掺氢比对微波瓣燃烧器燃烧特性的影响

为解决微尺度非预混燃烧中燃料同氧化剂混合慢、燃烧不稳定的问题,基于实验的方法研究了燃料掺氢以及微波瓣燃烧器对燃烧的影响,并将微波瓣燃烧器的燃烧温度同微圆管燃烧器进行了对比。在此基础上建立了微波瓣燃烧器以及微圆管燃烧器的三维仿真模型,研究了掺氢比对微波瓣燃烧器和微圆管燃烧器流场、火焰长度、燃料消耗率、燃烧产物以及燃烧温度的影响。研究结果表明:随着掺氢比的增加,微波瓣燃烧器中流向涡涡量以及射流核心速度不断提高,火焰长度、燃烧温度不断增加,OH,H2O质量分数的峰值逐渐增加,CO2质量分数的峰值不断下降,CO质量分数峰值变化极小。在同一掺氢比下,相比于微圆管燃烧器,微波瓣燃烧器能够使燃料同氧化剂提前反应且具备更长的火焰、更大的OH质量分数峰值以及更高的燃烧效率和燃烧温度。在掺氢比为50%时,微波瓣燃烧器的最高燃烧温度较微圆管燃烧器提高了110K。这表明微波瓣燃烧器和燃料掺氢的结合能促进微尺度燃烧,提高燃烧的稳定性。     

羽流问题研究概况

概要介绍了羽流研究的目的和意义，羽流研究的方法及国内外羽流研究的现状，阐明了用数值模拟的方法研究羽流问题的必要性和迫切性。     

轴向超声速通流串列构型弦长比对气动性能影响的数值研究

为避免高马赫数、大攻角来流引发的叶片颤振,将串列叶片技术引入到超声速通流风扇叶栅中,对其进行串列改型及气动性能研究。利用准二维数值模拟,对串列叶片前、后排叶片的弦长比参数进行了详细的对比研究。结果表明：影响气动性能的关键因素是后排叶片进口压力侧激波的落点,在本文研究条件下,随着弦长比的减小总压损失呈减小的趋势,当弦长比由0.99减小到0.43时,设计攻角下,15°折转角叶型总压损失可减小27%,30°折转角叶型总压损失可减小38%。进一步的研究表明,通过减小弦长比可有效控制后排叶片前缘斜激波在相邻叶片吸力侧的落点以实现损失降低,并且这种降低效应在小弯角叶型上比大弯角叶型更容易实现。     

中介机匣支柱尾迹效应诱发的高压压气机进口导叶共振现象在多级环境下的数值研究

为了解决某型燃气轮机高压压气机在进行数个小时试验后出现的悬臂式进口导叶断裂故障,以中介机匣与高压压气机进口级作为研究对象,采用约化方法在故障发生工况下进行了非定常数值模拟,得到了该工况下中介机匣内部的流场演化情况与作用在进口导叶叶身上的非定常气动力变化规律,结合叶片模态分析,对引起进口导叶疲劳断裂的原因进行了研究。结果表明：中介机匣支柱的尾迹效应是进口导叶受到周期性激励的主要原因。在故障发生工况下,钝体支柱流动尾迹的周期性激励频率与叶片自身一阶固有频率接近,导致高压压气机进口导叶产生共振,从而引起了叶片的疲劳断裂。     

火箭燃气喷流与弹体超声速绕流干扰流场数值分析

绕弹体的超声速气流与火箭发动机燃气喷流相互作用,在弹底部形成了复杂的干扰流场。应用四阶的ＭＵＳＣＬＴＶＤ格式,求解雷诺平均的Ｎ－Ｓ方程,对这一复杂流动进行了数值模拟,得到了流场结构随不同喷口压力比的变化规律。     

含潜入喷管发动机尾部流场冷流模拟

为了揭示含潜入喷管的固体火箭发动机尾部流动特征,按照几何相近和气动相似原则设计了通道为矩形的二维冷流实验模型,利用相位多普勒粒子分析仪（ＰＤＰＡ）对燃烧室尾部气流的时均速度和湍流脉动速度进行了测量。实验结果表明气流在潜入喷管入口上发生分离,再附点位于喷管前端部外侧,背部空腔内形成一个较为稳定的回流区,流场的轴向和横向湍流强度都比较大。     

Wake structure and similar behavior of wake profiles downstream of a plunging airfoil

Very limited attention has already been paid to the velocity behavior in the wake region in unsteady aerodynamic problems.A series of tests has been performed on a flapping airfoil in a subsonic wind tunnel to study the wake structure for different sets of mean angle of attack,plunging amplitude and reduced frequency.In this study,the velocity profiles in the wake for various oscillation parameters have been measured using a wide shoulder rake,especially designed for the present experiments.The airfoil under consideration was a critical section of a 660 kW wind turbine.The results show that for a flapping airfoil the wake structure can be of drag producing type,thrust producing or neutral,depending on the mean angle of attack,oscillation amplitude and reduced frequency.In a thrust producing wake,a high-momentum high-velocity jet flow is formed in the core region of the wake instead of the conventional low-momentum flow.As a result,the drag force normally experienced by the body due to the momentum deficit would be replaced by a thrust force.According to the results,the momentum loss in the wake decreases as the reduced frequency increases.The thrust producing wake pattern for the flapping airfoil has been observed for suffi ciently low angles of attack in the absence of the viscous effects.This phenomenon has also been observed for either high oscillation amplitudes or high reduced frequencies.According to the results,for different reduced frequencies and plunging amplitudes,such that the product of them be a constant,the velocity profiles exhibit similar behavior and coalesce on each other.This simi larity parameter works excellently at small angles of attack.However,at near stall boundaries,the similarity is not as evident as before.     

通用航空发展与军民融合培养飞行人才

介绍我国军民融合培养飞行人才的历史脉络,研究我国通用航空的发展对飞行人才培养带来的影响,提出了借鉴外国空军经验、大力普及航空知识、不断改进飞行员培训机制和模式,以及建立科学的飞行军官服役退役制度等措施,以实现飞行人才资源能军民共享、良性互动.     

飞行器阵风响应的CFD-6DOF仿真分析

飞行器在大气中飞行,不可避免地受到阵风的影响。阵风所附加的气动载荷引发飞行器飞行状态的改变,过大幅值的阵风影响飞行的性能与安全。针对这种状况,首先采用改进的Lamb-Ossen涡模型,建立尾涡形式的阵风场;然后采用基于CFD技术的非定常N-S方程求解,并在计算网格中引入"网格速度"来模拟阵风,对SWIM(Subsonic Wall Interference Model)尾涡中的定常气动特性进行验证;最后通过CFD-6DOF的耦合,对SWIM俯冲穿越尾涡场的飞行轨迹进行研究。结果表明:计算结果与实验值符合较好;SWIM在尾涡中飞行时出现抖动、下沉、改变飞行状态、剧烈翻转的现象,与实际飞行器进入尾涡中的轨迹特性类似。     

The AWIATOR airborne LIDAR turbulence sensor

The development and first flight tests are described of a short pulse direct measuring UV LIDAR for the measurement of gusts, turbulence and potentially wake vortices. The results of these stage 1 tests confirm that relative wind velocities can be measured with a standard deviation of below 10 m/s even at high altitudes with no appreciable aerosol concentrations. Operating the system under various flight conditions including rain, dense clouds, and clear air up to 24,000 ft was highly successful. Means to push the standard deviation below 1.6 m/s, foremost by increasing the laser output power and the efficiency of the light collecting system, are identified and quantified. Questions of instrument stability are addressed.