多体分离风洞自由飞试验

根据作者多年从事多体分离风洞自由飞试验的经验,对多体分离风洞自由飞试验技术的原理及特点、相似准则、试验装置等技术要点作了介绍,并根据技术特点及应用领域的不同对其进行了分类,对不同类型多体分离风洞自由飞试验的特点作了详细描述,并给出了不同类型实例的试验图像及分离体飞行轨迹曲线。     

Derivation and validation of a similarity law for free-flight wind tunnel tests of parallel stage separation

Aiming at the safety problem of the stage separation of parallel reusable high-speed air vehicles, this paper studies the unsteady test method and focuses on deriving a similarity law of parallel stage separation free-flight wind tunnel tests. The new similarity law considers the influences of aerodynamic force and gravity on the motions of the two stages, as well as the influence of aerodynamic interference between the two stages on each other’s motion. From the perspective of multi-angle physical equations, the conditions to ensure that the two-stage separation trajectory of a wind tunnel test is similar to that of a real air vehicle are derived innovatively, so as to ensure the authenticity and credibility of wind tunnel test results. The similarity law is verified by an HIFiRE-5 air vehicle, and the separation trajectories of wind tunnel tests and the real air vehicle are obtained by numerical simulation. The research shows that the similarity law derived in this paper can ensure that wind tunnel free-flight tests have the ability to predict the two-stage separation characteristics of real parallel vehicles. By analyzing the separation trajectory curve of the typical state, it is found that the new method can ensure that the trajectory error of a wind tunnel test does not exceed 1%, which indicates that this method is credible. The establishment of the new method lays the foundation for subsequent wind tunnel tests and provides support for research on the safety of the stage separation of parallel reusable air vehicles.     

某型飞机无动力投放模型自由飞控制律设计

针对某型飞机无动力投放模型自由飞试验中,由于受载机螺旋桨滑流影响,模型与载机分离后发生滚转、难以保证水平飞行的问题,根据模型自由飞试验不同阶段的飞行特点开发了专用控制律,具备直接链、投放控制、失速尾旋3种控制模态。论述了控制律的设计过程,以及在模型自由飞试验中的应用情况。试飞结果表明,该控制律很好地解决了模型与载机安全分离和大迎角水平飞行控制问题,提高了模型试验动作精准度。     

Optimization and verification of free flight separation similarity law in high-speed wind tunnel

Based on the similarity of separation time, a similarity law optimization method for high-speed weapon delivery test is derived. The typical separation state under wind load is simulated by the numerical method. The real separation data of aircraft, separation data of previous test methods, separation data of ideal wind tunnel test of previous methods, and simulation data of the proposed optimization method are obtained. A comparison of the data shows that the method proposed can improve the performance of tracking. Similarity law optimization starts with the development of motion equations and dynamic equations in the windless state to address the problems of mismatching between vertical and horizontal displacement, and to address the problems of separation trajectory distortion caused by insufficient gravity acceleration of the scaling model of existing light model. The ejection velocity of the model is taken as a factor/vector, and is adjusted reasonably to compensate the linear displacement insufficiency caused by the insufficient vertical acceleration of the light model method, so as to ensure the matching of the vertical and horizontal displacement of the projectile, and to improve the consistency between the test results of high-speed projection and the actual separation trajectory. The optimized similarity law is applicable to many existing free-throwing modes of high-speed wind tunnels. The optimized similarity law is not affected by the ejection velocity and hanging mode of the projectile. The optimized similarity law is suitable not only for the launching of the buried ammunition compartment and external stores, but also for the test design of projectile launching and gravity separation.     

大型飞机研制与模型自由飞试验技术

大型飞机研制过程中需要进行静态测力风洞试验,获得飞机小攻角条件下的气动特性,但对于飞机失速偏离尾旋研究,静态测力试验是不够的,无法获得飞机在失速过程中的动态特性与过渡过程。模型自由飞试验是一种动态试验,是通过飞机缩比模型来研究飞机的失速偏离尾旋问题,包括风洞模型自由飞试验和大气模型自由飞试验。     

高速风洞投放模型试验技术的关键问题及应用领域

基于高速风洞投放模型试验的经验,论述和总结了对试验技术的实际应用较为重要、且对试验结果有较大影响的几个关键问题：相似准则的选取问题、投放分离参数的模拟问题、风洞启动时流场对投放物模型的冲击载荷问题以及数据处理方法,分别对这四个问题的具体选取原则和处理方法进行了详细的总结和分析。重模型法能够确保模型投放轨迹的严格相似,但实用性较差;而轻模型法则正好相反。由于重模型法在实际使用中通常难以应用,因此轻模型法在风洞投放模型试验中获得了较多应用,但其模型垂直加速度不足的问题也需引起重视。投放分离参数的相似模拟,通常可通过采用弹簧或气缸提供的投放作用力来实现,弹簧具有简单、易行的特点,但模拟的准确性稍差;而气缸则正好相反。风洞启动时流场对投放物模型的冲击载荷问题常常能够影响到试验的顺利进行或影响试验结果。数据平滑处理可采用时间多项式拟合来实现,进而通过一次或二次微分获得气动力系数。对高速风洞模型投放试验的应用领域作了总结和介绍,将其分为飞机外挂物/内埋武器投放、子母弹抛撒/重块抛撒,以及头罩/导弹壳片分离三大类型试验,并对每一类试验在具体的试验技术,以及在上述几个关键问题上的特点分别作了介绍,给出了具体试验的图像和曲线。     

几种动态模型自由飞试验技术

目前在国外应用最广泛的动态模型自由飞试验技术包括三种方法，即：水平风洞模型自由飞，垂直风洞模型自由飞和露天投放模型自由飞，分析了每种方法的关键技术问题，比较三种方法的优缺点，说明在型号设计中应用范围。最后提出几点看法，并建议尽快建立必要的试验设施，研究试验方法，加速我国大迎角／尾旋动态模型试验技术的发展，为型号设计和航空科研服务。     

内埋武器投放分离相容性的风洞投放试验预测与评估

采用基于运动动力学相似的风洞投放试验对先进战斗机内埋武器投放分离相容性进行预测与评估，给出载机在不同飞行马赫数、攻角、弹舱长深比及舱内武器剩余数量、不同弹射力、折叠翼是否展开下，内埋导弹从载机弹舱投放分离后的运动轨迹和俯仰姿态角变化规律，研究这些因素对内埋导弹投放分离相容性的影响。结果表明：处于超声速飞行状态下（马赫数为1.5）的载机，攻角处于0°、2°、3°时投放内埋导弹后弹体俯仰角处于低头状态，利于攻击载机前下方敌方目标；在给定的初始分离条件下，对于两种不同的弹舱长深比，内埋导弹均能安全分离，但对内埋导弹俯仰方向运动影响较为显著；弹舱内武器剩余数量对内埋导弹分离特性影响较小，导弹能快速地远离载机干扰流场，投放分离后弹体俯仰角一直处于低头状态；随着内埋导弹初始分离速度增大，可使弹体快速地穿过载机的下洗流场，有利于内埋导弹与载机的安全分离；导弹的不同气动布局对内埋导弹分离相容性有一定的影响。     

地地战术导弹子母弹抛射与散布建模仿真

基于对子弹的抛射和末端弹道的物理过程建模进行了仿真计算,研究了各层子弹抛射速度、抛射延时给子弹分布带来的影响。结果表明,通过适当调整母弹弹道、抛射延时等参数,可以有效提高子母弹的覆盖面积。     

FL-23风洞级间分离与网格测力试验系统

近年来,随着飞行器研制不断高速化发展,一些型号要求在超声速条件下实现级间分离与网格测力试验。为了实现超声速飞行器级间分离与网格测力风洞试验,利用FL-23跨超声速风洞独有的投放机构,通过对上、下支撑及其控制系统进行改造升级,实现了X、Y两个方向的复合运动,建立了马赫数0.3～4.0的级间分离系统。经过多期型号试验验证,该系统对模型定位控制精度达到要求,满足飞行器高马赫数下开展级间分离与网格测力风洞试验需求。     

Conception of electronic wind tunnel and first results of its implementation

The problem of ensuring an ecological safety of modern civil and transport aircraft is directly related to the problem of aerodynamic efficiency. Ground-based tests have a wide spectrum of possibilities for investigations and for solution of the problems arising in these investigations. Ground-based aircraft tests are always characterized by the aspiration to test models of greater size in available transonic wind tunnels (TWT). In this situation, systematic errors caused by the influence of TWT test section Walls (TWTW) on a flowfield around model should be taken into account and excluded from the obtained results. This problem is extremely important for large transport aircraft models: in this case the requirements for the test data accuracy are especially stringent. Depending on the wind tunnel (WT) design peculiarities, this problem may be solved in different ways that are described in this article.     

风洞投放试验技术的研究现状与应用综述

多体分离是航空、航天和武器系统总体部门一直极为关注的关键问题,多体间的流场干扰效应产生的气动力和力矩对悬挂物分离相容性有重要影响,基于运动动力学相似的风洞投放试验技术是预测和评估多体分离是否相容的一种非定常试验方法。根据飞行器多体分离相容性的研究需求,结合作者在风洞投放试验技术的研究成果和经验,对风洞投放试验技术的国内外研究现状进行综述。首先回顾了风洞投放试验技术的发展历史,然后对低速和高速风洞投放试验的相似准则及缩比关系进行详细地论述与分析,进而对风洞投放试验的几个关键技术进行综述,最后对风洞投放试验技术存在的问题提出思考与展望。     

Experience in the use of computational aerodynamics to predict store release characteristics

In the early days, store separation tests were conducted in a hit or miss fashion—the stores would be dropped from the aircraft at gradually increasing speeds until the store came close to or sometimes actually hit the aircraft. In some cases, this led to loss of the aircraft, and made some test pilots reluctant to participate in store separation flight test programs.During the 1960's, the Captive Trajectory System (CTS) method for store separation wind tunnel testing was developed. The CTS provided a considerable improvement over the hit or miss method, and became widely used in aircraft/store integration programs prior to flight-testing. However, since fairly small-scale models had to be used in the wind tunnel tests, in many cases the wind tunnel predictions did not match the flight test results. No mechanism was then in place to resolve the wind tunnel/flight test discrepancies.During this same time frame Computational Fluid Dynamics (CFD) had finally matured to the point of providing a trajectory solution for a store in an aircraft flowfield. However, since the computational tools were necessarily (due to computer resource limitations) limited to linear techniques, and since most store separation problems occur at transonic speeds, these tools had limited application.Recent advances in computer resources have greatly improved the capability of CFD to predict store release characteristics. Instead of using linear or approximate schemes, time dependent Euler and Navier Stokes trajectories could be computed in a reasonable time frame.Three international CFD Challenges, held during the last decade of the 20th century, have shown that CFD can not only match wind tunnel test data, but also predict flight test trajectories for complex stores at transonic speeds. It appears that CFD has matured to the point that it can be usefully integrated into aircraft/store compatibility programs.     

子母弹不同舱段分离流场特性及运动特性研究

为研究子弹药在不同装配舱段下抛撒分离过程的干扰气动特性,以2层弹舱轴向排布子母弹系统为模型,基于有限体积法,结合非结构动网格技术,通过耦合求解任意拉格朗日欧拉(ALE)描述下的三维非定常可压缩N-S流体控制方程及六自由度刚体运动方程,对时序抛撒方式下子弹在不同舱段分离的三维非定常流场进行了数值模拟。得到了不同舱段下子母弹分离流场的干扰特性及子弹药气动参数变化曲线,分析了子弹分离过程的运动特性,揭示了子弹与母弹激波在不同分离阶段的相互作用过程。为进一步研究子母弹分离干扰流场机理提供了依据。     

小型通勤类飞机失速特性的自由飞验证试验研究

在对某小型通勤类公务机进行风洞实验预测时,发现飞机失速后其滚转特性会发生急剧变化。在分析该型飞机风洞实验结果的基础上,采用机翼加装失速条的失速特性方法,通过缩比模型自由飞试验进行飞行验证,分析在巡航构型和着陆构型状态下原始机翼和机翼加装失速条后的试飞结果。结果表明:缩比模型自由飞试验能够验证机翼风洞试验的预测结果,加装失速条的失速特性改进方法可以改善飞机失速特性。     

Aerodynamic characteristics of store during lateral jet assisted separation from cavity using free drop technique

Aimed at the problem of store separation from internal cavity, this paper innovatively puts forward a separation scheme of using lateral jet to assist store safe separation. The jet ensures that the store is continuously subjected to down head moment during separation, so as to ensure safe separation. The wind tunnel free drop test technique with lateral jet is established, which can ensure that there is no support interference in the motion process of the store and more truly simulate the motio...     

Initial virtual flight test for a dynamically similar aircraft model with control augmentation system

To satisfy the validation requirements of flight control law for advanced aircraft,a wind tunnel based virtual flight testing has been implemented in a low speed wind tunnel.A 3-degree-offreedom gimbal,ventrally installed in the model,was used in conjunction with an actively controlled dynamically similar model of aircraft,which was equipped with the inertial measurement unit,attitude and heading reference system,embedded computer and servo-actuators.The model,which could be rotated around its center of gravity freely by the aerodynamic moments,together with the flow field,operator and real time control system made up the closed-loop testing circuit.The model is statically unstable in longitudinal direction,and it can fly stably in wind tunnel with the function of control augmentation of the flight control laws.The experimental results indicate that the model responds well to the operator's instructions.The response of the model in the tests shows reasonable agreement with the simulation results.The difference of response of angle of attack is less than 0.5°.The effect of stability augmentation and attitude control law was validated in the test,meanwhile the feasibility of virtual flight test technique treated as preliminary evaluation tool for advanced flight vehicle configuration research was also verified.     

风洞虚拟飞行试验模拟方法研究

风洞虚拟飞行试验是把飞行器模型安装在风洞中具有三个转动自由度的专用支撑装置上,让三个角位移可以自由转动或者按照飞行器的飞行要求实时操纵控制舵面,来实现较为逼真的模拟飞行器真实机动运动过程,进而达到探索其气动／运动耦合机理的目的。发展风洞虚拟飞行试验,其模拟方法是必须要解决的核心理论问题。针对某典型导弹,开展了铅垂平面内三自由度俯仰运动的开环控制和闭环控制飞行仿真模拟,分析了风洞虚拟飞行试验和真实飞行之间的主要差异及其影响,研究了风洞虚拟飞行试验的模拟方法。结果表明：对铅垂平面内的三自由度俯仰运动,采用俯仰角速度反馈的经典三回路自动驾驶仪闭环控制方式,风洞虚拟飞行试验能够较为逼真地模拟真实飞行过程。     

风洞虚拟飞行模型机与原型机动力学特性分析

在低速风洞虚拟飞行试验系统中,采用三自由度（3-DOF）球铰支撑动力学相似缩比飞机模型,在气动力矩作用下试验模型可绕质心自由转动。这种带约束的运动与具有六自由度（6-DOF）的真实大气飞行存在差别,鉴于此,对各影响因素逐个剖离并进行了数值模拟和对比分析。结果表明：位移约束使两者间的动力学特性产生较明显的差异,缩比的影响符合相似准则规律,机构摩擦、模型重心与支撑点不重合影响较小,常值干扰力矩对模型的初始响应有一定影响。对比分析结果可以用于指导风洞虚拟飞行试验的开展,并有助于完善风洞虚拟飞行试验技术及其拓展应用。     

民用飞机进气道低速大迎角性能风洞实验和数值计算分析

为了研究民用飞机进气道在起飞低速大迎角状态下的流场特征和性能,对设计马赫数为0.785的进气道进行了风洞实验和数值计算,来流马赫数为0.2,迎角变化为0°～25°,流量系数为0.29～2.07.研究结果表明:在起飞工况条件下,进气道正常工作迎角可达到25°;在起飞单发失效工况条件下,进气道外罩上流动分离迎角在13°～1...