冲角变化对涡轮静叶栅流场的影响

为了研究亚临界600MW汽轮机高压第九级静叶原型和改型叶栅的变冲角气动特性,对两套环形叶栅在0°和±10°冲角下在哈尔滨工业大学能源科学与工程学院的低速环形风洞中进行了对比实验研究。实验结果表明,冲角变化仅影响改型和原型叶栅流道前半部分的横向压力梯度,对流道后半部分的流动影响不大;与原型叶栅相比较,改型叶栅不仅降低了流动损失,而且比原型叶栅具有更好的变冲角特性。     

冲角变化对涡轮静叶栅流场的影响

为了研究亚临界600MW汽轮机高压第九级静叶原型和改型叶栅的变冲角气动特性,对两套环形叶栅在0°和±10°冲角下在哈尔滨工业大学能源科学与工程学院的低速环形风洞中进行了对比实验研究.实验结果表明,冲角变化仅影响改型和原型叶栅流道前半部分的横向压力梯度,对流道后半部分的流动影响不大;与原型叶栅相比较,改型叶栅不仅降低了流动损失,而且比原型叶栅具有更好的变冲角特性.     

超高温升中心分级燃烧室设计及计算分析

针对航空发动机高推重比、高温升的需求,提出1种中心分级旋流燃烧室的设计方案。在保证与现有单环腔燃烧室(SAC)进出口尺寸、机匣尺寸限制不变的情况下,对设计模型进行了3维数值模拟,并与现有的单环腔燃烧室数值模拟结果及试验结果进行了对比分析。研究结果表明:设计油气比为0.045时,设计中心分级燃烧室温升可达1356 K,出口温度分布可达0.137,出口径向温度分布可达0.096;此外,与SAC相比,中心分级燃烧室可获得更低的总压损失,更低的出口温度分布系数以及高工况下可获得更高的燃烧效率;污染排放性能表明,中心分级燃烧室在慢车点CO排放比SAC的稍高,在设计点NOx排放按g/kg燃油计比SAC的低。     

Planetary Radiation Budgets

The energy state of a planet depends fundamentally on its radiation budget. Measurements made from space over past decades have led to significant revisions of ground-based estimates, both of the reflected fraction (the Bond albedo) of solar radiative flux and of the emitted thermal infrared radiation flux, for the Earth as well as for the other planets. After a brief survey of methods and difficulties in accurately determining planetary radiation budgets, we note contradictions in existing tabulations of global parameters, in particular Bond albedo. For the Earth, such contradictions are unjustified, considering that global and annual means as well as the seasonal cycle of Earth Radiation Budget components have now been determined with high accuracy. The Earth's Bond albedo is close to 0.3. Net storage of energy in the Earth-ocean system is close to zero, with a well-established annual cycle of amplitude close to ±12 Wm⁻². Some contradictions remain for the other terrestrial planets. For the giant planets, modern reduced values of the Bond albedo imply reduced but still significant internal energy generation.     

在静止扩压环形叶栅中捕获轴流压气机非定常耦合流型的实验研究

本文研究了在静止扩压环形叶栅中如何实现非定常自然流型(UNFT)向非定常耦合流型(UCFT)的转变，以及耦合流型对轴流压气机能带来多大的时均性能提高。在环形叶栅台上的大量实验研究表明：当以一定方式实现非定常耦合流型后，其分离旋涡缩小，流场中涡量减小，流动损失下降，时均性能有较大幅度提高。实验中将常规的气动感头测量和小惯性热线风速仪测量以及数字式PIV瞬态场测量技术相结合，来获得非定常两代流型的流动图案和时均性能及其相互比较。     

处理轮毂转速的实验研究

在低速环形叶栅实验台上圆弧斜槽处理轮毂相对静子扩压叶栅环的旋转频率对叶栅端壁区流动进行了影响实验探索。结果表明：轮毂处理能够消除叶栅端壁区的低速团,减小流动堵塞,叶栅流通能力最大提高了26．2％。轮毂处理消除端壁分离的能力与处理轮毂的旋转方向和相对转速密切相关。随着处理轮毂转速的增加,叶栅流通能力增加,并且存在局部非线性较强的转速范围。因此,轮毂处理的设计还应该考虑叶排与处理槽相对运动带来的流动非定常性。     

灰色系统理论在年用电量预测中的应用

年用电量系统具有灰色系统的特征,因此,可以用灰色系统模型对年用电量进行预测.运用灰色模型(GM(1,1))对年用电量做出预测,并与传统方法进行比较,结果证明GM(1,1)模型优于传统方法,是一种有效的预测年用电量的模型。     

高职院校人才培养质量报告概述及撰写方法

高职院校人才培养质量年度报告是高职院校提高教学质量,健全质量保障体系的重要举措,通过分析质量报告的概念,发布质量年度报告的意义,从而提出撰写质量年度报告应注意的问题及报告的结构框架。     

培训对农民工工资收入的回报

培训能够为农民工带来多少工资回报以及教育与培训何者能够为农民工带来更高的工资回报是学界一直探讨的话题。基于此,本研究利用Mincer模型构建农民工人力资本挣得函数,实证结果显示参与培训对于农民工的工资收入有正向影响,高于教育年限每增加一年带来的工资收入回报。培训是促进农民工工资增长的有效方式。     

Long term variability of total ozone yearly minima and maxima in the latitudinal belt from 20°N to 60°N derived from the merged satellite data in the period 1979–2008

This paper deals with the behavior of the annual cycle of total ozone (ACO3) and its amplitude (O3_AMP) in the latitudinal belt from 20°N to 60°N. The prominent feature of the O3_AMP spatial pattern is the sharp maximum over the north-east coast of Asia. The spatial correlation of O3_AMP with its highest/lowest value varies with location: in the middle latitudes it correlates predominantly with the values of annual maxima of total ozone, while in the lower latitudes, there is a strong negative correlation with the values of ACO3 minima. Regarding temporal evolution of O3_AMP we detected distinct negative trend in the period of 1979–1995 which is caused by stronger negative trend of maxima than the negative trend of minima in ACO3. In the period 1995–2008 we found the positive trend of ACO3 in most regions due to stronger positive trend of maxima than that of minima in ACO3 in the middle latitudes (especially over the central and northern Europe and the north-east Asia). In the lower latitudes a weak negative trend of O3_AMP was identified and linked to weaker positive trend of maxima than positive trend of minima in ACO3. The behavior of the temporal trends was linked to the changes in Brewer–Dobson circulation and to the trends of tropopause pressure.