高空低Re数下低压涡轮气动特性

低压涡轮是航空发动机的重要部件,其效率变化对发动机推(功)重比、耗油率有显著的影响,因此,为提高航空发动机性能的研发,有必要对低压涡轮内部流动及换热特性进行全面细致地研究.采用气热耦合计算流体动力学(Computational fluid dynamics,CFD)计算方法,对某航空发动机低压涡轮高空低雷诺数下的流动特性进行深入研究,分析雷诺数对低压涡轮效率、流动特性的影响.结果表明随着雷诺数(Re＜2× 105)的增加,附面层分离损失不断降低使得低压涡轮效率单调增加.     

某型发动机压气机包容性研究

通过对某型涡轮风扇发动机压气机的结构设计、强度设计,结合航空涡轮发动机压气机的技术发展和使用要求,根据设计规范对发动机包容性的规定,进行该型发动机压气机包容性研究。为该型发动机包容性设计提供依据,积累设计数据、丰富设计数据库,完善该涡轮风扇发动机设计体系。     

涡扇发动机的工作原理及应用综述

涡扇发动机全称为"涡轮风扇发动机",广泛应用于民机、战斗机等领域。涡扇发动机有不同的类型,其基本部件有进气道、风扇、压气机、燃烧室、涡轮和尾喷管。每个部件都承担着各自的功能,最终服务于发动机的整体工作。国内外涡扇发动机都有长足的发展,各式涡扇发动机在不同领域发挥着重要作用。本文将从涡扇发动机的发展和分类、部件的结构和作用、整体的工作原理和性能参数以及涡扇发动机的典型代表等四个方面对涡扇发动机开展学习和研究。     

航空发动机数据共享关键技术研究

航空发动机数据共享涉及政策保障、数据基础、平台支撑等多方面,是系统工程。本文通过对航空发动机两个部件级(压气机、涡轮)数据、一个特性级(强度寿命)数据、一个过程级(发动机维修)数据的分析,制定了航空发动机基础数据格式,在此基础上提出了航空发动机数据共享平台架构框架,识别出航空发动机数据共享利益主体及利益诉求。     

航空发动机部件激光冲击强化研究进展与展望

航空发动机部件服役环境恶劣、工作载荷复杂,容易发生高周疲劳断裂,严重影响发动机安全可靠性.激光冲击强化是一种新兴的表面塑性强化技术,可通过残余压应力预制和微观组织改善显著提升金属材料高周疲劳性能,已在航空发动机部件生产和修理中实现了批量化应用.将深入讨论风扇/压气机叶片、涡轮叶片、涡轮盘、机匣、作动筒、导管、齿轮等部件激光冲击强化研究进展和应用情况及有待解决的问题,分析总结近年来航空发动机部件激光冲击强化研究历程及特点,并就未来设备、机理、工艺和应用等方面研究进行展望,希望通过全行业、全技术链的力量创新协同,推动激光冲击强化技术在我国航空发动机部件上的规模化工业应用.     

柴油机涡轮增压器的使用保养

涡轮增压器是利用发动机排出的废气驱动涡轮,同轴带动压气机旋转作功,向发动机输送压缩空气。它由涡轮壳、中间壳、压气机壳、转子体、浮动轴承及密封(环)件等主要零件组成,浮动轴承和密封是影响涡轮增压器寿命的关键。由于增压器轴承工作在高温、高速和轻载的条件下,必须有规定的润滑油压力和足够的润滑油流量。涡轮增压器轴承的润滑油密封以及压气机端的压缩空气和涡轮端燃气的密封,都是使用者必须给予重视的。     

航空发动机总体方案论证耦合模型研究

方案论证是航空发动机设计流程中的重要环节,本文提出了一种航空发动机总体方案论证耦合模型。该耦合模型可以对发动机压比、压气机流路、压气机效率、涡轮效率、涡轮前温度和涡轮冷气量进行快速评估,并给出调整建议。加速发动机方案论证的进程,缩短航空发动机设计周期。     

金属高温疲劳研究与发展

一、高温疲劳问题的重要性疲劳是使机械失效的一般机理。高温疲劳则是使热机械失效的特殊机理。这种失效在燃气涡轮发动机中尤为严重。一般地说,空中使用比地面使用严重,军用比民用严重。发动机的一些主要另件-压气机盘和叶片、燃烧室、涡轮导向叶片、工作叶片和涡轮盘、轴承等的寿命很大程度上受高温疲劳限制,其中涡轮部件又是整个发动机寿命的最危险部分。原因是     

中国航发研制的AES100首台发动机实现转速达标

正近日,中国航发自主创新研制的AES100民用涡轴发动机按程序磨合运转并顺利达到100%设计转速,发动机运行平稳,工作参数正常,实现转速达标。转速达标是新机整机试验的关键环节。AES100民用涡轴发动机转速达标,有效验证了发动机在全转速范围的压气机、燃烧室、燃气涡轮、动力涡轮、附件传动等部件和燃油控制、滑油、空气、电气等系统之间的匹     

ATR发动机建模及特性分析

空气涡轮冲压发动机(ATR)是一种组合推进系统,来流空气经进气道激波之后,又经压气机再次压缩。由于转子系统的引入,ATR发动机的燃烧室—进气道相互作用及工作模态转换方式比冲压发动机更加复杂。为分析压缩系统的工作特性,以预冷式ATREX发动机为研究对象,利用尾喷管阻塞机制、涡轮—压气机匹配、燃烧室Rayleigh方程等建立非设计点稳态数学模型。计算给定飞行条件下,发动机压缩系统工作状态随燃料流量的变化过程,分析双压缩机制的耦合作用,得到ATR发动机工作特性的一般结论。     

高原环境增压器离心压气机特性试验研究

针对所研制的高压比涡轮增压器压气机,基于构建的进气高原模拟试验台架,开展高原环境下车用增压器压气机特性试验分析与研究,以探讨高压比压气机高原特性的变化规律,并获得相应的验模试验数据。结果表明:在高原环境下,随着海拔的升高,压气机质量流量减小,同转速下最高压比基本保持不变,效率、雷诺数有所降低。海拔自1 000 m升高至4 500m,质量流量减小26%~44%,效率降低1%~3.5%,压气机进口气体雷诺数降低约30%,近50%以上工况不满足雷诺数处于自模区假设。同时,压气机稳定工作流量范围拓宽,最高可拓宽11%,发生在高压比高转速工况。随海拔的升高,压气机体积流量减小,体积流量特性变化幅度较小,约3%(小于折合质量流量变化特性);因此,忽略系统效应的喘振线差异,可以采用体积流量特性进行变海拔高原环境离心压气机特性及内部流动对比研究。在高原环境下,以折合参数绘制的通用特性与零海拔特性差别较大,尤其是4 500 m海拔,不具备较好的可比性和参照性;而以相似参数绘制的通用特性同时也存在差异,但与折合流量特性、实际流量特性相比,随海拔变化最小,可用于不同海拔特性对比研究。由于雷诺数变化的影响,离心压气机特性随海拔高度存在差异,以马赫数相似为基础的特性曲线绘制方法存在偏差,不再有效;此时,对压气机在高原特性的研究,需要采用实际流量和实际转速;但在不同海拔特性曲线对比研究方面,采用相似参数为基础绘制的特性曲线具有较好的直观可比性。     

Dynamic test and fatigue life evaluation of compressor blades

High-cycle fatigue (HCF) has been identified as one of the primary causes of gas turbine engine failure. To verify the reliability of the high cycle fatigue fracture of the 5 MW gas turbine engine blade being developed by Doosan Heavy Industries & Construction Co., Ltd., dynamic tests were conducted using real size compressor rigs according to previous studies. The dynamic safety margin of the 5MW gas turbine engine blade was calculated on the basis of the ratio between the dynamic stress and endurance limit stress respectively determined through the compressor rig and fatigue tests. The HCF characteristics and the fatigue life stability of the DGT-5 compressor blades were verified through these processes. A fatigue life design procedure for the gas turbine compressor blade was established on the basis of the design, analysis, and test processes implemented in a previous study. In sum, the 5 MW class gas turbine compressor blades were found to be well designed in terms of resonance stability and fatigue life.     

钛合金高周疲劳特性的影响因素分析

高周疲劳（HCF）亦称高循环疲劳，它是航空燃气涡轮发动机的主要失效方式之一。高周疲劳失效几乎涉及航空发动机每一个钛合金零件，如压气机叶片、压气机内环和机匣等，会导致发动机重要部件的过早失效，甚至整个发动机和飞机的损失。但仅研究高周疲劳并不能解决实质问题，必须研究各种损伤对钛合金材料高周疲劳特性的影响。损伤通常包含低周疲劳、外物损伤、在缺口或应力集中处形成裂纹和接触疲劳等，这些损伤都可能降低高周疲劳性能。本文主要介绍和总结了国内外有关低周疲劳和外物损伤对钛合金高周疲劳特性影响的研究现状。     

Method for evaluating the reliability of compressor impeller of turbocharger for vehicle application in plateau area

As turbocharging diesel engines for vehicle application are applied in plateau area, the environmental adaptability of engines has drawn more attention. For the environmental adaptability problem of turbocharging diesel engines for vehicle application, the present studies almost focus on the optimization of performance match between turbocharger and engine, and the reliability problem of turbocharger is almost ignored. The reliability problem of compressor impeller of turbocharger for vehicle application when diesel engines operate in plateau area is studied. Firstly, the rule that the rotational speed of turbocharger changes with the altitude height is presented, and the potential failure modes of compressor impeller are analyzed. Then, the failure behavior models of compressor impeller are built, and the reliability models of compressor impeller operating in plateau area are developed. Finally, the rule that the reliability of compressor impeller changes with the altitude height is studied, the measurements for improving the reliability of the compressor impellers of turbocharger operating in plateau area are given. The results indicate that when the operating speed of diesel engine is certain, the rotational speed of turbocharger increases with the increase of altitude height, and the failure risk of compressor impeller with the failure modes of hub fatigue and blade resonance increases. The reliability of compressor impeller decreases with the increase of altitude height, and it also decreases as the increase of number of the mission profile cycle of engine. The method proposed can not only be used to evaluating the reliability of compressor impeller when diesel engines operate in plateau area but also be applied to direct the structural optimization of compressor impeller.     

Performance test and component characteristics evaluation of a micro gas turbine

This study aims to analyze engine performance and component characteristics of a micro gas turbine based on detailed measurement of various parameters. A test facility to measure performance of a micro gas turbine was set up and performance parameters such as turbine exit temperature, exhaust gas temperature, engine inlet temperature, compressor discharge pressure and temperature, and fuel and air flow rates were measured. The net gas turbine performance (power and efficiency based on the gas turbine shaft end) was isolated and analyzed. With the aid of measurement based simulation, component characteristic parameters such as turbine inlet temperature, compressor efficiency, turbine efficiency and recuperator effectiveness were estimated. Behaviors of the estimated characteristic parameters with operating condition change were examined and sensitivities of estimated parameters to the measured parameters were analyzed.     

Ferrographic and spectrometer oil analysis from a failed gas turbine engine

An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor parts that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph and with plasma, atomic absorption and emission spectrometers to see whether this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a contributory factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2–0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations (more than 2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. Attempts to pinpoint the failure initiation site were inconclusive, but the oil analyses did eliminate a lubrication system bearing or shaft seal failure as the cause of the engine failure.     

An investigation on the performance of a Brayton cycle waste heat recovery system for turbocharged diesel engines

A Brayton cycle waste heat recovery (WHR) system for turbocharged diesel engines was proposed and the performance of a diesel engine integrated with the proposed system was investigated. The waste heat recovery system is integrated with the turbocharging system of diesel engines, using the turbocharger compressor as the Brayton cycle compressor. The engine cycle simulation code GT-Suite 7.0 was used to investigate the performance of a diesel engine integrated with the WHR system. A Brayton cycle turbine was designed and its performance was simulated with a through-flow model. The turbocharging system of the original engine was modified and the energy flow distribution between the diesel cycle and the Brayton cycle was optimized. Results show that the fuel economy of the diesel engine can be improved by 2.6% at high engine speed and 4.6% at low engine speed under engine full load operating conditions when equipped with the Brayton cycle WHR system. The influence of turbocharger parameters on the WHR engine performance was invesgated.     

Modal characteristics and fatigue strength of compressor blades

High-cycle fatigue (HCF) has been identified as one of the primary causes of gas turbine engine failure. The modal characteristics and endurance strength of a 5 MW gas turbine engine blade developed by Doosan Heavy Industries & Construction Co., Ltd. in HCF fracture were verified through analysis and tests to determine the reliability of the compressor blade. A compressor blade design procedure that considers HCF life was performed in the following order: airfoil and blade profile design, modal analysis, stress distribution test, stress endurance limit test, and fatigue life verification. This study analyzed the Campbell diagram and estimated resonance risk on the basis of the natural frequency analysis and modal test of the compressor blade to guarantee safe and operational reliability. In addition, the maximum stress point of the compressor blade was determined through stress distribution analysis and test. The bonding point of the strain gage was determined by using fatigue test. Stress endurance limit test was performed based on the results of these tests. This research compared and verified the modal characteristics and endurance strengths of the compressor blades to prevent HCF fracture, which is among the major causes of gas turbine engine damage. A fatigue life design procedure of compressor blades was established. The 5 MW class gas turbine compressor blade is well designed in terms of resonance stability and fatigue endurance limit.     

Robust model of a transient wind tunnel for off-design aerothermal testing of turbomachinery

Short duration wind tunnels offer an economical approach to study the aero-thermal operation of propulsion components, while reproducing temperature ratios, Reynolds and Mach numbers of the actual engine conditions. The present paper aims at modeling with high fidelity the von Karman Institute compression tube facility. This wind tunnel was simulated using the EcosimPro suite to characterize the behavior of each subcomponent during the whole test envelope, including the turbine map at off-design. The numerical predictions were then assessed through the comparison with experimental data. The model was proven to be an effective tool to accurately evaluate all the operating regimes that a research turbine experienced during the experimental sequence. Consequently, the present model allows exploiting the complete test run duration to obtain unique experimental data from the turbomachinery operating at far off-design conditions. The capability to experimentally test components at off-design is fundamental to understand the flow physics of any gas turbine engine operating at extreme conditions and to characterize the transient performances of fluid-machinery in high-speed propulsion concepts. However, technical dissemination on these aspects is scarce.     

Modal characteristics according to the tip shape and assembly condition of the turbine blade

To determine the reliability of a 5 MW gas turbine engine blade in high cycle fatigue (HFC) fracture being developed by Doosan Heavy Industries & Construction Co., Ltd., resonance characteristics are verified based on the turbine blade tip shape and assembly condition. In this study, the modal characteristics of compressor and turbine blades are investigated, and a Campbell diagram is established. During the preliminary study, modal analysis and holographic modal test of the first-, fifth-, and tenth-stage compressor blades were performed. Based on the preliminary study result, the natural frequency and Campbell diagram analysis for the turbine blades were performed. This research compared and verified the modal characteristic and resonance stability according to the tip shape and assembly condition of the blade to prevent any HCF fracture. In conclusion, the resonance stability of the shrouded blade is far superior to that of the squealer blade. Suitable assembly conditions must be applied.