搜索到3557篇“ LEADING-EDGE“的相关文章
Aerodynamic characteristics of a pitching airfoil with leading-edge morphing
2024年
This paper focuses on the effect of the phase offset of Leading-Edge(LE)morphing on the aerodynamic characteristics of a pitching NACA0012 airfoil.Assuming an unstretched camber and using polynomial interpolation,an explicit expression for LE nonlinear morphing is proposed and implemented for the large pitching motion of the airfoil.Flow field results and aerodynamic forces are obtained by solving the unsteady Reynolds-averaged Navier-Stokes equations for both the airfoil’s pitching motion and LE morphing.Furthermore,the index of instantaneous aerodynamic power is used to quantify the work done by the airflow in a dynamic process.According to the instantaneous aerodynamic power and energy map,which denotes the energy transfer between the airfoil’s oscillation and flow field,the airfoil is subject to stall flutter.The results show that LE morphing with an optimal phase offset of 315°reduces the energy extraction from the flow field,suppressing the stall flutter instability.This optimal phase offset is effective at different pitching axis positions of the airfoil.The results signify that LE morphing can suppress stall flutter by advancing the occurrence of the first LE vortex and increasing the nose-down moment during the upstroke period.
Chaoyuan WENYuting DAIYuntao XUChao YANG
关键词:AERODYNAMICSOPENFOAM
Design optimization and testing of a morphing leading-edge with a variable-thickness compliant skin and a closed-chain mechanism
2024年
Climate warming and the increased demand in air travels motivate the aviation industry to urgently produce technological innovations.One of the most promising innovations is based on the smoothly continuous morphing leading-edge concept.This study proposes a two-step process for the design of a morphing leading-edge,including the optimization of the outer variable-thickness composite compliant skin and the optimization of the inner kinematic mechanism.For the compliant skin design,an optimization of the variable thickness composite skin is proposed based on a laminate continuity model,with laminate continuity constraint and other manufacturing constraints.The laminate continuity model utilizes a guiding sequence and a ply-drop sequence to describe the overall stacking sequence of plies in different thickness regions of the complaint skin.For the inner kinematic mechanism design,a coupled four-bar linkage system is proposed and optimized to produce specific trajectories at the actuation points on the stringer hats of the compliant skin,which ensures that the compliant skin can be deflected into the aerodynamically optimal profile.Finally,a morphing leading-edge is manufactured and tested.Experimental results are compared with numerical predictions,confirming the feasibility of the morphing leading-edge concept and the overall proposed design approach.
Zhigang WANGXiasheng SUNYu YANGWenjie GEDaochun LIJinwu XIANGPanpan BAOQi WUAndrea DA RONCH
关键词:KINEMATICSLEADING-EDGE
Investigation of non-uniform leading-edge tubercles in compressor cascade:Based on multi-objective optimization and data mining
2024年
Corner stall receives noticeable attention in the aeroengine field as an important phenomenon in highly-load compressors.Non-uniform leading-edge tubercles,as an effective method to delay stall,are introduced into the compressor.In this paper,the shape of leading-edge tubercles was controlled by a third-order Fourier function.To judge corner stall,a more precise stall indicator for compressor cascade with flow control methods was defined.Besides,the total kinetic energy of the secondary flow at large incidence was adopted as a parameter for stall evaluation to save computing resources.The results of multiobjective optimization reveal that the loss coefficient exhibited negligible variation at design incidence,while the total kinetic energy of secondary flow showed a significant reduction at large incidence,resulting in a substantial increase in stall incidence.In the optimal profiling cases,the stall incidencewas delayed from 7.9°to 11.6°.The major purpose of the research is to provide proper design guidelines for nonuniformleading-edge tubercles and uncover the flow controlmechanisms of leading-edge profiling.Hence,the geometric features that meet different optimization objectives were extracted through geometric analysis near the Pareto Front and through Self-OrganizingMap(SOM)dataminingmethods in the optimization database.Besides,flow field analysis reveals the flow control mechanism of leading-edge tubercles.The convex-concave-convex structure at the 0%-70%blade height region can form two branches of leading-edge vortex pairs that are opposite in the rotation direction to the passage vortex.The two branches of leading-edge vortex pairs mixed with the leading-edge separation vortex to form two stronger mixed vortices,which can effectively suppress the development of passage vortex and delay stall incidence.
Jiezhong DONGWuli CHUHaoguang ZHANGBo LUOTianyuan JIZiyun ZHANG
翼伞前缘的优化设计与气动分析
2024年
翼伞因其优秀的滑翔能力和气动性能在航空航天等领域有着广泛的应用前景,因此对翼伞的气动分析尤为重要。存在切口的前缘作为翼伞区别于机翼的重要特征之一,对翼伞前缘的分析及改进可以有效提升翼伞的气动性能。运用有限体积法对二维不可压缩雷诺时均Navier-Stokes方程进行求解,数值仿真数据与原始翼型试验数据基本吻合。计算结果表明:切口的存在干扰了翼型前缘的气流运动,具体表现在前缘上、下表面会有分离气泡的产生,降低了翼型的升力,同时大幅度提升了翼型的阻力;针对相同的切口,设计了前缘双唇部构型,并与原始切口翼型对比,改进的切口翼型在整个迎角范围内气动性能均优于原始切口翼型,前缘双唇部构型有效遏制了切口处分离气泡的产生,并在一定程度上延缓了切口翼型的失速。以上研究可为翼伞前缘的优化设计提供参考。
李重贤钟红恩李新峰
关键词:翼伞气动性能翼型
飞机前缘缝翼滑轨机构装配定位方案优化
2024年
飞机前缘缝翼机构是机翼的重要组成部分,其装配质量严重影响飞机交付和缝翼组件的互换性,其中滑轨与缝翼连接点处偏差对缝翼前缘装配整体控制目标偏差的贡献度较大,因此滑轨机构的装配定位精度有待进一步提高。针对飞机前缘缝翼滑轨机构的结构特点及装配方案,分别设计第一定位平面选择沿机翼展向平面和滑轨径向平面两种定位方案,对比滑轨定位精度差异,发现结果存在均值漂移现象,通过单因素分析方法找到滑轨交点孔均值漂移的原因,提出采用偏心衬套的装配定位方案进行改进,并通过装配偏差分析验证其有效性。结果表明:滑轨交点位置均值漂移的根本原因是装配偏差模型中存在非对称零件公差的设计,以滑轨径向平面为第一定位平面的偏心衬套方式可以改善滑轨定位精度,减少均值漂移情况。
胡瑾刘顺顾群飞赵亦希
关键词:均值漂移单因素分析
高速平板边界层中定常条带的前缘感受性被引量:1
2024年
来流湍流度较高时,自由流涡波可在边界层内激发流向条带结构,并引起边界层的旁路(bypass)转捩。本文采用调和线性化Navier-Stokes方程(harmonic linearized Navier-Stokes,HLNS)方法模拟平板边界层条带对自由流涡波的前缘感受性,并通过直接数值模拟验证了HLNS方法的可靠性。针对马赫数4.8的高速平板边界层,分析了零频涡波激发定常条带的前缘感受性过程及定常条带的演化规律。研究结果表明,边界层外的自由流涡扰动对边界层条带的发展存在持续的激励作用;对于固定展向波数的自由流涡波,法向波数为0时激发的条带幅值最大;自由流涡波的法向波数在小于临界角度时仅影响条带的幅值,而不影响条带扰动的形函数剖面。随着当地雷诺数的增加,条带的幅值演化和形函数剖面呈现出很好的相似性;当地无量纲展向波数β=0.18时,归一化幅值最大。
刘洋赵磊
基于神经网络的复杂前缘飞行器FADS系统冗余设计
2024年
嵌入式大气数据传感(FADS)系统基于飞行器表面压力测量解算迎角、侧滑角、马赫数、来流动压与静压等飞行参数,能够有效解决探出机体的空速管前缘无法适应高超声速飞行器在巡航阶段所面临的严酷气动加热问题,同时满足飞行器对隐身性能的需求。目前,关于神经网络方法及FADS系统用于复杂型面前缘飞行器的分析和研究工作较少。针对自主返回的高超声速飞行器在着陆阶段的亚/跨声速条件,考虑薄前缘和进气道部件等影响开展复杂前缘飞行器的头部FADS系统冗余设计和验证。在复杂前缘飞行器头部开设15个测压孔,通过大量精细化数值仿真建立飞行器在不同来流条件下的压力数据库,并利用风洞试验对典型工况进行验证。针对复杂型面前缘飞行器,基于压力数据建立4套神经网络算法并开展冗余设计研究,包括1套9孔算法与3套冗余算法。其中,9孔算法的精度较高,对迎角的解算误差在0.07°以内,对侧滑角的解算误差在0.3°以内,对马赫数的解算误差在0.0012以内,对来流动压与静压的解算相对误差均在1.5%以内。此外,建立具有一定容错性的系统解算流程,在任意单个测压孔失效的情况下能够继续保持来流参数的有效输出。
周印佳万千徐艺哲齐玢石泳
关键词:神经网络风洞试验
B737NG前缘缝翼指示故障保留对签派放行影响的研究
2024年
波音737NG经常会遇到飞机前缘装置位置指示故障保留,该保留会影响到飞机的运行限制、机组操作、管制指挥及应急程序等,评估不当容易出现超标准放行情况,发生不安全事件。本文从系统原理、MEL保留放行、放行依据三个方面进行论述,分析了该保留的衍生风险,总结该保留对运行的影响,对航班的安全、正常、高效运行具有重要意义。
赵擎
关键词:前缘缝翼签派放行
具有前缘凹凸结构的组合翼型优化设计及其气动特性分析
2024年
为了不断探索翼型改型的方法和提高翼型的气动性能,将传统翼型与生物翼型进行轮廓修型设计得到组合翼型,通过数值模拟的方法对组合翼型进行气动特性分析.同时,对组合翼型进行前缘凹凸结构优化设计,采用正交试验优选出气动特性表现最优的参数,并对最优前缘组合翼型进行气动特性分析.研究发现:相比标准NACA64-618翼型,组合翼型在小范围攻角有着较高的升力系数,升力系数最大提高了7.3%,此外,具有前缘凹凸结构的前缘组合翼型升阻比最大提高了9.98%.组合翼型的弯度前移使得吸力面负压峰值区域面积增大,翼型上下表面压差增大,进而提高了气动性能;前缘组合翼型由于前缘凹凸结构的存在,在翼型吸力面靠近尾缘处,形成一对反向旋涡,增加了流体在翼型表面覆盖的面积,抑制了流动分离的提前发生,进而达到失速延迟的效能.
陈坤贵红亮赵培尧冯文慧郝振华
关键词:气动特性失速延迟
零质量射流下波浪前缘叶片气动性能数值研究
2024年
针对垂直轴风机叶片大攻角工况下因流动分离导致的失速及颤振抖振问题,引入零质量射流激励对波浪型前缘叶片进行流动分离控制.采用大涡模拟方法建立了波浪前缘叶片绕流数值模型,探究了主/被动耦合控制下叶片升阻力特性及其流动分离机理,分析了射流参数(射流位置、动量系数)对波浪前缘叶片气动性能及失速特性的影响机制,研究发现:受控前后大攻角下波浪型前缘能诱导产生较小尺度流向涡,降低后方大分离涡尺度,波浪前缘与零质量射流耦合控制对于大攻角下流动分离抑制较单一控制更优;零质量射流吹气时使前缘流向涡有更高的动能抵抗逆压梯度从而延迟流动分离,吸气时会吸走流向涡的低动量流体,抑制流向涡发展成大分离涡;射流布置在距基准前缘0.033c处,即位于前缘流向涡最前端,能最大程度地参与前缘流向涡的生成,升阻比的提升效果最好;且升阻比提升量随着动量系数增大而增大,但控制经济性在动量系数0.018时最优,研究结果为垂直轴风力机失速控制提供了有益参考.
王家辉邹琳张毓辰苗亚博徐汉斌
关键词:零质量射流大涡模拟气动性能

相关作者

陈前
作品数:103被引量:336H指数:11
供职机构:南京航空航天大学
研究主题:隔振 分子 颗粒阻尼 故障诊断 隔振器