SBIR Phase II: A Multi-Point Array Laser Doppler Velocimeter

这个小型企业创新研究第二阶段项目旨在完成一个研究/商业原型多点激光测速仪，用于实验室，也用于无人值守的海洋。在自然界中，单点速度的测量很少是足够的；当只有单点测速仪可用时，采用剖面法获得有关流场结构的信息。剖面信息总是通过传感器“头”的机械遍历得到。这种方式不仅牺牲了概要性，造成结构数据的次序丢失，而且空间结构、相干运动和时空尺度上的所有信息都丢失了。在研究需要的驱使下，P.I.设计了一种多点测速系统，在流场中同时形成多个样品体积。来自这些样品体的信号被分别传送到光电探测器。然后，需要一个多信号处理器将信号转换为同步多点速度数据，保留流的固有顺序信息，并将所有信息用于推导流体结构的时空尺度。在第一阶段，我们通过构建一个单速度分量多点测速仪成功地演示了该方法的原理，这在第一阶段的建议中得到了首次解释。在第二阶段，我们将扩展能力到一个2轴多点测速仪，带有方向识别光学器件和一个完整的多信号处理器。该仪器将在实验室和现场进行测试。

AGRAWAL 9502488 This Small Business Innovation Research Phase-II project is directed at the completion of a research/commercial prototype multi-point laser velocimeter for use in laboratories and also for use unattended in the ocean. Measurements of velocity at a single point are seldom sufficient in nature; when only single-point velocimeters are available, profiling is employed to obtain information regarding structures of a flow-field. Profile information has invariably been derived by mechanical traversing of a sensor 'head'. Not only is synopticity sacrificed in this manner, causing loss of order in structure data, but also all information on spatial structures, coherent motions, and space-time scales is lost. Driven by needs in his research, the P.I. has devised a multi-point velocimetry system which forms several sample volumes in the flow field simultaneously. Signals from these sample volumes are separately carried to photo-detectors. A multi-signal processor is then required to convert the signal to simultaneous- multi-point velocity data, retaining information on order inherent in the flow, and all information for deriving space-time scales of fluid structures. In Phase-I, we have successfully demonstrated the principle of the method by constructing a single-velocity- component multi-point velocimeter, as first explained in the Phase- I proposal. In Phase-II, we shall expand capabilities to a 2-axis multi-point velocimeter, with direction discrimination optics and a complete multi-signal processor. The instrument will be tested in the laboratory and the field.