Velocity Stacks...

[Rubber Chicken]

Hey all.

I'm an Aerospace Engineering student, and I'm taking CAD and CFD (computational fluid dynamics) classes.

Most of the final projects are things like flows over wings, or helicopter blades, but with my professors approval I wanted to do a case study on the flow though an intake of an internal combustion engine.

Specifically, I wanted to model the flow though a roof scoop and into a velocity stack on the NSX. And if possible optimize the roof scoop for the mass flow rates though each individual throttle body.

My problem is that I don't have any really detailed drawings of the hatch or the engine bay. I remember seeing the cutaway in the FAQ, but that's about it.

Is there any information that you all could provide me that you think would help me with this project? I'd be more than happy to share my results once I finished.

Any feedback/comments are welcome.

 

[Dr.Honda]

Try searching some of the various race-prepared NSX's. Recent thread on the Mugen NSX and on a German car that was supposedly a LeMans winner. I always thought that the NSX would look awesome with velocity stacks, would the transverse orientation of the engine make it difficult?

 

[Dr.Honda]

Oh, BTW wouldn't the side scoops become un-necessary? (I guess the right one already is)

 

[nsx4fun]

I think the right side scoop is used to draw cool air into the engine compartment. Not to cool the engine, but to reduce the temperature of everything else that is heated by the hot air from the engine & exhaust. So having two scoops for this purpose should improve things. So, I would say a ram air style roof scoop doesn't make the side scoops obsolete.

 

[MadMaxx]

While it's not Honda specific.. this is a fun read on the intake manifold construction w/ stacks...
http://www.sdsefi.com/air12.html

Actually, everything on that site is a good read...

MM

 

[MatDj]

If you cant find one...just go to one of the Acura dealer, take some measurements and pictures and design it.

I am an aerospace engineering graduate as well

I am really curious how the air flow looks like on the scoops' and surrounding surfaces. If you think about it, the opening doesnt really get much scooping effects, or i should say, it still can be improved, especially because it is located on the side. Just imagine this..at high speed, the air scoop's surrounding has a lot higher velocity, thus it tends to suck the air out of the scoop instead. As you know, higher velocity means less pressure. If the air flow is separated from the body ( especially during turns), i would guess the air flow into the scoop will be minimal.

Again, this is best to be done in the wind tunnel....if you have the software to do the simulation, that would be great as well. One suggestion, try to compare laminar and non laminar flow effects on the scoops...to maximize the amount of the air going into the scoops. For example, if you look at the HARIER's wings, on top of the wings, there are bunch of small standing fins. These are to create turbulance, and why is that ? I guess there are many ways to improve as you will discover. Also consider cost, ease of modification, etc. Who knows, if you cover the whole aspects, even acura will be impressed and hire ya as part of their engineering group.

Good luck of the project, i am sure you will do great. And keep us posted !

MatDj

 

[stevefromatl]

As a fellow GT grad, you're more than welcome to look at my engine bay.

 

[Rubber Chicken]

Originally posted by MatDj:
Again, this is best to be done in the wind tunnel....if you have the software to do the simulation, that would be great as well.

The CFD Software was developed in-house. It solves 2D or 3D geometries, inviscid or viscous flows including boundary layers, shockwaves, and several options for the methods used to solve them.

The biggest drawback, as with any CFD solver, is that it can literally take hours sometimes days for the solver to converge on a solution.

One suggestion, try to compare laminar and non laminar flow effects on the scoops...to maximize the amount of the air going into the scoops. For example, if you look at the HARIER's wings, on top of the wings, there are bunch of small standing fins. These are to create turbulance, and why is that ?

Same reason golf balls have dimples and frisbees have ridges on the outer lip?

Perhaps to keep the boundary layer from separating. I'm pretty sure I'm going to do my analysis in non-laminar conditions.

We ran some tests in our wind tunnel at tech, and its damned streamlined, and the results that came out of it matched non-laminar theory. So I'm basically convinced that if its not in absolutely perfect flow conditions, and coated with several layers of teflon, then its going to be non-laminar.


Thanks for the advice!

 

[Rubber Chicken]

Originally posted by stevefromatl:
As a fellow GT grad, you're more than welcome to look at my engine bay.

I may borrow a friend of mine's digital camera and take pics of a few things...

Where in Atlanta are you?

 

[Rubber Chicken]

Originally posted by nsx4fun:
I think the right side scoop is used to draw cool air into the engine compartment.

Yeah I need to be able to work these things into the model...

Where is that NSX Cutaway image? I can't find it in the FAQ, and a Search isn't helping either.



[This message has been edited by Rubber Chicken (edited 28 February 2003).]

 

[Rubber Chicken]

Originally posted by Rubber Chicken:
Yeah I need to be able to work these things into the model...

Where is that NSX Cutaway image? I can't find it in the FAQ, and a Search isn't helping either.

This image from an article on the GT NSX illustrates the problem I'm working on.

If anyone hasn't already seen it:
http://asia.vtec.net/beystock/honda/nsxgt2000/

Oh and if the results of this study turn out well, then I'm also interested in doing a rear diffuser study as well. We'll see. One at a time, for now.

[This message has been edited by Rubber Chicken (edited 28 February 2003).]

 

[ajnsx]

the trial nsx (white) here in japan has velocity stacks, its also featured in (i think december)an option2 video it runs off the track into the wall, maybe a japenese website has some more info on it? (it was also at the tokyo auto salon this year)

[This message has been edited by ajnsx (edited 03 March 2003).]