为了研究长中短复合叶片对小流量工况下燃油离心泵非定常特性的影响规律,基于CFD技术对某型燃油离心泵进行了非定常数值模拟.首先,分别建立原型方案和带有长中短复合叶片的优化方案的离心泵三维模型和网格模型.其次,基于RNG k-ε湍流模型,对两个方案中泵内流动非定常特性进行数值计算.仿真结果表明:长中短复合叶片减弱了叶轮流道内的大尺度漩涡,降低了叶轮的出口滑移,使得压力分布更加均匀.同时,叶轮与隔舌的动静干涉造成了蜗壳内一定程度的压力脉动产生,且长中短复合叶片的压力脉动幅值相对较低.另一方面,小流量工况下,优化方案中离心泵的增压值为12.9MPa,效率为26.9％,比原型方案中离心泵的增压值和效率分别提高了3.5％和2.6％.

In order to study the complex transient flow characteristics of a high-pressure aero-fuel centrifugal pump within its full working envelope, a certain type of centrifugal pump is numerically simulated, in which the simulation results are compared with the experiment results to verify the effectiveness of the present simulation method. Then, the verified simulation method is selected to analyze the transient flow characteristics, in which the time-frequency characteristic of pressure pulsation at monitored positions is analyzed by using fast fourier transform. In addition, the unsteady flow structures are studied by focusing on the relative speed, turbulent kinetic energy and so on. The results show that the main frequency of pressure pulsation in the impeller and volute is rotation frequency and blade frequency, respectively, where different monitoring points show similar trend. Meanwhile, the flow is relatively stable under design flow rate condition. However, a certain large-scale vortex appears in the impeller channel under small flow rate conditions, which mainly exists at the exit of the impeller channel near the tongue. In addition, turbulent kinetic energy at the exit of the impeller and the tongue has a large distribution range and changes seriously, where a certain hydraulic loss is produced.

燃油离心泵是航空发动机控制系统的关键动力元件,结合当前航空燃油离心泵技术发展和设计需要,本文总结对比了离心泵典型参数化设计及优化设计方法.分析了离心泵四种参数化设计方法的技术特点及其局限,考虑到离心泵参数设计方法中存在的随机性和盲目性问题,进一步补充分析了离心泵的结构优化方法,包括基于启发式算法的全局优化方法、基于梯度的优化设计方法和基于代理模型的优化设计方法三类,并指出了三类优化设计方法亟待解决的科学和技术问题.在此基础上,通过分析国外航空发动机燃油离心泵的发展状况,指出了我国航空发动机燃油离心泵所面临的技术挑战、问题和技术发展方向,并立足于现有国内设计基础,给出了夯实我国航空燃油离心泵设计能力需开展的基础性研究工作.

针对航空燃油离心泵工作时出现的汽蚀问题,采用正交试验法对离心泵叶轮进行优化设计.选取叶轮出口直径D2、叶轮出口宽度b2、叶片数Z、叶片厚度H为正交试验的4个因素,完成了正交试验并对试验结果进行极差分析,得到了以泵汽蚀余量为优化指标的影响排序,并最终获得最优参数组合.通过流场仿真对现用离心泵和优化后离心泵的泵汽蚀余量和蒸汽质量分数进行对比,优化后的航空燃油离心泵泵汽蚀余量小于现用离心泵泵汽蚀余量,且蒸汽质量分数降低了19.98％,说明优化后的离心泵抗汽蚀性能显著提高.

为了研究浮筏参数对船用离心泵性能的影响,选择1台立式船用离心泵为研究对象.基于Kriging模型建立了浮筏正面开腔体的正长l1、侧长l2、正厚t1、侧厚t2、正宽w1/侧宽w2与浮筏重量、泵振动特性之间的近似模型,其中12组数值方案由最优拉丁方方法确定.同时对浮筏质量最小和最大振动烈度最小的2种方案进行了振动特性分析.研究结果表明:l1和t2对浮筏质量影响最大;随着l1增大,浮筏质量先减小后增大;随着t2增大,浮筏质量先增大后减小,接着再增大后减小;t2对浮筏振动烈度的影响不大;随着l1,w1,t1,l2和w2增大,浮筏的振动烈度都是先减小后增大;浮筏最大振动烈度最小和质量最小的2种方案使得振级落差均获得显著提升,振级落差由14.2 dB分别提升到22.6和21.8 dB.

为了理解离心泵内部复杂的流动机理,揭示其内部的流动规律,以一叶轮形式为半开式的小型离心泵为例,采用表面油膜显示法,对其叶片及叶轮后盖板表面的流动情况进行了可视化试验研究.通过调整试剂成分比例,共设计6个试验方案,对比了不同油膜试剂的显示效果,并根据叶轮表面的流线分布对叶轮表面附近的流动情况进行了分析.试验结果证明了油膜显示法捕捉离心泵表面流动特征的可行性,为进一步理解离心泵内部复杂的流动机理提供依据.

为了更加准确和实际地研究泵运行位置、工作水位和潜水泵高度等因素对一体化预制泵站内流状态和筒体强度的影响,基于VOF气液两相流模型对一体化泵站进行流动数值计算,并采用Workbench平台对筒体进行单向流固耦合计算.结果表明:潜水泵对称运行时,入口偏流角较小,有利于提高泵的使用寿命.液位越低时流场越杂乱,流速越高,防沉积效果也最好,但同时也需要兼顾泵站的有效容积.一体化预制泵站的应力从筒底至筒顶逐渐减小,应变则逐渐增大.随着工作水位和安装高度的上升筒体最大应力均下降,随着安装高度的上升筒体最大应变减小.

文中以高速高压离心泵为研究对象,基于ANSYS-Fluent流场仿真软件,采用标准k-ε湍流模型、SIMPLE算法对高速高压条件下运行的离心泵在叶轮有无平衡孔的两种情况分别进行内部流场全流道三维数值模拟,分析叶轮上的平衡孔对离心泵性能及轴向推力的影响,探讨了其减小轴向力的效果.数值模拟的结果表明,若平衡孔的大小合适,平衡孔对泵扬程影响不大,但是对离心泵轴向推力的减小有效.

针对服务于航天低温循环系统的半开式复合叶轮离心泵效能利用率低的问题,研讨了其内流场在3种不同叶顶间隙下的工作情况.应用ANSYSY-Fluent软件对3种不同叶顶间隙的流场进行三维定常全流场数值模拟,得出3种叶顶间隙对离心泵内流特性的影响规律.通过对实物泵的水力特性试验以及试验结果与数值模拟结果对比分析,得出叶顶间隙是半开式离心泵存在能量损耗原因之一,减小叶顶间隙有利于提高效能利用率,并确认了试验数值模拟的可靠性.

A new hybrid algorithm which is based on quantum particle swarm optimization(QPSO)algo-rithm and Broyden quasi-Newton algorithm was proposed to reduce the effect of initial value selection on con-vergence speed and accuracy in solving the variable cycle engine(VCE)model.Firstly,based on the analysis of the VCE geometrical characteristics and the analysis of the steady-state characteristics of the external duct through backpropagation(BP)neural network method, a component model was established which can reflect variable geometry property and mode switching and other states of the VCE.Secondly, based on the model performance calculation,a QPSO based Broyden quasi-Newton hybrid algorithm was used to solve the VCE model cooperating equations, which improved the convergence and calculation efficiency of the hybrid algo-rithm by introducing the divergence coefficient to combine the two single algorithms.The effectiveness, effi-ciency and accuracy of the algorithm were verified by the simulation of high-order nonlinear equations.Final-ly,the steady state and dynamic simulation of VCE component model were carried out.The results of VCE model show that,compared with the results of GasTurb performance calculation,the trends of velocity charac-teristics and altitude characteristics are basically the same with those of GasTurb,the error between VCE mod-el and GasTurb is less than 2%.The hybrid algorithm based on QPSO and Broyden quasi-Newton algorithm can solve the VCE model efficiently and quickly.The established VCE model can be used for performance simulation and analysis.

针对多变量系统存在不确定性导致的控制性能下降问题,提出了一种基于最优控制律的增广模型参考自适应控制器补偿设计方法.通过采用最优LQR控制律实现系统性能的优化设计从而建立基本控制器,以反馈控制结构为框架,对该最优LQR基本控制器实现增广设计,以改善系统的动态跟踪和抗干扰特性,以双转子航空发动机为对象实现控制器的仿真验证.结果表明:通过增广自适应控制实现了原LQR基本控制器对系统不确定性的跟踪补偿,有效地实现了控制指令跟踪,达到了期望响应性能,控制误差小于0.25％,超调量小于0.5％,且调节时间小于1.5s,符合发动机控制系统技术要求;同时,改善了原基本控制系统在不确定性时的不稳定控制效果,保证了系统一致渐近稳定.

In order to solve the problem of multivariable robust adaptive controller design with external dis?turbances which caused by the variable cycle engine's wide range of flight envelope,an adaptive law based on projection was given and applied to the model reference adaptive controller design. First,the traditional design method of adaptive law with problems of order tracking when system existed external disturbances were clarified by the theoretical analysis and simulation analysis of a variable cycle engine's state point. Then adaptive law on the basis of the theoretical framework of projection was designed. And the solutions of the state error 's dynamic equations were limited within the setting range of convex sets, so as to realize the stability requirements that state error's dynamic equations was not greater than zero, finally the projection multi-variable robust adaptive control design based on LQR controller was finished to improve the robustness of adaptive control system. The simulation results of variable cycle engine have shown that:the design method of adaptive law based on projection improves the robustness problem of traditional method, effectively suppresses external disturbances, achieves the expected control effect when joined different external random noise signals. Meanwhile,at the different state points,the steady control errors are less than 0.5%,the overshoot values are less than 1%,the adjust times are less than 1.2s,the errors of dynamic tracking are less than 0.5%,the results conform to the aero engine control system technology's requirements.

针对变循环航空发动机存在建模不确定情况下的多变量控制器设计问题,给出了一种最优律下的增广模型参考自适应跟踪补偿设计方法,阐明变循环发动机建模不确定性并引出LQR(Linear Quadratic Regulator)基准控制器动态跟踪不足的问题,进而在基准控制器反馈控制结构框架下,分别实现以下技术突破:确定期望闭环动态的参考模型、基于李亚普诺夫函数严格稳定证明下建立存在建模不确定性的自适应律等,最终以达到系统跟踪误差渐进为零的目标,改善系统不确定性的动态跟踪问题.对变循环航空发动机的控制器仿真结果表明:增广模型参考自适应控制方法改善了原LQR基准控制器对存在建模不确定性时的控制问题,有效地实现了控制指令跟踪,达到了所期望的动态响应,且自适应参数一致渐进稳定.同时,各标称点的稳态控制误差均小于0.3％,系统超调量小于0.8％,调节时间小于1s,符合航空发动机控制系统技术要求.

通过分析型线参数化系数与结构参数的相关性联系,实现基于型线的参数化改型,从而达到多级导流一体式诱导轮与叶轮性能优化的目的.采用最小二乘法实现叶轮型线拟合,将拟合型线模型的计算流体力学(CFD)仿真结果与原模型的试验结果进行对比,结果表明:仿真结果与原模型试验结果扬程值和效率值误差均小于2％,使用的拟合方法能够实现型线优化.通过分析拟合型线参数化系数与叶轮进出口安装角等的相关性联系,对不同结构参数模型进行型线优化,并对其性能进行仿真对比.结果表明:3组型线模型的内流场整体上正常稳定,其叶轮的各个流道出口和蜗壳隔舌处存在一定范围的低压区,且由于隔舌处漩涡流动的影响使得扩散管出口存在一定区域的高速团.型线3为最优的型线模型,其扬程值与效率值均达到了优化目的,且在设计工况下,其性能提高最为明显.

以某U型节流槽等压差活门为研究对象,开展了内流场性能数值模拟研究.基于三维建模造型技术对所设计的压差活门进行初步建模,然后采用周期性网格网格单元划分等压差活门的结构化网格;进而通过CFD数值模拟进行了内流场仿真分析,并对不同出口节流开度的等压差活门模型进行了对比研究.内流场状态表明:U型节流槽等压差活门不同流量以及不同出口节流开度下在节流口处由于面积突变,压力梯度变化较大,等压差活门的压降主要集中在此处,且均存在一定范围低速团与二次旋涡流等.仿真结果预测的外特性性能表明:等压差活门的压差在不同流量工况下和相同流量的不同出口节流开度下,压差维持在0.9MPa左右,符合设计要求.且不同出口节流开度下压差变化趋势相似,出口节流开度越大,压差越大,小流量下相应更快.

以诱导轮与叶轮组合式航空燃油离心泵为研究对象,开展了轴向力出口间隙补偿优化研究.进行了轴向力的数值模拟,并将仿真结果与理论计算进行对比,对比表明两种方法计算的轴向力结果变化趋势一致,误差不大于4％,且设计流量工况下误差最小,进而验证了基于Pumplinx环境下该型离心泵轴向力数值仿真的正确性.通过改变出口间隙宽度分析离心泵的轴向力变化,仿真结果表明:扩大出口间隙至0.2mm时,增大了轴向力,且影响了泵的增压能力;而减小出口间隙至0.1mm和0.13mm时实现了轴向力的补偿,且出口间隙为0.1mm时性能最优.最后对出口间隙为0.1mm时的轴向力性能进行了分析,分析表明:该条件下不同截面的压力分布正常稳定,且设计点的轴向力为3620N,从而实现了诱导轮与叶轮组合式离心泵的轴向力间隙补偿.

针对航空发动机全包线工作下的多变量变增益控制器设计问题,给出了一种改进的埃德蒙德算法(以下简称KQ算法)并进行了仿真应用.首先,阐明了多变量KQ算法的控制原理与优化算法,进而通过闭环期望函数选择、控制器结构选择以及控制器参数优化进行了KQ控制器设计,并针对所设计的KQ控制器,给出了稳定性证明和系统奇异值分析.分析表明所设计KQ控制器能够使系统闭环稳定,且具有满意的低频指令跟踪、干扰抑制能力、传感器噪声的抑制、高频未建模动态的鲁棒稳定性和低频发动机建模误差不敏感等性能,满足发动机控制要求.其次,通过调度变量选择、设计点KQ控制器设计以及采用插值方法的非设计点KQ控制器设计等过程实现某型涡扇发动机的多变量KQ变增益控制器设计研究,并进行仿真验证.仿真结果表明,设计点条件下,当涡轮后温度和增压比参考输入均为阶跃信号时,其被控参数响应速度很快,且上升时间均小于1s,耦合影响小于6％,设计点KQ控制器满足控制要求;非设计点条件下,利用插值方法建立的KQ变增益控制器具有较好的性能,能够实现该型涡扇发动机全包线控制性能要求.

With the development of the aero engine control technique, aero fuel centrifugal pump with combination inducer and impeller meet the requirements better than the divided pump. This paper established the hybrid network of the centrifugal pump which adopted multi?block topology structure and octree format, analyzed the internal flow field performance of the pump based on numerical simulation. The simulation datas compared with test datas show that under different calculation conditions, head error of the simulation data and experimental data is less than 1%, and the efficiency value of error is less than 5%. The simulation method can accurately calculate the performance of the pump. The simulation analysis shows that the asymmetry of the impeller internal pressure is appreciable under different flow conditions because of the inlet length, under other small flow conditions. The most dramatic change is the pressure in the impeller channel, and the pressure under large flow conditions is lower than that under other flow conditions. In fixed location of the pressure side, there may produce low speed flow group, the situation is the same as in the entrance to the attachment of back pressure side.

为了获得某型组合式叶轮航空燃油离心泵不同叶片包角下的工作特性,对其内流场特性进行数值模拟研究.分别采用定点法和曲线拟合法建立了组合式叶轮的三维模型;利用PumpLinx软件对泵的内流场和出口工作压力特性进行数值仿真计算;在进行样机试验验证数值模拟方法准确性的基础上,基于原包角参数设计基础上增大和减小叶片包角下,进行离心泵的内流场及压力特性研究.仿真结果表明:随着包角增大,叶轮流道内摩擦力的升高导致离心泵增压能力下降;而叶片包角减小,叶轮出口相对速度液流角增大,对泵的增压能力产生积极作用.在叶轮基本外尺寸确定的情况下,必定存在使得泵性能最优的叶片包角,所给出数值模拟方法可用于指导离心泵的工程设计与优化.

为研究一体式诱导轮与叶轮航空燃油离心泵的汽蚀特性,对该型离心泵进行了汽蚀特性研究.首先在泵的设计中进行了汽蚀特性理论计算;进而通过CFD软件Pumplinx对该型号泵进行了汽蚀性能数值模拟,研究了最差汽蚀工况下的汽蚀特性;然后针对不同汽蚀余量值给出离心泵不同状态下的气液两相分布;最后对离心泵的流量-临界汽蚀余量曲线进行预测,并与理论计算值、试验数据进行对比.研究表明,当进口压力为0.013177MPa时,一体式诱导轮与叶轮航空燃油离心泵产生临界汽蚀状态,小于技术要求最小进口压力0.0325MPa,因此该泵在其工作范围内不会产生汽蚀现象.不同流量下离心泵理论计算与数值模拟的汽蚀特性曲线与试验数据吻合,满足高汽蚀特性需求.