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You can't realistically have a gas turbine in line in the intake tract (which is how I understand this - please correct me if not); better to use your second choice of driving a seperate fan. I seem to remember though that gas turbines are most efficient at constant speed; not sure how relevant this would be. |
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Tiny gas turbines are bl00dy expensive - probably cost more than most cars ...... |
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Yeah, but this is the halfbakery where small gas turbines are cheap, plentiful and come in myriad colors. |
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8/7 - but this would probably be primarily used in racing |
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If you're gonna go, go all the way. [link] |
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[chud]: If you mean "why can't you have a gas-turbine in-line in the intake tract", because the exhaust from a gas turbine is too hot to be used as the intake air for a petrol engine. |
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Angel: Well, you can use a high-bypass compressor design, vent the actual exhaust seperately, and use an intercooler ..... that would work and the weight penalty wouldn't be that high, air-air intercoolers are failrly light. |
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Hm. That would make the gas turbine directly analogous to a turbocharger, really. The hi-bypass cold-section functionally matching the turbocharger compressor and the turbine hot-section matching the exhaust driven hot-side of the turbocharger. |
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angel - i thought that the heat would be a benefit, increasing speed/efficiency of reaction. if its a problem with the engine being damaged would ceramic/composite cylinders help? |
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[chud], I think the extreme heat might cause premature ignition. Also, there likely wouldn't be a whole lot of oxygen left after passing through the burner of a turbine. |
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Although i dealt with oxygen in the idea (which would also help cooling) and you could fit a really good intercooler. The premature ignition is a problem - one solution could be to inject the fuel into the cylinder fractionally before ignition. |
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Ooops, you did talk about O2. Sorry 'bout that. The thing I think about your using precise fuel metering/timing to combat it is that it will never be as precise as electronic ignition timing and the gains you get from the supercharging will be lost by poor combustion control. |
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If you insist on a gas turbine in the induction system, the thing that makes the most sense to me is [8th of 7]'s approach. |
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The other thing that could be done is to use a gas turbine, running at a constant speed, to drive a turbocharger at max boost all the time with the wastegate handling all of the spillover/overboost. (I've mentioned this one before, a few times. It is not an idea original to me though. It was proposed for F1 racing some time ago but dropped as F1 rules prohibit the use of any ancillary combustion devices). |
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Is this where I get to wax enthusiastic about miller cycle engines? |
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I'm no engineer but I see problems with an additional gas turbine mounted on the air intake consuming it's own share of oxygen AND releasing its own share of combustive gasses. You'll need some serious plumbing in the block or you might as well add a few more bricks in there instead. |
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i was looking at something like this recently in a model jet engines book...this design is kinda (like, the theory behind it) used already, just sparcly...instead, on the exhaust, right before the turbine they added a combustion chamber like in a jet turbine engine, effectivly turning the turbo's turbine into a jet engine, and by spraying light amounts of fuel into the chamber, it powers the turbo, with zero-lag when time comes to throttle up. I'm right now redesigning the idea they had in the book to make it more efficient, ill have design-ideas on my website in a few days (http://cancerouspete.ath.cx) |
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This is just a thought. How about using a small bleed air compressor to keep the turbo spinning at low RPMs. Bleed air is used to start aircraft gas turbines spinning when their APUs break. |
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But doesn't the bleed air come from an already running turbine/jet ? Isn't that why it's called bleed air? |
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If it's from an air compressor isn't it just "compressed air?" |
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//we have taken a squirrel fan blower, // |
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I never knew that squirrels could run so fast. |
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U dont want to increase preliminary temperature in the engine couse what gives power is the difference in temp before and after combustion, therefore the wide use of intercoolers in turbocars!
pressure= good, and problems with premature ignition can be controled by using hi pressure direct injection!
summary: bad idea! but use it only to drive a secondary fan is not bad at all unless u dont consider fuel economy an imoprtant future in a car! |
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It's too bad you can't mark comments for spam here. |
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Indeed, this user inspired my new idea for a [marked-for-spam] button. I think he's spammed over 10 ideas now. |
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