low-and high-speed flight experiments on transition detection.doc

low-and high-speed flight experiments on transition detectionThis paper describes in flight measurements in low and high speed experiments to investigate laminar-turbulent transition on airfoils. The low-speed experiments were carried out using a laminar wing glove for a sail plane . High speed experiments on an modified A320 hybrid laminar fin were conducted in close collaboration with Airbus. Different surface sensor measuring techniques (piezofoil, surface hot wires, wall microphones) were used in the low-speed experiments. The piezofoil technique was applied in the high-speed in-flight experiments to prove the operation（手术, 行动，活动, 操作） robustness （强度(坚固性）, the functional capability , durability , and reliability under atmospheric conditions（大气状态） in cruise flight on modern airplanes . all measuring techniques were successfully implemented for the particular task and the laminar-turbulent transition was detected with a high degree of certainty. investigations a complete piezofoil sensor array was glued directly to the fin without causing any interference between the boundary layer flow and the sensor foil. This technique therefore offered the good potential to detect transition in the boundary layer under flight conditions especially in high-speed tests.摘要 该报告介绍了如何在高、低速飞行试验条件下，测量翼剖面层流-紊流的转变。低速试验用层流翼套套在一架滑翔机上完成，高速试验（在一架与空客合作的）改装的A320混合层流垂尾上完成。低速试验应用(piezofoil、表面热导线、墙壁麦克风)三种表面传感器测量技术。采用一种压箔技术验证了现代飞机在高速飞行中的操作强度、机动能力、耐久性和可靠性。该项任务中，成功地采用了全部测量技术，测出的层流-紊流变化高度可靠。For the high-speed 高速试验中，将一个完整的压箔传感器阵列直接粘在垂尾上，克服了附面层流和传感器箔之间的任何干涉 。这种技术适用于飞行条件特别是高速飞行试验条件下，检测边界层层流的变化。I introductionThe investigations presented in this paper are aimed at finding the laminar turbulent transition in the boundary layer on an airfoil, particularly the spatial development and growth of flow instabilities such as Tollmien - Schlichting(TS) waves that lead to transition1介绍本文调查的目的是为了寻找在翼剖面界面层层流-紊流的转变，主要是研究在空间发展和不稳定流的成长如Tollmien-Schlichting型扰动It is well known that the generation of TS waves strongly depends on the environmental flow conditions.众所周知, 产生一次TS波 极其需要依赖环境流量条件。It is therefore necessary to investigate the transition under real flight conditions as well as in wind-tunnel tests.因此很有必要, 探讨实际飞行条件和风洞测试的转换。Based on the experience gained in the Deutsche Forschungsgemainschaft-funded university group research project 1-3,where various measuring techniques for in flight experiments were developed , this paper focuses mainly on measurements with polyvinylidene fluoride(PVDF)-SENSOR ,surface hot wires as microphone sensor arrays and their feasibility to investigate and detect natural in flight experiments.由于德国科技协会基金会在大学群体研究项目1 - 3积累了大量经验,他们在飞行试验领域的测量技术有了发展, ,本文主要关注测量聚偏二氟乙烯(PVDF)-传感器、表面热导线作为微声阵列传感器,其次是它们的可行性研究和自然检测飞行试验。For industrial applications in the control of transition, for instance, a simple, robust and consistent measuring technique has to be developed and tested .过度控制已经被应用在工业中，例如, ,一个简单的,稳定连续的测量技术已经发展和测试中。This was only one reason for the A320 hybrid laminar fin (HLF) program, which was initialized by Airbus in the 1990s. 这也是空中客车公司在90年代初步展开行A320层流鳍(HLF)计划唯一理由。The program was multinational as well as multidisciplinary including the extraordinary cooperation of industry, research establishments, universities and suppliers, as an essential part of the overall laminar flow research activities within Europe 4, 5. 这个计划是多国家多学科的合作，作为欧洲层流研究活动的主要组成部分，它由的包括非凡的行业合作,研究机构,大学和供应商组成4, 5.Besides the scientific interest in the understanding of flow physics including transition mechanisms, both technical and managerial objectives were involved. 除了科学上对流体物理的兴趣,包括过渡的物理机制，它还有的技术和管理等方面的目的。First of all, the A320 vertical tailplane fin was modified in a way to establish laminar flow over the fin box without modifying the box itself. 首先, 为了在翼盒安装层流而不改动盒子本身，A320系列立式tailplane鳍被修改。 Furthermore, a suction system was built into fin nose to induce the hybrid laminar flow.此外, 在翼鼻安装了吸入系统 来感应混合层流流动。 Then measuring techniques based on experience gained in earlier wind-tunnel experiments were adapted for the A320 HLF. 然后利用早些时候的风洞测试得到的经验而改进的测量技术,非常适合于实验A320 HLF。Among others, an infrared camera, a traversable wake rake, hot films, an array of PVDF sensors, temperature probes, and pressure tap were used to control and monitor the flight experiments6.控制和监控飞行试验还用到了红外线摄影机,横穿尾流耙、热电影,一阵列PVDF传感器、温度传感器、测压孔等技术。The pvdf-sensor array , which could detect the laminar-turbulent transition on the fin, was applied by the Berlin Institute of technology.柏林理工学院应用pvdf-阵列传感器技术,可成功的检测到翼的层流- 混流的转换,Therefore ,it could demonstrate the success of the suction system also . this paper will show the results of the high speed tests with the pvdf-foil technique at the A320HLF .因此,它验证吸力系统成功的应用。本文展示pvdf箔片技术在A320HLF高速试验的成功验证These result will be compared with the results from the low speed experiments on the Twin laminar wing glove with respect to the potentials of the pvdf measuring technique. 这些结果将与Twin 的层流翼型的附面层低速试验结果进行对比从而得出pvdf的测量技术的潜力。2experimental setup 实验装置laminar wing glove, which was developed for the glob g103 Twin two-seater sailplane at the Institute for Aeronautics and Astronautics.层流翼型的附面层,是美国航空航天学会为Twinglob g103的双座(小型)滑翔机开发的。Berlin Institute of technology, was used for the low-speed in flight measurement(Fig.1). 柏林理工学院,将其应用于低速飞行测量(图1)。The measuring glove has a 2-d center part with a 1.0 m span and a chord length of 1.22m. 测量附面层 的二维中心部分宽1.0米，弦长1.22米。It has an exchangeable wing segment that was equipped with different surface sensor or actuators. (One sensor setup is shown in fig .5. )它的一个交换翼段安装了不同的表面传感器及其执行机构。(一个传感器安装图5。)。An array of 69 pvdf sensor was used .他还使用了一个阵列69式 pvdf传感器。A streamwise line of 17 sensor was located from 40 to 50% of the chord length to measure TS instabilities as a criterion for the different stages of transition. 在弦长的40 50%的地方有17个传感器安装在一个流向线方向，来测量TS不稳定度以作为不同阶段的变化标准。Four additional rows of 16 sensors each arranged in（） the spanwise（翼展方向的） direction were employed. 另外还使用了16个压力传感器，这16个传感器分成四列。The first spanwise piezosensor row was located at 46.3%and the fourth row at 49.6% of the chord length there were 1 4 mm between each row and 7mm between the spanwise sensors. 第一列位于弦长的46.3%处 第四列位于弦长的49.6%处 有每列相距1 4毫米，每个传感器之间相距7毫米。 Furthermore, surface hot wire and microphone sensor arrays were used on this glove. 再者,附面层还使用了 表面热丝 和微声阵列传感器。The flight experiments at the sailplane were mostly carried out at flight velocities from 22 to 30m/s , resulting in a chord Reynolds number of 1.7*106rec2.4*106 飞行试验时,(小型)滑翔机的飞行速度在22 - 30 米/秒之间,数据 是弦雷诺数在170 * 10 6 Rec 240 * 10时测出的。The measurement system (Sec.3.A) is located in the equipment support underneath the glove .测量系统(Sec.3.A)安装在附面层的下面的设备支架上。A Prandtl tube, which is also attached underneath the glove, is used to measure the freestream velocity.用来测量自由流速度的一个普朗特管,也一同附加 在附面层的下面。Because the angle of attack of a sailplane directly corresponds to the flight velocities by a defined wing loading, a certain flight velocity can describe the boundary conditions on the wing and on the glove, respectively.因为(小型)滑翔机的迎角直接符合 飞行速度下的翼加载，一定飞行速度 能 描述 机翼和附面层各自的边界条件 对。The difference in pressure between two pressure taps on the glove s top (px1,x2:x1/c=37.2%,x2/c=52%)are measured to get a second indication of the boundary conditions beside the freestream velocity.通过测量附面层顶端两测压孔之间的压力差(px1、2:x1 / c = = 37.2%,x2 /c= 52%) 我们可以获得第二组边界条件下的自由流速度的读数。The pressure different and the corresponding freestream velocity with a certain wing loading was measured in all flights.在航行过程压力差、自由流速度与翼加载在航行过程中将一次测出。Figure 2 shows this correlation between the pressure different (cp) relating to the freestream velocity(u8) for some flights.图二描述了某些飞行中压力差和自由流速度的联系。A thermocouple and a manometer were used to measure the air temperature and the absolute atmospheric pressure.实验中我们还用一个热电偶和压力计来测量空气温度和绝对的大气压力。Those parameters are continuously recoded to monitor the freestream boundary conditions. 这些参数经过连续编码来监测自由流的边界条件。The flight tests were performed in very calm air in the mornings or in the late afternoon.飞行试验一般是在上午或黄昏无风的时候进行。The freestream turbulence level itself was not measured in these tests.而自由流湍流的等级本身没有测试。Most flights tests with the laminar wing glove were carried out at a freestream velocity of 23.6m/s.安装有层流翼附面层的绝大多数测试都是在自由流速度23.6米 /秒进行的。For this velocity the sensor setups were applied on the glove.附面层安装有速度传感器装备。Figure 3 shows the velocity distribution of the gloves top side for in flight measuring and a calculated velocity distribution (X foil 7,Rec=1.92*106,a=5.4deg).图3所示在飞行测验中的附面层顶端的速度分布和理论的速度分布(X7,= 1.92 * 10 6、= 5.4deg)。By looking at Fig.3, quite a good conformity between measurement and calculation can be observed.从图3中我们得知 实测数据和理论数据完全符合 。Furthermore, the glove flow shows a relatively long area with a weak increase of pressure and thus provides a moderate amplification of the unstable boundary layer disturbances.再者,附面层流显示在相对的一段较长的区域有微弱的压力增加,因此 提供了一个适当的放大来抵消边界层流流的干扰。The amplification of the unstable disturbances was measured to describe the stages of transition on the glove.放大的不稳定的扰动的测量来描述的过渡阶段的手套。B. Hybrid laminar flow fin: 320b混合层流鳍:320The in-flight experiments at higher Reynolds and mach numbers were carried out on a modified A320 vertical tailplane (fig.4) in close collaboration with airbus.通过与空中巴士合作，利用修改过垂尾的A320的在飞行实验中 测得了更高的雷诺和马赫数 (图4),。 A special pvdf-sensor array was built and attached to the upper part of the fin downstream of a suction panel , which was used to control the transition. 一个特别pvdf-sensor阵列安装于 机翼的上表面的下半部分的一个吸板上,用来控制转变过渡。The geometry of the pvdf array was defined through the position on the upper part of the fin. pvdf的阵列的几何形状按照设计应当通过机翼的上表面。The array incorporated 32 sensors in two steamwise lines at a chord length of 23to 52.6%. 32个传感器构成这个阵列 ，他们在弦长全长的23%到 52.6%之间顺着两个steamwise线排列。The distance between the equally spaced sensor was 1.97% of the length (=56mm)of the fin(fig4).传感器之间的距离相等，这个间距为机翼全长的1.97% （大约55毫米)。The complete sensor array was glued to the fin and was plugged in to the borders. 这个完整的阵列传感器 贴在机翼的边沿部位。Interferences with the boundary layer flow through the sensor on the fin surface could not observe.边界层流流流经过机翼表面的传感器所引起的干涉可以忽略不计 。 Developing the sensor layout for this investigation, two streamwise sensor line were produced to have fallback positions in case of sensor failure. 试验中开发出一种新的传感器排列方式, 当传感器失效的时候两个两个steamwise线排列的传感器会让步。All sensors were adjusted in ground test to reach the same sensitivity and verified concerning their dynamic characteristics in the first tests. 所有的传感器在地面试验中调整到相同的敏感度 并且在第一次测试中还验证了他们的动态特性。The best sensors were chosen for the interpretation of the measurements after this basic test (fig4 active sensor ). 基本测试以后 我们应用最好的传感器应用于测量。（ig4active传感器)。Generally the sensor had really similar characteristics and only a few of them failed.一般情况下传感器的敏感度都差不多 ，只有少数传感器通不过测试。The main objective of this part of the Berlin institute of technology within the scope of the a320 HLF program was to prove the functional capability, durability, and reliability of pvdf sensor technique under real atmospheric conditions in cruise flight. 包括柏林理工学院的范围内的a320 HLF计划是是这项目的主要部分，其目的在于证明pvdf传感器技术在实际大气条件下巡航飞行的性能、耐久性与可靠性的。In particular, this means low temperatures (down to -16) and high velocities (up to ma=0.8).在特殊情况下,这意味着低温(- 16)和高速(up to ma =0.8%)。Furthermore, the test focused on the investigation of other environmental influence such as the noise level, resonance frequencies, or the acceleration occurring in modern airplane. 另外,该测试还聚焦于研究其他环境下的影响例如的噪音水平、共振频率,或现代飞机的加速度事故。The established criterion to ensure transition detection is a sufficient signal- to- noise ratio (SNR, see also Sec.3.b)所建立的标准,确保有足够的信噪比被检测到In contrast to the measurements with the sailplane glove, where TS instabilities can be used to define the transition, the transition on the A320 fin is presumably initiated by cross-flow instabilities due to the sweep angle of the A320 tailplane 8-10. 为了和滑翔机的附面层试验做对比TS不稳定性可以用来确定转变 ,A320机翼上得的转变 据推测是由于A320尾翼的扫描角上的错流的不稳定性引起的8-10The frequencies of instabilities in the high-speed case are higher than on the low-speed, two-dimensional glove on the sailplane. 在高速情况下不稳定的频率要比滑翔机低速、平面附面层情况下高。Therefore, the maxima of the rms values correspond to the intermittence and remain the criterion for transition in this case. 因此,最大值的有效值相对应的标准和间歇性过渡。The intermittence rate describes the probability of the occurrence of turbulent structures at a certain point in the flow. 介绍了利率的可能性的湍流结构发生在某个特定的时间点的流量。An intermittence of 50% can be considered the location of transition.一个50%的间歇可以认为是位置的过渡。3.sensor techniques3.传感器技术a. measurement data acquisition system答:测量数据采集系统A miniaturized and modularly arranged measuring system especially developed for in-flight measurement was employed in both case in order to record the data of the dense surface sensor at a high temporal resolution. 在飞行测量方面阵列测量的小型化和模块化得到了特别的发展 这些技术都被用于记录密集的表面传感器的高瞬态分辨率的数据。This multichannel measurement data acquisition system (MEDAS) consists of two parts. 多通道测量数据采集系统(MEDAS)由两部分组成。One part of MEDAS(the electronic box)was located close to the sensor array at the rear spar of the fin or underneath the glove of the sailplane. MEDAS的第一部分(电子箱)是位于靠近阵列传感器的机翼后梁或者是滑翔机附面层下部。The basic of this electronic box are a two-stage amplifier (charge and power amplifier for each channel) with electronically adjustable amplifier settings and a multiplexer, A/D converter, electric-optical converter next in line. 这种电子箱是一种由电子调节放大器设备、多路解调器、A / D转换器和电-光转换器构成的两级放大器(为每个频道供能和功率放大)。 The measuring computer in the cockpit includes the second, board part of MEDAS and makes it possible to control the measurement system on the fin and on the wing, respectively, during flight. 第二部分包括驾驶舱内的测量计算机和 MEDA的电子板他使在飞行中分别控制机翼上的和附面层上的测量系统成为可能 Communication and data transfer for storage between both parts of the measurement system are carried out via fiber optical transmission. The sampling rate of each channel was about 30kHZ.两个测量系统部分之间利用光纤完成之间的通信和存储数据传输每个通道采样率大约是30kHZ。b.pvdf sensor B. PVDF传感器pvdf-sensor arrays, well known as piezofoil sensor technique ,already have been successfully employed for measurements of unsteady surface force fluctuations on different applications of several years 11.PVDF阵列传感器，即所谓的piezofoil传感器技术，在近几年已经成功的应用于不同领域内测量非稳态表面上被迫震动。A PVDF sensor array consists of a thin PVDF (polyvinylidenfluorid) film (10to100 um thick), metallized on both side(fig5). 一个PVDF阵列传感器是将一个薄的PVDF(polyvinylidenfluorid)薄膜 (10to100um)以喷涂金属的方式喷在其的两边形成(fig5)。The upper metallic side is used as an electric ground, thereby also serving as an electrostatic and electromagnetic shield. 顶层金属是用作电子基面,同时也起到一个静电和电磁的屏蔽作用。By partially etching one side of the metallic coating, it is possible to create sensor arrays which are customized for a given measurement task. 通过只蚀刻金属涂层的一部分,就可以形成一个专门用来测量工作的阵列传感器Then each single sensor area is connected to the charge amplifier via thin wires.然后每个单一传感器通过细线连接到电荷放大器。 A single PVDF sensor can be considered as a plate capacitor with very low capacity and mass.一个单一的PVDF传感器可以被视为一种体形和容量都 非常小的平行极板电容器。The PVDF material has both piezoelectric as well as pyroelectric properties. PVDF材料具有良好的压电以及热电特性。When assuming a mechanical (piezoelectric) or a temperature (pyroelectric) change characteristic in laminar turbulent transition, the sensor material produces small electric charges. 当假设一个机械(压电)或温度（焦热电的 ）变化特征 在层流-混流的转变中 传感器的材料产生小的电荷。The sensor signals can be amplified by means of simple charge amplifiers. 传感器的信号通过简单的电荷放大器可以得到放大。The possible frequency range is limited only by the lower limiting frequency of the charge amplifier employed. 电荷放大器的可用的频率范围 仅限于低通。The choice of the charge amplifier depends on the measuring task. 不同的测量任务决定了电荷放大器的选择。Because the pyroelectric constant (which describes the pyroelectric properties) is some orders higher than the piezoelectric constant, a low-temperature gradient (2K) between sensor and fluid can be employed to obtain a higher SNR 12.因为热释电常量肯定高过压电常数, 利用传感器和流体之间的低温梯度( 2K)可以获得用来获得高信噪比12。This can be important for the minimization of sensor size and spacing in array measurement techniques. 在阵列测量技术中将传感器的大小和间距减到最小限度是非常重要的。Because of the closed foil on the wing surface, the sensor produces negligible roughness.由于翼面上的封闭箔片而在传感器上生产的粗糙可以忽略。 In this case the experiments showed the successful production of large sensor array ares up tu (1000*220) mm2with a smooth and undisturbed surface.一个光滑的和稳定的表面大型阵列传感器(1000 * 220平方毫米) 实验表明是成功的。 The cutoff frequency of the applied PVDF sensor array (including the entire measuring system )was about 30kHZ was therefore suitable for dynamic measurements at high velocities.PVDF阵列传感器(包括整个测量系统)的截止频率是大约30kHZ左右 所以它适合在高速度动态测量。 The custom-made sensor arrays used a 28um-thick polymer film (with a pyrocofficient, dr =-30*10-6c/m2k and a piezocoefficient d33=-33*10-12c/n )sandwiched between two 1-um Ni-Cu layers. 一个定制好的阵列传感器是将一个 28um-thick 聚合物薄膜（with a pyrocofficient, dr =-30*10-6c/m2k and a piezocoefficient d33=-33*10-12c/n）)夹在两个1-um镍铜层之间。In basic wind-tunnel experiments the upper one was costed using a 5-um-thick TESA TM film for protection from abrasive erosion.在基本的风洞试验中上表面要用5-um厚的TESA TM膜保护以免受摩擦侵蚀。 Both coated and noncoated sensors were tested.由涂层的和没有涂层的传感器都进行了测试。The results suggest that the coating layer has almost no effect at both low (ma=0.3)and high(ma=0.5)speeds 13.结果显示,涂层厚度在低速(ma)和高速(ma=0.5)试验中几乎没有影响13。therefore, the coating can be used to protect the sensor surface in real applications.因此, 在实际应用中涂层可以用来保护传感器的表面。c. surface hot wire sensor表面热-丝传感器a principle sketch of the surface hot wire sensor is shown in fig6.表面热-丝传感器的原