| 摘要 |
Despite a large number of various types of measurement techniques, it still remains a problem today in hydrodynamics to obtain experimentally an exact overall picture of the local velocity components in a flow field over an extended flow cross-section. The flow velocities are to be detected locally in terms of their components or vectorially and in a quasi-instantaneous manner. For this purpose, an optical beam, for example a bundle of laser light, is optically scattered in the velocity field of scattered particles (2) which are being carried along, and the light track (3) thereby generally visible is optically scanned by a receiving device and the received scattered light is herded to a Smeet laser-Doppler spectrometer, which analyses with sufficient rapidity the instantaneous Doppler shift of the wavelength of the scattered light with respect to the original light, and in the process, for example in a stepwise fashion and locally along the light track (3), instantaneously detects the magnitude and sense of direction of the velocity components respectively present. The direction is yielded by means of an additional position measurement of the measuring point from the instantaneous geometry, thereby known, of the optical arrangement. <IMAGE>
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