Journal of Visualization - Volume 5, issue 2

Authors: Tanida, Yoshimichi

Article Type: Other

Citation: Journal of Visualization, vol. 5, no. 2, pp. 113-113, 2002

Article Type: Other

Citation: Journal of Visualization, vol. 5, no. 2, pp. 115-120, 2002

Authors: Tesar, V. | Barker, J.

Article Type: Research Article

Abstract: A novel method of flow visualization by dye was used in conjunction with numerical solutions to investigate the formation stages of large stationary vortical motions located in the "trajectory bend" centers of impinging jet flows. The vortices dominate the flowfield and were found to have profound influence on the wall transport phenomena. Depending on the value of Reynolds number, four regimes were identified with different flow character.

Keywords: impinging jets, vortices, visualization, numerical solutions

Citation: Journal of Visualization, vol. 5, no. 2, pp. 121-128, 2002

Authors: New, T.H. | Lim, T.T. | Luo, S.C.

Article Type: Research Article

Abstract: Laser-induced fluorescence technique is used to study the near-field of an elliptical jet exiting normally into a cross flow, for elliptic jet having aspect ratio of 2 and 3. Results show that the non-uniform curvature of the elliptic geometry causes the leading-edge vortices at the interface between the jet and the cross flow to behave differently from that of a circular jet. In particular, when the major-axis is aligned with the cross flow there is an …intense interaction between the leading-edge vortices which culminates in the pairing of adjacent vortices. The pairing is suppressed when the major axis is perpendicular to the cross flow. Show more

Keywords: flow visualization, elliptical jet, jet in cross flow, laser-induced fluorescence, dye-injection

Citation: Journal of Visualization, vol. 5, no. 2, pp. 129-136, 2002

Authors: Shiomi, N. | Cai, W.X. | Kaneko, K. | Setoguchi, T.

Article Type: Research Article

Abstract: An Unsteady flow field with rotating stall cells in a high specific-speed diagonal flow fan has been investigated experimentally. Although a general feature of stall cells has already indicated, i.e., the number of stall cells is one and its propagating speed is approximately 80 percent of rotor speed, little has been known about the flow field when a rotating stall occurs because of its unsteadiness. In order to capture the behavior of the rotating stall cell, …measurements of the flow field at the rotor inlet were carried out with a single slant hot-wire. Those data were processed by a so-called "double phase-locked averaging" (DPLA) technique, which enabled to capture the flow field of the cell in the reference co-ordinate system fixed to the rotor. As a result, time-dependent ensemble averages of the three-dimensional velocity components at the rotor inlet have been obtained and the behavior of the rotating stall cell has been illustrated with each velocity component. Show more

Keywords: turbomachinery, rotating stall cell, unsteady flow, DPLA technique, fan

Citation: Journal of Visualization, vol. 5, no. 2, pp. 137-144, 2002

Authors: Choi, H.J. | Ko, Y.S. | Chung, S.H.

Article Type: Research Article

Abstract: To improve the understanding of flame propagation through a nonpremixed vortex ring, the characteristics of fuel concentration in a vortex ring have been investigated experimentally. The vortex ring was generated by the ejection of propane with a single stroke motion of a speaker. Planar laser-induced fluorescence (PLIF) technique was adopted by seeding acetone as a tracer to fuel stream, in which the PLIF signal intensity is directly proportional to the concentration of acetone. This technique provides …non-intrusive and instantaneous measurement of concentration field. Results showed that fuel concentration and its gradient decreased with the evolution of a vortex ring. When a nonpremixed flame propagated through a vortex ring, the flame location coincides with the inner most spiral mixing layer of fuel and air in a vortex ring. Show more

Keywords: vortex ring, acetone PLIF, nonpremixed flame, flame propagation

Citation: Journal of Visualization, vol. 5, no. 2, pp. 145-152, 2002

Authors: Ishigaki, T. | Shiono, K. | Rameshwaran, P.

Article Type: Research Article

Abstract: Secondary flow in a compound meandering channel with straight floodplain banks for overbank was investigated by a visualization method and velocity measurement using three-component laser Doppler anemometor (LDA). The secondary flow in a cross section was visualized by the neutral buoyant tracer method with a submergible video camera. Secondary flow vectors in a cross section were obtained by using PIV software with captured frames from video source through PC and also by LDA measurements. From the …comparison of the PIV and LDA results, it is found that PIV data show good agreement in quality with LDA measurements when the secondary flow is strong and stable as shown in this paper. Show more

Keywords: visualization of secondary flow, PIV, LDA measurement, compound meandering channel

Citation: Journal of Visualization, vol. 5, no. 2, pp. 153-159, 2002

Authors: Wierzbowski, M. | Stasiek, J.

Article Type: Research Article

Abstract: The use of thermochromic liquid crystal technique (LCT) and true-colour image processing system in heat transfer modelling is described. Experimental procedure, led on rig at Technical University of Gdansk, cover full-field flow patterns in heat exchanger element (flat plate with fine-tubes in-line, staggered and with vortex generators) describing local heat transfer coefficient and Nusselt number on the surfaces. Also the dependence of average heat transfer and pressure drop on Reynolds number and geometrical parameters …is investigated. Show more

Keywords: thermochromic liquid crystals, heat transfer, wind tunnel, vortex generator

Citation: Journal of Visualization, vol. 5, no. 2, pp. 161-168, 2002

Authors: Zharkova, G.M. | Zanin, B.Y. | Kovrizhina, V.N. | Brylyakov, A.P.

Article Type: Research Article

Abstract: Flow visualization tests have been performed to examine the structure of the near-wall flow over a low-aspect ratio straight wing installed at various angles of attack &b.alpha; and chord Reynolds number Re_c = U c/v = 1.76 ×10^5 . The experiments were carried out at two free-stream turbulence levels, &b.epsiv; = 0.1% and &b.epsiv; = 1%, the latter one having been achieved using a baffling grid. To visualize the flow, termochromic cholesteric liquid crystals and digital …processing of video images were used. At the low turbulence level and &b.alpha; = 27°, a flow stall on the lee side of the wing was observed, with a pair of large-scale vortices rotating in the wing plane. Simultaneously, no vortex structures were observed on the windward wing surface. It was found the flow patterns on either side of the wing significantly changed with increasing free-stream turbulence level. A separation bubble appeared near the leading edge on the lee side of the airfoil at &b.epsiv; = 1%, and large-scale stationary longitudinal vortices originated over the wing windward surface. The number and sizes of the longitudinal structures were found to be dependent on the angle of attack. Show more

Keywords: straight wing, boundary layer, longitudinal vortices, liquid crystals

Citation: Journal of Visualization, vol. 5, no. 2, pp. 169-176, 2002

Authors: Kikukawa, H. | Segawa, M. | Kohno, J.

Article Type: Research Article

Abstract: Sasebo and Oomura Bays situated in the northwest of Kyushu, Japan form a coupled bay linked by a channel. The tidal flow in and between these bays is visualized by the satellite images and the dispersion of Lagrangian particles is numerically studied. The satellite images are available to visualize the tidal flow at the mouth of Hario-seto from the maximum flood tide to the end of ebb tide at Tainoura. The seawater plume from the mouth of …Hario-seto goes southeastward and then rotates anti-clockwise. The time of one rotation is about 6 to 7 periods. The plume extends about 10 km from the mouth of Hario-seto. Lagrangian particles in Sasebo Bay also flow into Oomura Bay through Haiki-seto. Show more

Keywords: coupled bay, satellite image, Lagrangian particle, dispersion, plume, tidal flow

Citation: Journal of Visualization, vol. 5, no. 2, pp. 177-186, 2002