Projectile Detection of Luminous and Nonluminous Bodies

In a large hyperballistics range, detection of projectiles atstations becomes more complex. Range length permits variation of projectile luminosity and requires greater area for detection. A technique has been devised, using electrooptics, triggering instrumented stations with luminous or nonluminous projectiles. The phototube circuit response, effect of velocity, and effect of light screen thickness on performance are discussed. Data on performance are presented for velocities of 10 000 to 21 000 feet per second. Performance is predicted for velocities of 40 000 and 60 000 feet per second. Nonluminous models as small as 3/16-inch diameter spheres have been detected at a velocity of 21 000 feet per second.     

吸气式高超声速技术研究进展

总结了中国空气动力研究与发展中心(CARDC)在吸气式高超声速技术在试验设备、超燃冲压发动机、数值模拟以及机体/推进一体化飞行器等方面的研究进展。介绍了三种类型的高焓设备:脉冲式燃烧加热风洞、连续式燃烧加热风洞和电弧风洞。通过多种尺度的超燃冲压发动机的直连式和自由射流式试验,获得了发动机的基本性能及其随油气比、喷孔位置等的变化规律。对比连续式和脉冲式风洞试验结果,得知工作时间大于100 ms的脉冲式燃烧设备是开展发动机基本性能研究的经济、高效试验手段。成功研制了三维大规模并行数值模拟软件平台AHL3D并广泛应用于发动机研究。在0.6 m风洞中,完成了1.5 m带动力飞行器试验,获得了发动机工作和不工作状态下的飞行器推阻及升力特性。     

航空发动机试车台附加阻力修正方法

附加阻力(进气冲量阻力和外部冲量阻力)是航空发动机试车台架推力的重要组成部分,准确地确定附加阻力对提高发动机试车台推力测量的准确性有十分重要的意义。本文对发动机总推力和试车台的对比标定进行了介绍,对发动机在露天试车台、室内地面台和高空台上附加阻力的确定方法和修正方法进行了详细地研究,给出了高空台与高空台、高空台与地面台的对比标定试验结果。      

空投雷弹入水冲击头型特性参数分析

针对目前雷弹头型的多样性和多种描述方式,从雷弹头部外型特点出发,在前人描述外型的无量纲参数基础上,重点分析了Baldwin和Waugh的特性参数的优缺点,提出一种更为合理的具有普适性的无量纲新型特性参数,可以普遍描述雷弹头型,并且根据其与入水冲击阻力系数的关系,给出尖拱体长细比与入水冲击阻力系数的关系式和新型描述参数与入水冲击阻力系数的关系式,可以方便地求出各类头型垂直入水冲击载荷的峰值,为尖拱族结构入水冲击载荷计算提供了一种便捷的方法,拓展了不同头型的结构体垂向入水冲击理论。     

A numerical optimization of high altitude testing facility for wind tunnel experiments

High altitude test facilities are required to test the high area ratio nozzles operating at the upper stages of rocket in the nozzle full flow conditions.It is typically achieved by creating the ambient pressure equal or less than the nozzle exit pressure.On average,air/GN2is used as active gas for ejector system that is stored in the high pressure cylinders.The wind tunnel facilities are used for conducting aerodynamic simulation experiments at/under various flow velocities and operating conditions.However,constructing both of these facilities require more laboratory space and expensive instruments.Because of this demerit,a novel scheme is implemented for conducting wind tunnel experiments by using the existing infrastructure available in the high altitude testing(HAT)facility.This article presents the details about the methods implemented for suitably modifying the sub-scale HAT facility to conduct wind tunnel experiments.Hence,the design of nozzle for required area ratio A/A*,realization of test section and the optimized configuration are focused in the present analysis.Specific insights into various rocket models including high thrust cryogenic engines and their holding mechanisms to conduct wind tunnel experiments in the HAT facility are analyzed.A detailed CFD analysis is done to propose this conversion without affecting the existing functional requirements of the HAT facility.     

Contributions to data transmission at critical moments on unmanned aerial vehicles

As for unmanned aircraft, the knowledge of the aircraft performance is directly related with the navigation, guidance, and control system programming. Therefore, the measured data in each phase of the flight must be sufficiently precise to obtain a good characterization of aircraft. This article proposes new methods of sending information to ground, which make it possible to know the aircraft behavior accurately, and for this purpose, four contributions have been made for ALO (Avión Ligero de Observación, Spanish acronym for Light Observation Aircraft). Currently, the characterization is based on data obtained at ten samples per second, insufficient to acquire detailed knowledge of what happened during the whole flight of an aircraft. As a result of these contributions, many more samples per second of accelerations and angular velocities are obtained at the most critical moments of the flight, such as takeoff or landing. Among the improvements included are data compression techniques, providing references to locate the measured data in time and identifying labels of each parameter.     

现代超临界翼型设计及其风洞试验

开展了现代超临界翼型的设计研究,对现役飞机的压力分布形态进行了分析,针对现役飞机在巡航状态和阻力发散点的压力分布进行对比,提取了现役飞机超临界剖面设计的要点。采用类函数/型函数变换(CST)参数化方法、基于二阶震荡及自然选择的随机权重混合粒子群算法(RwSecSelPSO)、雷诺平均Navier-Stokes(RANS)方程、Kriging代理模型结合定期望值型的目标函数建立了优化设计系统。针对提高阻力发散马赫数和降低巡航低头力矩的设计指标,利用优化设计系统通过调整目标期望值设计了一系列满足设计指标但阻力发散马赫数不同的超临界翼型,并选择了其中具有典型特性的翼型进行了对比分析,验证了提高阻力发散马赫数和低速失速特性的设计方法,指出了在阻力发散点形成平顶形压力分布的超临界翼型具有较好的综合性能。对设计的超临界翼型进行了高、低速风洞试验验证,试验结果表明:设计结果达到了设计指标要求,提出的低速改进方案有效,层流对超临界翼型失速特性影响较大。     

支板阻力特性实验

实验在超燃冲压发动机直连式试验台进行,燃烧式加热器出口气流马赫数为2.7,总温为1 337 K.利用推力测量系统对不同结构尺寸支板的冷流阻力和热试阻力进行了研究.比较了高度分别为37.5 mm和71 mm,后掠角分别为0°,30°和45°的支板冷流阻力,结果表明支板的冷流阻力随支板高度的增大而增大,随后掠角的增大而减小;实验还在燃烧模态下对不同当量比时支板的阻力进行了对比,结果表明支板的热试阻力比冷流阻力小,且支板的热试阻力随当量比的增加而减小.      

INS Simulator for Debugging INS/GNSS Data

The Inertial Navigation System's (INS) Simulator models in real-time are a data stream from INS describing a maneuver object's motion along the reference trajectory previously specified - the same trajectory which is used at same time for modeling a radio signal with GNSS Simulator. INS Simulator's specific features are as follows: converting the GNSS Simulator (coordinate and velocities of a rate of 1 Hz) data into the data of the autonomous navigation facility (coordinate and velocities of a rate of 100 Hz) with the addition of a selected model for INS error; possible synchronization of data streams against the external event (with an accuracy of up to 100 us)     

救生伞收口性能分析

通过对ACESⅡ弹射座椅所使用的C－9伞收口速度补偿曲线的理论。分析了救生伞采用收口技术后,＿能在高速状态下降低开伞动载,在低速状态下不降低最低安全高度的原因;并对国产ＨＴＹ－4型弹射座椅装备了收口的救生－13型伞后的性能进行了估算。假如收口阻力特征等于210m2、收口时间等于10ｓ则在3000m高度上开伞动载将减小40％;并论述了收口阻力特征和收口时间选取的原则。     

自然风条件下露天试车台推力修正的数值模拟研究

为研究航空发动机在露天试车台的推力修正方案,开展航空发动机在不同自然风风速(0到5m/s)、风向(0到90°)下露天试车的数值仿真计算。分析不同自然风条件露天试车发动机进气道周围和进气道气动交界面流场分布特点,发现已往基于测量二次气流的室内试车台推力修正方法无法用于露天试车台;通过内流法推导出适用于露天试车台的航空发动机进气附加阻力计算公式,在此基础上结合仿真结果计算露天试车台发动机进气附加阻力和台架迎风阻力,并分析的风速对各项修正阻力的影响规律,给出台架迎风阻力与环境风速之间的拟合关系式,研究不同风向的侧风对台架阻力的影响规律。研究结果为实际露天基准试车试验开展提供理论研究帮助,并为测量推力修正给予指导。     

About classical problems of airfoil drag

The drag of airfoils has long been determined from measurements in the wake behind the airfoil. The well-known formula of Squire and Young can be used to transfer the measured data to infinity downstream of the airfoil, where an exact relation to the drag exists. The Squire–Young formula is reviewed and an uncertainty in its derivation is discussed. A new formula of the same type is then derived, which also contains an uncertainty. This uncertainty can be reduced by experimental and numerical investigations of the wake displacement. Conversely, the displacement and the momentum of the wake must be investigated to reduce the uncertainty of the Squire–Young formula. In the second part of the paper, the determination of the drag directly by integration of the skin friction is investigated. Such a calculation is not difficult if the boundary-layer characteristics are computed numerically. An additional pressure drag must be regarded in this case. A new formula for the pressure drag is derived which shows that the uncertainty of the Squire–Young type formulas is contained in the evaluation of the pressure drag. This is another reason for further research on wake displacement.     

脊状表面航行器模型减阻特性的水洞实验研究

通过水洞实验研究具有横流方向的脊状表面航行器的阻力特性。运用三分力天平,分别对光滑表面航行器模型和脊状表面航行器模型在零迎角、不同水速下进行阻力测试,得到其减阻特性曲线。实验结果表明,脊状表面航行器模型具有很好的减阻效果,减阻量与脊状结构的特征尺寸、间距以及来流速度有密切关系。在实验工况内,最大减阻量达到11.7%。     

某运输机全机构型雷诺数效应阻力修正研究

采用CFD方法分析了雷诺数效应对某运输机全机构型阻力的影响。基于对某运输机的翼/身/架/舱组合体绕流进行的计算分析,归纳总结出了一种适应于复杂构型的低雷诺数到高雷诺数的阻力修正方法。通过验证可知,该修正方法修正效果良好,为工程中的阻力预测提供了一种简洁有效的方法。     

Prediction of aerodynamic characteristics of an aircraft model with and without winglet using fuzzy logic technique

This paper describes the potentials of an aircraft model without and with winglet attached with NACA wing No. 65-3-218. Based on the longitudinal aerodynamic characteristics analyzing for the aircraft model tested in low subsonic wind tunnel, the lift coefficient (CL) and drag coefficient (CD) were investigated respectively. Wind tunnel test results were obtained for CL and CD versus the angle of attack α for three Reynolds numbers Re (1.7×¹⁰⁵, 2.1×¹⁰⁵, and 2.5×¹⁰⁵) and three configurations (configuration 1: without winglet, configuration 2: winglet at 0° and configuration 3: winglet at 60°). Compared with conventional technique, fuzzy logic technique is more efficient for the representation, manipulation and utilization. Therefore, the primary purpose of this work was to investigate the relationship between lift coefficients and drag coefficients with free-stream velocities and angle of attacks, and to illustrate how fuzzy expert system (FES) might play an important role in prediction of aerodynamic characteristics of an aircraft model with the addition of winglet. In this paper, an FES model was developed to predict the lift and drag coefficients of the aircraft model with winglet at 60°. The mean relative error of measured and predicted values (from FES model) were 6.52% for lift coefficient and 4.74% for drag coefficient. For all parameters, the relative error of predicted values was found to be less than the acceptable limits (10%). The goodness of fit of prediction (from FES model) values were found as 0.94 for lift coefficient and 0.98 for drag coefficient which were close to 1.0 as expected.     

On The Stratospheric Measurements of Cosmic Rays

The results of measurements of cosmic-ray intensity in the Earth's atmosphere from 1957 up to now are presented. Balloon launchings performed several times a week at northern and southern polar latitudes as well as at midlatitudes yield a homogeneous data series for the study of the spatial distribution and temporal changes in the cosmic-ray intensity. The 11- and 22-year solar modulation, north-south asymmetry, energy hysteresis and a long-term trend in the cosmic-ray intensity are discussed. The fluxes and energy spectra of protons with energy > 100 MeV for about 100 solar energetic particle events in 1958-1992 are given. The role of cosmic rays in terrestrial atmospheric processes is briefly discussed.     

Instrumentation of a Pilot Counterflow Facility

In the VKF Counterflow Facility a small test model is launched upstream through the test section flow of a shock tunnel, thus producing relative velocities greater than that of either single component. This facility is presently capable of simulating model velocities greater than 30 000 ft/s (9.2 km/s) and altitudes from 50 000 to 200 000 ft (15.2 to 61 km). Instrumentation systems and components essential to the operation of this facility are described in this paper.     

湍流减阻新概念的实验探索

本文对当今湍流表面摩擦减阻新概念进行了初步的风洞实验探索。将垂直于流动方向的小尺寸肋条按一定的间隔距离固定在平板上,利用自制的悬挂式天平测量了不同风速时的阻力,获得了约１０．２％的减阻效果。实验中分别考察了肋条参数对减阻的影响,使用Ｘ型热线风速仪研究了雷诺应力的型态。从湍流边界层涡结构的观点出发,提出了边界层底部“微型空气轴承（ＭＡＢＳ）”减阻新概念以及涡结构干扰对减阻的影响,并认为平均速度型态的     

阻力伞及气囊气动特性风洞试验技术研究

对阻力伞、气囊等柔性减速器进行了风洞试验研究。采用高速摄像清晰地记录了阻力伞在M=1．0条件下的开伞过程、气囊在M=6．0条件下充气过程的外形变化，准确地测得了气囊在M=6．0条件下充气过程的阻力时间历程，且气囊充气过程外形变化的时间历程与阻力时间历程相符。此外，对阻力伞高速风洞试验的堵塞度影响进行了研究。结果表明，通过研究，为柔性减速器的气动特性测试建立了新的试验技术。