叶冠齿数和齿顶间隙对涡轮气动性能的影响

通过数值方法对某1.5级带冠涡轮的流场进行研究,对比分析了不同叶冠齿数和齿顶间隙对涡轮气动性能的影响.研究结果表明,泄漏流与主流掺混后形成一个涡流区,改变了叶栅上半通道的流场结构,使得顶部流体以负攻角进入下级静叶,造成攻角损失,改变了下级静叶的气动性能.同时发现间隙相对于齿数对涡轮气动性能的影响程度更为显著,间隙相同,齿数从1增加到4时,涡轮效率增加0.75％;齿数相同,间隙从2mm减小到0.5mm时,涡轮效率增加1.82％.     

New model-based method for aero-engine turbine blade tip clearance measurement

Active control of aero-engine turbine tip clearance is one of the best chances for engine performance uplift currently. To do that, the first requirement is real-time measurement of tip clearance in aero-engine working environment. However, turbine complexity makes it unlikely for tip clearance sensors to be loaded. In recognition of that, this paper proposed a model-based method for tip clearance measurement. Firstly, by considering previously wrongly neglected factors such as load deformation, a mathematical model to monitor dynamic tip clearance changes is built to improve calculation accuracy. Then, after clarifying the coupling relationship between engine models and tip clearance models, this paper builds a component-level mathematical model integrating dynamic characteristics of turbine tip clearance, which helps realize accurate measurement of tip clearance in working environment. How tip clearance affects turbine efficiency is studied afterwards and reported to aero-engine model, so as to mitigate performance difference between aero-engine model and real engines caused by turbine tip clearance. Lastly, by hardware-in-the-loop simulation, tip clearance model demonstrates 15.9% better accuracy than previously built models in terms of turbine centrifugal deformation calculation. As tip clearance measurement model takes averagely 0.34 ms in calculation, meeting the operation requirement, it proves to be an effective new way.     

Experimental investigation of the full coverage film cooling effectiveness of a turbine blade with shaped holes

The film cooling effectiveness of two turbine blades at different turbulence intensities(0.62% and 16.00%) and mass flux ratios(2.91%, 5.82%, 8.73% and 11.63%) is studied by using the Pressure-Sensitive Paint(PSP) measurement technique. There are a baseline and an improved turbine blade in current work, and their film cooling hole position distribution is the same. But the hole shape on suction surface and pressure surface is changed from cylindrical hole(baseline)to laid-back fan-shaped hole(im...     

基于均匀设计法的涡轮叶栅水滴型前缘修型结构的数值优化研究

为了最大程度地降低端区二次流对涡轮叶栅带来的流动损失,对某典型低压涡轮叶栅引入水滴型前缘修型结构并进行设计参数优化。首先使用控制变量法研究单一设计参数变化对流动控制效果的影响;然后基于均匀设计法,对不同设计参数组合的水滴型前缘修型结构的流动控制效果进行数值模拟,获取控制端区二次流最优的设计方案。结果表明：控制变量优化下的最佳设计方案可以使总压损失降低6.1%;均匀设计优化下的最佳设计方案可以使总压损失降低8.61%。与控制变量法相比,均匀设计法得到的水滴型前缘修型优化结构能够更大程度地降低前缘马蹄涡强度,延后通道涡到达吸力面的位置,减小通道涡对主流的影响范围,进而从流动机理层面证实了均匀设计法优化水滴型前缘修型的可行性。     

涡轮流量计转子内完全三元流场的变域变分有限元解

三、涡轮流量计仪表特性曲线的计算由动量矩原理可知,当转子处于平衡时,可得到力矩平衡方程 T_d=∑T_i=T_h T_b T_t T_m T_P T_f下面分别讨论各力矩的大小。     

评涡轮流量计Thompson-Grey的理论模型

运用流体动力学分析,指出了涡轮流量计的Thompson—Grey理论模型中存在的各种缺陷。计算结果表明,改进后的模型与实际情况的吻合程度有了很大提高,涡轮流量计仪表系数的理论估计值与实际值之间的偏差由原来的±(4％～6％)下降至±1.5％以内。     

气冷涡轮气热耦合数值模拟

应用有限差分方法进行气冷涡轮气热耦合计算,研究了影响气热耦合计算精度的几个因素,包括:流场壁面附近的计算网格、湍流转捩模型以及能量方程中普朗特数的计算等。为了能够应用高精度离散格式,并加快计算速度,采用了气热耦合动力学的微分方程与相应的差分格式,采用了结构化网格。数值计算结果与试验进行对比表明,在流场壁面附近应采用正交性好的网格,并在计算中考虑转捩的影响;而普朗特数的变化对本次计算的影响不大。     

基于P-ε-N曲线整体推断的涡轮盘寿命可靠性分析

疲劳寿命符合对数正态分布,并且对数寿命的标准差随弹性应变幅和塑性应变幅的减小而增大。采用基于异方差回归分析的整体推断方法在现有低循环疲劳试验数据的基础上,得到了航空发动机涡轮盘材料GH4133在温度250℃下的P-ε-N曲线;利用P--εN曲线对某涡轮盘进行低循环疲劳寿命可靠性分析,得到置信度0.95,可靠度0.998 7的轮盘寿命为1 866次循环,合683飞行小时,与涡轮盘疲劳试验分析得到的技术寿命接近。整体推断得到的P-ε-N曲线精度较高,利用P-ε-N曲线进行轮盘寿命可靠性设计分析具有计算简便、节约试验成本的优点。     

带冲击-气膜双层壁结构的涡轮导叶冷却特性源项法数值研究

为了降低由于大量冷却孔导致的计算资源消耗,采用源项法对带冲击-气膜双层壁冷却结构的Mark II涡轮导叶传热进行了简化数值模拟,并与不采用源项法的结果进行了对比。分析了冷却孔网格密度以及流量系数经验关系式对源项法模拟精度的影响。结果表明,采用源项法能够基本准确地模拟叶片表面温度分布并且缩短75%的计算时间。当冷却孔进出口面网格最小尺度小于孔径的1/10时,数值模拟结果将不随面网格密度改变。影响模拟精度的主要因素是经验关系式能否准确模拟总冷气流量以及横流对流量系数的影响。     

上端壁翘曲对涡轮叶栅流场的影响

利用N－S方程求解程序，对采用不同端壁结构的三套大转角涡轮叶栅进行了数值模拟，探讨了上端壁翘曲对涡轮叶栅内气流流动的影响。计算结果表明,上端壁翘曲后，上半翼殿内的二次流流场发生了明显的变化，非轴对称端壁是控制叶栅内二次流流动的一种有效的方法。