Abstract
For the investigation of unstable or unsteady flow Phenomena such as a highly separated flow around a body, one should grasp the direction and situation of the body-surface flow at every moment.Though various surface tracing methods have been used in the visualization of limiting streamlines, most of them can only yield streak lines representing the mean direction of body-surface flow during a time.A few chemical film staining methods are able to follow flow fluctuation by changing the reacted color reversibly, even so the rate of response seems to be rather slow.In this respect, a new surface tracing technique is proposed by use of liquid crystal sheets which are known to be capable of showing quick response to temperature variation by reversible metachromatism, The visualization of surface flow near the tip on a three-dimensional hydrofoil model of marine propeller blade shape was carried out, in the circulating water channel, to examine the applicability of this method.Point heat sources made by electricall heated copper rods are inserted in the model surface and used as the tracer generators.For reference, surface tuft method was also executed.Photographs were taken at several attack angles to produce fluctuating flow for simulating that of an actual propeller blade rotating in the ship wake.The observed result shows that such a liquid crystal sheet method with point heat sources is quite available for visualizing the fluctuation of body-surface flow.
