Needless to say, I came in early the next morning to see the results (I told you I was a geek). Using the Batch Run command in Flow, I was able to run all the simulations at once (overnight). Once I was happy with the mesh and input variables, I cloned “y up” twice to “x up” and “y down.” The only difference between studies now is the direction of gravity (as mentioned above). I ran one study (y up) with a variety of meshes to make sure my values were acceptable. I am running these studies to check out the convection flow and how the bulb orientation affects cooling. Any results I get are strictly for comparison purposes. I also conveniently left out the connection between the board and the aluminum base. All my dimensions are guesses, including the LED size and circuit board thickness and shape. I also do not work for Cree, or any other bulb manufacturer for that matter. If you recall from my last post, I used sketch pictures and a lot of Google to come up with my design. I used a Volume Heat Source on each of the 8 LED “cubes” of 8.8W (total), and a Diffuse Radiation Source on the same bodies of 2.2W (total).Īt this point, I think it is important to discuss some assumptions I have made along the way.
The bulb I am studying is a 60W equivalent which is an 11W LED. Here are the numbers I used: More Googling led me to a Wikipedia page that shows the heat and radiation output of standard LEDs, called Luminous Efficacy. I also added Global Goals to make sure the solver focused on the maximum temperature of the solid and fluid (air). Then Clone the study and just change the direction of gravity to “rotate” the bulb for each study. Set up Materials (Plexiglass for shell, Aluminum for the base, and PCB for the boards), and Heat/Radiation sources on the LED blocks themselves. Using SOLIDWORKS Flow Simulation, I was able to virtually simulate each of these scenarios and see which mounting scenario was most appropriate for this type of cooling. Some of my fixtures are side-mounted, some have the bulb pointing up, and some have the bulb pointing down. Since this bulb uses convection to cool the circuit boards, I want to see how that works and how effective this process is depending on how I mount the bulb. In my last blog post Studying the Next Generation of LED Light Bulbs, I talked about how these light bulbs look like regular light bulbs and how they don’t have the ugly heat sinks.
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