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A new closed-form method for inertia force and moment calculation in reciprocating piston engine design

Science China(Technological Sciences) 2018年第6期61卷 879-885页

作者： xie zhifeng XU QuanYong GUAN NanXiang ZHOU Ming Institute for Aero-Engine School of Aerospace Engineering Tsinghua University Beijing 100084 China

The piston crank mechanism is an important component of a reciprocating piston engine. It is an inherent vibration system, and as such, the calculation of unbalance quantity is a critical procedure in balancing mechanism design, which is adopted to balance inertia loading. The traditional method usually applies a Taylor series expansion with the crank-conrod ratio, then a Fourier transform with the crank angle. The Taylor expansion generally ignores the influence on calculations resulting from the high order terms. However, the high order terms of the Taylor expansion will also contribute to the low order terms in the Fourier series. This will induce poor precision in the inertia loading calculation, especially in a high crank-conrod ratio engine. Thus, this paper proposes a new closed-form method, which only adopts a Fourier transformation for the calculation. The coefficients of the Fourier transformation terms contain the contributions of all order terms of the crank-conrod ratio. Therefore, we named it as a closed-form method. Compared with the traditional method, the closed-form method improves the numerical accuracy of the secondary reciprocating inertia force by 1.5%–4%, when the crank-conrod ratio varies from 0.25 to 0.4. Using this new closedform method to design a balancing mechanism, the primary and secondary reciprocating inertia forces can be completely balanced. For an engine, where the primary and secondary inertia forces are balanced, the ratio of the residual inertia force to the total inertia force using the traditional method is 1.5%, while the ratio decreases to 0.5% using the closed-form method. The closed-form method is independent of engine configurations, including centric and eccentric engines, and single and multicylinder engines. Examples of applications using the proposed method are provided.

关键词： piston engine balance inertia loading closed-form vibration

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Aeroelastic simulation of the first 1.5-stage aeroengine fan at rotating stall

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Chinese Journal of Aeronautics 2020年第2期33卷 529-549页

作者： Feng LIANG zhifeng xie Aiguo XIA Ming ZHOU School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Beijing Aeronautical Technology Research Center Beijing 100076China

A massive parallel aeroelastic simulation platform has been built to investigate the first1.5-stage fan of an aeroengine at rotating *** Computational Fluid Dynamics(CFD)solver and Computational Structural Dynamics(CSD)solver are coupled directly by non-matching mesh *** unsteady rotor/stator interaction is solved by the Sliding Mesh Interface *** original rotor blades are shrouded by the midspan *** unshrouded fan is also created to investigate the effects of the midspan *** the shrouded fan and unshrouded fan have stable aeroelasticity at the designed *** rotating stall,the stalled region rotates at 30%of the rotor speed on the absolute reference *** energy spectrum of the rotating stalled flow is measured *** shows that the first two order excitations are much stronger than the higher order *** the flow of rotating stall,the fifth backward travelling wave mode of shrouded fan is resonated by the fifth excitation of the rotational stalled flow because the rotational speed of the stalled region coincides with the modal rotational speed,while for the unshrouded fan,the first bending mode is resonated by the second excitation of the rotational stalled flow,forming two waves in the circumference of the annulus *** rotating stall,the vibration of the shrouded blades is still under control but the vibration of the unshrouded blades is diverged and out of control.A novel tool,i.e.,resonance map,is proposed to predict the *** provides a perspective to explain the effects of midspan shrouds at a theoretical level,and it would also be helpful in the structural design of blades.

关键词： Aeroelasticity Computational Fluid Dynamics Midspan shrouds Rotating stall Turbomachine blades

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Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

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Chinese Journal of Aeronautics 2018年第9期31卷 1920-1928页

作者： Ke ZHANG Xudong HUANG zhifeng xie Ming ZHOU School of Aerospace Engineering Tsinghua University

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.

关键词： Aircraft engines AMESim Common rail Fuel injection Mathematical models Pressure effects Structural design

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An isogeometric numerical study of partially and fully implicit schemes for transient adjoint shape sensitivity analysis

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Frontiers of Mechanical Engineering 2020年第2期15卷 279-293页

作者： Zhen-Pei WANG zhifeng xie Leong Hien POH Department of Civil and Environmental Engineering National University of SingaporeSingapore 117576Singapore Institute of High Performance Computing(IHPC) Agency for ScienceTechnology and Research(A*STAR)Singapore 138632Singapore China Academy of Launch Vehicle Technology Beijing Institute of Astronautical Systems EngineeringBeijing 100076China

In structural design optimization involving transient responses,time integration scheme plays a crucial role in sensitivity analysis because it affects the accuracy and stability of transient *** this work,the influence of time integration scheme is studied numerically for the adjoint shape sensitivity analysis of two benchmark transient heat conduction problems within the framework of isogeometric *** is found that(i)the explicit approach(β=0)and semi-implicit approach withβ0.5 are generally preferred for their unconditional stability;and(iii)Crank–Nicolson type approach(β=0.5)may induce a large error for large time-step sizes due to the oscillatory *** numerical results also show that the time-step size does not have to be chosen to satisfy the critical conditions for all of the *** is recommended to useβ≈0.75 for unconditional stability,such that the oscillation condition is much less critical than the Crank–Nicolson scheme,and the accuracy is higher than a fully implicit approach.

关键词： isogeometric shape optimization designdependent boundary condition transient heat conduction implicit time integration adjoint method

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Prospects of sea launches for Chinese cryogenic liquid-fueled medium-lift launch vehicles

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Chinese Journal of Aeronautics 2021年第1期34卷 424-437页

作者： Zhengyu SONG zhifeng xie Limin QIU Dalin XIANG Jinglin LI China Academy of Launch Vehicle Technology Beijing 100076China Beijing Institute of Astronautical Systems Engineering Beijing 100076China College of Energy Engineering Zhejiang UniversityHangzhou 310027China

This paper introduces the sea-launch technology of a cryogenic liquid-fueled medium-lift *** first reviews the current state of sea launch technology,and then gives a brief introduction of China’s New Generation Medium-lift Launch Vehicle(NGMLV).The innovations in the NGMVL,such as responsive test and launch control,a H3 launch model,and unmanned operations,provide convenience for sea *** on these innovations,this paper proposes a sea launch scheme,including the system configuration,test and launch processes,and an improved adaptive design for the ***,the launch platform is discussed in detail,which integrates the functions of sea transportation,assembly and test,as well as technical and launch *** layout and function divisions,fluid filling,gas supply and distribution systems,and lossless storage technology of LH2 are described in *** breakthrough in sea launch technology will enable China to launch medium and large satellites and constellations‘both on land and sea’,especially into low-inclination Low-Earth Orbits(LEOs),and it allows China to remain competitive in the fast-paced space industry.

关键词： Autonomous operations Launch platform Launch vehicles Liquid hydrogen storage Sea launches

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基于改进磁链估算器的航空飞轮电机起动性能

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清华大学学报（自然科学版） 2019年第6期59卷 417-424页

作者：吕凯雄周明谢之峰卜建国清华大学航空发动机研究院北京100084

航空飞轮电机(aero flywheel motor)是将航空活塞发动机(piston aero-engine)的起动机、飞轮和发电机集成为一体的新型电机。鉴于航空发动机的特殊要求,具有响应速度快、控制结构简单、鲁棒性好等优点的直接转矩控制(direct torque cont... 详细信息

航空飞轮电机(aero flywheel motor)是将航空活塞发动机(piston aero-engine)的起动机、飞轮和发电机集成为一体的新型电机。鉴于航空发动机的特殊要求,具有响应速度快、控制结构简单、鲁棒性好等优点的直接转矩控制(direct torque control,DTC)适合作为航空飞轮电机的起动算法。直接转矩控制的一个核心环节是磁链估算器,它主要受磁链初值、直流偏移、电阻变化、逆变器非线性等的影响。为了解决这一问题,该文设计了一种改进的低通滤波式磁链估算器,通过对航空飞轮电机的转子进行定位来确定磁链初值,并把逆变器非线性的影响转换为对电阻实时补偿的问题,并基于改进的磁链估算器进行了航空飞轮电机起动仿真。结果表明:改进的磁链估算器改善了航空飞轮电机起动瞬间的收敛性,并降低了电磁转矩和直轴电流波动。

关键词：航空活塞发动机航空飞轮电机直接转矩控制磁链估算器电阻补偿

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基于木马技术的网络渗透测试研究

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计算机应用与软件 2014年第5期31卷 125-127页

作者：谢志锋王庆生太原理工大学计算机科学与技术学院山西太原030024

目前,国内网络渗透测试的自动化程度不高,效率较低,鉴于此,结合木马的隐蔽性、自启动性、自动恢复性以及易植入性的特点,提出一种利用木马进行网络渗透测试的设计思想。对测试系统的总体框架进行研究和设计,并对实现过程中的关键技术进... 详细信息

目前,国内网络渗透测试的自动化程度不高,效率较低,鉴于此,结合木马的隐蔽性、自启动性、自动恢复性以及易植入性的特点,提出一种利用木马进行网络渗透测试的设计思想。对测试系统的总体框架进行研究和设计,并对实现过程中的关键技术进行探讨与研究。

关键词：木马技术渗透测试系统设计

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闭式整体叶盘五坐标插铣刀位轨迹规划

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航空学报 2010年第1期31卷 210-216页

作者：任军学谢志丰梁永收姚倡锋刘博西北工业大学现代设计与集成制造技术教育部重点实验室陕西西安710072

针对闭式整体叶盘通道开槽工艺问题,研究了叶盘通道五坐标开槽插铣加工方法。进行了闭式叶盘通道可加工性分析,给出了通道加工区域划分方法;基于最小面积原理研究了叶盘插铣通道边界最佳直母线求解算法,分别针对叶片曲面及叶盘内外环面... 详细信息

针对闭式整体叶盘通道开槽工艺问题,研究了叶盘通道五坐标开槽插铣加工方法。进行了闭式叶盘通道可加工性分析,给出了通道加工区域划分方法;基于最小面积原理研究了叶盘插铣通道边界最佳直母线求解算法,分别针对叶片曲面及叶盘内外环面,提出了通道偏置直纹包络面的生成方法,给出了闭式整体叶盘五坐标插铣刀位轨迹。研究结果表明:该方法能解决闭式整体叶盘通道插铣区域划分和直纹包络面生成问题,可有效实现闭式整体叶盘的五坐标开槽粗加工。

关键词：闭式整体叶盘铣削边界线直纹包络面刀位轨迹

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多尺度特征融合的残缺卷烟编码识别

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计算机辅助设计与图形学学报 2021年第5期33卷 780-788页

作者：吴鹏周志鹏黄家栋谢志峰盛斌上海大学上海电影学院上海200072 上海电影特效工程技术研究中心上海200072 上海交通大学计算机科学与工程系上海200240

针对背景紊乱、字符残缺的卷烟图像,提出多尺度特征融合的残缺卷烟编码识别方法,以进行端到端的训练与应用.首先使用特征提取网络从图像中提取多尺度融合特征;然后提出区域优化模块,对提取到的融合特征进一步优化,识别与定位网络学习这... 详细信息

针对背景紊乱、字符残缺的卷烟图像,提出多尺度特征融合的残缺卷烟编码识别方法,以进行端到端的训练与应用.首先使用特征提取网络从图像中提取多尺度融合特征;然后提出区域优化模块,对提取到的融合特征进一步优化,识别与定位网络学习这些优化后的特征能更加鲁棒地完成识别与定位任务;最后使用匹配算法对识别与定位结果进行匹配,得到最终结果.在完整卷烟编码数据集中进行实验,与现有方法相比,所提方法在识别精度与效率上均有全面的提升.在残缺卷烟编码数据的识别转录实验中,所提方法的识别效率与人工相比有较大提升.

关键词：卷烟编码特征融合字符识别字符定位

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交互式前景抠图技术综述

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计算机辅助设计与图形学学报 2014年第4期26卷 511-519页

作者：沈洋林晓谢志峰盛斌马利庄丽水学院工学院丽水323000 上海交通大学计算机科学与工程系上海200240 洛阳师范学院信息技术学院洛阳471022

交互式前景抠图技术是在有限的用户交互下将前景从图像或视频中分离出来.文中综述了近年来主要的图像及视频交互式抠图方法,并就采样和传播、测地距离等不同类型的方法进行性能分析;然后在具体的例子中讨论了这些算法的优点和局限性;最... 详细信息

交互式前景抠图技术是在有限的用户交互下将前景从图像或视频中分离出来.文中综述了近年来主要的图像及视频交互式抠图方法,并就采样和传播、测地距离等不同类型的方法进行性能分析;然后在具体的例子中讨论了这些算法的优点和局限性;最后就抠图技术今后的发展和关键问题进行了总结.

关键词：图像抠图 alpha图视频抠图

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