hughdogz Posted March 14, 2009 Share Posted March 14, 2009 Hey guys, I'm still working on a design for a custom intake using those group buy flanges. I'm still learning how to use CFD simulation, so it is still a learning experience for me. I want to minimize having to do custom bends, but it looks like I'll have to do something to avoid vorticies, even at such a small velocity. For my first attempt, I just guessed on the boundary conditions, 200 mm/s fixed velocity at the outlets, and the inlet is "free". After reading MONZTER's thread, he was getting ~4000 mm/s and I want half the HP (flow) as him, so Im re-runing it again at 2000 mm/s. Here is the CAD model, to do a CFD I have to model the inside (which is kind of wierd but that's the way it works). The simulation has 30 time steps, to ramp up the flow and give the solver an easy time at converging. Here is zero velocity at time step 0: Velocity contours at full speed: Here you can see the big vortices / swirl that I need to get rid of (the big one and the one near the first runner): I re-ran the model at 2000 mm/s and it is about the same. 2 & 3 are the only ones getting a good shot of the flow.: ] Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted March 14, 2009 Share Posted March 14, 2009 seems like you would be best off to angle the throttle body so the back wall (i guess you'd call it that) is straight, to try and 'aim' the airflow along the back wall of teh plenum, and reduce the low pressure zone, and cavitation just after teh throttle body. Quote Link to comment Share on other sites More sharing options...
hughdogz Posted March 14, 2009 Author Share Posted March 14, 2009 seems like you would be best off to angle the throttle body so the back wall (i guess you'd call it that) is straight, to try and 'aim' the airflow along the back wall of teh plenum, and reduce the low pressure zone, and cavitation just after teh throttle body. Good point. I appreciate the input Nizm0Zed. That is what I'm going to try to do with the next version. I turns out that I didn't have the runner spacing correct, so I had to fix that. Also, I didn't have the right element selected for the boundary layer, for the first runs it takes a lot longer to run with the right one. Ugh...I need a Cray!! The FEA computations are taking too long. ========== [Edit: A little better, but now it looks like I'm generating swirl after the flow hits the "back corner" of the intake] Quote Link to comment Share on other sites More sharing options...
skib Posted March 14, 2009 Share Posted March 14, 2009 thats badass man Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted March 14, 2009 Share Posted March 14, 2009 no worries chief, but, DISCLAIMER! I was drunk when i worte that, so if its doesnt work, dont blame me..... looking at your new design, perhaps tighten up the plenum, so teh wall runs paralell to the runners, upto about half way between teh second and third runners. Looking at that, it seems to be cavitating because there is too much space to fill? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted March 15, 2009 Share Posted March 15, 2009 Maybe its worth a shot trying to help the air distribute more evenly amongst the groups of cylinders (1/2, 3/4, 5/6). Maybe you could play with some flat guides placed around the inlet, maybe as marked in red as in the pic below. I doubt they'll work to be honest, but I've always been curious. If they show any promise it might be worthwhile experimenting with various lengths and directions/shapes of the guides as well. Dave Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted March 15, 2009 Share Posted March 15, 2009 Dave is on to something with his "guides" idea. In commercial HVAC duct design we use turning vanes (like what Dave calls guides) to better direct the airflow through duct work and to keep the air attached for less static pressure. Perhaps a small vane near each runner inlet and maybe one or two others strategically placed in the plenum would help. The size and shape of the vanes would be critical for improving airflow over the relatively broad range of airflow velocity you see in an intake manifold. Quote Link to comment Share on other sites More sharing options...
hughdogz Posted March 16, 2009 Author Share Posted March 16, 2009 I'm fairly convinced now that the flow diverters will have to extent to the "swirl zone": Next, I'll try a design that is more compact, like an RB26 or 2jz Quote Link to comment Share on other sites More sharing options...
hughdogz Posted March 16, 2009 Author Share Posted March 16, 2009 Here is rev 4: I think I should make the taper less and adjust the inlet angle more towards the "back wall". Also, I'll try using a straight section instead of a curved one. I really need my 64-bit workstation. Doing this on a 32-bit laptop with 3GB RAM really limits what you can do... Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted March 17, 2009 Share Posted March 17, 2009 Interesting thread and awesome program! What would happen if you tappered the runners... say your using 1 5/8" runners... what if you used 1 5/8" at the head and 1 3/4" at the plenum and increased the overall volume of the plenum. My logic here.... tappering the runners should naturally create vacumn and enlarging the plenum volume would decrease the velocity of the air coming in. I'm thinking that this would maybe make the runners suck the air in more evenly than the air being slammed into the runners ? I really don't know just curious on this one. -Ed Either way... props on crunching the numbers! Quote Link to comment Share on other sites More sharing options...
hughdogz Posted March 21, 2009 Author Share Posted March 21, 2009 This might be taking a step back, but it was intersting anyway... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted March 21, 2009 Share Posted March 21, 2009 That is really nice software. Just out of curiosity, if it's not too hard to model, try throwing one of those crappy turbine blade intake thingys that supposedly swirl the air on the way in. See what your computer spits out. Another idea is to make it like a header...bring the runners together in a cluster at the intake. I know the "equal length" rule will be tough to keep though. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 21, 2009 Share Posted March 21, 2009 Let me know if you wanna try your hand at an rb25det intake, I have a spare stocker laying on the floor I can measure for you. Quote Link to comment Share on other sites More sharing options...
hughdogz Posted March 22, 2009 Author Share Posted March 22, 2009 Thanks for the input guys! That is really nice software. Just out of curiosity, if it's not too hard to model, try throwing one of those crappy turbine blade intake thingys that supposedly swirl the air on the way in. See what your computer spits out. Another idea is to make it like a header...bring the runners together in a cluster at the intake. I know the "equal length" rule will be tough to keep though. Hi Cygnus, on my next go-around I'm going to try to make the inlet come in parallel to the runners (like an RB25). Also, I'd like to revisit Helix's guide / diverter idea, extending them almost to the runner entrances. I could also try closing up the plenum some more, so the flow is forced to have a straight shot to runner six... Here is the turbine blade model (not sure if they are right). I threw in five "swirl-ators". I just went by some crappy pics of swirl effect throttle bodies off Ebay. I'm not sure they were much help, what do you think? Let me know if you wanna try your hand at an rb25det intake, I have a spare stocker laying on the floor I can measure for you. Sure! That shouldn't be too difficult to do. Pics and general measurements would work great. Quote Link to comment Share on other sites More sharing options...
J__ Posted March 22, 2009 Share Posted March 22, 2009 that looks great! take a look at this picture. its the intake of a porsche 968. notice the skew of the intake you should plot in the design and see if it eliminates the dead zones. Quote Link to comment Share on other sites More sharing options...
hoov100 Posted March 22, 2009 Share Posted March 22, 2009 what about going with a dual TB's on your original design? Quote Link to comment Share on other sites More sharing options...
Niku-Sama Posted March 24, 2009 Share Posted March 24, 2009 Thanks for the input guys! Hi Cygnus, on my next go-around I'm going to try to make the inlet come in parallel to the runners (like an RB25). Also, I'd like to revisit Helix's guide / diverter idea, extending them almost to the runner entrances. I could also try closing up the plenum some more, so the flow is forced to have a straight shot to runner six... Here is the turbine blade model (not sure if they are right). I threw in five "swirl-ators". I just went by some crappy pics of swirl effect throttle bodies off Ebay. I'm not sure they were much help, what do you think? http://home.comcast.net/%7Ehughhenderson/pics/Intake_CFD/swirl-ators.png http://home.comcast.net/%7Ehughhenderson/pics/Intake_CFD/swirl-ators_2.png http://home.comcast.net/%7Ehughhenderson/pics/Intake_CFD/swirl-ators_3.png http://home.comcast.net/%7Ehughhenderson/pics/Intake_CFD/velocity_streamlines_12_rev5_swirl.png Sure! That shouldn't be too difficult to do. Pics and general measurements would work great. i think hes talking about the "Turbonator" or some variant of it, theres a few different rip offs of one another some go across the diameter of the intake tube and some dont. http://www.tornadofuel-saver.com/?gclid=CM3N4obDvJkCFR0SagodOkJT7w http://www.turbonator.com/Contact.htm http://www.vorteccyclone.com/index.html the turbonator link is on contacts because on their home page theres a really annoying guy yelling at you the instant the page loads and i cant find a way to stop it before i wanna smash my speakers Quote Link to comment Share on other sites More sharing options...
hughdogz Posted March 24, 2009 Author Share Posted March 24, 2009 i think hes talking about the "Turbonator" or some variant of it, theres a few different rip offs of one another some go across the diameter of the intake tube and some dont. http://www.tornadofuel-saver.com/?gclid=CM3N4obDvJkCFR0SagodOkJT7w http://www.turbonator.com/Contact.htm http://www.vorteccyclone.com/index.html the turbonator link is on contacts because on their home page theres a really annoying guy yelling at you the instant the page loads and i cant find a way to stop it before i wanna smash my speakers Ahh...Yes those look a lot different than what I tried to make. I was going by one of these: http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=swirl+throttle+body&_sacat=See-All-Categories Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted March 25, 2009 Share Posted March 25, 2009 This one: Actually looks like you are getting really even flow out of it, and if I'm reading the image correctly, still maintaining a pretty good flow rate still. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.