变冲角下吸力面小翼对压气机叶栅气动性能的影响

为了进一步揭示吸力面小翼对压气机叶栅间隙流动的影响机理,采用数值模拟方法对压气机叶栅加装吸力面小翼控制间隙流动进行研究,着重考察了吸力面小翼在不同来流冲角下(-5°、0°、+3°)对叶栅气动性能的影响。结果显示,负冲角时,吸力面小翼有效降低了叶尖泄漏损失及遏制了压力面分离。随着冲角增加,叶顶最大压差作用区向叶栅上游移动,泄漏涡与通道涡的相互作用增强,吸力面小翼对叶栅气动性能的改善逐渐降低。     

Method for utilizing PIV to investigate high curvature and acceleration boundary layer flows around the compressor blade leading edge

Particle Image Velocimetry (PIV) is a well-developed and contactless technique in experimental fluid mechanics, but the strong velocity gradient and streamline curvature near the wall substantially limits its accuracy improvement. This paper presents a data processing procedure combining conventional PIV and newly developed Mirror Interchange (MI) based Interface-PIV for the measurement of the boundary layer parameter development in the blade leading edge region. The synthetic particle images are used to analyze the measurement errors in the entire procedure. Overall, three types of errors, namely the errors caused by the Window Deformation Iterative Multigrid (WIDIM) algorithm, the discrete data interpolation and integration, and the wall offset uncertainty, comprise the main measurement error. Specifically, the errors due to the discrete data interpolation and integration and the WIDIM algorithm comprise the mean bias, which can be corrected through the error analysis method proposed in the present work. Meanwhile, the errors due to the WIDIM algorithm and the wall offset uncertainty contribute to the measurement uncertainty. Computational fluid dynamics-based synthetic particle flows were generated to verify the newly developed PIV data processing procedure and the corresponding error analysis method. Results showed that the data processing method could improve the accuracy of PIV measurements for boundary layer flows with high curvature and acceleration and even with significant flow separation bubbles. Finally, the data processing method is also applied in a PIV experiment to investigate the boundary layer flows around a compressor blade leading edge, and several credible boundary flow parameters were obtained.     

Effects of surface roughness on the aerodynamic performance of a high subsonic compressor airfoil at low Reynolds number

The aerodynamic performance of compressor airfoil is significantly affected by the surface roughness at low Reynolds number (Re). In the present study, numerical simulations have been conducted to investigate the impact of surface roughness on the profile loss of a high subsonic compressor airfoil at Re = 1.5 × 10⁵. Four roughness locations, covering 10%, 30%, 50% and 100% of the suction surface from the leading edge and seven roughness magnitudes (R_a) ranging from 52 to 525 μm were selected. Results showed that the surface roughness mainly determined the loss generation process by influencing the structure of the Laminar Separation Bubble (LSB) and the turbulence level near the wall. For all the roughness locations, the variation trend for the profile loss with the roughness magnitude was similar. In the transitionally rough region, the negative displacement effect of the LSB was suppressed with the increase of roughness magnitude, leading to a maximum decrease of 14.6%, 16.04%, 16.45% and 10.20% in the profile loss at R_a = 157 μm for the four roughness locations, respectively. However, with a further increase of the roughness magnitude in the fully rough region, the stronger turbulent dissipation enhanced the growth rate of the turbulent boundary layer and increased the profile loss instead. By comparison, the leading edge roughness played a dominant role in the boundary layer development and performance variation. To take fully advantage of the surface roughness reducing profile loss at low Re, the effects of roughness on suppressing LSB and inducing strong turbulent dissipation should be balanced effectively.     

进气畸变下低速轴流压气机失速起始特性试验

为探索进气畸变对压气机失速起始特性的影响,本文以一台双级低速轴流压气机为研究对象,对均匀进气和多种进气畸变形式下的失速起始特性进行了详细研究。进气畸变包括1×90°稳态单波、2×90°稳态双波和1×90°周向旋转单波3种形式,压气机转速为600 r/min和800 r/min。试验结果表明,在均匀进气和固定进气畸变条件下该压气机均表现为模态波式失速起始特征,而在旋转畸变时观察不到失速前扰动信号。均匀进气时,失速前20～30个转子旋转周期即可观察到模态波的存在,其传播速度等于42%转子转速,并诱导产生旋转失速团,而且在失速发展过程中,失速团旋转速度保持不变。稳态进气畸变时,也是由模态波诱导产生旋转失速,但在失速团发展过程中,失速团的旋转速度会发生变化。旋转进气畸变时,失速前检测不到42%转子转速的模态波扰动,也没有发现尖脉冲扰动。     

吸雨对压气机叶栅气动性能影响的实验研究

针对雨水会导致飞机发动机非正常运行的实际问题,以压气机静叶叶栅为对象开展了压气机吸雨实验,探究了0.5马赫数和同一进口总压条件下不同来流含水量对压气机气动性能的影响.实验结果表明:来流水滴在压气机叶栅中会发生充分破碎,不同含水量来流破碎后水滴粒径基本一致,极限水滴破碎粒径约为13.3μm.随来流含水量增加,叶栅压力面静...     

引气对压气机流场模型影响的数值研究

为了研究引气对压气机流场的影响,采用数值方法对压气机引气的简化数学物理模型进行了引气量、引气面积、引气结构角度及长度四个引气控制参数共49个方案的对比探究.结果表明:受到引气抽吸作用的影响,引气槽上游主流的流动加速,下游主流减速.引气参数对主流热力参数的影响呈规律性,引气量主要决定热力参数变化的程度,引气面积主要改变热力参数变化的范围,而引气结构的角度和长度则主要影响引气结构内部的流动形式.     

叶片表面粗糙度对前弯压气机叶片流动特性影响的试验研究

为了探究叶片表面粗糙度对叶型性能的影响规律,对压气机前弯叶片进行了变雷诺数多攻角工况的叶栅试验。不同粗糙度(Ra=3.0,6.2,12.3)叶片是在轮廓度有所保证的前提下,通过线切割机械加工、喷砂工艺改变表面粗糙度的方式获得。试验结果表明,粗糙度升高确实会诱发层流提前转捩,引起吸力面层流分离泡消失,除此之外,在低雷诺数(Re=9×10~5)下,Ra=3.0与Ra=6.2下叶片表面马赫数分布基本一致,到Ra=12.3时才会较明显表现出叶片吸力面峰值马赫数降低的现象。随着雷诺数升高,叶片表面马赫数分布随粗糙度变化的差异性逐渐显现,但当处于堵塞负攻角i=-6.4°下,粗糙度Ra≥6.2后,叶片性能却维持稳定。另外,粗糙度的增加会降低压力面的粘性损失,升高吸力面的粘性损失及尾迹掺混损失,因此随粗糙度升高,低雷诺数(Re=9×10~5)下总压损失随粗糙度升高呈先增后降的趋势。在高雷诺数(Re≥1.08×10~6),i=2.6°～-2.4°下粗糙度升高会导致损失升高,甚至发生严重的湍流边界层分离。与此同时,发现被研究叶型吸力面前缘(20%弦长前)马赫数分布对粗糙度并不敏感,不会因粗糙度的不同而发生变化。     

叶片正弯对扩压叶栅气动性能的影响

为了研究叶片不同正弯曲角度对压气机叶栅气动性能的影响 ,在平面叶栅低速风洞上 ,对具有可控扩散叶型 (CDA)的直叶片和 15° ,2 0° ,2 5°正弯曲叶片压气机叶栅进行了实验。获得了不同弯曲角度扩压叶栅出口流场的能量损失系数、涡量以及叶片表面静压系数等的分布。结果表明 ,叶片正弯曲 2 0°时叶栅总损失降低最多 ,达16 15 %。正弯曲叶片吸力面形成“C”型压力分布 ,且这种分布随着叶片弯曲角度的增加而加强     

压气机叶栅非定常线性自回归气动降阶模型研究

为满足叶轮机械领域高效非定常气动计算的迫切需求,采用线性带外输入的自回归(ARX)理论建立了高亚声速压气机叶栅非定常气动性能降阶模型.该降阶模型构造简单,建立较为容易.通过逐渐增加输入/输出延迟阶数,可以获得较高精度的模型超参数.研究结果表明:降阶模型对线性非定常系统的气动参数响应具有较好的预测精度,但在部分无量纲总压...