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Simulation of Thermal Images

Simulation of Thermal Images. ECE 673 Summer 2003 Presented by Vijaya Priya Govindasamy. Outline. Objective Proposed Approach Implementation Results Conclusion Scope of improvement. Objective. To understand the way the simulation tool works for complex models

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Simulation of Thermal Images

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  1. Simulation of Thermal Images ECE 673 Summer 2003 Presented by Vijaya Priya Govindasamy

  2. Outline • Objective • Proposed Approach • Implementation • Results • Conclusion • Scope of improvement

  3. Objective • To understand the way the simulation tool works for complex models • To define complex models for simulation in MuSES • To understand the sensitivity of different parameters in running the simulation and their effect on simulation of complex models • To reason out the solution obtained at the end of the simulation (Do you see what you would expect to see)

  4. Need for Simulation • Reduces the time and cost of developing prototypes for test purposes • Gives more flexibility in controlling the parameters • Infrared prediction measurements are accurate and faster

  5. MuSES • MuSES – Multi-service Electro-optic Signature • MuSES is a thermal modeling tool, used to model the steady state and transient distribution of heat over complex surface descriptions of component systems. • MuSES models 3-D conduction, convection, and multi-bounce radiation. • The output from MuSES is the temperature map of the component system which can be viewed using the integrated post-processor

  6. Parts and Elements • Parts vs. Elements • collections of elements that have the same properties, materials, and surface conditions. • The thermal results are solved for the individual elements, but all properties (e.g. part type, materials, thickness, convection coefficient, etc.) are assigned at the part level. • The properties applied to the part will also apply to all of the elements assigned to that part. • Elements vs. Nodes • One or more thermal nodes, depending on the part type • Thermal results are calculated for each of the thermal nodes

  7. MuSES Interface Source: MuSES Manual

  8. MuSES Solution Procedure • Group geometry • Assign material properties • Set boundary conditions • Set solution parameters • Run simulation • Run signature simulation(optional) • View results using post-processor

  9. Meshing Requirements • The characteristics of a good quality mesh for import into MuSES are: • All adjacent polygons share common vertices (equivalenced mesh) • All polygons are 3 or 4-sided (triangles or quads) • All polygons are convex • All polygons have an aspect ratio near unity(e.g. no long and skinny polygons) • Polygons are spread uniformly across thesurface (e.g. avoid fans of polygons) • No overlapping or repeated facets • Surface mesh only (e.g. thin plates represented by their exterior surface only)

  10. Poor Mesh • MuSES treats overlapping and adjacent vertices as unconnected parts • The polygons should be uniform with aspect ratio of unity • Overlapping elements should be embedded on the host surface Overlapping elements Unconnected parts Source: MuSES Manual

  11. Previous Work Exhaust System Model Car Underbody Model Source: http://imaging.utk.edu/~priya/ece671

  12. Part Types • Assigned temperature parts • Temperature curves are assigned for such parts • Surface condition and Bounding box condition are assigned • Calculated Temperature parts • Only initial temperature value is given • Convective heat coefficient value is assigned • Temperature values are calculated as a result of numerical solution • Surface condition, Material properties and Bounding box condition are assigned

  13. Properties • Material Type • Given for calculated parts • Based on the type of material the numerical solution is carried out • Thickness • Does not mean anything with the geometry • Used only for calculation • Surface condition • Defines the emmisivity property • Paint codes are also used • Convective coefficient • The value of ‘H’ is given for calculated parts • Used in numerical solution

  14. Property Definition • Sample Property Definition • Engine Interior • The temperature is very high due to combustion • Engine Exterior • In real time the coolant fluid reduces the outside temperature Engine Temperature curve

  15. Property Definition • Sample property definition • Muffler Interior • Exhaust gas temperature • Muffler Exterior • Outside heat loss to the environment – convection & radiation Muffler Temperature curve

  16. Solution Analysis • Start time and End time • Step size • Tolerance slope and Tolerance • View factor rays • Number of iterations • Accuracy of the solution • Convergence parameter

  17. Original Geometry • Under body • Engine • Muffler • Transmission • Inverter • Radiator • Catalytic converter • Starter Motor • Batteries • Intake and Exhaust Manifold • Wheels • Upperbody

  18. Simulation result of Upper Body

  19. SimulationresultofUnderBody

  20. Construction of model Reasonable temperatures Medium complexity Tolerance slope of solution convergence - 5e-007 Assumptions Construction of the model

  21. Solution Justification Simulation result of Upper Body & Under body

  22. Temperature Curves Catalytic converter Engine Muffler

  23. Simulation of Thermal Images • Bidirection Reflectance Distribution Function • Displays the image as seen through a sensor • Uses the radiosity solution, environmental conditions and viewing geometry • Requires use of paint code at least by one surface • Two step process • First step: Computes radiances • Second step: Ray tracing

  24. Thermal Images of Upper Body Car Upperbody Infrared prediction View 1 View 2

  25. Thermal Image of Under Body Infrared Prediction of Car Under body

  26. Thermal Image Results and Statistics

  27. Thermal Image Results and Statistics

  28. Simulation of Toyota Model • Total number of parts when downloaded :281 • Reduced to 17 parts • Additional parts • Transmission • Complete drive train • Gas tank • Discs and Drums • Shock Absorbers

  29. Toyota Model Toyota Tundra Pickup Undercarriage Source:http://www.3dcadbrowser.com/browse.aspx?category=52

  30. Error Report • Time taken for view factor calculation – more than 72 hours • Following error generated after 3 days • This TDF file was written with MuSES Pro 7.0.0 • Model statistics: • Elements: 467262 • Vertices: 1401798 • Parts: 16 • Opened `d:\priya-MuSES\toyota.tdf' • There are 934525 thermal nodes in the model • Assigning radiation patches... • Computing view factors... • View factor calculation completed • Out Of Memory adding radiation nodes to the solver. • Please close some applications and try again.

  31. Error Report

  32. Scope of improvement • Problems associated with computer memory has to be solved • Simulation of laser scanned 3d models of real elements

  33. Report Revisited • Abstract (1/1) • Introduction (5/5) • Background • Proposed Approach • Theory and Methods(6/6) • Thermal Imaging • MuSES • Simulation of Thermal Images • Experimental Results(5/5) • Conclusion(1/1) • Reference(1/1)

  34. Thank You

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