Shigeki Segawa

Development and Evaluation of an Improved Correlation Based PTV Method

An improved correlation based Particle Tracking Velocimetry (PTV) algorithm was proposed in the present paper. The path tracking of the tracer particles was achieved through a correlation operation of the small interrogation window around the studied tracer particles at two-time steps. The central positions of the tracer particles were determined by the correlation operation of the tracer particle image with a Gaussian particle mask in order to improve the accuracy to identify the central positions of particles up to sub-pixel level. The performance of the present improved correlation based Particle Tracking Velocimetry (PTV) algorithm was evaluated by using both synthetic VSJ standard PIV images and actual PIV images of a self-induced sloshing. Compared with other conventional PTV methods, the present improved correlation based PTV algorithm was found to be able to provide better solution and more robust for suppression the effect of background noise in the PIV images.

A study on internal flow field of automotive torque converter—three-dimensional flow analysis around a stator cascade of automotive torque converter by using PIV and CT techniques

Abstract The internal flow field around the stator of an automotive torque converter is investigated experimentally in this study by using particle image velocimetry (PIV). The objective of this investigation is to understand the flow field around the stator that plays an important role in enhancing the characteristics of the torque converter performance. Computerized tomography (CT) technique was applied to analyse the three-dimensional flow field using a series of two-dimensional PIV results obtained from two orthogonal directions. The three-dimensional data obtained in this study is utilized to improve the performance of the torque converter through the optimal design of the stator. The experimental results obtained in this way can be used to validate the accuracy of computational fluid dynamics (CFD).

Application study of PIV measurement of flow field around lock-up clutch of automotive torque converter

Abstract A visualization of the flow field around a lock-up piston inside an automotive torque converter was carried out by use of the particle image velocimetry (PIV) technique. Consequently, it turned out that the flow velocity distribution on the surface of the lock-up piston was measurable. Using the experimental results obtained by this PIV measurement, a key for improving the response of a lock-up clutch operation can be acquired.

Development and Analysis of Multi-Laminar Chemical Delivery Platform Toward Single Molecular Application

The fluidic operations in microfluidic system such as chemical delivery, solution exchange, and chemical reactions by mixing are one of the most important technical issues to realize high-throughput and automated chemical / biochemical analysis with extremely small amount of species down to single molecular level. In order to realize such fluidic operations in micro and nano scale, we have been trying to develop a chemical delivery system to transport reagents to an arbitrary location in microchannel. In this work, we have developed and demonstrated a chemical delivery system in microchannel using precisely controlled multilaminar flow created by our previously developed multi-channel micropump embedded on the system. As a demonstration of the chemical delivery system, a single-molecule analysis of ATP dependent rotation of F1 - ATPase was investigated. As a result, ATP dependent rotation of F1 -ATPase was successfully investigated by addressing one of the streams, which are included or not included ATP, to the immobilized single-molecule of F1 -ATPase.© 2006 ASME

Analysis of the Pulse jet by stereo-PIV

Pulsed jets that are considered as the most conspicuous unsteady phenomenon are fundamental flow in the field of hydraulic machinery, combustion engines, etc. In the present paper, the structure of the pulsed jet from a circular nozzle was analyzed by the flow visualization of PLIF and the velocity measurement of stereoscopic PIV. The temporal and spatial structure change of the mushroom ring vortex formed near the front of the pulse jet is discussed.

Improvernent of PTV by using a Recursive Cross-Correlation Method

An improved Particle Tacking velocimetry (PTV) algorithm was proposed in the present paper. The path tracking of the traced particle was achieved through a recursive cross-correlation operation of small interrogation window around the studied particles at two time steps. The particles are tracked by using grid points velocities calculated by the recursive cross-correlation method. To reduce the tracking error, a variable interrogation window size setting which changed with the interrogation window size according with spatial density of particles was introduced to the recursive cross-correlation method. The performance of the improved algorithm is evaluated by the synthetic particle images.

Improvement of the correlation based PTV method

An improved correlation based Particle Tracking Velocimetry (PTV) algorithm was proposed in the present paper. The path tracking of the tracer particles was achieved through a recursive correlation operation of the small interrogation window at two-time steps. The central positions of the tracer particles were determined by the correlation operation of the tracer particle image with a gauss particle mask in order to improve the accuracy to identify the central positions of particles up to sub-pixel level. The performance of the present improved correlation based Particle Tracking Velocimetry (PTV) algorithm was evaluated by using both artifical VSJ standard PIV images and actual PIV images of a self-induced sloshing. Compared with other conventional PTV methods, the present improved correlation based PTV algorithm was found to be able to provide better solution.

Research on the Self-induced Sloshing Phenomena by Using PIV

The self-induced sloshing in a rectangular tank had been investigated experimentally by using Particle Imaging Velocimetry (PIV) technique. The instantaneous flow fields, time average results and phase average results of the PIV measurement were used to reveal the evolution of the vortical structures in the test tank. Based on the experimental result, resonated oscillation was suggested to be the mechanism of the self-induced sloshing, and the fluctuation of the inlet plane jet and the periodically shedding of the unsteady vortical structures were conjectured to be the excitation source of the self-induced sloshing.

Jet Mixing Enhancement by using LIF and PIV

An experimental investigation of vertical and turbulent structure change near a jet mixing flow caused by the lobed nozzle has been conducted. The technique of the Laser Induced Fluorescence (LIF) and Particle Image Velocimetry (PIV) were used to accomplish the flow visualization, instantaneous quantitative concentration measurements and velocity field measurements of the lobed jet mixing flows. Compared with circular jet flow, the lobed jet flow were found to have shorter laminar region, its spanwise Kelvin-Hemholtz vortices paring and combining process was accelerated, small scale turbulent vortices appeared earlier, and the bigger turbulent intensity was found in the lobed jet than that in circular jet flow. All these indicated the mixing enhancement performance of lobed nozzles over the circular nozzle.

An evaluation of Particle Tracking Velocimetry by Density Correlation Using PIV Standard Image

In the present paper, a new algorithm for particle tracking velocimetry (PTV) has been proposed. The algorithm consists on the following two main parts: (1) detection of particles positions by a multi-steps of thresholding, and (2) particle tracking over a two time steps of images by a density cross-correlation method. The performance of present PTV technique was evaluated by using the PIV standard images which distributed with using the internet The results show a good performance to get the high spatial resolution of velocities with a reliable accuracy.