Advanced Fluid Dynamics Laboratory
Department of Mechanical and Aerospace Engineering
Tokyo Institute of Technology

staff location Our Website Keywords Main Researches


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Ishikawadai 1st bldg.,
2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550,

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Turbulence, Turbulent Combustion, Turbulent Heat and Mass Transfer, Direct Numerical Simulation, Super Computing
Laser Diagnostic, Propulsion and Energy System in Next-generation
(Thermal Engineering, Fluid Engineering, Environmental Engineering)

Main Researches

< Direct Numerical Simulation of Turbulent Flows >

Direct numerical simulation (DNS) of turbulent flows gives nearly exact solutions of Navier-Stokes equations which describe motion of fluids. DNS of turbulence requires high accuracy spatial discretization method, and takes very long CPU time with huge memory. Recently, DNS is an important research tool to get more detailed information of turbulence structures which are difficult to obtain by experiments. In this laboratory, DNSs of various kinds of turbulent flows have been conducted with billions of computational grid points. These are one of the most largest DNS in the world.

From the above DNSs, it has been clarified that the universal fine scale structure, which is independence on flow fields and Reynolds number, and called as "coherent fine scale structure" exists in turbulence. The understanding of this fine scale structure is very useful in modeling and controlling of turbulent flows. The coherent fine scale structure also dominates drag reduction, heat and mass transfer, etc., which are important in engineering applications. In this laboratory, researches of many phenomenon related with turbulence have been conduced extensively based on the coherent fine scale structure.

Homogeneous Isotropic Turbulence

Homogeneous Isotropic Turbulence(Rel=270.1)

Hydrogen-Air Turbulent Premixed Flames

Hydrogen-Air Turbulent Premixed Flames(Rel=97.1)

< Direct Numerical Simulation of Turbulent Combustion >

To perform the direct numerical simulation of turbulent combustion, energy and many species conservation equations have to be solved in addition to the turbulent flow field. Flame is composed of many chemical species and many elementary reactions. To simulate the flame with high accuracy, higher spatial resolution and smaller time steps compared with nonreactive turbulence are required. As for hydrogen-air combustion, more than ten chemical species and dozens of elementary reactions should be considered. For methane-air combustion, several tens of chemical species and several hundreds elementary reactions are required. Therefore, these characteristics of the flame results in difficulty of DNSĀ of turbulent combustion.

In this laboratory, three-dimensional DNS of turbulent combustion with detailed kinetic mechanism, which was the first 3-D DNS in the world, has been conducted in 2000. In the turbulent combustion, interaction between fine scale structure and flame dominates the local characteristics of the turbulent flame and has significant effects on turbulent burning velocity . The investigation of detailed structure of the turbulent combustion may lead to the developments of high efficiency and low emissions combustors in near future.

< Time-Resolved Stereoscopic Particle Image Velocimetry >

Particle image velocimetry (PIV) is one of the measurement methods of flow velocity. PIV can give two or three velocity components at multi-points in a two-dimensional plane or a three-dimensional volume simultaneously. However, compared with hot-wire anemometry and laser doppler velocimetry, which is single or several points measurement, temporal resolution of conventional PIV is relatively low ( up to several tens Hz in general). In turbulent flows, velocity includes fluctuations more than several kHz. Therefore, the conventional PIV system has been failed to investigate turbulence structure in details.

In this laboratory, time-resolved stereoscopic PIV system (up to several tens kHz) has been developed by using high-speed CMOS cameras and high-repetition-rate Nd:YAG lasers for industrial processing. The maximum temporal resolution is 26.7kHz, which is the fastest PIV in the world still now. This time-resolved stereoscopic PIV may contribute the progress of turbulence research in near future.

Time Serise Vector Maps of  Turbulent Jet

Time Serise Vector Maps of Turbulent Jet
(1.799 kHz)

local flame structure

Local Flame Structure

< Simultaneous CH-OH PLIF and Stereoscopic PIV >

To investigate the local structure of turbulent flame experimentally, planar laser induced fluorescence (PLIF) is commonly used. PLIF of OH radicals has been useful to separate the unburned mixture and the burned gas, whereas that of CH radicals have been adopted to investigate characteristics of the flame fronts in turbulence because CH radicals are produced at the flame front and have very narrow width enough to represent the reaction zones. In high intensity turbulent flames, simultaneous CH and OH PLIF provides many important information about the local flame structure in turbulence.

In addition to flame structure which is given by radical PLIFs, characteristics of turbulent velocity field are very important to clarify the turbulent combustion mechanism. However, almost all previous experiments are limited to the simultaneous measurements of single radical PLIF and two/three velocity components in a two-dimensional plane. In this laboratory, to investigate local flame structure of turbulent premixed flames, simultaneous CH-OH PLIF and stereoscopic PIV system have been developed. The developed system was applied for relatively high intensity turbulent premixed flame in a swirl-stabilized combustor, and simultaneous two radical concentration and three component velocity measurement has been succeeded, which was also first report in the world.