How to improve spool, scientifically speaking

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03-13-12, 08:05 PM

#51

arghx

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Quote:

Originally Posted by First gen man

Hmm. Even being controlled by air seems hard to work out.. Maybe unless it's powered on exhaust pressure possibly? How would you go about installing an air powered actuator?

Think of an internal wastegate actuator.

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For spool up times do you want the vane placement as close to the turbine wheel as possible? After full boost is acquired, the lowest exhaust backpressure as possible while keeping full boost up? So most likely slowly spacing away as the RPM's rise? Can it work somewhat successfully on rpm alone?

That's the idea. As far as control strategies... you'd just have to mess around with it. You would most likely need a wastegate to control. Most diesels with variable vane turbos don't have one.

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03-13-12, 09:09 PM

#52

Speed of light

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Quote:

Originally Posted by First gen man

....For spool up times do you want the vane placement as close to the turbine wheel as possible? After full boost is acquired, the lowest exhaust backpressure as possible while keeping full boost up? So most likely slowly spacing away as the RPM's rise? Can it work somewhat successfully on rpm alone?

Actually, it's just the opposite. You shutter the vanes to accelerate the turbine and open them to reduce back pressure. The dynamics of turbine performance are quite complex (more so than compressor function) with several key variable inputs. My impression is that controlling the VGT based on mass flow vs. load might be a way to go--RPM and throttle position will necessarily factor in. Mass flow vs. turbine RPM also offers some intriguing possibilities as well.

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03-16-12, 09:01 PM

#53

First gen man

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Quote:

Originally Posted by arghx

Think of an internal wastegate actuator.

Ya I was thinking of having more complex control over the vanes, but really for what I'm thinking that sounds about right. Just snap the vanes to full open after full boost is aquired and use an external wastegate to regulate from there.
I think the rotary can keep full boost with full vane openings?

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03-16-12, 09:10 PM

#54

First gen man

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Quote:

Originally Posted by Speed of light

Actually, it's just the opposite. You shutter the vanes to accelerate the turbine and open them to reduce back pressure.

No, no. That's basically what I was trying to say. Open them after full boost. That is if by "shutter" you just mean shut. I said it like " moved closest to the turbine wheel."

Unless you really mean they shutter like flutter, ahahah that would be a strange concept..

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