Grant 302
basic and well known psychic
Managed a wool tuft test on the splitter yesterday afternoon.
Side view so you can see that some of the tufts are raised:
Frame 1:
Frame 2:
Video scrolling roughly between the two frames, goes forward, backward then forward:
I am accelerating from a stop between Frame 1 and 2 in a 50 mph zone.
There are 8 tufts in the test:
1- near the center directly on the splitter and does nothing for all the video taken.
2- on the splitter near the front just inboard of the stanchion/rod
3- on the stanchion/rod
4- raised ~3/4"
5- raised ~1.5"
6- on the splitter
7- raised ~1"
8- on the splitter most outboard in this test
I'll post later on my interpretation of what's going on later and follow up with a similar post for the on-ramp to freeway run.
These annotations show what I think is happening on my spitter at ~60mph:
Generally, there appears to be a high pressure stagnation area or slow recirculation (in blue judging by movement of tuft 4 and sometimes 6) in the center that breaks down to a outward vortex that 'bursts' into 'clean' attached flow (white 'rays' shown by tuft 8 and other droplet tests also #6 at higher speeds) near the outer side of the splitter before it rounds the front corner. Tests are showing that the area where there is forward flow on this splitter is relatively small and contained to the front/center where it quickly turns laterally toward horizontal as samples are taken further outboard. These two effects happen more inboard as speed increases, as shown by the 'scrolling' video clip. One can see how the tufts 'scoot' outward as I accelerate, and back inboard on deceleration (in other parts of video). Without going to the other video sections, at 80+ mph, most of the recirculation bubble is gone and all turns into attached/semi-turbulent (perhaps stream-wise vortex) flow in the areas roughly outside of the splitter rods (tufts 4-8 all flip to the top side like #8 but not stable).
From the tufts that are forced forward under the splitter, they often peek out like this:
...indicating that there is a vortex/recirculation bubble that follows the bottom of the leading edge of the splitter. Generally shown in dashed red (top photo), except where flow rolls under the bubble and toward the rear.
