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当θc=10°之尖锥边界层出现转捩流态时,由于背风面与迎风面边界层转捩的不对称性所诱导的气动负荷,包括诱导法向力,诱导俯仰力矩,以及诱导法向力的作用点要随雷诺数而变化,转捩诱导法向力的存在,证实边界层转捩会在物面上诱导出压力增量,即存在着转捩诱导压力。 相似文献
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通过对有压力梯度下的边界层进行研究,模拟低压涡轮叶片表面边界层的发展过程,并分析了叶片表面不同负荷分布形式情况下吸力面边界层特性对雷诺数的敏感程度。计算中,分别采用了三种典型的涡轮气动负荷分布形式:后加载、前加载、均匀加载等,并分别模拟了三种不同的雷诺数下的边界层发展情况。结果表明:在同一雷诺数情况下,不同负荷分布形式吸力面边界层发展呈现出明显差异;而不同负荷分布形式下叶片表面边界层特性对雷诺数的敏感程度也不一样,相对而言,均匀加载形式对雷诺数的敏感程度最小,更适应低雷诺数条件下工作。 相似文献
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郝红武 《西安航空技术高等专科学校学报》2006,24(1):50-52
在研究理论力学及材料力学知识基础上,结合学生知识能力结构培养要求,提出了基于等强度梁的静载荷应力、冲击动载荷应力、动载荷系数及固有频率测定的综合验证性实验项目解决方案,该方案兼顾了静态与动态测试的特点和要求,说明了静态应力与动应力的关系,解决了学生人数增加和常规力学实验设备短缺的矛盾。 相似文献
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郑晓辉郭腾飞余圣晖 《民用飞机设计与研究》2014,(3):15-20
前缘缝翼、襟翼活动面及其支承结构的疲劳试验是民用飞机取证前要开展的一项重要工作。在试验中采用主动驱动和随动加载方法加载,不仅能缩小试验规模,同时可提高试验精度。国内某型机采用此技术成功进行了前缘缝翼、襟翼及其悬挂结构的疲劳试验。从试验件及其支承设计、系统构成和载荷与运行三方面,介绍了一种适用于大中型固定翼飞机前缘缝翼和襟翼的疲劳试验技术。 相似文献
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It is confirmed that tandem-blade configurations have potential to enlarge the flow turning in two-dimension(2D) studies. However, the potential of tandem blades to enlarge the design space for highly loaded axial compressors was rarely investigated in open literatures. The present work aims to show the capability of tandem blades to break the loading limit of conventional blades for highly loaded compressors. The 2D models of the maximum static pressure rise derived in previous work were valida... 相似文献
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以高亚声速压气机叶型为研究对象,利用数值模拟手段研究了不同雷诺数Re条件下叶片近壁面分离泡结构和边界层发展的内在关联,基于Denton损失模型,揭示了低Re下压气机叶型性能退化内因;在此基础上,通过叶型改型设计,获得两种不同载荷分布的新叶型,对比分析了载荷分布对分离泡结构和叶型流动损失的影响。结果表明,Re从1.2×10~6降低到1.5×10~5时,吸力面分离泡长度增加11.2%轴向弦长,此时叶型边界层损失略有增加,而叶型尾迹损失增加接近150%,分离泡强烈的"位移效应"导致尾迹损失急剧增加是低Re下压气机叶型性能退化的主要原因;采用前加载叶型能够促使转捩提前发生,同时降低流向逆压梯度,有效抑制分离泡的形成和发展,改善低Re条件下高亚声速压气机叶型的气动性能。 相似文献
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赵俊辉 《民用飞机设计与研究》2013,(3):41-45
介绍了民用飞机整体油箱的布局形式和耗油顺序对飞机重量重心的影响,并对燃油箱设计时需要考虑的转子爆破、油箱惰化及结构疲劳等问题进行说明;提出了三种采用不同油箱分离面但采用相同耗油顺序的燃油箱,重点分析了燃油保持在外侧油箱对机翼根部弯矩的卸载作用和飞机重心在燃油消耗过程中的变化过程,并举例分析了三种油箱布局对典型装载的限制情况,为选择油箱分离面和选择耗油顺序提供相应的参考。 相似文献
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Xavier Collilieux Zuheir Altamimi David Coulot Tonie van Dam Jim Ray 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The International Terrestrial Reference Frame (ITRF), as a realization of the International Terrestrial Reference System (ITRS), is represented by a set of station positions and linear velocities. They are intended to be used as regularized coordinates to which some corrections should be added to access instantaneous coordinates. The latest ITRS realization is the ITRF2005, which has integrated time series of station positions to form long-term solutions for the four space geodetic techniques. Currently, a purely linear model is used to parameterize station displacements in the estimation process, plus occasional discontinuities in case of earthquakes or equipment changes. However the input data have been derived without applying surface loading models and so surface loading effects are supposed to be embedded in the coordinates as measured quantities. We evaluate the effect of applying a posteriori loading corrections, which include the effect of atmospheric, non-tidal ocean, and continental water loading, to time series of positions estimated from Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Global Positioning System (GPS) data. We notice that they reduce about 50% or more of the annual signals in the translation and scale parameter time series of the SLR and VLBI techniques, except in SLR Z translation. In general, the estimated secular frame definition is negligibly affected and estimated positions and velocities are not significantly modified for stations that have accumulated a large number of observations. A multi-technique combination of such derived frames allows concluding that, for some cases, loading model corrections might degrade co-located station coordinates almost as much as they benefit them. However, most significant improvement of the estimated secular coordinates is observed for stations with less than 100 estimated positions as demonstrated with a multi-technique combination. 相似文献