Question!

"Joe_Limon" (Joe_Limon) 08/08/2013 at 16:53 • Filed to: Throttle Body Thursday

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Has there ever been a car/engine with a throttle body like this before?

GRIVLET - Proud of Cobalt > Joe_Limon 08/08/2013 at 16:54

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how would this work? Interesting, but still a bit confused.

Joe_Limon > GRIVLET - Proud of Cobalt 08/08/2013 at 16:55

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The center piece moves axially, restricting flow when it moves to the right, and letting air through when moving to the left.

GRIVLET - Proud of Cobalt > Joe_Limon 08/08/2013 at 16:56

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interesting. Is this in solidworks?

Do a flow simulation, I would be super interested to see what it does.

killerkoolaid37 > Joe_Limon 08/08/2013 at 16:57

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So you're kinda going for the ram air principle on the engines of the SR71, where the cone compresses the air as it moves past?

DocWalt > killerkoolaid37 08/08/2013 at 16:59

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The SR71 engine is exactly what I first thought of. Neato.

Joe_Limon > GRIVLET - Proud of Cobalt 08/08/2013 at 17:00

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It is in solidworks. I'll have to see what is included in my simulation package at home, but for right now at work I'll see what my simplified simulation package can do.

SteyrTMP > DocWalt 08/08/2013 at 17:00

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Dammit! You beat me. I was about to say "Yeah, the SR-71."

Joe_Limon > killerkoolaid37 08/08/2013 at 17:01

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yes, compresses and restricts, in my mind hopefully in a more linear/efficient fashion then a conventional butterfly valve.

SteyrTMP > SteyrTMP 08/08/2013 at 17:02

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Without seeing any information, I have a high suspicion that the SCRAM jet uses the same concept, if not in a slightly less confined state.

Casper > Joe_Limon 08/08/2013 at 17:02

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How do you actuate the center though? Is there some sort of push rod or something? In concept it makes sense if you could over come the additional mechanics involved in actually having it work.

HammerheadFistpunch > Joe_Limon 08/08/2013 at 17:04

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I'm not sure an inlet shock spike has much advantage at subsonic speeds....granted, I'm not sure if induction air ever goes supersonic....hmmm, interesting question. It would reduce turbulence caused by the plate and screw I suppose, but its pretty minimal and I'm not sure reducing turbulence at the throttle body is advantageous since you want turbulence for homogenization of fuel. In either case going throttle-less is where the gas engine is headed anyway so it might be moot.

Joe_Limon > Casper 08/08/2013 at 17:05

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magnetics!

haha, no, I would imagine the easiest way would be with a pipe/rod mounted axially which is attached to the throttle cable.

Victorious Secret > Joe_Limon 08/08/2013 at 17:05

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So, scramjets in our cars?

Where do I sign up?

DrJohannVegas > Joe_Limon 08/08/2013 at 17:06

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Because of the interesting rules about the restrictor/throttle relationship in Formula Student/FSAE, some teams use a similar kind of throttle. IIRC, they call it a "spike" throttle.

Paul, Man of Mustangs > Joe_Limon 08/08/2013 at 17:08

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If you don't, I might see if I can get something together.

Joe_Limon > HammerheadFistpunch 08/08/2013 at 17:08

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In a restricted FSAE engine there is a supersonic limit to the intake restrictor that theoretically keeps the engines under 100hp. But I would think that is hardly the case for a conventional engine.

desertdog5051 > Joe_Limon 08/08/2013 at 17:12

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Sorta similar to the constant velocity carb on my motorcycle.

Never saw one like that but it should work.

HammerheadFistpunch > Joe_Limon 08/08/2013 at 17:13

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its certainly something to investigate, but in this case its looks like it might be counter productive if you are saying that keeping air subsonic limits power, since the idea of a shock spike is to compress and expand incoming air so as to slow it down to subsonic. (the SR71 inlet spike was there so that the engines could ingest subsonic air without stalling out the compressor and it moved out of the way when going faster and more and more bleed air went around the engine to power the ramjet portion of the engine.)

doodon2whls > Joe_Limon 08/08/2013 at 17:14

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Neat idea...

The entry and exit need some work to be ideal for laminar / attached flow at high airflow velocities...

Past solutions for more ideal unobstructed integrated intake trumpet and throttle bodies have employed slide valves or dual rotary valves (where the two halves of the valve rotate and become the side of the intake runner) that allow the air column to be completely unobstructed at WOT. Turbulence @ part throttle airflow turbulence is less of a concern for race cars... They are usually idle or WOT.

Slide Valve:

I couldn't find a decent pic of the dual rotary TB, but the 1999 NATCC Dodge Stratii had them on their highly strung 2.0L engines.

RamblinRover Luxury-Yacht > Joe_Limon 08/08/2013 at 17:14

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Biggest problem: larger minimum size for a given airflow, as the "minimum profile" obstructing airflow is always larger. Might present some problems in low-speed scenarios calling for an open throat. Also, actuation through the travel pathway of air means that unless meticulously designed, the actuation system produces likely comparable turbulence to a butterfly. The only scenario I see this being significantly better in is extremely high-speed flow for compressive effects and reduced turbulence... maybe.

Butterflies, for all that they're not terribly linear (though more so than you might think, taking into account the corrective effect of non-linear axial transmission from a linkage arm) are continually in use because they work. Their actuation system is inherently easy to set up, and they have some semi-beneficial effects on flow linearity if made right. Surface drag on them as ideal flat sheets is usually not too problematic either... except at very high speed.

All that being said, I have seen an engine with a non-butterfly throttle. It was a hit-and-miss engine (though watercooled unlike this picture):

Its throttle was a sliding plate over the throat aperture - open to the elements and effectively like a choke. Indeed, I think it had no choke, just a mix adjust screw and the one close on the airflow. P.R. Imitive.

GRIVLET - Proud of Cobalt > Joe_Limon 08/08/2013 at 17:15

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I'd be interested to see what the flow properties are and turbulence, maybe in a higher-velocity forced induction environment too.

doodon2whls > Casper 08/08/2013 at 17:16

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The actuator rod could be attached to the left side of the 'stinger' and held there with directional flow vanes across the throat of the trumpet.

Joe_Limon > Paul, Man of Mustangs 08/08/2013 at 17:16

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Even flowxpress wizard doesn't seem to like me today and it won't open.

Joe_Limon > HammerheadFistpunch 08/08/2013 at 17:18

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I was thinking more along the lines of making the engine happier at less then full throttle speeds by providing linear throttle manipulation along with reduced turbulence.

Joe_Limon > RamblinRover Luxury-Yacht 08/08/2013 at 17:21

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Butterfly valves are very efficient at full throttle. but at partial throttle they suck... er drag? I was thinking this sort of throttle would more so help every day driving scenarios.

6cyl > Joe_Limon 08/08/2013 at 17:25

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It might work on an single throttle or dual throttle motor but I don't think it would work well for ITB's.

RamblinRover Luxury-Yacht > Joe_Limon 08/08/2013 at 17:28

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It depends on the level of EGR in use. With a full electronic throttle and modulated EGR, the engine can be operating at fairly low Rs compared to how wide the throttle is, because it's not consuming that much stoichiometric mix or turning power out of it.

Granted, I'm on record as disliking both those things, but with a modern car they tend to both be in effect.

Saracen > HammerheadFistpunch 08/08/2013 at 17:34

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I thought the SR-71's Ramjet has a diffuser that slows the air down to subsonic speeds once it gets into high mach.

I also thought Scramjet stood for S upersonic C ombustion Ramjet.

Casper > Joe_Limon 08/08/2013 at 17:37

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Actually if you scaled this down into an ITB solution and used magnetic actuation like a fuel injector, it would probably be pretty fantastic. So much so that if strong/resilient enough, you could use it an a valveless engine concept, letting the "throttle body" be also the intake valve, then use something similar on the exhaust side. Even if you used it in conjunction with valves but in an ITB setup, it could be used to accelerate air flow into the runner to the valve port. Probably help with atomization and response.

LappingLuke > Joe_Limon 08/08/2013 at 17:37

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looks awfully restrictive all the time

Joe_Limon > 6cyl 08/08/2013 at 17:39

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That sounds like a design challenge!

Joe_Limon > Casper 08/08/2013 at 17:41

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I believe camless engines operate this way and don't require throttle bodies.

Joe_Limon > LappingLuke 08/08/2013 at 17:41

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Just put in a bigger diameter :D The cross secional area increases at a square rate, so this throttle won't be that much larger then a conventional butterfly valve.

HammerheadFistpunch > Saracen 08/08/2013 at 17:55

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The diffuser is the inlet spike, more or less. Excess bleed air is dumped over wing.

Casper > Joe_Limon 08/08/2013 at 17:56

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They do somewhat. What I was suggesting was using the shape more than anything to accelerate the air. Current designs vary widely. The main point was that magnets would work and could actually make it cooler in a throttle by wire system. It would be really cool to see it work if you could levitate the central cone completely free, removing obstructions from all sides equally.

6cyl > Joe_Limon 08/08/2013 at 17:59

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That looks so good.

Joe_Limon > Casper 08/08/2013 at 18:01

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That would be cool, but my brain hurts trying to imagine coding a control system that can compensate for dynamically varying drag forces on the cone.

Joe_Limon > 6cyl 08/08/2013 at 18:03

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Now imagine fuel injectors carefully placed on either side of the support plate, and a spiral rifling carved into the cone creating a vortex which more thoroughly mixes said fuel mixture.

6cyl > Joe_Limon 08/08/2013 at 18:05

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Screw that! Injectors in the cones to accelerate the intake charge!

Edit: that spiral idea is pretty cool

Joe_Limon > 6cyl 08/08/2013 at 18:09

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I like your idea, a nozzle at the tip of the cone will mean the high air mass will be directed directly at the fuel stream.

Also spiral cause vortex power :P

The WB > Joe_Limon 08/08/2013 at 18:12

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Flow separation is going to murder you here. With that sharp of a cone you'll be shedding turbulent flow all through the smallest part of your inlet. You can add diameter, but that doesn't solve the turbulence issue until you slow the flow down massively to make it laminar, which means an effective throttle is going to be enormous.

Mazda used a similar design for a mass airflow meter - a cone on a spring - that was ultimately abandoned due to flow limitations, and switched to the low restriction hot-wire.

The throttle as a concept could work, but I don't see there being any positives over conventional designs.

If this is an FSAE situation, you're going to hit critical mach on the taper, as Claude would say, F fast, which is going to make your whole inlet a shock front and murder your flow in the face with an axe, on top of the massive angles on the con-di sections of the nozzle which means it would flow terribly even without the needle.

It's a "Porch-uh" > Joe_Limon 08/08/2013 at 18:13

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I don't care what everybody else says, the biggest problem is that it's way too phallic.

Casper > Joe_Limon 08/08/2013 at 18:15

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Yeah, not to mention what happens when unexpected turbulence causes the cone to become completely unstable do something weird like reverse it's self, turn sideways, or manage to escape the magnetic restriction altogether. Really it would have to be a system using rare earth magnets for basic operation (probably closed) and then be pushed open at a very linear rate by an electromagnetic force. The permanent magnets would have to both attempt to provide closure resistance as well as equally stabilizing the cone, and the micro controller would have to sample at a very high rate to ensure it wasn't varying intake volume too much.

All in all, I don't see doing it with a few fridge magnets and a Netduino.

Joe_Limon > The WB 08/08/2013 at 18:17

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Good point, although it would be interesting to see whether the ID wall would help allow a sharper cone angle. Conventional venturi's rely on a single wall, the air in this scenario is effectively being guided by two.

Joe_Limon > It's a "Porch-uh" 08/08/2013 at 18:18

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phallic like a jet?

Joe_Limon > Casper 08/08/2013 at 18:24

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Now lets say that the cone can freely spin (be it by magnets, or a bearing in the shaft holding it), would a spiral rifling carved into it help? I'm imagining the inertia of the cone could help pressurize the air behind the valve after the intake valve closes.

The WB > Joe_Limon 08/08/2013 at 18:27

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It would be interesting, assuming you had identical cross sectional areas I would imagine the discharge coefficient would be much lower, I think you'd have to go so large to sufficiently overcome the extra friction drag that you'd have diminished throttle resolution.

If you run any CFD, post it, I'd be curious to see how it would stack up. We tried a few different types on the flow bench but never could beat the butterfly for part throttle and WOT (though barrel TB's do great at WOT.

Casper > Joe_Limon 08/08/2013 at 18:28

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That would be fascinating. Would the spin act to stabilize the cone once moving or would it simply cause it instability as it first started rotation... further, if you did add rifling to the cone, but immobilized it in the magnetic fields, would the spin applied to air help concentrate the central volume? Would this improve air velocity or decrease it? I am assuming decrease it due to the added resistance, but it could very well have an unintended impact with the smoother outer walling and increased air density at the center.

Who knows, I haven't had nearly enough coffee to contemplate such things.

Joe_Limon > Casper 08/08/2013 at 19:05

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I am guessing that as a car witnesses all sorts of nasty inertial linear/rotational forces that things could get very ugly.

It's a "Porch-uh" > Joe_Limon 08/08/2013 at 22:20

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Not sure I understand your question. Are you asking if it is phallic, like jets can be phallic?

Joe_Limon > It's a "Porch-uh" 08/09/2013 at 00:07

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The shape reminds me of a jet, I was wondering if you think jets were phallic too.