Masayasu Shimura
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Development of thermally assisted OH PLIF temperature measurement method based on a single femtosecond laser Open
Recently, OH planar laser-induced fluorescence (PLIF) using the broadband, ultrashort femtosecond-duration (fs-duration) and the thermally assisted vibrational transfer in excited state has been investigated in flames. In this present work…
Impact of a Centerbody on the Unsteady Flow Dynamics of a Swirl Nozzle: Intermittency of Precessing Vortex Core Oscillations Open
The precessing vortex core (PVC) is a self-excited flow oscillation state occurring in swirl nozzles. This is caused by the presence of a marginally unstable hydrodynamic helical mode that induces precession of the vortex breakdown bubble …
Stereoscopic Micro PIV Investigation of Velocity Boundary Layer Near Piston Top of a Tumble Enhanced SI IC Engine Open
To develop higher efficiency and lower emission gasoline engines, ultra-lean burning under high Reynolds number conditions is desired. It is believed that enhancement of tumble flow in the engine cylinder is effective for increase of turbu…
Simultaneous OH PLIF/Chemiluminescence and stereoscopic PIV measurements of combustion oscillation onset in turbulent swirling lean premixed flames Open
To yield an effective control to impede the progress of combustion oscillation and to lead to the development of completely stable combustors, it is necessary to reveal the mechanism of the destabilization. For revealing the destabilizatio…
Correlation between velocity and wall heat flux on a piston top in motoring mode of a tumble enhanced gasoline engine Open
Heat transfer inside an engine has been studied for improving thermal efficiency by mitigation of the cooling loss. Flow near a piston top and heat flux on it were simultaneously measured with a microPIV and a MEMS thin film sensor in a mo…
Simultaneous measurements of high-speed micro PIV and MEMS heat flux sensor in a tumble enhanced gasoline engine Open
In order to understand the effect of velocity boundary layer on the heat loss in a tumble enhanced engine, simultaneous measurements of high-speed microscopic particle image velocimetry (PIV) near the piston top and a micro electro mechan…
An investigation of early flame propagation in a lean-burn SI IC engine using time-resolved OH-PLIF measurement Open
This paper describes the ignition and early flame propagation in a high-tumble SI IC engine under super lean-burn condition (excess air ratio (λ) of 2.0). To elucidate the detail process, a high-tumble optically-accessible SI IC engine ope…
Near-wall flame propagation characteristics and the effect of surface reactions Open
To investigate near-wall flame behavior, two-dimensional direct numerical simulations (DNS) of methane/air and hydrogen/air premixed flames between two parallel walls are conducted under several conditions. Using the DNS results, the flame…
Direct Numerical Simulation of High EGR Rate, Lean TRF-air Turbulent Combustion with Tumble Flow Open
To investigate the flame propagation characteristics under a high efficiency spark ignition engine condition, a direct numerical simulation (DNS) of forced ignition of premixed mixtures in a constant volume vessel with a tumble flow has be…
Effects of Turbulence on Ignition of Premixed Gases at High EGR Rate and Low Equivalence Ratio Open
To determine the ignition criteria and effects of turbulence on the localized ignition delay time, direct numerical simulations (DNS) of forced ignition of premixed mixtures have been performed for Toluene Reference Fuel (TRF)-air mixture …
High EGR Rate, Lean TRF-air Turbulent Flame with Tumble Flow Open
To investigate the flame propagation characteristics under a high efficiency spark ignition engine condition, a direct numerical simulation (DNS) of forced ignition of premixed mixtures in a constant volume vessel with a tumble flow has be…
Influence of Surface Reaction on Near-Wall Premixed Flame Behavior Open
To investigate near-wall flame behavior including effect of the surface reaction, two-dimensional direct numerical simulations (DNS) of methane/air, hydrogen/air and n-heptane/air premixed ignition and propagation between two parallel wall…
A Fractal Dynamic SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames Open
Direct numerical simulation of a turbulent hydrogen-air premixed plane jet flame is performed to investigate fractal characteristics and to evaluate the fractal dynamic subgrid scale (FDSGS) combustion model. The DNS results show that the …
An Investigation into Dynamics of Premixed Flames Stabilized in Turbulent Swirl Flows Using High-Speed OH-PLIF Measurements Open
To investigate the characteristics of flame dynamics due to combustion oscillation, high-speed OH planar laser induced fluorescence (PLIF) measurements of methane-air turbulent premixed flame have been performed in a laboratory scale swirl…
Consumption rate characteristics of a fine-scale unburnt mixture in a turbulent jet premixed flame by high repetition rate PLIF and SPIV Open
A 10 kHz simultaneous measurement of OH-CH planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (SPIV) is applied to a methane-air turbulent jet premixed flame. The measurement of the flame tip for high Reyn…
Numerical Investigation on Ignition Criterion and Mechanisms of Ultra-Lean and High EGR Rate Heptane/Air Mixture Open
Direct numerical simulations (DNS) of ignition of an ultra-lean n-heptane/air mixture with high EGR at high pressure have been performed using a reduced kinetic mechanism to investigate the effect of the strain rate of turbulence on igniti…
Development of a Scale Self-Recognition SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames Open
A subgrid scale combustion model for large eddy simulation (LES) of turbulent premixed combustion is developed. The model describes the flame surface area based on fractal characteristics of flame surfaces, and the inner cutoff is predicte…
Flame propagation characteristics of hydrogen-air premixed flames in a constant volume vessel Open
Three-dimensional direct numerical simulation of a hydrogen-air turbulent premixed flame with decaying homogenous isotropic turbulence is conducted to investigate turbulence-flame interactions in a constant volume vessel. The detailed kine…