Tohoku University · Engineering
Professor Yuta Ozawa's research lab specializes in experimental and computational aeroacoustics and fluid dynamics, with a primary focus on supersonic jet flows, turbulence, and noise generation mechanisms. The lab investigates the interaction between unsteady flow structures and acoustic fields using advanced measurement techniques such as particle image velocimetry (PIV), schlieren visualization, and near-field acoustic measurements. Key research directions include the Reynolds number effects on jet transition, data assimilation of experimental and RANS simulation data, and the design optimization of industrial tools for multi-process forming. The lab also explores noise reduction strategies through nozzle geometry modification and flow control.
Figures are computed from collected data and may differ slightly.
The Reynolds number effect on the aeroacoustic fields of a supersonic jet was experimentally investigated via particle image velocimetry (PIV), schlieren visualization, and near-field acoustic measurements. Cold supersonic jets under ideally expanded conditions at a Mach number of 2.0 were produced with the Reynolds number, based on the diameter of the nozzle exit, ranging from 105 to 106. This study focuses on the laminar-to-turbulent transition of a supersonic jet, including a transitional con
Data assimilation using particle image velocimetry (PIV) and Reynolds-averaged Navier–Stokes (RANS) simulation was performed for an ideally expanded supersonic jet flying at a Mach number of 2.0. The present study aims to efficiently reconstruct all the physical quantities in the aeroacoustic fields that match well with a realistic, experimentally obtained flow field. The two-dimensional, two-component PIV measurement was applied to the jet axis plane, and the time-averaged velocity field was ob
The aeroacoustic fields of twin jets and the equivalent single jet were experimentally investigated using particle image velocimetry (PIV), schlieren visualization, and acoustic measurement. The present study focuses on the aeroacoustic fields of the twin jets, and the effect of the interaction between each jet was investigated using various nozzle spacing. The PIV results indicated that strong interaction causes elliptical jet growth on a cross-stream plane and a decrease in the Reynolds stress
This paper deals with a design and a shape optimization of a tool that combines punching of a tarpaulin with the tarpaulin grommet pressing in one operation.The tarpaulin grommet 0.5 mm thick with a diameter of 10 mm is made of DX51D+Z275MAC steel.The designed tool and its main shape dimensions are verified by using a numerical simulation in an ANSYS Workbench software and subsequently also by a practical experiment, i.e. verification and debugging functionality in cooperation with H + D kovo co
View Video Presentation: https://doi.org/10.2514/6.2021-2106.vid Supersonic jets of M=1.35 and 2.0 were measured by time-resolved near-field acoustic measurement and non-time-resolved particle image velocimetry (PIV). The multi-time-delay modified linear stochastic estimation (MTD-mLSE) was applied to the reduced-order acoustic and velocity field data based on the proper orthogonal decomposition (POD) coefficients. Time-resolved snapshots of the velocity field reconstructed by MTD-mLSE show the
The effects of nozzle geometry on the acoustic waves from Mach 1.9 supersonic jet are experimentally investigated. PIV and microphone measurements are conducted to analyze the relationship between flows and acoustic waves. In this study, three different nozzles of conical nozzle, convergent-divergent nozzle (C-D) nozzle, and tab C-D nozzle in which tab is attached in nozzle inlet to generate disturbance are considered. Three noise sources are identified. Conical nozzle case shows screech and bro
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