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One of the moderators asked me to post an introduction. A word of warning: I tend to be longwinded – the readers should be prepared to pace themselves.
My first involvement with automotive aerodynamics was from my senior design class as an ME student at Texas Tech. My team members and I tested pick-up bed modifications on a scale model in Tech’s wind tunnel. Our main finding was that a “wing” (extension of the cab upper surface) combined with a partial bed cover on the tailgate end produced a 17% reduction in drag. This was written-up by my prof’s in “Pickup Truck Drag Reduction Devices That Reduce Drag without Limiting Utility,” Maxwell, Jones, and Jones, SAE paper 881874 (published in 1988). If memory serves me correctly, a partial bed cover also reduces the lift by about 40%.
I stayed-on at Tech to do research on the efficiency of frontal cooling openings on a car for various vehicle speeds and cooling fan flow rates. I made a hollow wind tunnel model that was attached from its trailing end to the suction side of a blower. From my test run data, I discovered that my results could be correlated using just two dimensionless parameters. In a nutshell, these parameters make a little wind tunnel test data go a long way in predicting the pressure loss at any combination of vehicle speed and fan flow rate for a given cooling opening geometry. My advisor, Walt Oler and I wrote “Ram-Recovery Coefficient Correlations for Automotive Cooling Airflows”, SAE paper 910309 (published in 1991). All my results were confirmed in full scale tests conducted by Ford and Tech (Ford did not advertise this finding in any technical paper).
There was a lot of other vehicle aerodynamic research going on at Tech while I was there, such as a 3/8 Taurus model that was towed under water to visualize the under hood airflow. The viscosity and density of water allowed a reasonably representative Reynold’s number but with the time scale increased dramatically. With dye injection, you could see the flow patterns develop (in slow motion) in the engine compartment whereas a similar tests using smoke in a wind tunnel were almost indecipherable.
I pursued my next degree at the University of Texas at Arlington. At this point, I switched to supersonic wind tunnel research. The arc-heated tunnel I used at UTA was about 30 times more powerful than the low speed tunnel I used at Tech. It is basically an overgrown plasma torch and also proved to also be about 30 times more challenging to operate. My research in simulating scramjets eventually morphed into experiments in obtaining hydrogen from methane and ethane using a plasma torch. Based on my research, I suspect that it may be feasible to fuel a car or truck with methane and use an arc-pyrolysis process to create hydrogen just upstream of the engine. The byproduct would be a bucket full of high grade carbon black which may be used for other things.
I have been thinking quite a bit about ecomodding, but have not done anything yet beyond buying a station wagon instead of an SUV. I have “ecomodded” my house and swimming pool however. After working on this invention for over a year, I now have a patent pending on it. At this point the challenge is to become one of those 3% of inventors that actually make money off their inventions.
I applaud those of you who are engaging in ecomodding. The public needs to see and get accustomed to the look of aerodynamically efficient vehicles. Also a hearty hurray for you pathfinders making ecomods that aren’t visible – perhaps you all should display your mpg improvements numbers on the outside of your vehicles.
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