基于DSP技术的角位置伺服控制器设计

随着数字信号处理器(DSP)功能越来越完善、运行速度越来越快、价格越来越低,本文提出了基于DSP技术的角位置伺服控制器设计方法,包括控制器的整体结构设计、控制算法设计和可靠性设计.利用DSP可以实现模数转换、数模转换、数字I/O的采集及控制算法.本文设计的控制器可以大幅度减小控制系统的体积、元器件的数量,并且提高了控制...     

Research on modeling of heat source for electron beam welding fusion-solidification zone

In this paper, the common heat source model of point and linear heat source in the numerical simulation of electron beam welding (EBW) were summarized and introduced. The combined point-linear heat source model was brought forward and to simulate the welding temperature fields of EBW and predicting the weld shape. The model parameters were put forward and regulated in the combined model, which included the ratio of point heat source to linear heat source Qpr and the distribution of linear heat source Lr. Based on the combined model, the welding temperature fields of EBW were investigated. The results show that the predicted weld shapes are conformable to those of the actual, the temperature fields are reasonable and correct by simulating with combined point-linear heat source model and the typical weld shapes are gained.     

雷诺数对带蜗壳的离心压气机内部流场影响研究

为了探讨离心压气机性能随雷诺数的变化规律,对带蜗壳的全周流道流场进行数值模拟,分析雷诺数对内部流场结构的影响.结果表明:压气机工作于Re=5.7×104和Re =1.3 ×104下的最高效率比Re=1.4×105分别下降了4.5％和8.5％,所有工况在10％叶高附近效率最高.受到蜗壳的影响,全周流道计算所得压气机的效率值和工作范围均小于单流道计算结果.低雷诺数时,气流抗逆压梯度能力迅速减弱,叶顶泄漏流向下游发展过程中,会绕过相邻叶片前缘或顶部间隙进入其他流道;叶片表面约化静压沿径向的梯度增加,从而造成更严重的二次流动;前缘激波强度、附面层厚度和尾迹宽度均增加,流道内出现激波,压气机性能严重恶化.     

Research on windmill starting characteristics of MTE-D micro turbine engine

Micro turbine engine (MTE) is an important kind of propulsion system for miniature unmanned aircraft or missiles, because of its better high-speed performance (than propeller propulsion) and higher propulsion efficiency (obviously than rockets). Windmill start is a common air-starting mode used in micro turbine engine. The windmill starting characteristics are important to the practical use of micro turbine engine. In this paper, the windmill starting characteristics research for a 12 cm diameter (MTE-D) micro turbine engine is carried out by experiment and numerical simulation. The characteristic of rotor mechanical losses at low-speed condition is stud- ied, and the engine common working line of windmill starting process is obtained. Based on the engine windmill characteristics, the propane ignition characteristics under different inflow conditions are researched, and the envelope of propane ignition and propane flameout is determined. The experimental research of fuel supply and ignition characteristics is completed, and the envelope of fuel supply and ignition is obtained. The windmill stage, propane ignition stage, fuel ignition stage and acceleration process from idling-speed to 80% full speed of MTE-D micro turbine engine is optimized, and the optimization windmill starting parameters are collected. The successful wind-mill starting experiment under this condition with engine speed up to 80% full speed indicates that these starting parameters are reasonable. All the starting parameters of MTE-D micro turbine engine obtained in this work are dimensionless parameters, and the conclusions obtained in this study have some reference to other micro turbine engines with the similar structural form and starting process.     

Active generalized predictive control of turbine tip clearance for aero-engines

Active control of turbine blade tip clearance continues to be a concern in design and control of gas turbines. Ever increasing demands for improved efficiency and higher operating temperatures require more stringent tolerances on turbine tip clearance. In this paper, a turbine tip clearance control apparatus and a model of turbine tip clearance are proposed; an implicit active generalized predictive control （GPC）, with auto-regressive （AR） error modification and fuzzy adjustment on control horizon, is presented, as well as a quantitative analysis method of robust per- turbation radius of the system. The active clearance control （ACC） of aero-engine turbine tip clear- ance is evaluated in a lapse-rate take-off transient, along with the comparative and quantitative analysis of the stability and robustness of the active tip clearance control system. The results show that the resultant active tip clearance control system with the improved GPC has favorable steadystate and dynamic performance and benefits of increased efficiency, reduced specific fuel consump- tion, and additional service life.     

高负荷扩压叶栅中附面层吸除技术实验研究

通过分析某高负荷压气机叶栅内部的流动状况,确定了端壁开槽吸气以及端壁与吸力面同时开槽吸气两种附面层吸除方案,并在低亚声速条件下进行了风洞吹风实验。结果表明,附面层吸除是一种提高高负荷压气机叶栅气动性能的有效措施,通过吸走附面层流体可以改善壁面附近流动状况,角区分离减弱,流道内高损失区范围减小。随着吸气量的增加,改善压气机叶栅性能的效果越显著。吸气方案不同,其作用机理也不一样。     

冲角变化对弯掠压气机叶栅壁面静压分布的影响

实验研究了冲角变化对不同掠型叶片组成的平面扩压叶栅壁面静压分布的影响。结果表明,变冲角时弯掠叶栅端部横向、径向及流向压力梯度分布改善,正冲角时端壁与吸力面附面层相互作用减弱,避免了低能流体在吸力面角区的积聚及分离,同时也使得中径附近损失有所增加,但其总损失没有明显增大;负冲角时弯掠叶栅中径附近的损失增加在总损失中占主导地位,气动性能下降。在较大正冲角时弯掠叶栅仍能保持角区流动的稳定,若增大中径处的设计冲角能够获得更好的气动性能。     

树脂基复合材料/泡沫塑料夹层结构成型技术研究进展

总结归纳了树脂基复合材料／泡沫塑料夹层结构的五种典型成型工艺方法，并对其部分成型工艺的特点、优缺点等进行了较为详细的阐述。     

结构可靠性定寿模型

 本文提出一新的结构可靠性定寿模型,它综合考虑了安全寿命设计、损伤容限设计和无损检测的可靠性。根据该模型可以合理确定结构具有高可靠度的使用寿命和检修周期。     

大转角正弯扩压叶栅流场性能实验与数值研究

实验对不同冲角下三种叶型折转角环形压气机直、弯叶栅进、出口流场进行了详细的测量,并利用实验结果对数值模拟结果进行了校核,得到了详细的直、弯叶栅流道内的计算结果。结果表明,大折转角叶栅流道内旋涡由多涡结构向单一涡结构转变的趋势明显,叶片正弯使得流道内近吸力面的涡系径向掺混作用加强;叶展中部流动分离的加重导致集中涡系破裂,从而引起流道内气流的严重堵塞,这是损失激增的主要原因,因此,要在高负荷压气机叶栅中应用正弯叶片,必须有效抑制中部流动的恶化。