抛光行距根据抛光带宽确定。最后进行抛光实验,结果为精抛后粗糙度达到0.25~0.39μm,抛光前后叶型轮廓度变化0.007mm,抛光去除量在0.010~0.016mm之间,满足图纸要求。通过实验表明,五轴联动数控砂带抛光叶片型面可行,采用本文所述技术能够满足叶片型面抛光要求。     

Experimental research in rotating wedge-shaped cooling channel with multiple non-equant holes lateral inlet

The heat transfer in a novel smooth wedge-shaped cooling channel with lateral ejection of turbine blade trailing edge is experimentally investigated in both non-rotating and rotating cases. Beside the conventional inlet at the bottom of the channel, an extra coolant injection from 8 lateral non-equant holes is introduced to improve the overall heat transfer. The total mass flow rate ratio (lateral mass flow rate/total mass flow rate) varies from 0 to 1.0. The major inlet Reynolds number and rotation number respectively vary from 10000 to 20000 and from 0 to 1.16. Experimental results show that the lateral inlet decreases local bulk temperature and increases local heat transfer at the middle and the top of the static channel. In rotating cases, the lateral inlet notably improves the heat transfer at the high-radius half channel and compensates the negative effects induced by the rotation. Both intensity and uniformity of heat transfer inside the channel are enhanced while flow resistance decreases with proper mass flow rate ratio of coolant from two inlets. The most satisfactory total mass flow rate ratio is around 2/3. This new structural style of cooling channel has huge potential and provides new direction of heat transfer of turbine blade trailing edge.     

涡轮叶片外换热计算程序对比研究

对两种涡轮叶片外换热计算程序STAN 5和S1ICH的数值方法进行了比较.采用STAN5和S1ICH程序完成了VKI(Von Karman Institute)高压涡轮导叶和动叶叶栅的外传热系数计算,并将计算结果与试验数据进行了对比.结果表明,S1ICH预估的转捩位置、外传热系数的精度较高,同时S1ICH具有适应性广,收敛性好,准备初始参数方便的特点,满足工程设计计算的要求.      

高压压气机出口级叶型加工偏差特征及其影响

以高压压气机出口级叶片叶中截面作为研究对象,获得了实际压气机叶片加工偏差的分布特征,并分析了实际加工偏差对叶型气动性能的影响。以此为基础,研究了加工偏差对叶型性能的影响机理。研究结果表明,实际叶型加工偏差存在一定的系统性偏差,从而导致实际叶型气动性能的平均值偏离设计值。叶型偏差对叶型气动性能的影响存在一定的非线性效应,这在前缘区域更为明显,从而导致了平均叶型的气动性能与实际叶型平均性能出现了明显偏差。前缘附近的几何偏差对吸力面和压力面的速度峰值有较大的影响,因此前缘附近的偏差是使叶型的气动性能产生系统性偏差和增大不确定度的主要因素。根据对流动机理的分析,进口几何角偏差是导致叶型性能出现系统性偏差的主要原因;可以近似用均匀偏差来估计叶身加工偏差对正负攻角范围和损失的影响。     

电缆束火灾蔓延机理与预警研究

采用固体可燃物热解动力学模型和湍流燃烧大涡模拟方法,研究了电缆通道内电缆束的火灾行为,得到了电缆起火时间与火蔓延速度,通道内烟气温度、组分浓度和速度分布,以及电缆通道内壁与电缆表面温度随时间的变化,给电缆通道的防灭火系统设计提供了参考依据。     

Safety Analysis of Flow Parameters in a Rotor-stator Cavity

In order to ensure the safety of engine life limited parts (ELLP) according to airworthiness regulations, a numerical approach integrating one-way fluid structure interaction (FSI) and probabilistic risk assessment (PRA) is developed, by which the variation of flow parameters in a rotor-stator cavity on the safety of gas turbine disks is investigated. The results indicate that the flow parameters affect the probability of fracture of a gas turbine disk since they can change the distribution of stress and temperature of the disk. The failure probability of the disk rises with increasing rotation Reynolds number and Chebyshev number, but descends with increasing inlet Reynolds number. In addition, a sampling based sensitivity analysis with finite difference method is conducted to determine the sensitivities of the safety with respect to the flow parameters. The sensitivity estimates show that the rotation Reynolds number is the dominant variable in safety analysis of a rotor-stator cavity among the flow parameters.     

基于准静态载荷的航天器系统级正弦振动试验力限条件

以运载火箭研制方提供的准静态载荷为依据,提出了改进的航天器系统级正弦振动试验力限条件,并结合典型算例与目前采用的传统力限条件进行了对比研究。研究表明:改进的力（矩）限条件及相应的加速度下凹条件剔除了对界面合力（矩）无影响的过载项,物理概念更为清楚,计算方法更为合理;改进后的力限或加速度条件明显低于传统的试验条件,有利于减少航天器系统级试验中的过试验现象。     

Electrode design using revolving entity extraction for high-efficiency electric discharge machining of integral shrouded blisk

The integral shrouded blisk provides better performance with minimum weight, but its semi-open structure presents problems for its production. Manufacturing processes of these components require a removal of about 70%-90% of material from their blanks. Multi-axis electrical discharge machining (EDM) is commonly used for these processes, but its poor efficiency cannot meet the requirements of mass production. Strong flushing assisted high-current discharge is able to improve the machining efficiency. In this paper, this method was applied to manufacture the integral shrouded blisk. An electrode design method was proposed. Taking the largest revolving entity inside the flow channel as the base geometry, this laminated arc-shaped hollow electrode meets the requirements such as high pressure flushing, tool wear compensation, and easy to be made. A 4-axis linkage machining tool path with planetary motion was proposed. Taking an integral guide vane ring as an example, it has been experimentally verified that the time consumption for each channel using this method was reduced to a half of the ordinary EDM method, while the finished surface quality remains same.     

基于曲率分布控制的叶型前缘设计方法

为了实现对压气机叶片的优化,提出了一种基于曲率分布控制的前缘造型方法,实现了对叶型前缘曲率的直接、精确控制。将该造型方法应用于某工业级压气机的可控扩散叶型（CDA）上,通过数值仿真方法计算了叶型在设计来流马赫数下的全攻角工况性能。结果显示增加前缘曲率能有效拓宽许用攻角范围,减小尖峰扩散因子,在相同攻角下能削弱前缘吸力峰,抑制甚至消除前缘分离泡,避免提前转捩的发生。同时,调整曲率分布使其在靠近前缘点处尽可能"饱满"、减缓曲率下降速度,也有同样的效果。理论分析发现前缘曲率通过调整静压分布影响边界层发展起始流态,从而影响叶型性能。设计前缘几何形状时需要确保曲率连续性,调整曲率分布以减小前缘吸力峰的强度,避免分离诱导转捩的出现。     

力限振动试验夹具设计要求和力测量装置校核方法

文章总结了航天器系统级力限振动试验夹具设计思路, 提出利用合力和合力矩进行力测量装置有效性校核的方法。并通过航天器系统级力限振动试验, 对力测量误差原因进行分析, 指出通过提高加速度和力信号信噪比的办法可使相对误差减小到±10%以内或更低, 验证了力测量装置的有效性。