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Discussion Starter · #1 ·
I wanted to post a few thoughts about the radiator's air flow measurement. There is no doubt (in my mind anyway) that the LLY would benefit from improved airflow. KB, TxC, & others both have mods that help in this vane.

From previous wind tunnel studies I have performed on full size vehicles, the frontal wind flow pattern can be very surprising. Subtle changes in trim can cause reverse flow through some sections of the radiator while other sections have normal flow. A single point measurement is not sufficient to quantify the flow pattern or mass flow rate across the radiator.

The ability to accurately measure the airflow pattern would permit a better quantification of the effects of the shrouds, splash shield spacers, fan modifications, etc.

I have attached a couple of pictures of the flow measurement devices that one of our students built to measure air flow. These particular sensors were built for Ford and GM to use in their frontal tests of new vehicles. While these were built with a little more expensive process for consistance and accuracy, I believe with a few minor changes, someone could put together a nice array of air flow meters at a very reasonable price. Instead of using the metal tube and EDM cut blades, a pvc tube cut in about 1/2" slices could suffice. I haven't looked, but a hobby store would probably carry a set of propellers that could be modified to worked.

The meters have two optical recievers noted on the photos. With two receivers, one will always pulse before the other for a given flow direction. The first pulse signal from the receivers will change to the other sensor when the direction of the blade reverses. The frequency of the pulse is calibrated to air speed. The receivers react to the light being transmitted off of the optical transmitter and reflected back to the recievers. By having flow value and direction, you can get an accurate picture of true flow across the radiator.

Just one of these meters is not enough to get an accurate measure of flow pattern. A array of meters across the front of the truck is needed to obtain a complete flow pattern. By knowing the flow pattern, the cause and effect of the air flow modifications that are available now and the new ones to come could be measured for optimization.

Well, those are a few of my thoughts on air flow I wanted to share for what it is worth.



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