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MAE513 Spring 2001 Prof. Hui Meng & Dr. David Song Dept. of Mechanical & Aerospace Engineering Advanced Diagnostics for Thermo- Fluids Laser Flow Diagnostics.

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Presentation on theme: "MAE513 Spring 2001 Prof. Hui Meng & Dr. David Song Dept. of Mechanical & Aerospace Engineering Advanced Diagnostics for Thermo- Fluids Laser Flow Diagnostics."— Presentation transcript:

1 MAE513 Spring 2001 Prof. Hui Meng & Dr. David Song Dept. of Mechanical & Aerospace Engineering Advanced Diagnostics for Thermo- Fluids Laser Flow Diagnostics Laboratory Lecture 1 Introduction

2 Turbulent Flows Aircraft Automobiles, Ships Chemical Reactors Material Processing Heat Exchangers Turbines, Pipes Our Environment Atmosphere Galaxy Human Body (Blood Vessels, Lungs…)

3 High Efficiency Static Mixer

4 3D Model of Tab Wake Structures

5 Turbulent Flows  Predict (CFD, Validation)  Control (Topology + Dynamics)  Understand (Coherent Structures) Instantaneous Temporal Spatial (field) Velocity & vorticity field Pressure Species concentration Temperature Particle/droplet distribution (number density, size, velocity)... Need Measurement Need for Advanced Diagnostics

6 Laser Diagnostics: non-intrusive n No solid probes (hot-wire sensor, pitot tube) to obstruct or disturb the flow. n Using point (beam focus), planar (light sheet), volumetric (expanded) illumination Large measurement domain, high spatial sampling resolution n Light: carrier of information, thru physical processes (interaction with fluid) Mie scattering (from particles 0.1~ 100  ) Laser Induced Fluorescence (from particles or molecules) Rayleigh scattering (from molecules) Stimulated Raman scattering (from excited molecules) Direct informationInferred quantity Doppler shift  velocity Image  position - displacement (velocity) Intensity  concentration, temperature, air pressure

7 Available Techniques n Laser Doppler Velocimetry (LDV) V elocity time history at a point, turbulence statistics at one or two points n Particle Image Velocimetry (PIV) – Time-series 2D planar velocity field; turbulence statistics fields n Holographic Particle Image Velocimetry (PIV) – Instantaneous 3D volumetric velocity fields n Planar Laser Induced Fluorescence (PLIF) – Instantaneous 2D concentration field; Mean and fluctuation concentration ; Intensity of segregation n Combined PIV and PLIF Scalar Flux n Rayleigh scattering, Raman scattering, CARS, etc. – Temperature, species concentration n Liquid crystal color – temperature distribution on a solid surface n Pressure sensitive paint – Pressure distribution on a solid surface

8 Tools to Probe into Turbulence ----- velocity u(x,t) Experimental: Pointwise: LDV Planar: PIV Volumetric (3D)? Computational: Direct Numerical Simulation (low Re) Large Eddy Simulation RANS (Models Need Validation)


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