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Laser Flow Diagnostics Laboratory. Advanced Diagnostics for Thermo-Fluids. Lecture 1 Introduction. MAE513 Spring 2001 Prof. Hui Meng & Dr. David Song Dept. of Mechanical & Aerospace Engineering. Turbulent Flows. Aircraft Automobiles, Ships Chemical Reactors Material Processing
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Laser Flow Diagnostics Laboratory Advanced Diagnostics for Thermo-Fluids Lecture 1 Introduction MAE513 Spring 2001 Prof. Hui Meng & Dr. David Song Dept. of Mechanical & Aerospace Engineering
Turbulent Flows Aircraft Automobiles, Ships Chemical Reactors Material Processing Heat Exchangers Turbines, Pipes Our Environment Atmosphere Galaxy Human Body (Blood Vessels, Lungs…)
Understand • (Coherent Structures) Turbulent Flows • Predict • (CFD, Validation) • Control • (Topology + Dynamics) Need for Advanced Diagnostics Need Measurement • Instantaneous • Spatial (field) • Temporal • Velocity & vorticity field • Pressure • Species concentration • Temperature • Particle/droplet distribution (number density, size, velocity) • ...
Laser Diagnostics: non-intrusive • No solid probes (hot-wire sensor, pitot tube) to obstruct or disturb the flow. • Using point (beam focus), planar (light sheet), volumetric (expanded) illumination Large measurement domain, high spatial sampling resolution • Light: carrier of information, thru physical processes (interaction with fluid) Mie scattering (from particles 0.1~ 100m) Laser Induced Fluorescence (from particles or molecules) Rayleigh scattering (from molecules) Stimulated Raman scattering (from excited molecules) Direct informationInferred quantity Doppler shift velocity Imageposition - displacement (velocity) Intensity concentration, temperature, air pressure
Available Techniques • Laser Doppler Velocimetry(LDV) Velocity time history at a point, turbulence statistics at one or two points • Particle Image Velocimetry (PIV) • Time-series 2D planar velocity field; turbulence statistics fields • Holographic Particle Image Velocimetry (PIV) • Instantaneous 3D volumetric velocity fields • Planar Laser Induced Fluorescence (PLIF) • Instantaneous 2D concentration field; Mean and fluctuation concentration <’2>; Intensity of segregation • Combined PIV and PLIFScalar Flux <u> • Rayleigh scattering, Raman scattering, CARS, etc. • Temperature, species concentration • Liquid crystal color • temperature distribution on a solid surface • Pressure sensitive paint • Pressure distribution on a solid surface
Tools to Probe into Turbulence ----- velocity u(x,t) • Computational: • Direct Numerical Simulation (low Re) • Large Eddy Simulation • RANS • (Models Need Validation) • Experimental: • Pointwise: LDV • Planar: PIV • Volumetric (3D)?