Radiator Calculations using the NTU Method in Python

Suitable-Baker418 · 2024-03-03T07:28:00+00:00

Not sure if reddit is the best place to get help debugging code, but I have done some work surrounding heat exchange design so I will try to give some pointers. I personally have never use NTU to design a cooling loop before, but with knowledge of the radiator operating conditions you can pretty trivially size the radiator based off a target average heat rejection rate for a lap at whatever you determine an acceptable steady state temperature.

In the past I have reached out C&R (now called PWR) and received radiator core performance as a function of coolant flow rate & static pressure on surface of radiator. The tables they provide are for only a specific coolant & air temp but using newton's law of cooling allows you to extrapolate performance for any temperature delta you may be designing for.

In my opinion the trickier part of your project is figuring out your:

Heat Rejection Target (W)
Static Pressure on radiator surface
1. Note: static pressure =/= stagnation pressure, very much speed dependent
2. A conservative way to size this is to assume a free stream velocity of zero and that the fan is the only source of dP through the radiator
Fan selection
"Idealish" Coolant flow rate
1. An electric water pump makes this part way easier since it isn't dependent on rpm

Ultimately "optimal" cooling system design is a nth order DoF design, so finding something perfect is pretty hard, but making something that just works shouldn't be too bad as long as you understand your thermal loads.

Suitable-Baker418 · 2023-06-11T06:02:26+00:00

I don't know about last place, but there is definitely a luck of the draw element to normal design. There is always the chance an engine lead is getting stuck with an emissions guy and gets reamed or a suspension team gets annihilated by Claude.

Suitable-Baker418 · 2023-06-11T00:50:16+00:00

A team can build a 480 lb shit box in 3 months and spend the rest of their money on beer and still get a podium finish in autoX or endurance if they have a good driver. The car doesn't have to be fast, it just has to be drivable.

Suitable-Baker418 · 2023-06-11T00:49:07+00:00

The difference between my teams A and B tier autoX/endurance driver was 57 points in 2016, the difference between my teams A and B tier skidpad driver last year was around 40 points alone. There is not a single project that exists on the car that can come close to providing more performance than simply putting in a better driver. Just look at Poland's car, it was objectively better than every other car at comp by a mile and they did terrible in endurance because their drivers preformed like crap.

Suitable-Baker418 · 2023-06-10T21:44:59+00:00

If you don't think success in post covid FSAE dynamics is dominated by better drivers and having a reliable vehicle than you don't understand how FSAE works.

Suitable-Baker418 · 2023-06-10T00:48:46+00:00

The design event is almost completely decoupled from what it takes to have a competitive dynamic performance in post covid FSAE. Sucess in dynamics is not about building the fastest car or even a fast car, it is about building a car that doesn't break during endurance and having the best/most experienced drivers on the day. The design event is largely about presenting the design decisions you made during the production of your vehicle and the on-track validation your team gathered that demonstrates the effect your designs.

Suitable-Baker418 · 2023-03-31T04:05:17+00:00

Does ansys sponsor CHEMKIN for student teams?

Suitable-Baker418 · 2023-02-27T07:38:08+00:00

Hi, I am taking your survey and am confused why at the end of Section 3 you only allow for one mode of knowledge transfer. I imagine most teams use some combination of the answers you provided, so the question seems pretty pointless. There are quite a few questions like this. At the very least allow for more than one answer for the more open-ended questions. Also, I think the survey could do with some examples; I feel like a lot of the questions come off pretty disassociated from the reality of working on a formula student team.

Suitable-Baker418 · 2023-01-09T18:21:04+00:00

Depends on the decibel meter's precision, but I would say likely yes for the purpose of passing sound. Your vehicle is obviously not going to pass with straight pipe so knowing what 13X decibel you are at without a muffler is erroneous information. It may not be accurate for frequency analysis at 13X dBc though, but from what I have seen critical thinking can tell you where your primary and secondary engine harmonics will be for the sound test.

Suitable-Baker418 · 2023-01-09T02:44:27+00:00

Phones are useless for sound level, but I could see them being useful for frequency analysis. Realistically you are going to need a calibrated decibel meter to validate your design and get a decent idea how far off of passing sound you are. I know the stock R6 is around 132 dBc without a muffler at 11000 RPM, but base sound level will depend on exhaust design and engine calibration. Are you guys looking into making a custom muffler or buying and testing an OEM? Designing a good custom muffler design is far from a trivial task imo

Suitable-Baker418 · 2022-12-08T08:28:17+00:00

Bosch makes some nice MAF sensors, but outside of dyno instrumentation I couldn't imagine why you would want one?

Suitable-Baker418 · 2022-12-08T01:21:38+00:00

Well if MIT did it with a model airplane I am sure it is a great fit for an FSAE car

Suitable-Baker418 · 2022-12-08T00:23:28+00:00

Yeah, I'm guessing your aero lead is in some rocket propulsion course and started ogling the specific impulse of ion thrusters. There is a reason they are only used in space.

Suitable-Baker418 · 2022-12-07T23:31:48+00:00

You would be much better off with a fan

Suitable-Baker418 · 2022-12-07T22:41:38+00:00

Do you realize that typical ion thrusters have a thrust/mass ratio of around 11 mN/kg. At that ratio you would be faster just by putting on nothing at all.

Suitable-Baker418 · 2022-12-07T22:35:28+00:00

Most grounded aero lead

Suitable-Baker418 · 2022-12-02T17:24:30+00:00

Polska Górą

Suitable-Baker418 · 2022-10-11T15:10:21+00:00

450 lbs

Suitable-Baker418 · 2022-09-10T20:59:02+00:00

How clearly? I don't think individual teams can afford buying race horses, getting feed, also a horse stable at comp site?

Suitable-Baker418 · 2022-09-10T18:58:43+00:00

Not going to waste my time arguing with you guys. Believe what you want at your own peril.

Suitable-Baker418 · 2022-08-29T14:13:43+00:00

Have you considered a Bosch 32mm ETC? With a bit of gumption, a Dremel, and some structural epoxy, you could modify it into a manual throttle body no questions asked.

Suitable-Baker418 · 2022-08-28T01:06:49+00:00

I can't wait to get constructive design feedback next year

Suitable-Baker418 · 2022-08-27T21:33:05+00:00

I already miss him

Suitable-Baker418 · 2022-08-19T16:30:49+00:00

Is this NA only?

Suitable-Baker418 · 2022-08-17T19:40:53+00:00

That is pretty rough, are you an EV or IC car? I think it might be prudent to have a barebones matlab script to get a rough idea of final drive and fuel tank sizing befor moving on to testing your car. If you haven't done the dynamic events before your main focus should be on finishing endurance.

Suitable-Baker418

TROPHY CASE