地效翼风洞试验支架干扰数值分析

对地效翼移动地面风洞试验研究中的支架干扰进行了数值模拟和分析。分别对独立地效翼,带支架的地效翼及独立支架进行了数值模拟,计算采用可实现的κ-ε模型,通过求解定常不可压N-S方程,得出地效翼及支架周围流场分布情况。对几组计算结果比较分析了支架和地效翼的空气动力及由于干扰引起的空气动力,发现支架与地效翼之间的相互干扰随着地效翼迎角的增大而增强,如果忽略流动干扰造成的空气动力变化,地效翼升力误差很小,但阻力误差相对较大。同时对有干扰下和没有干扰下的流场进行了对比,分析了支架对翼尖涡流动及绕机翼流动的干扰。翼尖涡在地效翼翼尖附近的发展在0．5犮范围内基本不受支架的干扰;除支架对流场产生干扰外,移动带区域以外的固定地面附近粘性流动也对绕地效翼流动有一定的影响。本研究分析了风洞试验结果的可靠性,为地效翼风洞试验优化设计和地面效应风洞试验研究提供了参考。     

基于高空风修正的四维航迹优化算法

航迹预测是基于航空器航迹运行的核心技术,也是空中交通流量管理的基础技术。结合航空器飞行速度数据与航段飞行时间数据,分析高空风对航空器飞行时间的影响。基于GRIB2格式风数据,建立高空风修正模型,提出一种四维航迹优化算法进行航迹预测。利用中南区域实际航班飞行数据进行算例仿真,并与实际雷达飞行数据进行对比。对比结果表明,预测飞行时间总误差分别减少了7%和16.4%,从而验证了模型的有效性与正确性。     

大展弦比飞机模型边界层转捩模拟技术

针对大展弦比飞机模型高速风洞试验需求,进行了边界层转捩模拟技术研究.研究表明:与传统的金刚砂粗糙带相比,柱状转捩带具有粘贴牢靠、可操作性强等优势,已经推广应用于大展弦比飞机模型高速风洞试验;边界层转捩对大展弦比飞机模型气动特性有重要影响,不仅影响阻力,而且对升力与俯仰力矩均有明显影响;在目前国内低雷诺数风洞条件下建议在边界层固定转捩条件下进行风洞试验,以提高风洞试验精度.     

直升机在风切变气流场中的响应特性

为了研究直升机在风切变气流场中的响应特性,基于相关文献,建立了风切变工程化模型。根据旋翼的非均匀入流模型,建立了直升机非线性动力学模型,并利用四阶龙格—库塔法,对某型直升机在风切变场中的飞行特性进行了数值仿真。研究结果表明:样机进入风切变场后,飞行姿态立即出现俯仰震荡、左右摇摆的现象,10 s内,侧倾角的峰值差最大达到了73.14°,直升机下坠的高度为53.19 m,偏航距离为93.79 m。     

1．2m×1．2m跨超声速风洞条带悬挂支撑天平研制

条带悬挂支撑天平是1．2m×1．2m风洞条带悬挂支撑测试系统中的重要组成部分,为确保天平研制成功,通过有限元分析仿真提出了一种“E”型天平新结构。天平有限元仿真、静态校准、动校和风洞试验结果表明天平结构合理,性能优良。     

翼尖支撑双天平校准技术研究

翼尖支撑测力试验技术采用两台天平同时对同一风洞模型进行测力,开展双天平校准技术研究是实现该项试验技术成功应用的关键。基于双天平测量机理,研究并建立了双天平校准技术：利用两台单天平的校准公式,根据空间力系合成原理和天平载荷分量干扰修正技术构建了双天平同时工作的公式。通过对某专用双天平的单独校准、组合校准及风洞试验,对提出的双天平校准技术进行了验证。结果表明：双天平校准技术合理、可靠,可操作性强,能够为翼尖支撑测力试验技术提供必要的理论基础和试验依据。     

Classification and quantification of solar wind driver gases leading to intense geomagnetic storms

Classification and quantification of the interplanetary structures causing intense geomagnetic storms (Dst?≤??100?nT) that occurred during 1997–2016 are studied. The subject of this consists of solar wind parameters of seventy-three intense storms that are associated with the southward interplanetary magnetic field. About 30.14% of the storms were driven by a combination of the sheath and ejecta (S?+?E), magnetic clouds (MC) and sheath field (S) are 26% each, 10.96% by combined sheath and MCs (S?+?C), while 5.48% of the storms were driven by ejecta (E) alone. Therefore, we want to aver that for storms driven by: (1) S?+?E. The Bz is high (≥10?nT), high density (ρ) (>10?N/cm³), high plasma beta (β) (>0.8), and unspecified (i.e. high or low) structure of the plasma temperature (T) and the flow speed (V); (2) MC. The Bz is ≥10?nT, low temperature (T?≤?400,000?K), low ρ (≤10?N/cm³), high V (≥450?km), and low β (≤0.8); (3) The structures of S?+?C are similar to that of MC except that the V is low (V?≤?450?km); (4) S. The Bz is high, low T, high ρ, unspecified V, and low β; and (5) E. Is when the structures are directly opposite of the one driven by MCs except for high V. Although, westward ring current indicates intense storms, but the large intensity of geomagnetic storms is determined by the intense nature of the electric field strength and the Bz. Therefore, great storms (i.e. Dst?≤??200?nT) are manifestation of high electric field strength (≥13?mV/m).     

不同条件下平面叶栅风洞流场品质的实验研究

为了全面认识亚声速平面叶栅风洞的流场品质及其影响因素,以西工大高亚声速平面叶栅风洞为研究对象,实验测量并分析了空风洞的来流品质以及安装叶栅实验件后来流马赫数、来流攻角、叶片数对叶栅流场准确性、均匀性以及周期性的影响。研究结果表明：空风洞内主流区域宽广且基本均匀,马赫数偏差不超过0.005,气流角偏差不超过；加装叶栅实验件后的周向流场分布表现出不对称,靠近可移动上侧壁的三个通道的来流均匀性和准确性普遍较差,叶栅中间和偏向可移动下侧壁的通道来流均匀性和准确性较好；来流攻角对叶栅进口流场品质的影响比马赫数更大,在负攻角和较小的正攻角下,叶栅进口流场品质较好；在较大的正攻角下,叶栅来流均匀性和准确性明显下降；叶栅进口流场品质直接影响着叶栅通道内以及出口流场的周期性。     

低速空降风洞试验的关键技术

低速空降风洞试验的一个重要目的是研究伞降人员在离机初期的运动姿态和空间轨迹，考察伞降人员的离机安全性。从不带伞空降风洞试验出发，分析归纳单次出舱和连续出舱空降风洞试验中的一些关键技术，包括试验方法的选取、相似参数的确定、空降模型的设计加工和调整技术、载机支撑方式和支撑干扰的影响、空降模型出舱姿态的控制、空降轨迹捕获和分析技术等。进而初步探讨带伞空降风洞试验的一些特有问题，旨在为进一步发展低速空降风洞模拟试验技术提供支持。     

Thermospheric winds over Abuja during solar minimum period

Monthly variations of averaged nighttime thermospheric winds have been investigated over Abuja, Nigeria (Geographic: 9.06°N, 7.5°E; Geomagnetic: 1.60°S). The reports are based on Fabry-Perot interferometer measurements of Doppler shifts and Doppler broadening of the 630.0 nm spectral emission. The results were obtained during a period of weak solar activity with the solar flux (F10.7) typically below 70 solar flux units. Inspection of the average monthly thermospheric winds from October 2017 to December 2017 found December meridional winds to be more equatorward than the October and November winds. Zonal winds are eastward with pre-midnight maximum speeds going above 100 m/s. Compared to Jicamarca zonal winds in the Peruvian sector for the same month of October, the magnitude of maximum Abuja zonal wind speed is weaker. We compare the observed diurnal variation with the recently updated Horizontal wind model (HWM 14). Most of the observational features of thermospheric wind diurnal variation are captured in the model variation. The HWM14 generally showed good agreement with the Abuja October and November zonal wind observations but overestimates the December meridional winds. Expected longer period analysis of the results from Abuja will stimulate a better understanding of wind climatology over the West African sector.