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为探究涡轮高效设计技术,从低维优化层面出发,提出了一种基于粒子群优化算法的多级低压涡轮一维设计和优化方法.该方法以涡轮效率为目标,通过建立涡轮子午流道形式以及气动特性等约束条件将涡轮一维设计转化成包含约束限制的极大值优化问题.在验证粒子群算法优化性能的基础上发展了多级低压涡轮一维气动优化设计程序,该程序通过优化地选取涡轮各级的多个设计变量,有效地生成满足多个约束条件的级最佳速度三角形以及最佳初步子午流道形式.利用该程序完成了原型低压涡轮的优化改型工作,三维数值模拟结果表明,优化改型方案在设计点和非设计点的气动性能均获得了不同程度的改善. 相似文献
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《中国航空学报》2020,33(3):870-878
Rotor blades fault of aeroengine compressor is mostly caused by mechanical and aerodynamic excitation. And the excitation factor of high intensity sound wave to rotor blades should not be ignored. Experimental researches are conducted on a multistage high pressure compressor. When high level vibration occurs on the first stage of rotor blades, the noise spectrum presents typical characteristic for discrete multi-tone in the compressor. The amplitude of blade vibration displacement and the sound pressure level of characteristic frequency noise increases and decreases simultaneously and reaches the maximum value at the same time. This frequency merely occur on a certain speed range and is locked in a specific range which presents no variation with the rotating speed. When high level vibration occurs on the first stage of rotor blades, the noise spectrum presents a sharp peak and the propagation state of the characteristic frequency is a helix structure in the compressor. It can be confirmed that acoustic resonance occurs in the multistage compressor. The acoustic resonance frequency and its side band frequencies are generated by modulation of a rotating noise source at the rotor speed which is the excitation source of the rotor blades vibration. 相似文献
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采用阵列天线对GPS接收信号进行干扰抑制,在信号处理时引入时延,形成空时二维处理的模式.空时二维抗干扰由于运算量大而导致在实际实现困难,必须进行降维处理.多级维纳滤波(MWF)方法可以有效降低滤波器的维数,但是经典的MWF方法存在子空间维数估计不准的问题.本文对于多级维纳滤波方法进行了分析,利用MWF的分析滤波器将接收信号矢量映射为另一信号矢量.通过对该信号矢量的协方差矩阵进行分析,找到一种判断子空间维数的稳健方法.仿真表明该方法能够准确地估计出噪声子空间维数.与传统的设定MSE门限的方法相比较,得出用本方法估计子空间维数更为准确可靠,抗干扰性能更优的结论. 相似文献
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提出了多级压缩锥导乘波体的设计方法,该方法应用吻切锥理论和零攻角圆锥绕流基准流场通过流线追踪生成具有多个压缩面的乘波体。对以吸气式冲压发动机为动力的高超声速飞行器,应用多级压缩乘波前体可充分发挥前体的预压缩作用,为进气道的正常工作提供所需的均匀流场。以二级压缩乘波体为例阐述了该设计方法,设计方法通过对二级压缩基准流场进行重构,使其符合Taylor-Maccoll流动模型以获得新的二级压缩基准流场。同时编写设计程序生成了一级、二级和三级压缩乘波体,通过数值模拟结果校验设计方法的正确性,并对其压缩性、升阻比、总压恢复系数等性能进行了对比分析。 相似文献
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《中国航空学报》2023,36(2):1-16
In this study, the influence of inter-stage bleeding on the compressor performance and inter-stage flow field of a multistage axial compressor is investigated by both experimental and numerical methods. The experiment is conducted on a four-stage low-speed axial compressor, and a specific computational model is built to simulate the experiment environment accurately. To illuminate the fluid mechanisms of bleeding effect in detail, both the experiment and the simulation are carried out twice, i.e., in the first time, the mass flow rate upstream the bleed location is constant under different bleed rate conditions; while in the second time, the mass flow rate downstream the bleed location is constant under different bleed rate conditions. The results demonstrate that inter-stage bleeding has little influence on upstream compressor characteristics, and affects the upstream flow field only in the rear half of the stator. The bleed effect on the downstream flow field is embodied in the variation of an incoming flow profile, an increase as the compressor inlet flow coefficient decreases. Therefore, such an effect is only significant on compressor characteristics at small flow coefficient conditions. In multistage compressors, the variation of compressor characteristics and flow field caused by inter-stage bleeding is the comprehensive result of the bleeding and the variation of the upstream working condition. In addition, the comparison between numerical and experimental results shows that the flow moves towards top half of span through the downstream rotor passage in the numerical simulation, whereas the trend of flow field variation with different bleed rates at the outlet of the downstream rotor and stator is the same with that at the inlet of the downstream rotor in the experiment, which means that the numerical method has overestimated the radial mixing intensity of the flow. 相似文献
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基于hp自适应伪谱法的固体运载火箭轨迹优化 总被引:1,自引:0,他引:1
多级固体运载火箭轨迹优化是一个多阶段多约束的最优控制问题。hp自适应伪谱法融合了有限元法和全局伪谱法的思想,采用双层优化策略对细化单元数和插值基函数的阶次进行自适应调节以满足精度和快速性要求。对基于hp自适应伪谱法的多级固体运载火箭主动段轨迹优化问题进行了数值计算,结果表明该优化方法能够很好的满足过程约束和终端入轨条件,具有收敛速度快、对初值不敏感等优点,有一定的工程应用价值。 相似文献