In this paper, Aeolian tone and the related flow field of a circular cylinder (CC) and a tapered circular cylinder (TC1) are predicted using the numerical simulation for incompressible flow. The number of computational grids is 4 million. The Reynolds number based on diameter at middle span and uniform flow velocity is 2.65 × 104. The Aeolian tone spectra are calculated using the formula of FW-H and sound sources around the cylinder are computed based on Powell-Howe vortex sound theory. As a result, comparing these distributions of the sound source, the vortex sound intensity of TC1 is less than of CC in span wise direction. Aerodynamic sound spectra by the experiment and calculation provided good agreement.

Prediction of Aeolian Tone Radiated from a Tapered Circular Cylinder and Vortex Sound in Wake

The present paper describes the observation of horseshoe vortex around the jucnture, between flat plate and circular cylinder. In the case of inclined cylinder, the three-dimensional separation region in front of the body is smaller and the flow stability is stable. The milk-painting method is useful for visualizing the flow field in laminar flow and also the limiting streamline in turbulent flow. The oil-film method and the tracer method are also applied for observation of this flow.

https://www.jstage.jst.go.jp/article/jvs1990/11/Supplement1/11_Supplement1_115/_pdf

Observation of Horseshoe Vortex in Juncture Flow

A new technique for wall friction measurement, non contact and instantaneous measurement, is developed. The method is a kind of the so-called image measurement using oil flow on wall and image analysis technique. Oil flow owing to wall friction is very small and also strongly depends on way of painting. The possibility of the measurement is examined in a flat plate flow.It is possible to measure the wall friction, if small displacement of oil can be measured. The spatio-temporal derivative method of image analysis is effective for this measurement. The ordinary oil film method for circulating water channel, based machine oil and liquid paraffin with carbon black powder, is employed here from the practical view point.The present method was applied to a juncture flow around a circular cylinder on the flat plate, the so-called horseshoe vortex, in which it is impossible to use any probe for wall friction measurement. The limiting streamlines on stern hull are also measured. The result is agree with the visualized one with milk painting method.

https://www.jstage.jst.go.jp/article/jjasnaoe1968/1994/176/1994_176_59/_pdf

Hiroshi Horiuchi

Papers

Observation of Horseshoe Vortex in Juncture Flow

Image Measurement of Wall Friction Using Oil Film