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Micro air vehicle motion tracking and aerodynamic modeling.

机译：微型飞行器运动跟踪和空气动力学建模。

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摘要

Aerodynamic performance of small-scale fixed-wing flight is not well understood, and flight data are needed to gain a better understanding of the aerodynamics of micro air vehicles (MAVs) flying at Reynolds numbers between 10,000 and 30,000. Experimental studies have shown the aerodynamic effects of low Reynolds number flow on wings and airfoils, but the amount of work that has been conducted is not extensive and mostly limited to tests in wind and water tunnels.;In addition to wind and water tunnel testing, flight characteristics of aircraft can be gathered through flight testing. The small size and low weight of MAVs prevent the use of conventional on-board instrumentation systems, but motion tracking systems that use off-board triangulation can capture flight trajectories (position and attitude) of MAVs with minimal onboard instrumentation. Because captured motion trajectories include minute noise that depends on the aircraft size, the trajectory results were verified in this work using repeatability tests. From the captured glide trajectories, the aerodynamic characteristics of five unpowered aircraft were determined.;Test results for the five MAVs showed the forces and moments acting on the aircraft throughout the test flights. In addition, the airspeed, angle of attack, and sideslip angle were also determined from the trajectories. Results for low angles of attack (less than approximately 20 deg) showed the lift, drag, and moment coefficients during nominal gliding flight. For the lift curve, the results showed a linear curve until stall that was generally less than finite wing predictions. The drag curve was well described by a polar. The moment coefficients during the gliding flights were used to determine longitudinal and lateral stability derivatives. The neutral point, weather-vane stability and the dihedral effect showed some variation with different trim speeds (different angles of attack). In the gliding flights, the aerodynamic characteristics exhibited quasi-steady effects caused by small variations in the angle of attack. The quasi-steady effects, or small unsteady effects, caused variations in the aerodynamic characteristics (particularly incrementing the lift curve), and the magnitude of the influence depended on the angle-of-attack rate.;In addition to nominal gliding flight, MAVs in general are capable of flying over a wide flight envelope including agile maneuvers such as perching, hovering, deep stall and maneuvering in confined spaces. From the captured motion trajectories, the aerodynamic characteristics during the numerous unsteady flights were gathered without the complexity required for unsteady wind tunnel tests. Experimental results for the MAVs show large flight envelopes that included high angles of attack (on the order of 90 deg) and high angular rates, and the aerodynamic coefficients had dynamic stall hysteresis loops and large values.;From the large number of unsteady high angle-of-attack flights, an aerodynamic modeling method was developed and refined for unsteady MAV flight at high angles of attack. The method was based on a separation parameter that depended on the time history of the angle of attack and angle-of-attack rate. The separation parameter accounted for the time lag inherit in the longitudinal characteristics during dynamic maneuvers. The method was applied to three MAVs and showed general agreement with unsteady experimental results and with nominal gliding flight results.;The flight tests with the MAVs indicate that modern motion tracking systems are capable of capturing the flight trajectories, and the captured trajectories can be used to determine the aerodynamic characteristics. From the captured trajectories, low Reynolds number MAV flight is explored in both nominal gliding flight and unsteady high angle-of-attack flight. Building on the experimental results, a modeling method for the longitudinal characteristics is developed that is applicable to the full flight envelope.
机译：小规模固定翼飞行的空气动力学性能尚未得到很好的理解，需要飞行数据才能更好地理解雷诺数为10,000至30,000的微型飞行器（MAV）的空气动力学。实验研究表明，雷诺数较低的气流对机翼和机翼有空气动力学影响，但是所进行的工作量并不广泛，并且主要限于风洞和水洞的试验。飞机的飞行特性可以通过飞行测试来收集。 MAV的体积小且重量轻，无法使用传统的机载仪表系统，但是使用机外三角测量的运动跟踪系统可以在最少的机载仪表情况下捕获MAV的飞行轨迹（位置和姿态）。由于捕获的运动轨迹包括取决于飞机大小的微小噪声，因此在这项工作中使用可重复性测试验证了轨迹结果。从捕获的滑行轨迹中，确定了五架无动力飞机的空气动力学特性。五个MAV的测试结果显示了在整个测试飞行中作用在飞机上的力和力矩。此外，空速，迎角和侧滑角也由轨迹确定。低攻角（小于约20度）的结果显示了标称滑行飞行期间的升力，阻力和力矩系数。对于升力曲线，结果显示直到失速的线性曲线通常小于有限机翼的预测值。阻力曲线由极坐标很好地描述了。滑行飞行中的力矩系数用于确定纵向和横向稳定性导数。中性点，风向标稳定性和二面角效应在不同的修剪速度（不同的迎角）下显示出一些变化。在滑行飞行中，空气动力特性表现出由攻角的微小变化引起的准稳态效应。准稳态效应或较小的非稳态效应引起了空气动力学特性的变化（特别是升力曲线的增加），并且影响的大小取决于攻角率。通常，它能够在较宽的飞行范围内飞行，包括在狭窄空间内进行的机动，栖息，悬停，深度失速和机动等机动。从捕获的运动轨迹中，可以收集许多不稳定飞行过程中的空气动力学特性，而无需进行不稳定风洞测试所需的复杂性。 MAV的实验结果表明，大的飞行包络线包括高攻角（大约90度）和高角速度，并且空气动力学系数具有动态失速磁滞回线和较大值。攻击飞行，开发并改进了一种空气动力学建模方法，用于高攻角下的非稳定MAV飞行。该方法基于分离参数，该分离参数取决于攻角和攻角速率的时间历史。分离参数说明了动态操纵过程中沿纵向特性继承的时间滞后。该方法被应用于三个MAV，并与不稳定的实验结果和名义滑行飞行结果基本吻合。用MAV进行的飞行试验表明，现代运动跟踪系统能够捕获飞行轨迹，并且可以使用捕获的轨迹确定空气动力学特性。从捕获的轨迹中，在标称滑行飞行和不稳定的高攻角飞行中都探索了低雷诺数MAV飞行。在实验结果的基础上，开发了一种适用于整个飞行包线的纵向特性建模方法。

著录项

  • 作者

    Uhlig, Daniel V.;

  • 作者单位

    University of Illinois at Urbana-Champaign.;

  • 授予单位 University of Illinois at Urbana-Champaign.;
  • 学科 Aerospace engineering.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 229 p.
  • 总页数 229
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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