Figure 1. Meshed truck engine model geometry. (Click to enlarge.)
Figure 3. Engine Model Parameters set up in RadTherm. (Click to enlarge.)
Figure 4. Fluid Stream Node Visualization setup to flow through the exhaust system after the turbo charger. (Click to enlarge.)
Figure 6. Fluid stream nodes in exhaust components.
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Engine Model
The generic Diesel Engine model of RadTherm was used to generate engine surface temperatures, exhaust gas flow rates and exhaust inlet temperatures.
Figure 2. Vehicle Speed curve used by the engine model and wind convection model.
The engine speed curve drives several important thermal parameters: wind-based convection on the vehicle exterior surfaces and engine exhaust temperatures and flow rates.
Exhaust Flow with 1-D Fluid Stream Network
A fluid stream part—a new feature in Version 8—was used to capture the advective flow effects down the exhaust line after exiting the turbo charger. For more information on fluid stream parts, view the online manual included with the Version 8 installation, or view a video/html tutorial on our website. See Figure 3 at left. RadTherm 8 includes part-level radiation patching, allowing for 360-degree patches to be set up in "bands" along a driveshaft or other rotating component, to generate a single view factor averaged for all elements in the band. This prevents unrealistic hot spots from forming in one side of the driveshaft, and is valid for non-reflective part surfaces.
Figure 5. Rotating Part 360-degree View Factor Radiation Patches outlined in blue. Some parts have one element per patch; others (drive shaft) have multiple elements per patch. (Click to enlarge.)
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Figure 7. For rotating parts, additional convection beyond wind+vehicle speed can be imposed. In this case, convection on the rotating driveshaft and tires was tripled.
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Figure 8. Rotating Part View Factor Radiation Patch Parameters set up in RadTherm. (Click to enlarge.)
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