大涵道比航空发动机风扇/增压级鸟撞性能数值模拟研究

针对民航客机涡扇发动机鸟撞问题,以某民机大涵道比涡扇发动机风扇/增压级为研究对象,将风扇鸟撞造成的缺损进行简化,构建了四种简化的鸟撞损伤模型.在此模型的基础上,采用数值模拟方法,预测和分析鸟撞损伤引起的风扇气动性能变化.通过分析得出,鸟撞后风扇流量、压比、效率、裕度均显著下降,缺损超过两片叶片后性能显著恶化.其中靠近损...     

民用大涵道比涡扇发动机吸鸟过程动态性能仿真研究

为验证民用大涵道比涡扇发动机对《航空发动机适航规定》CCAR33.76吸鸟适航条款的适用性,针对吸鸟条款中的中鸟附加完整性子条款开展数值仿真研究。基于风扇叶片鸟撞过程动力学仿真结果及鸟撞前后风扇特性数值计算结果,以某型发动机为例建立吸鸟过程动态性能仿真模型,完成了发动机从吸鸟开始到最终稳定的动态过程仿真,获得了吸鸟过程及最终稳定后的性能变化情况。结果表明:吸鸟后发动机性能急剧变化的主要因素是风扇叶片的塑性形变,通过起飞状态发动机吸鸟前后稳态节流特性对比,起飞推力下降约8%,满足持续的功率或推力损失不超过25%的条款要求;随着转速下降,风扇外涵喘振的风险极高,需改进设计保证吸鸟后风扇外涵仍具有足够的裕度;吸鸟前后,涡轮进口温度及发动机排气温度均下降,不存在超温风险。     

Flow through aerodynamic torque converter installed in new type turbofan engine

It is desired to increase the core engine speed of the turbofan,to get the best efficiency for the next leap of the en-gine technology.The conventional mechanism in which the front fan is directly connected to the output shaft ofthe core engine has a limit of increasing the spool speed because the fan diameter is very large.The authors haveproposed a new driving system in which the front fan is driven through the aerodynamic torque converter.Thefront fan can work at the conventional speed while the core engine runs more efficiently at higher speed.Con-tinuously,in this paper,the flow through the converter is simulated numerically by CFX-5 with the k-εturbulencemodel of the commercial CFD code.The secondary flow occurred on the hub wall affects markedly the flow con-dition on the blade surfaces,and the flow along the suction surface of the driver blade separates near the trailingedge,which is deviated to the blade tip by the centrifugal force due to the wheel rotation.     

风扇系统噪声对发动机整机噪声的影响

作者以某4缸发动机为例，采用声压测试的方法，通过对发动机上安装和未安装风扇时的噪声进行了试验比较。试验结果表明，风扇噪声主要是宽频带噪声，并得出了在不同频率范围风扇噪声对发动机噪声的影响。     

Corner flow control in high through-flow axial commercial fan/booster using blade 3-D optimization

This study is aimed at using blade 3-D optimization to control corner flows in the high through-flow fan/booster of a high bypass ratio commercial turbofan engine. Two kinds of blade 3-D optimization, end-bending and bow, are focused on. On account of the respective operation mode and environment, the approach to 3-D aerodynamic modeling of rotor blades is different from stator vanes. Based on the understanding of the mechanism of the corner flow and the consideration of intensity problem for rotors, this paper uses a variety of blade 3-D optimization approaches, such as loading distribution optimization, perturbation of departure angles and stacking-axis manipulation, which are suitable for rotors and stators respectively. The obtained 3-D blades and vanes can improve the corner flow features by end-bending and bow effects. The results of this study show that flows in corners of the fan/booster, such as the fan hub region, the tip and hub of the vanes of the booster, are very complex and dominated by 3-D effects. The secondary flows there are found to have a strong detrimental effect on the compressor performance. The effects of both end-bending and bow can improve the flow separation in corners, but the specific ways they work and application scope are somewhat different. Redesigning the blades via blade 3-D optimization to control the corner flow has effectively reduced the loss generation and improved the stall margin by a large amount.     

摩托车发动机冷却风扇试验系统

本文主要介绍摩托车离心式冷却风扇试验台的原理和设置 ,论述了在试验台上测试风扇动力性能的方法以及如何测试和计算冷却风扇在不同转速下的流量、压力、消耗功率和效率 ,为设计和选择性能良好的风扇提供依据。     

Unsteady operation of new type turbofan engine with aerodynamic torque converter reducing front fan speed

Introduction In turbofan engine technology of the 21st century, it is desired to select the best possible operating conditions for each engine section, to reduce the operating costs, fuel burn, and noise levels. The conventional mechanism in which the front fan is directly connected to the rest of the core engine arrests the optimization of the spool speed in order to avoid the flow blockage at the sonic speed. In such circumstances, the rotational speed of the front fan can be reduced using …     

Counter Rotating Fans- An Aircraft Propulsion for the Future?

In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time.A lot of propfans (Hamilton Standard, USA) with different numbers of blades and blade shapes have been designed and tested in wind tunnels in order to find an optimum in efficiency, Fig.1. Parallel to this development GE, USA, made a design of a counter rotating unducted propfan, the so-called UDF, Fig.2. A prototype engine was manufactured and investigated on an in-flight test bed mounted at the MD82 and the B727. Since that time there has not been any further development of propfans (except AN 70 with NK 90-engine, Ukraine, which is more or less a propeller design) due to relatively low fuel prices and technical obstacles. Only technical programs in differen     

不同海拔高度硅油风扇离合器对发动机性能影响的研究

在内燃机风扇离合器高海拔(低气压)模拟试验台上，研究了不同海拔高度(0km～5km)下硅油风扇离合器的分离、结合特性，以及对发动机性能的影响。研究结果表明：随着海拔高度的增加，发动机输出转矩和功率下降、烟度排放增加。燃油消耗率在小负荷时增加较多，在大负荷时增加较少。硅油风扇整个分离与结合时间呈现减小趋势。硅油风扇转速在小负荷时变化不明显，在大负荷时将逐渐降低。     

Counter Rotating Fans—An Aircraft Propulsion for the Future？

In the mid seventies a new propulsor for aircraft was designed and investigated - the so-called PROPFAN. With regard to the total pressure increase, it ranges between a conventional propeller and a turbofan with very high bypass ratio. This new propulsion system promised a reduction in fuel consumption of 15 to 25% compared to engines at that time. A lot of propfans (Hamilton Standard, USA) with different numbers of blades and blade shapes have been designed and tested in wind tunnels in order to find an optimum in efficiency, Fig.1. Parallel to this development GE, USA, made a design of a counter rotating unducted propfan, the so-called UDF, Fig.2. A prototype engine was manufactured and investigated on an in-flight test bed mounted at the MD82 and the B727. Since that time there has not been any further development of propfans (except AN 70 with NK 90-engine, Ukraine, which is more or less a propeller design) due to relatively low fuel prices and technical obstacles. Only technical programs in different countries are still going on in order to prepare a data base for designing counter rotating fans in terms of aeroacoustics, aerodynamics and aeroelasticities. In DLR, Germany, a lot of experimental and numerical work has been undertaken to understand the physical behaviour of the unsteady flow in a counter rotating fan.     

Performances and acoustic noise of micro multi-blade fan

In this paper, the performances and the acoustic noise of the traditional type micro multi-blade fan were investi- gated experimentally and numerically, to optimize the specifications of the fan for the resident circumstances. The acoustic noise level decreases but the efficiency deteriorates slightly with the increase of the blade number of the impeller. Besides, the acoustic noise decreases with the increase of the distance between the impeller outlet and the volute tongue, in accompanying with the increase of the input and the deterioration of the fan efficiency.     

叶顶开槽——小翼结构对提升轴流风机性能影响的数值研究

为了有效抑制叶顶泄漏流的发展,降低叶顶泄漏损失,针对两级动叶可调轴流风机提出在吸力面构造叶顶小翼并开设斜槽的新型叶顶改型方案。采用Fluent数值模拟了5种叶顶改型方案对风机性能和流场特征的影响,分析了不同方案下流场、叶顶静压、叶顶泄漏量和动叶区做功能力的变化。结果表明：吸力面小翼可有效降低叶顶损失,小翼上开设顺流向斜槽可进一步提高风机性能,逆流向斜槽会使性能略有降低;顺流向单斜槽为最佳改型方案,在设计流量下全压和效率分别提升166 Pa和0.942%;叶顶间隙处产生额外的涡流,叶顶泄漏流得到抑制,动叶区做功能力得以提升。     

水冷内燃机风扇的优化设计

探讨了水冷内燃机风扇的优化设计方法，并对475型柴油机风扇进行了优化设计计算。计算结果表明，优化设计技术的应用可以较明显地改善内燃机风扇性能。     

离心风机内泄漏数值优化研究

利用流体分析软件ANSYS CFX对某一高效离心风机进行了内部三维数值模拟,得到其流体动力学特征和内泄漏损失特征.根据理论公式对风机泄漏量进行了估算,比较理论计算泄漏量与数值模拟计算泄漏量.首先,在设计工况点对未加装防涡圈的风机进行数值计算,发现在蜗壳内部有一些大的旋涡,并观察到一些重要的流动现象.然后,对加装防涡圏后的离心风机进行整机数值模拟,结果表明,加装防涡圏后蜗壳内部的漩涡明显减小,漩涡强度减弱,流场得到改善,泄漏损失明显减小.最后,对不同间隙的加装防涡圈后的风机进行数值模拟,结果显示,随着间隙的减小,泄漏量明显减小,所以在保证安全运行的条件下,间隙应尽可能小.     

基于内部流场分析的离心风机改型设计

本文以某型离心风机为基础,依靠数值模拟的方法,基于对风机内部流场的分析,对其进行优化改型设计。主要分为三个方面：其一,将叶轮的直叶片改型为前掠正弯叶片,控制端区低能流体堆积,抑止叶栅流道分离流动的发生;其二,根据弯掠优化得到的叶轮设计改型风机机壳,以适应弯掠叶轮的出口气动条件;并根据弯掠叶轮与改型机壳内部流动的分析,对叶轮采取根切的优化方法,保持风机全压和流量在合理的大小。得到的优化设计风机,在保持全压和流量基本与原型相等的条件下,效率提高5%以上。     

某型涡扇发动机地面台架起动试验研究

为了分析大气环境温度对发动机起动过程的影响,采用三段积分法计算发动机起动特性,开展了不 同大气环境温度条件下某型涡扇发动机地面起动试验研究。结果表明：冷态条件下,发动机的起动特性与理 论计算结果一致,标准大气温度下发动机起动时间和脱开时间均为最短;热态条件下,发动机起动最快时的 大气温度比理论计算温度低2 K左右,起动时间和脱开时间均快于冷态时间（约快2.9 A#热态起动比冷态起 动的风扇、压气机转速出现时间早约0.5 a热态供油压力、排气温度的建立更早;分析认为,热态试验结果比 理论计算温度低的原因与大气温度变化引起的燃油粘度、滑油粘度、空气密度等变化及热态发动机焓值的变 化有关。该试验研究结果可为地面起动试验提供参考。     

CDA叶型在高压头、高效率轴流通风机设计中的应用

针对于低速CDA(可控扩散叶型)叶型的气动特点,研究了将低速CDA叶型应用于高压头风机设计中的具体技术路线,以及叶型生成与空间积迭问题。在此基础上分析了CDA叶片风机的流场特点。     

发动机缸体瞬态强度分析

针对发动机缸体结构复杂,工作过程中受到多种交变激振力作用的特点,建立了较详细的缸体瞬态强度分析有限元模型,模拟了缸体在发动机工作过程中的动态强度变化历程。得出：缸体与缸盖及变速器相连的紧固螺栓孔周围的整体应力水平较高,但随发动机工作负荷变化的波动量较小;缸体主轴承座周围动态应力和变形成分较高,且随发动机工作负荷变化的波动量较大;而缸体两侧壁的动态变形和应力与静态变形和应力水平较低。研究表明：在建模时考虑活塞和曲轴对缸体的接触作用,合理简化缸体结构,准确深入揭示工作过程中缸体的动态强度随时间的变化,为缸体动态结构强度设计提供可靠依据。     

内燃机冷却风扇温度控制液压驱动系统技术研究

对内燃机冷却风扇温度控制液压驱动系统方案进行了探讨 ,对选定的比例阀无级测控系统的液压驱动子系统、温度测控子系统设计中的有关问题进行了研究 ,通过就 WD6 15 .6 7柴油机研制的样机系统相应的试验 ,说明内燃机冷却风扇温度控制液压驱动系统原理的正确性、可行性与先进性 ,装载这种系统的内燃机可明显地提高动力性、改善经济性并降低内燃机噪音。     

内_外函分流的某涡轮风扇燃气发生器性能试验

途述了带外函道的双转子发动机内、外函分流,各自通流阻力可以改变的燃气发生器试验装置和试验结果。本燃气发生器试验结果将为涡轮风扇发动机在陆上应用提供有价值的试验数据和发动机改装途径。