搜索结果: 136-150 共查到“航空器结构与设计”相关记录739条 . 查询时间(0.513 秒)
空空导弹固体火箭冲压发动机设计参数优化
超声速进气道 遗传算 优化设计
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2015/9/8
为使空空导弹在较宽的空域范围内获得优化的综合性能,提出了以导弹综合特性为目标函数来优化固体火箭冲压发动机设计参数的思路,以空空导弹在飞行高度分别为5,10km和15km的飞行距离和飞行速度的综合性能参数为目标函数,建立了固体火箭冲压发动机设计参数优化模型,利用遗传算法进行了固体火箭冲压发动机设计参数的优化.优化的结果表明:当参数选择适当时,采用非壅塞固体火箭冲压发动机的空空导弹在较宽的工作包线内也...
涡轴发动机加速过程中的寿命延长优化控制
SQP优化算法 涡轮静子冷却叶片温度
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2015/9/8
在涡轴发动机加速控制中,同时考虑发动机性能和寿命,优化加速控制策略,设计寿命延长控制.分析了加速过程中的气动稳定性、强度、燃烧稳定性以及功率等限制条件,采用序列二次规划法(SQP)优化算法进行加速控制中的燃油流量优化;根据燃气涡轮第1级静子冷却叶片温度最大值及其叶片型面与端壁的最大温差是影响发动机寿命的主要因素,采用两种寿命延长优化算法,一种是改变涡轮前温度的限制值,另一种是将涡轮前温度和动力涡轮...
轴对称矢量喷管有效喉道调节方法
调节方法 矢量偏转 落压比
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2015/9/8
基于三维雷诺平均Navier-Stokes方程对轴对称矢量喷管内流场进行了数值模拟,分析了不同落压比下轴对称矢量喷管有效喉道及流量系数随矢量偏转角的变化规律.研究发现:矢量偏转角超过一定值时,轴对称矢量喷管有效喉道位置发生倾斜,有效喉道面积减小,流量系数降低,矢量偏转角越大落压比越低,流量系数降低幅度越大.根据研究结果提出了一种针对矢量偏转状态的轴对称矢量喷管有效喉道调节方法,方法以落压比和矢量偏...
等离子体气动激励抑制机翼失速分离的实验
介质阻挡放电 流动控制 失速分离 机翼
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2015/9/8
进行了等离子体气动激励抑制机翼失速分离的风洞实验,研究了等离子体气动激励频率、电压、占空比和激励位置等对流动控制效果的影响.研究表明:在来流速度35m/s时,等离子体气动激励可以有效地抑制机翼大攻角下吸力面的流动分离,将机翼临界失速迎角由17°提高到19°;施加激励后,机翼最大升力系数提高了9.45%,阻力系数减小20.9%;激励频率在200Hz时,控制效果最好,对应的量纲一激励频率为1;迎角越大...
离心风扇非定常气动力和气动噪声特性数值研究
壁面压力脉动 声学有限元 单音噪声
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2015/9/8
将Lighthill方程转变为频域Helmholtz弱积分形式并采用Galerkin方法离散.基于声学有限元方法考虑声波在复杂固壁(叶轮和蜗壳)内的散射和反射等作用,利用Ffowcs Williams-Hawking(FW-H)方程耦合非定常流场计算结果数值预测了某离心风扇的噪声辐射,流场计算结果和蜗壳壁面动态压力测量结果在基频上吻合较好.结果表明:基频压力脉动分量在噪声源特性中占据主导地位且靠近...
采用排间界面静压约束伴随方法的多级压气机叶片优化
优化设计 排间界面 压强分布约束
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2015/9/8
为解决伴随优化应用在多级压气机中出现的优化工况点漂移问题,在前期薄层N-S方程伴随方法基础上,对目标函数——出口熵增不仅施以质量流量、总压比约束,还添加排间界面静压展向分布作为新的约束条件.以某5级压气机为对象,对其中第1级转、静叶分别在首1.5级和全5级压气机环境下进行了优化.结果表明,施加排间界面静压展向分布约束能够显著解决优化工作点漂移问题,优化后5级压气机的效率提高0.4个百分点.
2015年6月25日，中华人民共和国科学技术部社会发展科技司、资源配置与管理司组织专家对“十二五”国家科技支撑计划“基于近地飞艇的区域核化环境和生命迹象实时监测系统”（2011BAK16B00）项目进行了验收。验收专家组审阅了有关验收材料、听取了项目组汇报，进行了质询和讨论，同意该项目通过技术验收和财务验收。
Simulation of the Compressible Taylor Green Vortex using High-Order Flux Reconstruction Schemes
Compressible Taylor Green Vortex High-Order Flux Reconstruction Schemes
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2015/7/6
In this paper, we investigate the ability of high-order Flux Reconstruction (FR) numerical schemes to perform accurate and stable computations of compressible turbulent ows on coarse meshes. Two new F...
Studies of Wings Supporting Non-unique Solutions in Transonic Flows
Wings Supporting Non-unique Solutions Transonic Flows
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2015/7/6
Non-unique numerical solutions of transonic flows over airfoils have been found, first for potential flow equation, and later for Euler and RANS equations. The studies have also been...
Airfoils Supporting Non-unique Transonic Solutions for Unsteady Viscous Flows
Airfoils Supporting Non-unique Transonic Solutions Unsteady Viscous Flows
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2015/7/6
Non-unique numerical solutions of transonic flows have been found, first for potential flow equation, and later for Euler and RANS equations. The studies conducted so far have been m...
Robust Airfoil Optimization Using Maximum Expected Value and Expected Maximum Value Approaches
Robust Airfoil Optimization Maximum Expected Value Expected Maximum Value Approaches
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2015/7/3
Deterministic engineering design often leads to unexpected or physically unrealizable results. This is due to the fact that deterministic design is not able to capture the effects of even slight natur...
Further Studies of Mesh Refinement: Are Shock-Free Airfoils Truly Shock Free?
Mesh Refi nement Are Shock-Free Airfoils Truly Shock Free
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2015/7/3
The Garabedian-Korn airfoil is studied at its inviscid design condition and in the neighborhood thereof. This airfoil was designed with a hodograph method to be shock-free at M = 0.750 and Cl = 0.629....
Optimization of Flow Past a Moving Deformable Airfoil using Spectral Difference Method
Optimization Flow Past Moving Deformable Airfoil Spectral Diff erence Method
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2015/7/3
In this paper we examine the low Reynolds number flow past a harmonically plunging,pitching, and deforming airfoil, both individually and in combination. The lift and thrust characteristics of t...
Further Studies of Airfoils Supporting Non-Unique Solutions in Transonic Flow
Further Studies Airfoils Supporting Non-Unique Solutions Transonic Flow
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2015/7/3
Non-unique solutions of the Euler equations were originally discussed by Jameson in 1991 (“Airfoil Admitting Non-Unique Solutions to the Euler Equations,” AIAA Paper 1991-1625, June 1991) for several ...
A Computational Framework for Low Reynolds Number 3D Flapping Wings Simulations
Computational Framework Low Reynolds Number 3D Flapping Wings Simulations
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2015/7/3
This paper describes the work done in the development of a fast and accurate numerical solver for flows around flapping wings at low Reynolds numbers. In the first part, the fi...