Monochromatic flow profile sensor with time division multiplexing and calibration models für fluids

剪切层流在基础研究和工业应用中都具有突出的重要性，其例子涵盖了从湍流研究到空气动力学或热流测量的范围。为了确定它们，通常需要高的空间分辨率。此外，基于激光的测量方法可能会产生来自墙壁的反射，这可能会导致系统测量误差。通过激光多普勒速度剖面传感器，即使在大工作距离下也可以实现高度空间分辨的流剖面测量，其特性已经在德国研究基金会资助的一个研究项目中进行了研究。该传感器是基于两个重叠干涉条纹系统的利用，这些干涉条纹系统被定义的波前曲率扭曲。使用双通道测量，迄今为止是由两个激光波长产生的，可以以微米级的空间分辨率确定随流携带的粒子的位置。在墙壁附近的测量可以使用荧光散射粒子进行，然而，仅采用一个激光波长的传感器是必要的。因此，一种基于时分复用的单色轮廓传感器将被研究和实现，直到该转移项目中的演示器。除了在墙壁附近的测量，这个项目的一个关键方面将是传感器校准模型的开发。由于干涉条纹系统的几何形状取决于周围介质的折射率，因此工作流体的任何变化都需要重新校准。特别是在液体中，基于旋转速度参考的校准是不切实际的，因此无法预期市场的深度渗透。这个问题将通过开发一个校准模型来解决。

Shear layer flows are of outstanding importance in basic research as well as in industrial applications with examples covering the range from turbulence research to aerodynamics or heat flow measurement. For their determination, high spatial resolutions are required in general. Furthermore, reflections from walls can occur at laser-based methods, which might result in systematic measurement errors. The aim of highly spatially resolved flow profile measurements even at large working distances can be achieved by means of the laser Doppler velocity profile sensor, whose properties have been investigated within a research project funded by German Research Foundation. The sensor is based on the utilization of two superposed interference fringe systems distorted by defined wavefront curvature. Using a two-channel measurement, which so far has been generated by means of two laser wavelengths, the position of particles carried with the flow can be determined with micrometer spatial resolution. Measurements in the proximity of walls can be performed using fluorescent scattering particles, however, a sensor employing only one laser wavelength is necessary to this end. Hence, a monochromatic profile sensor based on time division multiplexing is to be investigated and realized until a demonstrator within this transfer project. Beside measurements in wall proximity, one key aspect of this project will be the development of a model for sensor calibration. Since the geometries of the interference fringe systems depends on the refractive index of the surrounding medium, any change of the working fluid would demand a new calibration. Especially in liquids, a calibration based on rotating velocity references is impractical, so that a deep penetration of the market cannot be expected. This problem will be solved by developing a calibration model.