轴流式压气机特性线外推方法

针对现有轴流式压气机特性线雷诺相似外推方法的不足,提出划分虚拟微元级分段计算压气机特性的方法,将工质压缩过程分解成若干微元压缩段的叠加,使工况变化时微元压缩段进出口相似条件能够得到保证。在雷诺相似的基础上,将每一个微元压缩段外推,得到各微元压缩段特性图,并重构出压气机整机特性图。实例分析表明,新方法可以明显减小现有雷诺外推方法产生的误差,由于虚拟微元级概念的引入,拓宽了压气机特性线获取的途径,提高了获取特性线的可靠性。     

轴流压气机特性计算模型的研究

提出了一套计算多级轴流压气机变工况的损失模型和落后角模型。用射线误差表示法表示了２台不同设计规律、不同翼型的多级轴流压气机的试验特性与计算特性线之间的误差。比较了１台２级轴流压气机的速度场的试验值与计算值，证明本模型具有较高的精度和较大通用性，所采用的射线误差表示法适用于单级及多级压气机的误差表示     

INVESTIGATING MULTISTAGE AXIAL FLOW COMPRESSOR INSTABILITIES

A numerical methodology for investigating compressor instabilities in a multistage environment is presented. The method is based on a stage-by-stage dynamic compression model and considers air compressibility explicitly throughout the compressor. It involves discretizing the compression system into distinct elements and a use of the local elemental characteristic of mean performance. The models are presented in both nonlinear and linearized forms. The linearised form permits well surge condition prediction for multistage axial compressors, while the non-linear form is able to investigate the growth of local flow disturbances, and helps to develop practical control strategy. Validations were carried out using the data from several aircraft engine compressors. A good experiment-model consistency is achieved.     

利用欧拉方程计算进气畸变在压气机内传递特性的方法研究

介绍了一种计算进气畸变的方法。通过求解非稳态情况下的三维欧拉方程,计算压气机各截面气流参数分布,从而了解进气畸变在压气机各截面的传递特性。以Stage35单级压气机为例,比较了计算得到的压气机特性线和试验得到的特性线,验证了模型的有效性。进行了周向总压和总温畸变的计算,得出了畸变在压气机内的传递特性。     

高效率空气滤清器过滤性能测试分析研究

空气滤清器是保护内燃机、燃气动力设备及空气压缩设备正常工作的必要进气处理设备,随着对进气空气洁净度要求的提高,原有的空气滤清器过滤性能测试方法已经不适用于评价高效率空气滤清器的过滤性能.分析了计重法测量空气滤清器过滤效率的局限性,并介绍了采用分粒径计数法测量过滤器效率的相关方法.通过对比分析不同测试方法的测试结果,提出采用计重效率和分粒径计数效率结合的测试方法来对高效率空气滤清器的过滤效率进行评价,以获得对其过滤性能全面而客观的了解.     

Performance simulation of a turboprop engine for basic trainer

A performance simulation program for the turboprop engine (PT6A-62), which is the power plant of the first Korean indigenous basic trainer KT-1, was developed for performance prediction, development of an EHMS (Engine Health Monitoring System) and the flight simulator. Characteristics of components including compressors, turbines, power turbines and the constant speed propeller were required for the steady state and transient performance analysis with on and off design point analysis. In most cases, these were substituted for what scaled from similar engine components’ characteristics with the scaling law. The developed program was evaluated with the performance data provided by the engine manufacturer and with analysis results of GASTURB program, which is well known for the performance simulation of gas turbines. Performance parameters such as mass flow rate, compressor pressure ratio, fuel flow rate, specific fuel consumption and turbine inlet temperature were discussed to evaluate validity of the developed program at various cases. The first case was the sea level static standard condition and other cases were considered with various altitudes, flight velocities and part loads with the range between idle and 105% rotational speed of the gas generator. In the transient analysis, the Continuity of Mass Flow Method was utilized under the condition that mass stored between components is ignored and the flow compatibility is satisfied, and the Modified Euler Method was used for integration of the surplus torque. The transient performance analysis for various fuel schedules was performed. When the fuel step increase was considered, the overshoot of the turbine inlet temperature occurred. However, in case of ramp increase of the fuel longer than step increase of the fuel, the overshoot of the turbine inlet temperature was effectively reduced.     

涡旋压缩机轴向问隙中流体在层流流态下的泄漏研究

对有油润滑涡旋压缩机轴向间隙中流体的层流流态进行了分析，建立了纯油单相层流流动和气、油两相层流流动的流动模型，并对流体在两种层流流态下的泄漏量进行了计算。该计算为进一步研究涡旋压缩机涡旋腔中的泄漏提供了重要的理论根据。     

Dynamic performance analysis of turbine flow sensor based on CFD simulations

The research on the dynamic performance of flowmeters has great significance for the accurate measurement of flow onsite. A simulation method for dynamic characteristics of turbine flow sensor was proposed in this study. This method was used to investigate the dynamic performance of three turbine flow sensors with different diameters. The amplitude-frequency characteristic, phase-frequency characteristic, transfer function, and step response are analyzed based on the results of the simulation. The results indicate that turbine flow sensors can be analyzed as a first-order system. The frequency of pulse flow is the main factor affecting the sensor's performance. The phase difference increases as the frequency increases, and the maximum phase difference reaches 50°. The gain of the small-diameter turbine flow sensor is susceptible, while the phase difference and time constant of the large-diameter turbine flow sensor are susceptible. For step flow, the time constant generated by the negative step is larger than that by the positive step. The analysis results provide bases for evaluating the dynamic performance of turbine flow sensors used online.     

Influences of flow loss and inlet distortions from radial inlets on the performances of centrifugal compressor stages

Journal of Mechanical Science and Technology - Radial inlets are typical upstream components of multistage centrifugal compressors. Unlike axial inlets, radial inlets generate additional flow loss...     

油液特性对柱塞泵流量脉动影响的仿真分析

为研究油液特性对轴向柱塞泵流量脉动的作用规律,对比分析了油液的压缩性、黏性、含气量和流动状态与柱塞泵流量脉动之间的关系,运用FLUENT流场仿真软件对轴向柱塞泵的运动特性进行模拟。数值仿真结果表明：压缩性对泵源流量脉动的影响最大,油液黏性的影响次之,含气量的影响较小,流动状态的影响最小,以上因素的影响程度占油液特性影响的比例分别为86.8%、9.45%、3.59%、0.16%;油液的黏性对泵容积效率的影响最大,压缩性的影响次之,含气量的影响较小,流动状态的影响最小。模型的准确性得到了实验验证,为开展柱塞泵动力学建模以及机电液系统全局耦合性能仿真分析提供了理论依据。     

1.5级涡轮动叶的非轴对称端壁造型数值研究

为探究端壁造型对涡轮动叶气动性能及流场特性的影响,分析非轴对称端壁造型对涡轮转子叶片的压差作用,开展基于非轴对称端壁造型的理论研究,提出一种涡轮动叶轮毂上凸、下凹的造型方案,研究非轴对称端壁造型对涡轮流场二次流损失的影响。数值模拟分析表明：非轴对称端壁造型对减小横向压差具有重要作用,在动叶轮毂鞍点处进行非轴对称端壁造型,比在通道内造型效果更好;涡轮动叶下端壁不同区间造型可有效降低涡轮动叶通道内的二次流流动损失,使用非轴对称端壁造型方法可有效地减小动叶出口总压损失系数0.132 2%。     

基于遗传算法的轴流汽轮机级效率优化

提出一种基于遗传算法的轴流汽轮机级通流部分的优化设计方法。该方法以轴流汽轮机级效率为优化目标,利用遗传算法通过使汽轮机级在满足一系列约束条件下效率最大化来搜索最佳的通流部分几何参数和气流参数。级效率计算和约束条件分析由一个轴流汽轮机级设计工况计算程序得到。遗传算法中每个个体的适应度由级效率和由约束条件得到的罚函数项组成。该方法应用于某型机第一级通流部分的优化设计,优化结果显示,可求得具有最佳效率的通流部分几何形状和气流参数。     

采用流场分析提高涡轮流量传感器性能的研究

以10 mm口径液体涡轮流量传感器为研究对象,经过对传感器内部流场进行分析,提出通过减小靠近叶片顶端的叶片受力面积,提高传感器测量性能的方法。从对特性曲线的分析出发,结合传感器数学模型,提出了一种利用不同流量点的仪表系数平方差Δ(K~2)评价传感器性能的方法。在此基础上,结合CFD仿真和传感器样机实验测试,研究了不同叶轮叶片形状参数对传感器性能的影响。实验结果表明:改变叶轮叶片形状能有效提高传感器的测量性能,切角参数为0.25时,传感器性能最优;此方法同样适用于其他口径涡轮流量传感器结构的优化。     

叶轮机械叶片的计算机辅助设计

本文讨论了基于叶轮机械三元流动通用理论的叶型设计及优化过程,改进了叶型积迭和叶片加工用平面样板曲线的计算方法,发展了绘制叶片和叶轮的各种平面投影、空间轴测投影及消除被遮盖的隐藏线的计算机绘图方法,并已获得实际应用。本文给出了典型的实例。     

对转涡轮低压转子叶片的流固耦合数值分析

采用对转涡轮设计能提高航空涡轮发动机性能,其中无导叶方案是发展趋势之一。在无导叶对转涡轮中,低压转子叶片受到较大的高压转子出口气流激励。基于ANSYS/CFX软件,采用流固耦合数值分析方法对低压涡轮转子叶片进行了分析,得到了高压涡轮转子叶片尾流作用下的低压涡轮转子叶片振动的应力和变形变化规律。叶片温度对振动应力和位移的平均值、幅值和周期的影响较大,叶片材料密度对振动周期产生明显的影响,高低压转叶轴向间距的选择应兼顾涡轮效率等因素。     

Improved model to determine turbine and compressor boundary conditions with the method of characteristics

Method of characteristics is still a powerful tool to incorporate variety of boundaries appearing in the internal combustion engines in the wave action techniques. Striving to the higher accuracy of one-dimensional techniques for modelling of engine manifolds leads to the necessity of considering variable properties and concentration of the gas. Innovative algorithm for the simulation of a turbocharger gas turbine and compressor based on extended equations of the method of characteristics is presented in this paper. This algorithm enables consideration of variable inlet and outlet pressure as well as consideration of variable gas properties and concentration. Improved model assures much better conservation of mass flow rate, when variable gas properties are considered, at only slightly increased computational time.     

Effect of honeycomb seals on loss characteristics in shroud cavities of an axial turbine

The loss in efficiency due to shroud leakage or tip clearance flow accounts for a substantial part of the overall losses in turbomachinery.It is important to identify the leakage loss characteristics in order to optimize turbomachinery.At present,little information is available in the open literature concerning the effect of honeycomb seals on the loss characteristics in shroud cavities of an axial turbine,despite of the widespread use of the honeycomb seals.Therefore,interaction between rotor labyrinth seal leakage flow with and without honeycomb facings and main flow is investigated to provide the loss characteristics of the mixing process of the re-entering leakage flow into the main flow.The effects of honeycomb seals on the flow in shroud cavities and interaction with the main flow are analyzed.An additional study on the impact of subtle shroud cavity exit geometry is also presented.The investigation results indicate that the honeycomb seal affects the over tip leakage flow and reduces mixing losses when compared to the solid labyrinth seal.The leakage flow interactions with the main flow have considerably changed the flow fields in the endwall regions.The proposed research reveals the effects of honeycomb seals on the loss characteristics in shroud cavities and the impact of subtle shroud cavity exit geometry,and it is helpful for the design optimization of turbomachinery.     

地面及飞行通用的燃气轮机最佳循环参数简化解及其应用

本文系统地推导出对地面及飞行燃气轮机通用的、各最佳循环参数的定比热循环参数的定比热简化解,包括前所未见的较繁的耗油率最佳压比的解,与压气机及涡轮定等熵效率或定多变效率的两种变比热准确作比较。从而看出：简化解可初估性能随压比变化的趋势及各最佳压比,可作准确解的起步,也可初估各最佳压比及其性能受部件参数及飞行条件影响的趋势;此外,简化解简捷地探求新循环的作用,也值得注意。     

Theoretical considerations of static and dynamic characteristics of air foil thrust bearing with tilt and slip flow

The thrust pad of the rotor is used to sustain the axial force generated due to the pressure difference between the compressor and turbine sides of turbomachinery such as gas turbines, compressors, and turbochargers. Furthermore, this thrust pad has a role to maintain and determines the attitude of the rotor. In a real system, it also helps reinforce the stiffness and damping of the journal bearing. This study was performed for the purpose of analyzing the characteristics of the air foil thrust bearing. The model for the air foil thrust bearing used in this study is composed of two parts: one is an inclined plane, which plays a role in increasing the load carrying capacity using the physical wedge effect, and the other is a flat plane. This study mainly consists of three parts. First, the static characteristics were obtained over the region of the thin air film using the finite-difference method (FDM) and the bump foil characteristics using the finite-element method (FEM). Second, the analysis of the dynamic characteristics was conducted by perturbation method. For more exact calculation, the rarefaction gas coefficients perturbed about the pressure and film thickness were taken into consideration. At last, the static and dynamic characteristics of the tilting condition of the thrust pad were obtained. Furthermore, the load carrying capacity and torque were calculated for both tilting and nontilting conditions. From this study, several results were presented: (1) the stiffness and damping of the bump foil under the condition of the various bump parameters, (2) the load carrying capacity and bearing torque at the tilting state, (3) the bearing performance for various bearing parameters, and (4) the effects considering the rarefaction gas coefficients.     

三种井下螺旋涡轮水力性能研究

螺旋涡轮主要用于井下涡轮式交流发电机,其水力性能对发电机性能有重要的影响。利用CFD方法对三种不同型式的螺旋涡轮内流场作了三维紊流数值模拟,并在此基础上计算出涡轮的主要外特性曲线,得出了三种涡轮的水力性能。与等螺距涡轮相比,变螺距涡轮和非等宽叶片涡轮改善了内部流体的流动特性,压力损失减小,压降随转速变化更平稳,同时其效率特性也有改善,从而具有更好的水力性能。该研究为井下涡轮式发电机的性能提升和结构改进提供了有力的依据。