为了探究压气机效率受雷诺数变化的影响,运用数值模拟对一台三级风扇进行 1.88×105～3.73×106雷诺数区间内的计算,并针对某七级压气机开展 7.4×104～3.64×105区间内的节流试验,拟合了效率与雷诺数的函数.研究给出了风扇/压气机在雷诺数降低后的效率、压比和流量损耗率,获得了效率随雷诺数变化的数值关系.所得结果与经验方法较为吻合,压气机效率与雷诺数之间满足形式上的幂次关系,关系式中的常数项与压气机型号及工作条件有关.

通过对某型压气机进行一维、二维和三维的计算,并以S2流面计算结果为主,对该型压气机进行静叶调节优化,对静叶调节前后的压气机流场进行分析与验证.结果表明:通过基于压气机S2流面的静叶调节方法,既能优化压气机整体参数,也可以改善压气机各级以及沿径向的气流参数分布,证明了这种方法具有一定的可行性.

面向工业界提出的工程技术人才需求,以培养出具有航空发动机工程设计、实践能力和工程创新、合作意识的高素质人才为目标,南京航空航天大学于2011年将"航空发动机总体设计"课程作为专业必修课引入飞行器动力工程专业培养计划,这在国内尚属先例.该课程国内尚无可用中文教材、无可借鉴的教学经验,课程组通过引入国外英文教材,参考国外教学方法和考核方法,经过7年的教学实践探索,目前已基本建成了一套完善的教学课件、大作业题库、辅导资料资源库等教学资源,形成了以课堂讲授、实践设计、过程考核为特点的教学方法,学生一致认为通过对课程学习熟悉了发动机总体设计流程,并提高了团队合作能力和工程实践能力.

采用数值模拟的方法,对轴流压气机进入旋转失速、退出旋转失速过程以及加入叶片摆动耦合使压气机退出旋转失速的过程进行了三维数值模拟.对比了加入与未加入叶片摆动对压气机退出旋转失速状态过程中的流量影响.数值计算表明,在加入合适的叶片摆动耦合后,可以使得压气机退出旋转失速状态的流量减小1.6％,压比上升1.7％.结合两种退出方式的旋转失速过程对比,得到该压气机失速团破碎的条件:部分叶片通道全叶高消除显著的流动分离,出现具有一定"稳定裕度"的优质流动,导致失速团传播途径受阻,使失速团迅速破碎、消失.

为了充分利用材料应力极限,探索高负荷离心压气机的设计方法,在常规离心叶轮的基础上,利用新的设计思路实现了带转速差的离心串列叶轮设计,采用经过校核的数值计算方法,对带转速差的离心串列叶轮压气机内部流动进行了详细数值模拟,从性能与流场细节分析了传统离心叶轮与带转速差的离心串列叶轮的差异.结果表明:相比于常规叶轮,合理布局的带转速差的离心串列叶轮在设计点整级等熵效率提高了1.96％,压比提高了0.14;激波与附面层相互作用引起的损失减小,二次流引起的"射流-尾迹"流动结构得到抑制;叶片载荷分布得到重新分配,改善了叶轮出口流场品质,降低了叶轮出口处绝对马赫数,扩压能力与无叶扩压段的总压恢复系数得到进一步提升,从而有效提高了整级压气机全工况性能.

民用多级轴流压缩机产品实际工作中工况点变化较为显著,因而需要满足不同的性能参数的特点.本文采用CFD方法,以静叶可调的15级压缩机为研究对象,考虑压缩机在夏季、冬季以及年平均三种不同条件下的工作环境,通过大范围内各级静叶角度的调节,进行全工况特性的数值模拟,研究静叶角度的改变对整台压缩机性能的影响,校验压缩机与实际工况下工作性能需求的匹配性,并得出相应工况点合适的静叶角度,同时研究静叶角度变化对压缩机级间匹配的影响.

针对一个重复级设计的四级轴流压缩机开展S2流面气动优化.在维持压缩机原有重复级设计特征和转、静子叶型不变的前提下,开展转、静子叶排S2流面气动参数径向分布的优化.CFD计算结果表明,S2流面气动优化,使得第一级动叶吸力面分离推迟,低马赫数区域减小,设计点总压比达到设计要求,等熵效率提高了9.4％,该四级重复级风洞压缩机性能显著提高.

轴流风机的工程设计过程是一个反复设计和择优的过程,寻求一种能快速有效的进行风机修改并拥有可信的计算结果的验算方法就显的十分重要.根据风机设计阶段的CFD验证结果和风机设计进出口设计要求,基于叶片排特性进行风机的一维性能计算与设计形成了风机的一维设计方法.通过工程实际中风机的计算与优化设计验证了该方法的实用性与可靠性,证明了该一维设计方法具有十分重要的工程应用价值.

针对航空发动机压气机级间参数测试中叶型探针的堵塞影响,采用试验和数值模拟相结合的方法,进行相互检验及校正,分析了堵塞影响随探头形式与数量变化的关系,以及堵塞影响随来流状态参数变化的规律,明确堵塞效应引起压气机特性变化的量级.确定了影响压气机特性的主要因素为压气机的流量、压升及叶型探针的堵塞比等参数,并在此基础上得到采用压升修正系数和流量修正系数修正探针堵塞影响的方法.

A four-stage low speed model compressor is designed for a high pressure compressor.Detailed flow field measurements are taken in the third stage.The results of the flow field measurements and 3D flow field calculation are compared with the simulation targets,which show that the low speed model compressor reaches the design goal.Below the 70%span,the low speed model compressor can reproduce the flow structure in the high pressure compressor.It also shows that the design method of the low speed model compressor for high pressure compressor is valid,and that the similarity criteria are reliable.Owing to the fact that the actual tip clearance of the rotor blade is bigger than the design value as a result of imperfect machining,the low speed model compressor does not fully represent the flow domain in the tip area of the high pressure compressor above the 70% span.

The unsteady surface pressure on stator blade of an axial compressor was measured by means of mounting micro-sensors onto blades surface.The unsteady blade surface pressure was analyzed.There are different factors to play decisive roles on the unsteady surface pressure and unsteady force with the decrease of flow coefficient.Before stall,unsteady blade surface pressure depends on the wake and potential perturbation of adjacent blade row.But after stall,unsteady blade surface pressure depends on the stall cells.Before stall,maximum amplitude of unsteady blade surface pressure and unsteady force occurs at the flow coefficient of maximum total pressure rise.However,after stall,the amplitude of unsteady surface pressure and unsteady force will be much greater than at the maximum total pressure rise.On the other hand,the frequencies of unsteady surface pressure and unsteady force change with the decrease of flow coefficient.Before stall,the dominant frequencies are represented by blade-passing frequency and its harmonics,but after stall,the dominant frequencies are represented by stall cell passing frequency.

介绍了旨在改善高压压气机性能的低速模拟试验方法,及其在国内外的发展情况.在参考国外成功经验的基础上,基于一定的相似准则,摸索出了一套低速模型压气机的设计方法.为了验证该方法的可行性,针对某方案设计的高压压气机后面级设计了一台4级重复级低速模型压气机.借助全三维黏性流场计算,证明该压气机模拟级进、出口各主要气动参数沿径向的分布,以及转子、静子叶片表面压力系数的分布与高压压气机的被模拟级是一致的.从数值计算的角度初步证明了利用该方法设计低速模型压气机是可行的.

To study the stator-rotor interactions on the blades surface pressure,a numerical simulation has been carried out for a low-speed single-stage axial compressor. Results for periodical unsteady flow have been obtained. Based on this,the change law of the pressure and aerodynamic forces on the blades surface has been analyzed. The influence of different mass flow on the pressure and aerodynamic forces on the blades surface has been studied by changing the static pressure of the downstream. Lastly,an experiment has been carried out on the rig of low-speed compressor. The numerical simulation results agree well with the experiment.

Fixed-pitch wind turbines commonly use stalled blades, and the ratio of lift coefficient to drag coefficient will rapidly decrease when the velocity of the wind exceeds the designed value, then the output of the power will be fixed under a safe value. As the main part to get power from the wind, Wind turbines' aerodynamic performance is very important and decides the power coefficient. How to evaluate the design of the wind turbine, and how to design a high performance wind turbine is important. First, the main methods to analyze the aerodynamic performance and the design methods of horizontal-axis wind turbines are introduced. Then the role of CFD technology in research of the wind turbines is explained. By using CFD software, a horizontal-axis wind turbine is studied. Through the analysis of the flow field and the pressure distribution on the blades, the deficit of the design will be found, which is helpful to improve the blades. At last, the feasibility of the combination of CFD and optimization techniques is discussed. The method relies on the interaction between a genetic algorithm, an artificial neural network, and a database of full three-dimensional computation results of fluid dynamic. On this foundation, users can generate various objectives and constraints for the optimization design of the geometric blade element shape parameters of the wind turbine.

Improving the aerodynamic performance of the wind turbine, especially in deep stall, is the emphasis of the aerodynamic investigation of the wind turbine. It is known that experiments are an effectual way to investigate the aerodynamic performance of the wind turbine, and to understand the details of the flow field. By measuring the 3-D flow field and the aerodynamic performance of the wind turbine in deep stall, researchers can investigate the 3-D stall mechanism of the wind turbine, study the 3-D flow characteristics and the aerodynamic performance of the wind turbine under different unsteady flow field, and explore the inner flow law of the wind turbine under different flow conditions. These studies can provide the academic support for designing high performance wind turbine under any flow conditions. The test results of the wind turbine can be used to verify the reliability of the program, which also can be used to calculate the flow field of the wind turbine. So in this paper, an experiment facility is built up, and the test system of full 3-D flow field and aerodynamic performance in deep stall of the wind turbine is designed. The test system and test procedures include: using the rotating-frame-traverse-probe mechanism to traverse five-hole-pressure-probe to measure the inner and outlet flow field of the wind turbine at different axial position; and using the PIV system to measure the flow field of the wind turbine at different circumference positions; as well as measuring the blade surface steady and unsteady pressure by instruments with static taps at the blade surface.

The 3-D time-accurate unsteady numerical simulation of the first-stage rotor of a three-stage transonic fan with oblique slots and cavity treatment of casing is performed. By studying the stall margin and the performance of the rotor, results show that the casing treatment can substantially extend the stall margin of the rotor and decrease isentropic efficiency in all of the operating range. The proposed rotor is compared with the one with no casing treatment. And the unsteady interaction between the casing treatment and the rotor blade rows under the transonic condition is analyzed. The simulation result shows that the physical reason of the extending stall margin by using this casing treatment is the unsteady flow. The flow can inject to the leading edge of the tip by the difference of the static pressure in the slots. The difference between the steady simulation and the unsteady simulation shows that the interaction between the casing treatment and blade rows is unsteady.

在低速大尺寸单级压气机实验器上,实验研究了动态进气畸变对压气机稳定边界的影响.并采取在静子叶片表面埋入微型压力传感器的方法,分析了压气机流场的动态压力特性.实验结果表明,动态总压畸变的旋转频率和旋转方向对压气机稳定性有很大的影响,当畸变相对转速(n)在0～+0.5之间时,压气机失速推迟;分析动态压力的频谱特性后知道,在压气机失速前一般存在与失速相关的压力扰动,动态总压畸变影响这种压力扰动,从而影响压气机的不稳定流动状态.

To study the amplitude and frequency of the aerodynamic force on stator blades,micro-sensors are buried under the surface of stator blades of a low-speed single-stage axial compressor to measure the unsteady pressure on blades.The measure covers different axial spacings between rotor and stator,different speeds and an extensive range of massflow.And the amplitudes and frequencies of aerodynamic forces are analysed by means of Fourie Transform.Under the effects of rotor wake,the dominant frequencies of pressure fluctuations on stator blades are the rotor blade passing frequency and its harmonics.But in the fore part of suction side,the higher harmonics of the rotor blade passing frequency are more prominent than those in other parts of stator blade.Otherwise,the fluctuations of pressure as well as the aerodynamic force on stator blades intensify with the decrease in the mass flow,the increase in the rotate speed or the decrease in the axial spacing between rotor and stator.

The unsteady surface pressures on the rotor blades of a single-stage low-speed axial compressor were measured by means of mounting micro-sensors on the surface the blades.The effects of up-stream blade wakes on the spectrum of rotor blades unsteady surface pressure were analyzed.On the rotor blade pressure surface,the dominant frequencies of unsteady surface pressure are the up-stream blade wake passing frequency and its harmonics,and the amplitudes of pressure fluctuations decrease from leading edge to trailing edge.However,on the blade suction side from leading edge to trailing edge,the amplitudes of pressure fluctuations increase at the fore part where flow accelerates and decrease at the rare part where flow decelerates.Flow separation produces pressure fluctuations of large amplitudes,possibly with the dominant frequencies differ from up-stream blade wake passing frequency and its harmonics.