Burns Ross A, Danehy Paul M
Research Engineer, National Institute of Aerospace, AIAA Member. NASA Langley Research Center, Hampton, VA, 23681.
Senior Researcher, Advanced Measurements and Data Systems Branch, AIAA Associate Fellow. NASA Langley Research Center, Hampton, VA, 23681.
AIAA J. 2017 Dec;55(12):4142-4154. doi: 10.2514/1.J056154. Epub 2017 Oct 31.
Femtosecond laser electronic excitation tagging (FLEET) velocimetry was used to study the flowfield around a symmetric, transonic airfoil in the NASA Langley 0.3-m TCT facility. A nominal Mach number of 0.85 was investigated with a total pressure of 125 kPa and total temperature of 280 K. Two-components of velocity were measured along vertical profiles at different locations above, below, and aft of the airfoil at angles of attack of 0°, 3.5°, and 7°. Velocity profiles within the wake showed sufficient accuracy, precision, and sensitivity to resolve both the mean and fluctuating velocities and general flow physics such as shear layer growth. Evidence of flow separation is found at high angles of attack. Velocity measurements were assessed for their accuracy, precision, dynamic range, spatial resolution, and overall measurement uncertainty as they relate to the present experiments. Measurement precisions as low as 1 m/s were observed, while the velocity dynamic range was found to be nearly a factor of 500. The spatial resolution of between 1 mm and 5 mm was found to be primarily limited by the FLEET spot size and advection of the flow. Overall measurement uncertainties ranged from 3 to 4 percent.
飞秒激光电子激发标记（FLEET）测速技术被用于在美国国家航空航天局兰利0.3米跨声速风洞实验装置中研究一个对称跨声速翼型周围的流场。研究的名义马赫数为0.85，总压为125千帕，总温为280开尔文。在攻角为0°、3.5°和7°时，沿着翼型上方、下方和后方不同位置的垂直剖面测量了速度的两个分量。尾流中的速度剖面显示出足够的精度、准确性和灵敏度，能够分辨平均速度和脉动速度以及诸如剪切层增长等一般流动物理现象。在大攻角时发现了流动分离的迹象。对速度测量的准确性、精度、动态范围、空间分辨率以及与当前实验相关的总体测量不确定性进行了评估。观察到测量精度低至1米/秒，而速度动态范围接近500倍。发现1毫米至5毫米之间的空间分辨率主要受FLEET光斑尺寸和流动平流的限制。总体测量不确定性范围为3%至4%。
