Turbo Inlet Air Flow Question

Hey Capt, I don't know what you are exactly trying to do.
As I recall you have 12-71s, One of the advertisers here has some really nice crankcase breather stuff.
The new stuff is pretty decent.
Oh, by the way I recently saw a Russian jet that ingested a projectile and most of the turbine blade damage was toward the outer edge of the compressor blades!
Does that help?

I would think that the inlet air velocity should be higher in the center, simply due to lack of drag.
I'm not sure that the comparison with anything hitting jet blades makes sense BTW, because there are centrifugal forces involved with the turbine rotation, that do not affect the inlet section you are interested in.
Besides, in a turbo (contrarily to jets) the compressed air flow is forced perpendicularly to the inlet, rather than along the same direction.

I wasn't arguing with the jet engine comparison as such, just with the object hitting its external fan.
Which I would expect to hit the fan blades wherever its position is in front of them at the instant of impact.
And right after that, if there's one way it can deviate in its path, I think it's outward, but more due to centrifugal effect than air speed.

If we stick to the air flow inside the inlet section, I see no reason why it should be much different (speed aside) from a NA engine.
Hence my inference that the only thing affecting air speed inside the inlet is the drag along its sides.

That said, if there's something I'm NOT, it's a fluid dynamics engineer.
So, happy to stand corrected if anyone knows better.
In fact, you made me curious by now to learn more about this!

That air flow is at its best in the center when away from the fan blade, but the velocity meets high pressure at the center of the fan hub, and it accelerates to the outer edges of the turbo. As the air flow has to work around that bubble of high pressure, it will be at its fastest as it reaches the outer edges of the blade.

Interesting and very logical explanation, thanks.
When I said that in the inlet section I would expect the air flow to behave similarly to a NA engine, I did think that the fan blade and its bulb are bound to introduce some relevant differences.
But CR in his OP mentioned a nipple placed "inches" before the fan blade, so I assumed that we were still talking of the unrestricted section of the inlet. Now, I appreciate that this is a bit of a "how long is a piece of string" question, but how large would you think the high pressure bubble can be in front of the fan?
Just curious.

Haven't studied the dimensions of a DD turbo, but the area is quite small, nonetheless present. In addition the widest portion of the fan blades at the outer edge also create the most low pressure path to work together with the core of higher pressure, setting up the stream.

I don't recall that hub extending past the blades. I actually recall the hub being recessed slightly. Been too long...

Hi guys, interestingly enough, the design, size and configuration of the air filter can alter the air flow in relationship to how
it "hits" the turbo blades..i.e. smooth or choppy w/vortex. That said, sorry to hear you are looking at Racor unit. Walker AIRSEP was factory installed and made standard at DDC during the Penske years. To truly upgrade, install an AIRSEP kit, and all the engineering is done for you, and say goodbye to oil leaks. See schematic example of system. We are happy to help.

Interesting discovery. The top 1.25" hose is apparently worn and weakened, losing some of its structure and collapses under load. Replacing all four of these with new silicone hoses...whereas I used to think a hose that was soft and supple was in good shape..........

No, filters are new. Hoses are extremely soft. Replacing the hoses, disassembling and cleaning all thoroughly and reinstalling. New hoses are much more firm silicone than the existing. Makes me think they were either an improper replacement prior, or they've just deteriorated with time and heat? Weird. Never woulda thunk it.