Notices
Series I Tech Garage The place to discuss anything technical about the RX-8 that doesn't fit into any of the categories below.

Quantitative Coolant Flow Simulation

Old 09-29-2014, 09:47 AM
  #26  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Originally Posted by Arca_ex View Post
Wow those are some pretty interesting results. Good stuff.

I guess the next interesting thing to know would be what volume of flow is most effective for removing heat.

Also pretty cool to finally know how much horsepower the water pump consumes. Almost 7BHP at redline is more than I thought it would be.
Technically more flow is always going to allow more heat to escape the system. If a radiator can expel a certain maximum amount of heat, assuming there's appropriate airflow, the flow through it will always be the limiting factor. Since coolant can only absorb so much heat in one go, once that amount is expelled it won't get any cooler and the more flow more times the coolant is able to revive that amount of heat.

Higher flow will also always be better at mitigating hot spots in the engine for the same reasons.

Here's something I found when I first started.
http://stewartcomponents.com/index.p...ormation_id=14
Legot is offline  
Old 09-29-2014, 10:07 AM
  #27  
Add gas, add oil, repeat
iTrader: (1)
 
WaitingforFI's Avatar
 
Join Date: Oct 2004
Location: ATL - PDK - RYY
Posts: 445
Liked 27 Times in 22 Posts
Legot,
Can your software model the ideal impeller?
Have you compared the Mazmart thermostat vs. the stock thermostat?
WaitingforFI is offline  
Old 09-29-2014, 10:40 AM
  #28  
Registered
iTrader: (46)
 
9krpmrx8's Avatar
 
Join Date: Jan 2007
Location: San Antonio, Texas
Posts: 33,739
Liked 335 Times in 270 Posts
Now you need to do the 09-11 RX-8 water pump.

9krpmrx8 is offline  
Old 09-29-2014, 10:55 AM
  #29  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Holy **** that's a beautiful piece engineering! See how the vanes sweep forward at the edges? That's a design element that increases flow velocity. Those holes in the base are to equalize pressure on both sides of the base disk, and help with bearing stresses. What nice impeller! I wouldn't be able to model something that fancy without scanning the physical impeller, anyone want to donate one?

I don't think I can model the ideal impeller, sorry FI. What do you mean model the mazmart vs stock thermostat? Do you mean modeling the two impellers using their temperatures (it would barely change the results) or do you mean cavitation inside of the thermostat (which is entirely possible and the same for both, but why)?

Last edited by Legot; 09-29-2014 at 11:03 AM.
Legot is offline  
Old 09-29-2014, 11:05 AM
  #30  
Add gas, add oil, repeat
iTrader: (1)
 
WaitingforFI's Avatar
 
Join Date: Oct 2004
Location: ATL - PDK - RYY
Posts: 445
Liked 27 Times in 22 Posts
I was thinking more along the lines of flow; is there a big difference between the MAzmart and stock.
Judging by your response to 9k's pic I am thinking that it's probable that the S2 impeller is a better product. If that is the case: 1) Is it possible to swap an S2 water pump into an S1 or if that is not possible, could just the impeller be swapped?
WaitingforFI is offline  
Old 09-29-2014, 11:37 AM
  #31  
Registered
iTrader: (46)
 
9krpmrx8's Avatar
 
Join Date: Jan 2007
Location: San Antonio, Texas
Posts: 33,739
Liked 335 Times in 270 Posts
The S2 uses a whole different front cover, a swap is not really feasible because the oil filter on the S2 is located on the front cover, etc. As for swapping the impeller, I am not sure. We have a parts car R3 here but I really don't want to pull the water pump off,
9krpmrx8 is offline  
Old 09-29-2014, 11:58 AM
  #32  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
If you want to tear it up, press out the impeller, send it to me, and wait to get it back, I can 3D scan it and adapt it to the s1 housing.

Maybe BHR or someone else in my area has one that they're willing to let me borrow, hmmmm..... I can see it now "BHR water pump $2000 msrp."
Legot is offline  
Old 09-30-2014, 06:25 AM
  #33  
Registered
 
KuroSama's Avatar
 
Join Date: Sep 2014
Location: Oahu
Posts: 10
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Legot View Post
I can see it now "BHR water pump $2000 msrp."
^This!

Also, if the impeller can be simply pressed out of the housing, what's stopping a dedicated DIY-er from finding a used S2 pump and swapping impellers into their S1 pump?
KuroSama is offline  
Old 09-30-2014, 08:25 AM
  #34  
Registered
iTrader: (10)
 
GK1707's Avatar
 
Join Date: Jan 2012
Location: Queens, NY
Posts: 1,052
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by Legot View Post
hmmmm..... I can see it now "BHR water pump $2000 msrp."
GK1707 is offline  
Old 09-30-2014, 09:38 AM
  #35  
Chief Meteobraptologist
iTrader: (1)
 
Loki's Avatar
 
Join Date: Jun 2009
Location: Montreal
Posts: 4,536
Liked 293 Times in 261 Posts
This is awesome work man. Love this stuff.
I can send you before and after AP logs for when I installed mine if you're interested. Same location, same regime, ambient temp logged so can be compensated out. I saw a consistent decrease of 10-15F average and peak temp.
Loki is online now  
Old 09-30-2014, 10:47 AM
  #36  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Charles, I was making a joke. I completely respect that you're able to produce and sell products, but understand something. I'm literally just a kid, in school, with no loyalties and nothing to lose.

Your products are expensive, not needlessly so (most are probably still the best), but they are. No-one really cares.
Legot is offline  
Old 09-30-2014, 12:07 PM
  #37  
FULLY SEMI AUTOMATIC
iTrader: (9)
 
200.mph's Avatar
 
Join Date: Aug 2008
Location: BALLS DEEP
Posts: 4,955
Liked 535 Times in 472 Posts
Originally Posted by Charles R. Hill View Post
Apparently, Kid, you do. LOL
Graduate school, assume some responsibilities in life, and then talk to me about expensive products.
Maybe I should invite your parents over for dinner sometime.
i would suggest getting pics of his mom before inviting his parents to dinner first jic.
200.mph is online now  
Old 09-30-2014, 09:57 PM
  #38  
Moder8
iTrader: (1)
 
04Green's Avatar
 
Join Date: Aug 2009
Location: Oviedo, Florida
Posts: 2,548
Liked 32 Times in 22 Posts
Cool data..

It looks like the stock S1 starts to cavitate around 7K (flow rate levels off, line gets squiggly). Looks like it gets worse from there.

At the track, my coolant light used to go off at about 8K from foam in the coolant, it would go off as soon as the RPM dropped. So this kind of correlates.

Foam is a lousy heat transfer fluid. today, sustained running above about 7,500 results in a temp creep (1 degree every 5 seconds) at both Roebling and Sebring. Enough that I abandon sessions when it is above 85 degrees out.

I will have a Remedy pump in (looks a lot like the one on the page before this) before DarkSide at Roebling, where I expect mid-80s in the afternoon. I will see if the temp issue goes away. If my coolant bottle still works, I will plug in the sensor and see what happens.

My thought is that if the pump is moving 90 gallons a minute of liquid with a remedy, that is possibly better for cooling than 110 gallons a minute of foam? But that is only if 90 gallons a minute is sufficient to cool the engine. That is a lot of water. That would fill a 15,000 gallon swimming pool in under 3 hours. Or, fill a gallon jug in 2/3 of a second. Or, a 55 gallon barrel in about 35 seconds. Again, I will know more in about 6 weeks.

Or, am I completely off base. Fluid Mechanics in 1984 did not cover this all that much.
04Green is offline  
Old 10-01-2014, 11:21 AM
  #39  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Sure thing Charles, just let me know and I'll send them over

Green, the cavitation doesn't really cause foam. Cavitation is the formation of vapor bubbles in a liquid due to ultra low pressures. In all liquid, if the pressure is low enough it will turn into a gas regardless of the temperature. Since, in an impeller, the low pressure would only be behind the blades, once the liquid/vapor "foam" leaves the area of low pressure the vapor bubbles instantly implode and turn back into liquid.

It would be possible for foam to be created due to the low pressures at the impeller if the coolant was somehow really well oxygenated, but once all of the coolant flows through the impeller it would get trapped at the highest point in the system (the throttle body). Also, liquids hold significantly less gas at higher temperatures, so that's unlikely.

The formation and rapid destruction of vapor bubbles due to cavitation is what causes the reduction of flow since the volume of the fluid/vapor mixture sucked through the impeller in is effectively larger than what's being pumped in or out of the pump housing.

I have an animation that demonstrates what I'm talking about really well for both pumps, but it's going to take a day or so to render and upload them both.

Last edited by Legot; 10-01-2014 at 11:23 AM.
Legot is offline  
Old 10-01-2014, 12:59 PM
  #40  
Registered
 
niteshade247's Avatar
 
Join Date: Oct 2011
Location: bluesprings MS
Posts: 553
Likes: 0
Liked 0 Times in 0 Posts
Legot you seem to have a good grasp on what cavitation realy is. Us navy has studied this to death and back again then studied some more as cavitation from a subs prop at speeds is a realy bad thing. Back to cars cavitation isn't just at the pump your low and high pressure observation is right on. There is a high pressure zone on the back side of the thermostat and low pressure on the front side the more you pump the higher the high pressure zone gets. Not to mention all the twists and runs of the cooling system it's self creating turbulence slowing flow rates in the hole system. I'd say the mazmart pump is better for the fact it's flow rate is lower alowing high pressure zones to decrease as well as turbulence in the system in turn getting better flow through out the hole system. Your data is grate but because you don't look at the grater picture your conclusion is incorect. I discovered all this years ago when I built my 350 small block and slapped a high flow water pump on thinking more pump flow would be better I was greatly wrong over heated constantly because of what I just mention it wasn't till I went to a more stock lower flow pump did my heating problems go away. With all the fins in the coolant chamber of the engine more faster flow is going to create cavitation as well loosing flow through the block but lower that flow through the block will decrease cavitation in the block and increase flow. You realy need to do a model of the hole thing if you realy want true flow numbers and cooling ability of bouth stock and mazmart pumps.
niteshade247 is offline  
Old 10-01-2014, 01:16 PM
  #41  
Moder8
iTrader: (1)
 
04Green's Avatar
 
Join Date: Aug 2009
Location: Oviedo, Florida
Posts: 2,548
Liked 32 Times in 22 Posts
@ Legot Yes, same issue with boat prop. I miss that boat....

If I am not foaming though, why would the float sink and trigger the dash light, only to have it go back out a few seconds after I dropped below 7,000 RPM (Engine)? I cannot run that part of the test, my coolant float is all the way dead, I checked today.

Or, given the flow resistance, once the pump cavitates, the bubbles stay in the housing, collect, screw up the flow, and enough made it out through the thermostat to sink the float...

I have no doubt that the bubbles will collapse back into the fluid. It is just when that will occur. And where.

Either way, I think it is freaking cool that you start to predict cavitation about the same place I have what I think are cavitation related problems. The question that really needs to get asked is if under-driving the water pump will help cure the issue? Looking back, I assume you are showing impeller RPM, right, which is close to double crank RPM? (have pity on the poor EE that barely passed Fluids).
04Green is offline  
Old 10-01-2014, 01:17 PM
  #42  
Registered
 
niteshade247's Avatar
 
Join Date: Oct 2011
Location: bluesprings MS
Posts: 553
Likes: 0
Liked 0 Times in 0 Posts
Forgot to add too is did you account for the viscosity of the coolant? That can play a big part in foaming and cavitation. Straight water has a different viscosity than water with coolant wich can change flow rates as well. Grate question green I hadn't even thought of that he did say at engine speed so is that the rpm of the engine or impeller?

Last edited by niteshade247; 10-01-2014 at 01:21 PM.
niteshade247 is offline  
Old 10-01-2014, 02:46 PM
  #43  
Driving my unreliable rx8
 
Join Date: Oct 2012
Location: Alvarado, Tx
Posts: 2,051
Liked 1 Time in 1 Post
Yeah and the imploding bubbles from cavitation can remove metal they cause a lot of problems but I would not expect a foam without a surfactant in the system. Water doesn't foam without soap. A little shake test with some coolant might show if it foams or not.

The increased Viscosity should reduce the Foaming action. It will also slow the flow rate. I would imagine it would decrease cavitation also.

9300 engine rpm is 11125 Water pump RPM. His chart showed Water Pump RPM.
logalinipoo is offline  
Old 10-01-2014, 05:43 PM
  #44  
Registered
iTrader: (46)
 
9krpmrx8's Avatar
 
Join Date: Jan 2007
Location: San Antonio, Texas
Posts: 33,739
Liked 335 Times in 270 Posts
Niteshade247, the word is spelled GREAT. Sorry that was bugging the **** out of me. Carry on.

And 04green, you have a faulty coolant level sensor.
9krpmrx8 is offline  
Old 10-01-2014, 06:15 PM
  #45  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Sorry, if this first make much sense, I'm on a bus.

I did the simulation using pure water, I think I mentioned that somewhere. The reason being that pure water is the same for everyone, while there are several coolant/coolant mixes that someone could be using each is probably more viscous and less likely to cavitate (improving flow efficiency and increasing power consumption across the board). Also, it was my understanding that allot of racing leagues only allow water as coolant.

Shaking the coolant in a container to see if it foams won't show you anything. Cavitation and foaming are not the same thing. Foam is created when air is forcefully mixed into something, it cannot happen inside this pump. Cavitation is when a gas is created from the original liquid due to low pressure. It would be impossible for any air bubbles to collect anywhere aside from the peripheral hoses, the flow is way too high.

About the rest of the system having an effect the pump, yes, it does. However it's much less of an effect than you'd expect. The radiator is designed to be minimally restrictive on the system, as are the two main radiator hoses. The peripheral coolant hoses are at the mercy of the flow through the two rad hoses (I think every one is a venturi), and will not significantly effect flow through the pump. I'm estimating accuracy of the flow rate to be in the 0% to +15% range between the simulation and the real world.

Cavitation is actually really well handled within the pump housing, sure it's not great that it happens all, but there are some measures against it. For one, the weird lump on the outlet side is a measure to keep pressure at the impeller higher than the outflow pressure. This high pressure region before the true outlet completely eliminates the possibility of cavitation outside the pump itself.

I have exactly one guess as to why people "see" improvements from the mazmart impeller, but I have to review the data.

The two graphs that have to do with rpm are showing the Engine rpm, that's why they both say Engine RPM.
Legot is offline  
Old 10-02-2014, 10:06 AM
  #46  
Chief Meteobraptologist
iTrader: (1)
 
Loki's Avatar
 
Join Date: Jun 2009
Location: Montreal
Posts: 4,536
Liked 293 Times in 261 Posts
Question: wouldn't you need to take into account (or did you) the cooling system pressure? When fully warmed up the system runs what, 15psig static all around?

Also for the coolant mix, wouldn't the vaporization characteristics be significantly different from pure water, the vapour pressure would be higher, so harder to cavitate? All of this is rusty for me, but, well, I was thinking in the shower.
Loki is online now  
Old 10-02-2014, 10:19 AM
  #47  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Originally Posted by Loki View Post
Question: wouldn't you need to take into account (or did you) the cooling system pressure? When fully warmed up the system runs what, 15psig static all around?

Also for the coolant mix, wouldn't the vaporization characteristics be significantly different from pure water, the vapour pressure would be higher, so harder to cavitate? All of this is rusty for me, but, well, I was thinking in the shower.
Yes, the static pressure throughout the simulation was set to 88kPa, the stock pressure of the coolant bottle cap.

I'm not sure about the vaporization properties of coolant vs water, I'm terrible with chemistry.
Legot is offline  
Old 10-02-2014, 10:41 AM
  #48  
Chief Meteobraptologist
iTrader: (1)
 
Loki's Avatar
 
Join Date: Jun 2009
Location: Montreal
Posts: 4,536
Liked 293 Times in 261 Posts
Originally Posted by Legot View Post
Yes, the static pressure throughout the simulation was set to 88kPa, the stock pressure of the coolant bottle cap.

I'm not sure about the vaporization properties of coolant vs water, I'm terrible with chemistry.
Wouldn't you want 189 kPA, since it's atmospheric + 88 pressurization? psig vs psia.
Loki is online now  
Old 10-02-2014, 11:11 AM
  #49  
Scrappy
Thread Starter
iTrader: (1)
 
Legot's Avatar
 
Join Date: Jun 2014
Location: Gilbert, AZ
Posts: 1,181
Liked 3 Times in 3 Posts
Originally Posted by Loki View Post
Wouldn't you want 189 kPA, since it's atmospheric + 88 pressurization? psig vs psia.
I want to say no, but you're probably right.

This is unfortunate.
Legot is offline  
Old 10-02-2014, 12:29 PM
  #50  
Registered
 
niteshade247's Avatar
 
Join Date: Oct 2011
Location: bluesprings MS
Posts: 553
Likes: 0
Liked 0 Times in 0 Posts
There is a lot of missing data with this sim but none the less great work. It gives a good base line to look at.
niteshade247 is offline  

Thread Tools
Search this Thread
Rate This Thread
Rate This Thread:

Quick Reply: Quantitative Coolant Flow Simulation


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.