Optimization of dynamic performance for a ground catapult with reusable supply of the working fluid

A task of minimizing the guide length of a ground catapult was set in order to ensure the mobility for unmanned aircraft systems. A scheme with reusable supply of the working fluid into the pneumatic drive cylinder was proposed. A method of parametric optimization of dynamic performance for a catapult was formulated. The method and models were verified with respect to the basic integral indicators.     

某型无人机系统涡轮阻尼器的性能仿真

涡轮阻尼器作为制动装置应用于某型无人机气液压发射系统和拦阻网回收系统.建立了阻尼器的阻尼力矩数学模型,并进行仿真计算和数值分析.结果表明:转子半径、流体介质密度对阻尼力矩的影响起主导作用;定子半径、转子叶片与定子叶片轴向间隙、流体介质动力黏度对阻尼力矩的影响相对较小.采用具有不同结构尺寸和不同流体介质的阻尼器进行阻尼力矩的测量试验,研究结果表明仿真结果与试验结果表现出较好的一致性,证明了阻尼力矩数学模型的正确性,为涡轮阻尼器的工程研制提供可靠的理论依据.      

纯电动城市客车EMB执行机构驱动电机制动性能分析

传统气压制动系统存在压缩机、制动油箱和空气管路,占据较大空间,而采用电子机械制动(EMB)系统代替,不但可以减小空间,还能实现对夹紧力的快速响应和精确控制。以纯电动城市客车为目标车型,讨论了EMB执行机构方案,根据传统气压盘式制动器最大夹紧力推导出电机的堵转转矩和空载转速。据此设计了永磁无刷直流驱动电机,堵转转矩为10 N·m,空载转速为370 r/min。在Maxwell 2D中搭建驱动电机有限元模型,分析电机在消除间隙阶段和夹紧力增加阶段的制动性能。结果表明所设计的驱动电机制动性能可满足要求。     

外部扰动影响下风扇和压气机稳定裕度的计算方法

为了定量评定燃气涡轮发动机的风扇和压气机的气动稳定性，分析了影响风扇和压气机稳定性的外部扰动参数，介绍了工程计算气动扰动和燃扰动对风扇和压气机的影响所采用的标准型扰动，给出了在外部气动扰动和热扰动作用下的风扇和压气机的稳定裕度变化的一种计算方法，可供工程研制中参考。     

一种涡轮机匣挂钩槽疲劳寿命研究的试验方案

提出了一种针对涡轮机匣挂钩槽疲劳寿命的试验方案.该方案首先对涡轮机匣进行数值分析,得到危险部位的应力分布,再通过常温下机械加载来模拟危险部位总应力场,并在该载荷下获取涡轮机匣挂钩槽疲劳寿命.利用该方案,对新制作的涡轮机匣结构改进措施、原有涡轮机匣维修措施以及腐蚀影响进行了试验研究.结果表明:①新制作的涡轮机匣挂钩槽增加倒圆半径为0.8mm的圆角后,安全寿命在50%,95%置信度下可分别增加69%和198%;②原有涡轮机匣挂钩槽铣倒圆半径为1.5mm的内圆角后可以获得与新制作的涡轮机匣挂钩槽相近的疲劳寿命;③腐蚀会严重影响涡轮机匣挂钩槽的疲劳寿命.      

液氧煤油补燃发动机起动过程氧预压泵加速起旋方案研究

为降低液氧煤油补燃发动机起动所需入口压力,需解决起动过程氧预压泵起旋迟缓产生附加阻力导致主泵入口压力过低而发生断裂汽蚀的问题。开展了两种预压泵加速起旋方案研究,分别为已工程应用的液氧涡轮方案和本文提出的氦起动涡轮方案。对比介绍了两种方案对发动机气液系统和预压泵结构的影响。建立了预压泵加速起旋相关的数学模型,针对加速起旋机理、效果和影响因素等进行了仿真分析。结果表明:液氧涡轮方案,预压泵结构变化较小,为提升加速起旋效果,涡轮供应路应尽量增大通径、缩短长度,降低动态流阻和静态流阻,涡轮喷嘴流通面积则需根据其对涡轮流量和压降的综合影响来选择。氦起动涡轮方案,预压泵结构和流路变化较大,起动涡轮速比和效率是降低氦气用量的限制性因素。     

The wells air turbine for wave energy conversion

The wave energy devices currently in operation in the United Kingdom and India and those that are to be built in Europe are based on the principle of the oscillating water-air column. In these devices the pneumatic energy of the oscillating air column is converted to mechanical energy of rotation by a Wells turbine. A monoplane (single plane) Wells turbine can absorb only a certain maximum pneumatic pressure amplitude due to tip speed limitations. For wave energy devices which produce large amplitudes of pneumatic pressure a biplane Wells turbine with or without guide vanes can be used. The prediction methods currently available and parameters controlling the aerodynamic performance of the Wells turbines are reviewed. Some novel techniques to improve the performance of Wells turbine are suggested.     

影响液体火箭发动机涡轮效率的某些因素分析

分析了液体火箭发动机中所用涡轮的各种损失因素,并建立了相应的数学模型,给出了计算方法。对于喷嘴中的二相流损失,采用龙格-库塔法求解一维定常全耦合的二相流控制方程。用迭代的方法进行冲击式涡轮及有小反力度的涡轮的设计计算,以使设计出的涡轮参数与效率相统一。通过对计算路径的控制,使得本方法和程序能同时用于冲击式涡轮及有小反力度的涡轮的设计计算;在计算结果中,还着重对二相流损失对涡轮效率的影响进行了分析。     

前置涡轮组合脉冲爆震发动机性能分析

为解决纯脉冲爆震发动机地面启动问题,并提升其低马赫数下的性能优势,提出了一种利用外涵中爆震室头部压力驱动内涵中涡轮转动部件的前置涡轮组合脉冲爆震发动机,建立了相应的性能分析方法,并对其部件特性及整机性能进行了计算研究。结果表明,近似稳态的涡轮总温总压进口条件可以在该组合发动机中实现,同时随着爆震室头部侧向开孔面积与爆震室面积之比(即驱动面积比)增大,流入发动机内涵驱动涡轮的气体流量增大,而涡轮前总温、总压及涡轮落压比减小,组合发动机整机推进性能增大;通过改变驱动面积比的大小,可以获得不同的压气机增压比以适于不同的飞行马赫数,进而实现发动机宽广的工作范围。     

一种直升机自旋训练过程涡轴发动机控制规律设计与仿真

针对直升机自旋训练过程中涡轴发动机快速响应要求,提出了一种以燃油流量和导叶角为控制量的鲁棒控制规律抑制自由涡轮转速瞬态下垂.首先,通过改进UH-60直升机/T700发动机综合模型,使之能够模拟自旋进入及自旋恢复过程动态变化.其次,提出并设计一种基于燃油流量和导叶调节的涡轴发动机鲁棒控制规律,并通过典型的自旋训练过程仿真,验证了该控制规律相比仅以燃油流量为变量的控制规律,自由涡轮转速瞬态下垂量降低至3%以下,且燃油流量变化更加平缓,改善了执行机构的工作条件.     

Wind Power System Using an Adaptive Sherbius Induction Machine

A wind turbine driven variable speed power generation system using a static Sherbius scheme in the generation mode is described. A control methodology to adapt the power output characteristics of double output induction generator to the output characteristics of the driving turbine is proposed. The control scheme has been implemented and experimental test results show that the induction machine can be made to adapt to the desired characteristics.     

Kinematic deformation scheme for multilayer thin structures with significantly dissimilar layers

An improved kinematic scheme of elastic deformation for multilayer thin structures with significantly dissimilar layers is proposed as well as a problem solution algorithm; the algorithm is based on a priori calculation of kinematic relations that represent a nature of variation of elastic displacements over the layer packet thickness and do not result in a considerable increase of the problem dimension.     

两相脉冲爆震涡轮发动机原理性试验

为验证脉冲爆震涡轮发动机（PDTE）的可行性,建立了PDTE原理性试验系统,主要由脉冲爆震燃烧室、离心压气机和向心涡轮等组成.以汽油为燃料,空气为氧化剂,开展了PDTE原理性试验研究.试验结果表明:爆震燃烧室、压气机与涡轮三者能够协调工作,发动机能够在自吸气模式下长时间稳定连续工作,发动机工作频率最高达18Hz.研究中所采用的气动阀对爆震反传压力波具有很好的衰减作用,低频下衰减效果更为明显,发动机工作在6Hz时压力波峰值可衰减93.8%,在18Hz时衰减幅度降为78.4%.反传压力的降低有利于爆震燃烧室与压气机之间的匹配工作,同时可缩短反传距离,有助于提高发动机工作频率.      

A power and thermal management system for long endurance hypersonic vehicle

Due to the pneumatic heating and combustion effect, the scramjet engine of hypersonic vehicle faces high temperature challenge. It is necessary to comprehensively consider its thermal management and power generation together. A new Power and Thermal Management System (PTMS) combined with Supercritical Carbon Dioxide (SCO₂) closed Brayton cycle and fuel vapor turbine is proposed and discussed in this paper. The new PTMS can meet the cooling requirement of hypersonic vehicle at Mach number 6–7, and avoid the coking and scrapping in the scramjet cooling channels. Compared with the PTMS only based on fuel vapor turbine, the new PTMS utilizes the waste heat of scramjet to generate more electricity. In addition, it can reduce the use of fuel sink for cooling, and the additional weight penalty can be compensated for long endurance hypersonic flight.     

教与学优化算法在风力机变桨自抗扰控制中的应用

随着风力机的发展越来越智能化,除了要求风力机的运行可靠性,还要求其有稳定的输出功率。为了使风力机变桨控制器在运行过程中具有优良的动态品质,提出了一种自抗扰控制(ADRC)的变桨距控制方案,但ADRC也存在参数多、整定难度大这一明显缺点。为此,将教与学算法应用到ADRC的整定过程中,实现了参数的自动整定。仿真结果验证了通过教与学算法自动整定ADRC参数的可行性,与传统PID控制器相比,整定后的ADRC能较好地满足风力机变桨距控制要求,有效维持了风力机输出功率的稳定性。     

透平内部非稳态流动试验研究进展

为探究透平内部流场的非稳态特性及其演变特征,通过归纳国内外透平内部流动的试验研究,回顾了轴流透平、向心透平采用的试验方法及取得的研究进展,分析总结了试验方案与研究中存在的问题。目前,轴流式透平与平面叶栅的试验数量较多,试验的压力温度较低;向心式透平试验研究还比较少,并且试验多处于高温高压环境;随着接触式测量设备性能的大幅提升,其目前在透平非稳态试验中得到广泛应用,例如气动探针已经能够满足1×106Hz的高频采集要求;上游尾迹以及叶顶泄漏涡扰动下轴流式透平叶表附面层的转捩机制,以及向心式透平盘腔泄漏流与主流流场的非定常掺混等问题还有待进一步研究。     

A New Hybrid Control Scheme for an Integrated Helicopter and Engine System

A new hybrid control scheme is presented with a robust multiple model fusion control(RMMFC) law for a UH-60 helicopter and an active disturbance rejection control(ADRC) controller for its engines.This scheme is a control design method with every subsystem designed separately but fully considering the couplings between them.With three subspaces with respect to forward flight velocity,a RMMFC is proposed to devise a four-loop reference signal tracing control for the helicopter,which escapes the closed-loop system from unstable state due to the extreme complexity of this integrated nonlinear system.The engines are controlled by the proposed ADRC decoupling controller,which fully takes advantage of a good compensation ability for unmodeled dynamics and extra disturbances,so as to compensate torque disturbance in power turbine speed loop.By simulating a forward acceleration flight task,the RMMFC for the helicopter is validated.It is apparent that the integrated helicopter and engine system(IHES) has much better dynamic performance under the new control scheme.Especially in the switching process,the large transient is significantly weakened,and smooth transition among candidate controllers is achieved.Over the entire simulation task,the droop of power turbine speed with the proposed ADRC controller is significantly slighter than with the conventional PID controller,and the response time of the former is much faster than the latter.By simulating a rapid climb and descent flight task,the results also show the feasibility for the application of the proposed multiple model fusion control.Although there is aggressive power demand in this maneuver,the droop of power turbine speed with an ADRC controller is smaller than using a PID controller.The control performance for helicopter and engine is enhanced by adopting this hybrid control scheme,and simulation results in other envelope state give proofs of robustness for this new scheme.     

Output Power Controller for a Wind-Driven Induction Generator

A constant stator power output controller for a wind-driven grid-connected induction generator is described. The load torque of the generator is controlled by varying the rotor resistance electronically. A dynamic model for the wind energy conversion system is proposed for both controlled and uncontrolled operation.The model is then used to predict the changes in shaft speed,turbine torque, and stator power output in response to change in wind speed. Data pertaining to a 60 kW commercial wind turbine generator is used in this investigation. Results based on analog computer simulation demonstrate the feasibility of the controller for scheduling a desired power output from the induction generator.Results of the tests on a laboratory induction generator driven by amicrocomputer-controlled dc motor drive simulating the characteristics of the wind turbine are included.     

永磁直驱风电系统中最大功率点跟踪控制优化的仿真研究

分析了风力机特性、永磁直驱电机模型、变换器控制策略及各种功率跟踪控制算法优缺点,并提出一种基于爬山搜索法的最大功率点跟踪(MPPT)控制方法的优化。在MATLAB/Simulink环境下搭建了永磁直驱风力发电系统模型,仿真分析了控制方法对最大功率点的跟踪效果,结果表明当风机起动及风速变化时MPPT控制方法能够使系统快速稳定在新的工作点,捕获得最大功率。由此验证了改进优化后的控制方法及所搭建模型的准确性与有效性。     

Variable Speed Wind Energy Conversion Using Synchronous Machine

A power generation scheme using a synchronous generator with an excitation control system driven by a variable-speed wind turbine is described. The proposed scheme has been analyzed over a wide speed range and under wind gusting conditions. Performance characteristics show that it is feasible to use variable-speed fixed-pitch wind turbines to generate electric power.