Complex automation of aerodynamic experiment in T-106 transonic wind tunnel

The system of complex automation of aerodynamic experiment in T-106 TsAGI transonic wind tunnel is presented. Data acquisition processes, as well as control processes for the model’s Mach number and angle of attack are automated on the basis of new data acquisition and control system involving IVK M2 data acquisition software package and VMIC control software package. The results of balance and pressure experiments (and of the combined ones) are presented. Stages of experimental results processing are described.     

Convergence to unconfined flow of the three-dimensional transonic self-correcting wind tunnel

The mixed difference method (ref. [1]) is used to investigate the convergence problem of the three-dimensional transonic self-correcting wind tunnel. The interior wind tunnel and the exterior unconfined flow-fields are described by the transonic small disturbance equation. In order to determine whether the unconfined-flow is obtained in the interior tunnel, two flow variables at a control surface are needed. They are the perturbation velocity components parallel to the free stream and perpendicular to the control surface. Their distributions are evaluated at the control surface for both the interior and exterior regions. The results of the numerical calculations indicate that after several iterations of one flow variable at the control surface the interior wind tunnel flowfield converges to the free-air flowfield.     

The use of computational fluid dynamics in TsAGI experimental works

The paper describes methods to calculate the flow around an aircraft model in a wind tunnel. It formulates special boundary conditions to achieve the necessary flow parameters in the control section, as well as to simulate some features of wind tunnel walls, for example, perforation. In order to accelerate the numerical solution convergence, a method for implicit smoothing is suggested allowing the calculation duration to be reduced several times. The cases of practical use of this methodology are given. It is shown that in the conditions of the TsAGI subsonic wind tunnel, it is possible to simulate the effect on the model from the elements of the structure that are missing in this tunnel, for example, the running track. A mathematical model of the European Transonic Windtunnel (ETW) with slotted walls is presented. It is shown that the flow in the reentry affects the main flow in the test section of this tunnel. Data on the effect of the model support in the TsAGI wind tunnel T-128 are given. The peniche height used in the half-model tests has been justified. The conclusion is made that the mathematical model of the wind tunnel is an obligatory part in experimental studies.     

基于多信号流图的亚跨超声速风洞故障诊断方法

为了在风洞系统发生故障时实现快速准确的诊断与定位,提出了基于多信号流图模型的风洞测试性建模方法;针对风洞结构复杂、解析建模困难等特点,首先通过分析系统组成与设备的功能结构对风洞进行了层次性划分,并根据实际运行中出现的故障情况得到了风洞关键设备的FMEA结果;而后以FD-12亚跨超声速风洞为研究对象建立了系统的多信号流图模型,利用故障模式与测点对应关系建立了相关性矩阵;最后采用TEAMS-RT算法对系统的测试性水平进行了分析和评估,验证结果表明该方法对于风洞系统的测试性建模与故障诊断是有效的,为风洞系统健康管理相关研究提供了参考。     

Numerical study of the injection process in a transonic wind tunnel: The numerical details

Numerical prediction of an injection process was successfully performed. The physical problem corresponds to the mixing of a number of parallel supersonic jets with a subsonic main stream, in the presence of solid walls. In practice, this arrangement is to be used as a boosting device in a transonic wind tunnel, with the ultimate objective of extending the tunnel’s envelope without penalizing the main compressor. Five supersonic nozzles are installed at the floor and five at the ceiling of the transition module’s entrance section. Due to the great difference between cross-sectional typical lengths of nozzles and tunnel, the numerical tool has to have a three-dimensional capability. The core of the code is an adaptation of the finite-difference diagonal algorithm, and turbulence effects are properly tackled by the use of the Spalart and Allmaras one-equation scheme. Some simplifications were adopted in order to render the problem minimally tractable, especially in this initial numerical simulation stage, which is the reporting objective of this article. Albeit this, and due to the magnitude of the problem in hand, these simplifying initiatives were not sufficient to bring the calculations down to a scale of reasonable computer costs. Hence, a sequence of grids, coupled with a division of the computational domain, was adopted. Boundary conditions were thoroughly worked, especially the ones related to the domain of calculation’s entrance plane. This plane is important because of the many viscous gradient regions that project against it. Among the many settings under which a tunnel can operate there is one defined as the “design condition”, or else as the “design point”, as it is sometimes called. For a tunnel equipped with an injection system, the design point asks (besides many other specifications) for equal static pressures at the section where the supersonic jet meets for the first time the main stream coming from the tunnel circuit. We have simulated five different operating settings of the tunnel and among them the design condition. Therefore, we have results for the design as well as for many off-design points. The idea was to simulate the many tunnel settings and also to test the code’s ability to handle all these different situations. The code was duly validated and verified, and in the sequel the steady flow field in the mixing region was calculated. Many interesting and very important results were obtained, among which we would point out the existence of compression and expansion domes at the supersonic regions, the calculation of the many engineering parameters related to the injection process, and especially the determination of the injection’s gain threshold.     

Numerical study of the injection process in a transonic wind tunnel. Part II: The off-design points

For many years now, injection has been of great utility in the wind tunnel activity. Sometimes injection is the sole source of power. Other times it is used in an auxiliary fashion in conjunction with the main compressor. This paper focuses on this last instance. In a transonic facility, some supersonic injectors are installed at the entrance of the transition section, with the ultimate aim of expanding the Reynolds number envelope without demanding extra power of the main compressor. The objective of this work is the numerical investigation of the mixing process between the supersonic streams coming out of the injectors, and the tunnel main subsonic current. In a first part of this reporting, the present authors have advanced the basic information, and discussed the results for the physical situation that was designated as “the design point”. This corresponds to a setting such that, exactly at the entrance of the mixing section — where the two flows start to interact —, the static pressures of the two mixing streams are equal. To obtain such state, one acts upon the stagnation pressure of the supersonic nozzles. The design point corresponds to a working condition, for which, in principle, losses are minimized. The aim of the present paper is to report upon a set of conditions that we refer to as the “off-design points”; here, the initial static pressures of the two currents are not equal. Besides investigating these new settings, many comparisons with the operation at the design point are also performed. Initially, an overview of the flow field for all cases is presented, and attention is called to the expansion and compression domes, that now, for the off-design points, are much more illustrative. After that, a thorough study is undertaken comprising the mixing layers growth behavior, and the performance of the mixing chamber in terms of pressure losses, overall gain and efficiency. As a consequence of these analyses, the nozzles stagnation pressure for a zero gain was obtained. This is an important result, because it represents the threshold for the efficient use of the injection process.     

风洞系统非线性块状结构模型

本文将非线性块状模型的建模思想引入风洞系统模型的建立过程中,针对主排气阀和栅指电液伺服机构具有死区非线性特性,分别用含有死区输入的Hammerstein块状模型描述其动态特性,将主排气阀和栅指机构的输出作为风洞流场的输入,建立两输入两输出多变量耦合动态模型.两个独立的Hammerstein子模型与线性动态耦合的风洞流场模型串联构成一个非线性多变量块状模型.采用自适应加权递推辨识算法在线辨识Hammerstein子模型参数,采用带有遗忘因子的递推最小二乘法辨识风洞流场模型参数.仿真与风洞现场测试结果验证了本文方法的有效性.     

Current status of computational methods for transonic unsteady aerodynamics and aeroelastic applications

The current status of computational methods for unsteady aerodynamics and aeroelasticity is reviewed. The key features of challenging aeroelastic applications are discussed in terms of the flowfield state—low-angle high speed flows and high-angle vortex-dominated flows. The critical role played by viscous effects in determining aeroelastic stability for conditions of incipient flow separation is stressed. The need for a variety of flow modeling tools, from linear formulations to implementations of the Navier-Stokes equations, is emphasized. Estimates of computer run-times for flutter calculations using several computational methods are given. Applications of these methods for unsteady aerodynamic and transonic flutter calculations for airfoils, wings and configurations are summarized. Finally, recommendations are made concerning future research directions.     

风洞试验角度机构校准方法研究和系统建立

为了对风洞试验角度机构进行准确校准,研究校准方法,包括校准项目、校准技术要求、校准器具和小确定度评定等,建立校准系统,进行校准试验,正确评价风洞试验角度机构的技术性能。     

高速风洞微型测量系统研制及应用

研制了一种高速风洞微型测量系统,由电气接口模块、增益控制模块、低通滤波模块、扫描采集模块、主控模块、LAN总线接口模块组成,实现了电压信号放大、低通滤波、模数转换、数据处理与分析等功能,静态校准结果表明关键性能指标与风洞常规测量系统相当,满足风洞试验信号采集需求。将该系统成功应用于2.4米跨声速风洞标模测力试验,开展了对比试验以及测量精度试验,并与常规测量系统试验结果进行了对比,试验结果表明微型测量系统精度和稳定性满足试验要求,能够适应高速风洞应用环境。     

ExVis and wind tunnel experiment data

Visualization specialists and aeroscientists at NASA Ames collaborated in investigating how information technology can improve the aeronautical design process. The author discusses ExVis software tool created to support interactive display and analysis of data collected during wind tunnel experiments     

结冰风洞试验段转盘控制系统设计与应用

结冰是飞机的重大安全隐患,结冰风洞是研究飞机结冰与防除冰的地面试验设备,飞机模型安装在试验段转盘上,通过精确控制转盘带动模型旋转模拟姿态变化;研制了适用于低温、低气压、高湿度环境的转盘机械机构;设计了以317T-CPU、IM174模块和交流伺服的转盘控制系统总体方案,开发了功能完善的转盘监控软件;通过参数优化、主从偏差控制和全闭环位置控制,实现了3个试验段5套转盘机构单转盘、上/下或左/右转盘高精度同步控制;解决了特殊环境下转盘控制系统运行维护问题.转盘控制系统运行超过8年,转盘角度范围±180°,转盘角度和同步控制精度不低于0.02°,各项技术指标达到设计要求,保证了结冰风洞各项试验任务顺利完成.     

Optotrak系统在风洞模型变形与姿态测量中的应用研究

风洞试验中模型的变形量与空间姿态角是非常重要的参数,变形量可用于CFD修正,而模型姿态角的准确度直接影响到试验数据的质量和特性.为了准确获取这些参数,介绍了一种基于三线阵CCD交汇原理的光学测量设备——Optotrak系统,以及应用该系统开展的测量试验技术.通过在沿翼展方向的多个剖面上安装Marker点,获取模型在不同...     

风洞试验绳牵引并联支撑系统自适应滑模控制

针对绳牵引并联支撑系统在风洞试验中的应用,提出一种自适应滑模控制方法以提高飞行器模型动态试验的运动精度.首先,详细分析了系统不确定因素,并重点考虑了气动力与绳弹性变形的影响,重构了系统动力学方程;基于奇异摄动理论,提出一种复合控制律,其中对慢变状态量采用自适应连续非奇异终端滑模控制,对快变状态量采用微分控制;通过李雅普诺夫函数法对系统的稳定性进行了分析,确定了控制律中微分增益项的影响.最后,以两种典型的动态轨迹为例,考虑气动力建模,对所设计控制律进行多参数仿真分析.结果表明该复合控制律可以减小绳弹性以及气动力等不确定性参数对跟踪误差的影响,提高运动控制精度,因此该控制方法有效可行,可为绳牵引并联支撑的动态试验应用提供理论指导.     

基于MSP430F5529的简易风洞控制系统设计

基于MSP430F5529设计了一个简易风洞控制系统。选用超声波传感器检测乒乓球在简易风洞中的位置,微控制器MSP430F5529通过对乒乓球当前位置的分析判断控制直流电机的转速,从而完成对乒乓球升降高度的实时控制。     

低速增压风洞风扇段温度监控系统研究

介绍了在低速增压风洞安全连锁系统中对风扇段轴承进行温度监控的监控系统。它是针对低速增压风洞内部的高压力、高雷诺数、多连锁节点的特点,基于单总线建立的温度监控系统。此监控系统由6只温度传感器组成,采用单总线方式,通过温度采集仪并入风洞安全连锁系统中,在满足监控精度的同时避免了多传感器带来的系统布线,有效地满足了风洞对高压力密封性多节点同时监控的要求,并保障了风扇段轴承温度监控数据的可靠性。     

基于CompactRIO的风洞喷管执行器位置监测系统开发

针对大型超声速风洞喷管设备,采用Compact RIO模块化仪器架构和LabVIEW开发平台,通过传感器、数据采集卡及上/下位机软件实现了对喷管执行器位置数据的采集、状态显示、分析、存储和预警等功能。利用该系统对2米超声速风洞喷管执行器进行监测分析,实验表明,该系统能实时显示喷管型面工作状态,及时判断故障产生的位置和超限情况,满足了执行器位置监测的实际需求,为操作者提供了有效的监测工具,提高了风洞喷管运行的安全性和可靠性。     

基于单片机的风洞模型姿态控制系统设计

传统的角度控制均采用旋转编码器,虽然技术成熟,但价格昂贵;本文介绍选用自整角机及其变送器代替传统的光电编码器,通过两个步进电机实现模型姿态的控制.应用单片机作为控制器,实现对实验模型攻角和侧滑角的改变,角度变化范围分别可以在-15度到 20度、-180度到 180度,系统最后控制精度和测量精度均为0.5度.     

基于DSP的杆式风洞天平实时动态补偿系统

杆式应变天平是一种六维力传感器,在风洞试验中测量飞行器模型所受的各个方向的力和力矩。但是,其动态响应超调量大,调节时间长,无法满足动态测试的要求。选用数字信号处理器(DSP)TMS320F2812,研制了一种实时动态补偿系统,实现对应变天平六路输出信号的动态补偿,加快应变天平的动态响应速度。     

环形低速风洞自动控制系统设计及其测量不确定度评定

为了满足矿用风速传感器的快速、准确、自动化检测和矿用气体传感器风速影响测试的需求,设计了一种环形低速风洞自动控制系统。该系统采用PLC为主控单元,根据风速与静压差的关系,通过对大气压力、空气温度、静压差的自动采集与计算,利用PID控制模块对变频器进行快速控制,最终通过控制电动机转速的变化,实现风速的自动输出。以检测GFY15矿用风速传感器为例,对测量过程中的皮托管、自动控制系统、风洞风速的不均匀性、不稳定性和流场紊流度等的不确定度进行了分析评定,结果表明,该自动控制系统能够满足矿用风速传感器自动化检测的需求。