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

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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

Reynolds stress constrained large eddy simulation of separation flows in a U-duct

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Propulsion and Power Research 2014年第2期3卷 49-58页

作者： quanyong xu Yantao Yang School of Aerospace Tsinghua UniversityBeijing 100084China Center for Applied Physics and Technology College of EngineeringPeking UniversityBeijing 100871China

This paper presents Reynolds stress constrained large eddy simulation(RSC-LES)method applied to a U-duct *** from traditional Reynolds-averaged Navier-Stokes/detached eddy simulation(RANS/DES)hybrid method(including DES method),the RSC-LES method solves the LES equations in the whole computation domain with the near-wall regions being constrained by a prescribed Reynolds *** doing so it is possible to overcome the log-law mismatch(LLM)problem in hybrid *** RSC-LES results show better agreement with experiment *** with RANS and DES,RSC-LES gives more accurate pressure coefficients and friction coefficients on the wall,because the RSC-LES method captures the separation point and reattachment point on the inner *** computation results show that the RSC-LES method has the potential to solve the log-law mismatch problem of RANS/DES hybrid method and predict complex phenomena of internal flow field.

关键词： Reynolds stress constrain Large eddy simulation U-duct Separation Internal flow Computational fluid dynamics

Simulation of coupling characteristics of motion and heat transfer between airflow and ice crystals in a single-stage compressor

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Propulsion and Power Research 2024年第4期13卷 570-585页

作者： Ping Huang xueqin Bu Guiping Lin quanyong xu Chunhua Xiao School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China Key Laboratory of Icing and Anti/De-icing China Aerodynamics Research and Development CenterMianyang 621000China Hangzhou International Innovation Institute Beihang UniversityHangzhou 311115China Institute for Aero Engine Tsinghua UniversityBeijing 100084China Institute of Low Speed Aerodynamics China Aerodynamic Research and Development CenterMianyang 621000China

This paper investigates the coupling characteristics of motion and heat transfer between airflow and ice crystals in a single-stage *** motion and phase transition process of ice crystal particles were modeled using the Eulerian trajectory method and vali*** heat and mass transfer processes between airflows in compressor and ice crystals were simulated and *** melting ratio,catching efficiency,and sticking efficiency of ice crystals were obtained,as well as variations in temperature and humidity ratio in the airflow due to ice crystal phase *** results show that the ice crystals sticking to blades in the single-stage compressor account for 10.35%of the impact mass flow ***,the presence of ice crystals causes a 0.466 K decrease in the airflow temperature and a 0.114 g/kg(a)increase in the humidity *** theoretical model and calculation method provide strong support for future ice crystal icing simulations and engine operation research.

关键词： Ice crystal icing Compressor performance Two-phase flow Phase change Eulerian method

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航空发动机整机性能仿真中的功率平衡方法

航空动力学报 2022年第12期37卷 2707-2718页

作者：徐全勇吴锋清华大学航空发动机研究院北京100084 中国航发四川燃气涡轮研究院四川绵阳621000 西北工业大学动力与能源学院西安710072

提出了一种在CFD三维整机仿真中实现功率平衡的计算方法。推导确定了决定平衡关系的关键变量:涡轮前温度与物理转速。提出了基于稳态流场和功率经验关系实现功率平衡的数值迭代方法。本文将该迭代方法与CFD三维求解耦合,发展了一种可用... 详细信息

提出了一种在CFD三维整机仿真中实现功率平衡的计算方法。推导确定了决定平衡关系的关键变量:涡轮前温度与物理转速。提出了基于稳态流场和功率经验关系实现功率平衡的数值迭代方法。本文将该迭代方法与CFD三维求解耦合,发展了一种可用于三维整机CFD耦合仿真的功率平衡计算方法。采用该功率平衡计算方法对MTJ-80涡喷发动机开展了三维整机CFD数值计算,实现了整机性能三维仿真与控制规律的耦合和预测。在控制燃油量不变的条件下,通过转速迭代可以实现压气机和涡轮的功率差小于0.1%,可以预测固定燃油供给量条件下所能达到的稳态运转转速。在控制转速不变的条件下,通过调节燃油量实现压气机和涡轮的功率差小于0.15%,可以预测固定转速条件下的燃油流量。数据验证结果表明:该功率平很给计算方法可以与CFD三维整机计算耦合,并且具有很强的收敛性,解决了以往整机三维性能仿真过程中的功率不平衡问题。

关键词：功率平衡性能求解三维整机仿真多场耦合涡轮发动机

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外商直接投资对我国自主创新作用的实证分析——基于区域层面的面板数据分析

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世界经济研究 2007年第6期 14-18页

作者：徐全勇中共浦东新区区委党校经济研究室

本文利用我国区域层面的面板数据,分析了外商直接投资对我国各个省发明专利、实用新型专利和外观设计专利等三种专利的作用,发现外商直接投资不但没有促进各省的发明专利数量的提高,反而有抑制作用,外商直接投资对我国技术创新的作用主... 详细信息

本文利用我国区域层面的面板数据,分析了外商直接投资对我国各个省发明专利、实用新型专利和外观设计专利等三种专利的作用,发现外商直接投资不但没有促进各省的发明专利数量的提高,反而有抑制作用,外商直接投资对我国技术创新的作用主要体现在促进了我国实用新型专利和外观设计专利数量的发展上。在市场换技术的引进外商直接投资过程中,外商凭借技术优势和资本优势,控制了技术和市场,抑制了国内企业的研发行为。要建设创新型国家,提高我国企业的核心技术水平,必须引导我国企业加大研发投入,建立我国企业自主研发体系,提高国内企业的研发能力,同时利用内外资企业之间的竞争效应、模仿效应、产业关联效应和学习效应。

关键词：外商直接投资专利自主创新

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可控扩散叶型的扩稳优化

航空动力学报 2017年第7期32卷 1762-1768页

作者：徐全勇阙晓斌吴锋清华大学航天航空学院北京100084 北京航空航天大学能源与动力工程学院北京100191 中国航空发动机集团有限公司四川燃气涡轮研究院航空发动机高空模拟重点实验室四川江油621703

采用正问题方法,将叶型几何参数化、叶型性能分析程序与遗传算法相结合,对某传统可控扩散叶型(CDA)进行叶型损失和攻角范围的综合性能优化设计。结果表明:优化叶型与原叶型具有相近的设计点损失,而其攻角范围由原来的11°增大至17.5°,... 详细信息

采用正问题方法,将叶型几何参数化、叶型性能分析程序与遗传算法相结合,对某传统可控扩散叶型(CDA)进行叶型损失和攻角范围的综合性能优化设计。结果表明:优化叶型与原叶型具有相近的设计点损失,而其攻角范围由原来的11°增大至17.5°,其中负攻角范围增大了近4.5°。另外,优化叶型的损失随攻角变化也更为平缓,意味着可以在更为宽广的攻角范围内保持稳定的性能。分析表明:吸力面速度峰值位置由原叶型40%弦长处前移至20%弦长处,增加了减速区的长度,使减速更为平缓,是正攻角裕度增大的主要原因。负攻角裕度增加有两方面原因,优化叶型喉道面积增大且喉道位置与设计点吸力峰值位置错开,具有较大的堵塞裕度;压力面前部区域速度较为平缓,甚至略微加速,直至30%弦长后才开始减速扩压,避免了因压力面前缘处的较大速度尖峰以及随后的持续扩压导致附面层的过早分离。

关键词：可控扩散叶型设计附面层转捩优化压气机

可变面积的非对称姿态模拟射流喷管设计与仿真

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机械工程学报 2018年第2期54卷 184-190页

作者：陈鹏飞吴锋徐全勇彭晋徐倩楠中国航发四川燃气涡轮研究院航空发动机高空模拟技术重点实验室绵阳621703 清华大学航天航空学院北京100084

可变面积和可变姿态的自由射流喷管因其能够实现试车台能力的最大化、降低成本和快速调节等优点,将成为地面风洞试验研究的新趋势。为解决在大迎角范围内满足不同推进系统地面试验所需的气流能力和试验舱物理空间之间的矛盾,同时使其具... 详细信息

可变面积和可变姿态的自由射流喷管因其能够实现试车台能力的最大化、降低成本和快速调节等优点,将成为地面风洞试验研究的新趋势。为解决在大迎角范围内满足不同推进系统地面试验所需的气流能力和试验舱物理空间之间的矛盾,同时使其具备真实高度、马赫数和姿态的模拟能力,提出了一种基于非对称机械臂的姿态模拟射流喷管方案。根据试验舱结构与现代战机飞行包线,确定自由射流喷管的设计指标与初步流场布置;建立2-RRR机械臂机构数学模型,运用Deanvit-Hartenberg(D-H)法开展了机构计算与求解研究;通过仿真分析了射流喷管的初步功能实现情况,并验证了该设计方案的可行性,为射流喷管的研究与发展奠定了基础。

关键词：风洞自由射流喷管可变面积姿态模拟非对称机械臂

High-pressure synthesis and properties of CeO_2-ZrO_2 solid solution

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Chinese Science Bulletin 2001年第10期46卷 801-806页

作者： xu Dapeng, WANG quanyong, LU Zhe, LIU Zhiguo, ZHANG Gongmu & SU Wenhui1. Department of Physics, Jilin University, Changchun 130023 China 2. International Center for Materials Physics, Chinese Academy of Sciences, Shenyang 110015, China 3. Center for Condensed Matter and Radiation Physics, China Center of Advanced Science and Technology (World Laboratory), Beijing 100080, China Department of Physics Jilin University Changchun China International Center for Materials Physics Chinese Academy of Sciences Shenyang China Center for Condensed Matter and Radiation Physics China Center of Advanced Science and Technology (World Laboratory) Beijing China

Using nanoparticles of CeO2 and ZrO2 prepared by the chemical precipitation method as starting materials, the single-phase cubic Ce0.5Zr0.5O2 solid solution (c-Ce0.5Z0.5O2) has been synthesized under 3.1 GPa at 1073 K for the first time. The structure of the c-Ce0.5Zr0.5O2 has not been changed before and after annealing at 773 K for 1 h. Only an unknown EPR signal (g =1.990) has been observed in the c-Ce0.5Zr0.5O2 and not varied after annealing at 773 K for 1 h, which exhibited that there exists no Ce3+ in the c-Ce0.5Zr0.5O2 and the Ce4+ has not been reduced into Ce3+ after annealing. The transport mechanism is ionic for the c-Ce0.5Zr0.5O2. The bulk conductivity (a =1.2×10-5 S/cm at 823 K, σ=2.1 ×10-3 S/cm at 1123 K) is the same as that of CeO2, but smaller than that of Y2O3-stabilized ZrO2. A marked curvature at T = 823 K has been observed in the Arrhenius plot of the bulk conductivity. The activation energy below 823 K is lower than that above 823 K, and the reason has been discussed.

关键词： CeO2-ZrO2 nanocrystalline high-pressure and -temperature solid-state reaction solid solution.

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肼基单组元火箭发动机的动态响应

航空学报 2023年第21期44卷 341-353页

作者：蒋耀东徐全勇马玉林程瑶辽宁工程技术大学力学与工程学院阜新123000 清华大学航空发动机研究院北京100084 辽宁工程技术大学创新实践学院阜新123000

单组元火箭发动机是航天器姿态调整和轨道控制的重要元件。针对肼基单组元火箭发动机对入口流量变化形式的动态响应,建立发动机推力室内推进剂的流动、分解和传热仿真模型,并利用这些模型对发动机进行了3种不同推进剂供给方式(稳态式供... 详细信息

单组元火箭发动机是航天器姿态调整和轨道控制的重要元件。针对肼基单组元火箭发动机对入口流量变化形式的动态响应,建立发动机推力室内推进剂的流动、分解和传热仿真模型,并利用这些模型对发动机进行了3种不同推进剂供给方式(稳态式供给、线性式供给和脉冲式供给)的数值模拟与计算分析。计算结果表明:发动机各点的温度会因位置差异而对入口流量的响应变化存在不同。压强、速度和推力对入口流量变化的响应非常迅速,三者在总体上的变化趋势与入口流量的变化趋势保持同步。速度和推力在稳态式供给和脉冲式供给中都存在高于起动阶段稳定值的尖峰,在稳态式供给中,速度和推力尖峰分别高出起动阶段稳定值的8.6%和4.7%,在脉冲式供给中,第1次脉冲阶段,速度和推力尖峰分别高出起动阶段稳定值的6.2%和3.0%,第2次脉冲阶段,速度和推力尖峰分别高出起动阶段稳定值的9.3%和5.2%。

关键词：肼动态响应推进剂供给推力单组元火箭发动机