Investigation of the Aerodynamic Character in Turbine Cascades with Aft-loaded Profile

For evaluate the aerodynamic character of the turbine cascades which have the aft-loaded profile, the experimental investigation was carried out on the low speed annular wind tunnel. And the detailed measurements of the aerodynamic parameters were made from upstream to downstream of the two type turbine cascades, the one is the conventional straight blades cascade, the other is the curved blades cascades. The static pressure distributions on the endwall and the blade surface were also carried out. The influence of the aft-loaded profile and the curved blade on the development of loss and the pressure distribution was discussed, and analyses the different flow phenomena and mechanism in two type turbine cascades.     

汽轮机静叶栅二次流损失的数值研究

基于有限元有限体积法和全隐式多网格耦合算法,对某汽轮机高压级有一定扭曲度的静叶栅流场进行了三维稳态数值模拟,分析计算了叶栅通道内上下端壁二次流发展的特点及叶栅的气动特性。计算结果表明,叶栅端壁二次流损失与叶型型面及上下端壁面的汽流情况有密切关系。同时揭示了叶栅通道内的涡系演变特点,发现在流道尾部二次流强度发展迅速,在靠近背弧上下端部附近形成两个明显漩涡区,进而引起总压损失系数和出口汽流角沿叶高方向产生明显变化,这对存在一定扭曲度叶栅的气动特性研究及设计有一定的指导意义。     

Optimum Profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic Performance

Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures) by controlling the characteristics of the secondary flow in a blade passage. This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow. Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage, non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit com...     

叶片周向弯曲角度对扩压叶栅气动性能的影响

为了改善扩压叶栅气动性能,采用拟压缩性方法对不同周向弯曲角度的正弯曲叶片压气机叶栅内三维粘性流场进行了数值模拟.结果表明,随着弯曲角度的增加,端部流动状况逐渐得到改善,叶栅中部流动损失逐渐增加.正弯20°时可基本控制端部扩压因子至0.6以下.叶片弯曲角度的选择应以能满足设定目标的最小角度为最佳,过大的角度将会导致动静叶间匹配困难和较大的吸力面尾缘回流区     

某型汽轮机调节级气动特性数值研究

对采用寇蒂斯级设计思想、具有局部进气的汽轮机复速级进行了三维整级数值模拟,分析了设计工况下该复速级的流动特点.计算结果表明,气流流出复速级喷嘴后,每个喷嘴组边界流体的散射作用不强烈,在边界上基本只影响了附近的一个叶栅流道,流动的主体方向沿着轴向进行;当级的压比较大,流动达到超音速时,每个喷嘴组出口流动沿周向的不均匀性非常严重,交替出现尾迹低速区和主流低压区,使喷嘴区域内处于不同位置的动叶片受力状态发生较大变化;超音速喷嘴出现的过膨胀低压区,压力在整个级内是最低的,会加剧动叶流道的非定常流动效应.     

基于典型鸟类翅膀特征的小型轴流风机叶片仿生设计与试验

基于提取的雀鹰、长耳鸮翅膀的表面特征对小型轴流风机的叶片进行仿生优化,以求提高风机的气动性能。设计出8种仿生风机模型,通过CFD计算选出最优的仿生风机模型进行性能试验验证,并与原型风机进行了对比。对比试验流量-静压曲线发现,仿生风机气动性能明显好于原型风机,最大质量流量提高了6.1%,最大静压提高了7.0%,并发现V型截面好于圆弧型截面。本研究为叶片仿生参数的进一步优化提供了前期基础。     

叶片倾斜角度对小型轴流风扇静特性的影响

采用叶片周向倾斜设计法,改变一直叶片小型轴流风扇叶型,得到不同周向倾斜角的小型轴流风扇,并对其内部流场进行定常流动的数值模拟,分析直叶片、前倾斜叶片、后倾斜叶片等风扇叶型对气动性能的影响。模拟结果表明,采用叶片前缘倾斜设计可减弱附面层分离,改善风扇流动状况,从而达到提高风扇静压和效率的目的。     

蒸汽轮机末级应用海豚型静叶的数值仿真

分别对海豚型叶型和常规设计的蒸汽轮机叶型进行了一级全三维气液两相数值计算,对比发现所设计的海豚型叶型在改善常规叶型流场的气动性能、提高汽轮机轮周效率的同时,可以提高流道内叶片段区域的湿蒸汽干度,改善流道内湿蒸汽的分布。海豚型叶型具有短的扩压段,使激波和附面层干扰区域具有更强的防汽流脱落能力,这样可减少此区域内水膜被高速汽流急剧撕裂成二次水滴的可能。海豚型叶型通道内湿蒸汽湿度沿叶高的分布特点有利于在叶片上表面开设除湿槽,进行高效除湿。     

压气机动叶CLOCKING效应对叶片气动负荷的影响

为研究某型燃气轮机中间三级轴流压气机第二级动叶片的CLOCKING效应及其对静叶片气动负荷的影响,采用基于谐函数(harmonic)的非定常计算方法对三级压气机进行数值模拟,分析流场尾迹输运以及叶片非定常气动负荷.计算结果表明,动叶片处于不同CLOCKING位置时,非定常流场具有截然不同的熵输运特点,因而在不同的气流激振力作用下各列叶片气动负荷差别较大.在CLK2位置上,静叶片气动力始终为正值,且波动幅值明显比其它位置小,气动力方向角波动范围最小,且气动力矩波动幅值和方向改变次数最少,具有最稳定的气动负荷.     

基于AxSTREAM的后导叶动调轴流风机的气动设计

基于叶轮机械设计软件AxSTREAM完成了对带后导叶的动调轴流风机3种运行工况下的动叶设计.并对比分析了设计后动叶在运行工况点的性能,找到同时适合运行工况的最佳动叶型.根据最佳动叶对R级动叶可调轴流风机匹配后导叶进行整机的三维气动数值验算.结果表明:气动设计得到的叶型中工况c设计出的动叶在3种工况下运行最合理,同时,匹配后导叶后,充分地利用动叶出口旋绕动能,提高通风机的全压效率和全压压比,设计工况点下的性能均有提高;同时也为动调风机的工程应用提供了快速高效的设计方法.     

变风速下风力机叶片载荷特性研究

根据风力机的气动理论,并考虑风切变和风力机结构、几何参数的影响,建立了风力机叶片的气动载荷计算模型。以基本风速、渐变风速、阵风风速和脉动风速4种风速类型建立了变风速模型,并应用于叶片载荷计算模型,实现变风速下的叶片气动载荷的计算。以某MW级风力机为对象,给出了数值计算流程并进行了实例计算,结果显示：风力机叶片的气动载荷主要分布在叶片的中段和叶尖,且载荷大小随风速起伏变化,叶根的气动载荷随风速变化的趋势不明显,风速较大时,叶片上的载荷波动较为显著。结果可为叶片的结构设计和动力学分析提供参考。     

Aerodynamic performance of high-turning curved compressor cascade with boundary layer suction

The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.     

Aerodynamic performance of high-turning curved cascade with boundary layer suction

The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed. The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates. The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage. Moreover, higher loading over the whole blade height, lower total pressure loss, and higher passage throughflow were achieved with a relatively small amount of boundary layer removal. The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used, and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.     

尾缘射流式垂直轴风力机气动特性数值分析

为抑制翼型表面流动分离并提高风力机叶片气动性能,将可靠性较高的吹气射流技术应用于垂直轴风力机叶片尾缘。采用数值模拟方法分析不同尾缘射流角度对垂直轴风力机风能利用系数、力矩系数及单叶压力与整机涡量的影响。模拟结果表明:在最佳尖速比(2.63)时,10°射流可以有效降低翼型尾缘脱落涡频率,有效控制叶片尾迹效应,整机效率及运行稳定性均优于0°尾缘射流式垂直轴风力机;在较低尖速比时,风力机单叶力矩峰值均集中在120°相位角,尾缘10°射流对整机力矩系数有显著提升效果;在较高尖速比时,单叶翼型压力面存在较大正压区,风能利用系数最大可提高11%左右,气动性能明显优于无射流垂直轴风力机。尾缘射流降低了风力机叶片所需承受的轴向载荷,提高了风力机输出功率。不同角度尾缘射流均能有效降低叶片表面流动损失进而延缓流动分离,数值结果为尾缘射流式垂直轴风力机的工程应用提供了部分参考价值。     

Numerical investigation on bowed blades of large meridional expansion Turbine

To improve the performance of the Turbofan engine,several measures should be considered during design process.Such measures,relating to aerodynamic characteristic design,include the maximum enthalpy per stage,the shortest axial length,the minimum blade rows and the highest efficient in design and off design condition.To satisfy theses design characters,the meridian geometry of the engine will be excurvature at a high degree transition part between HP and LP turbines.The study is to investigate the effect of blade bowing on flow loss at blade tip and root of the type of turbine.Such turbine,tending towards separation,with severe secondary flow at the tip and strong radial flow at exit,was simulated by the 3D N-S solver Numerca,and there were several different stacking line bowing schemes in all.The results show that tip negative bowing and root positive bowing is able to weaken radial flow,consequently reduce the flow loss at the tip and root.     

变马赫数下压力面小翼对扩压叶栅气动特性的影响

为探究变来流马赫数下压力面叶尖小翼对扩压叶栅气动特性的影响,对Ma=0.5、Ma=0.6和Ma=0.7来流马赫数下的原型叶栅和加装不同宽度的压力面叶尖小翼的扩压叶栅流场特性进行了实验研究. 结果表明:在高亚声速的来流条件下,压力面叶尖小翼可以有效减小叶顶两侧压力梯度,阻碍流体流入叶顶间隙,控制叶顶泄漏流动,减小流场损失,改善流场流动状况. 随着小翼宽度的增加,改善程度增大,同时马赫数的变化与控制效果成正比. 当Ma=0.7时,与原型叶栅相比,PW2.0方案的流场改善程度最大,总压损失系数降低了6.53%.     

Numerical investigation on bowed blades of Iarge meridional expansion Turbine

To improve the performance of the Turbofan engine,several measures should be considered during design process.Such measures,relating to aerodynamic characteristic design,include the maximum enthalpy per stage,the shortest axial length,the minimum blade rows and the highest efficient in design and off design condition.To satisfy theses design characters,the meridian geometry of the engine will he excurvature at a high degree transition part between HP and LP turbines.The study is to investigate the effect of blade bowing on flow loss at blade tip and root of the type of turbine.Such turbine,tending towards separation,with severe secondary flow at the tip and strong radial flow at exit,was simulated by the 3D N-S solver Numerea,and there were several different stacking line bowing schemes in all.The results show that tip negative bowing and root positive bowing is able to weaken radial flow,consequently reduce the flow loss at the tip and root.     

基于数值仿真的离心风机叶片优化设计

为了提高离心风机的效率,提出一种基于CFD数值模拟仿真分析的优化设计方法,首先对离心风机内部流场进行数值模拟,然后根据数值模拟获得的风机性能数值进行优化设计。以9-26-10D型离心风机为研究对象,改变叶片相关参数,通过数值模拟计算与分析可得到:当风机的流量在19 000 m3/h附近时,效率较高;将离心风机的叶片数量更改为18片,与16叶片数的原始模型相比,在流量为19 000 m3/h处,风机的全压提高了130.70 Pa,效率提高了1.75%;将离心风机的叶片圆弧半径更改为112.5 mm时,与125 mm半径的原始模型相比,在流量为19 000 m3/h处,风机的全压提高了429.33 Pa,效率提高了5.77%。结果表明:这种方法可以对离心风机叶片进行优化设计。     

Control of endwall secondary flow in a compressor cascade with dielectric barrier discharge plasma actuation

Three dielectric barrier discharge plasma actuators were mounted at the positions of 20%, 40% and 60% of chord length on the endwall in a compressor cascade. The downstream flow field of the cascade has been measured with a mini five-hole pressure probe with and without the plasma actuation. The measured results show that the plasma actuation most effectively reduces total pressure loss and flow blockage when the actuators are operated simultaneously. As each of the actuators is operated independently, the actuator at the position of 20% of chord length most effectively reduces flow blockage, and the actuator at the position of 60% of chord length fairly reduces total pressure loss. However, negative pressure loss reduction occurs with the plasma actuator at the position of 40% of chord length. In brief, the plasma actuation placed on the endwall in the cascade apparently influences the endwall secondary flow, and the optimal locations and strength of actuation are critical for the control of endwall secondary flow in a compressor cascade with the plasma actuators.     

轻型客车侧窗区域气动噪声的数值模拟与验证

应用商用计算流体软件Star-CD,计算了某轻型客车外部非定常流场及其侧窗区域的气动噪声。通过稳态雷诺平均那维尔斯托克斯方法获得气流分离区的分布并预测气动噪声声源位置。采用分离涡模拟方法与计算气动声学方法获得非定常流场特性与侧窗区域监控点的气动噪声声压级。采用激光粒子测速试验结果验证了数值模拟方法的正确性。从非定常气流分离现象和涡流结构特征角度解释了气动噪声产生的主要原因,研究结果有助于在汽车开发早期阶段降低气动噪声。