Anyone else like way technical auto related trivia, science, aero stuff?

[mikeinatlanta]

First let me say that I don't have a question needing an answer. This is posted solely because I find the subject fascinating. I spend hours thinking about this stuff.

It's a nice calm 75 degree sunny day at high noon. The track temperature is 115. While moving, what is the temperature of the air going into your oil cooler scoop 8" off the track? Same question for your radiator inlet 18" and your hood scoop 30" off the track. Please try and substantiate any opinion.

[Windsor]

First off, where was 75* measurement taken? 6' off of the deck?

From there, if you throw away a lot of other considerations, you could possibly calculate the air at 8/18/30" altitude.

Here are just some of those considerations:
Is there a breeze mixing things up?

Is it linear or are there things like fences/walls/trees making eddy flows by the time it hits the track?

When was the last time another vehicle blew through your sampling area knocking the temp of everything but the track surface back down to 75 but adding a bit of their own temp from the radiator/oil cooler/engine/exhaust/tires/etc?

[narly1]

No answers but:

Radiated heat follows the inverse square law.

I found online that the accepted height for measuring temperature for weather reporting purposes is 5' +/- 1'. To me this infers that at that height any additional heat rise caused by heating & reradiation from the prevailing surface (in this case pavement) is minimal.

Earl

[mikeinatlanta]

For the sake of discussion let's say there 75 came from a temperature monitoring station that just happens to be as close as one can be to the pavement. Calm, no other traffic. Basically, where would the temps be before any other variables are introduced. Of course, once that baseline is established then the variables impact is where it heads.
E.g. If there is a temperature gradient, does a 5mph crosswind impact the gradient across the track? Would a potential gradient across a wide track on long straight impact air resistance and horsepower depending on where you are across said track? Something like a standing 1.5 mile run on a 75' wide runway.

[mikeinatlanta]

No answers but:

Radiated heat follows the inverse square law.

I found online that the accepted height for measuring temperature for weather reporting purposes is 5' +/- 1'. To me this infers that at that height any additional heat rise caused by heating & reradiation from the prevailing surface (in this case pavement) is minimal.

Earl

I get how the inverse square law would apply to an object absorbing radiant heat from the pavement, however, how does that apply to the actual air temperature?

[narly1]

I get how the inverse square law would apply to an object absorbing radiant heat from the pavement, however, how does that apply to the actual air temperature?

I suspect you can't calculate (or at best, estimate) temperature at given height if all you know is the 5' height temp or the prevailing ground surface temp. Too many variables IMO, the most important being how still the air is. Then you've got the chemical make-up of the air (dust, pollutants, water vapour (aka humidity) in the mix)...

Thus the best you can probably do is measure at the height of interest.

Earl

[F500guy]

Seems to me it would be some simple radiant heat calculation. Do some empirical test, turn on your electric burner and hold a pan 8 inches above the burner and use a IR gun to measure temp.

[mikeinatlanta]

I suspect you can't calculate (or at best, estimate) temperature at given height if all you know is the 5' height temp or the prevailing ground surface temp. Too many variables IMO, the most important being how still the air is. Then you've got the chemical make-up of the air (dust, pollutants, water vapour (aka humidity) in the mix)...

Thus the best you can probably do is measure at the height of interest.

Earl

It is not necessary to address all possible variables for a hypothetical discussion. What would it be with perfectly pure, perfectly still, and completely dry air? One would think that that variables would come into play only after establishing a baseline.

[mikeinatlanta]

Seems to me it would be some simple radiant heat calculation. Do some empirical test, turn on your electric burner and hold a pan 8 inches above the burner and use a IR gun to measure temp.

That would only serve to measure the rate at which the pan absorbed the radiant heat, not the air temp. If using an IR thermometer and measuring across the radiant heat it only measures the temp of the object on the other side with the burner making no difference.

[F500guy]

That would only serve to measure the rate at which the pan absorbed the radiant heat, not the air temp. If using an IR thermometer and measuring across the radiant heat it only measures the temp of the object on the other side with the burner making no difference.
At some point, the Steady state of the system would be a Delta(t) at which the air temp and heat transferred from the metal to the air would equalize the radiant heat transferred to the metal from the heat source. Rate of heat transfer was not asked in the original question so not sure how long it would take to reach equilibrium. Just saying, for sake of argument.

[mikeinatlanta]

At some point, the Steady state of the system would be a Delta(t) at which the air temp and heat transferred from the metal to the air would equalize the radiant heat transferred to the metal from the heat source. Rate of heat transfer was not asked in the original question so not sure how long it would take to reach equilibrium. Just saying, for sake of argument.

"For sake of argument" for sure. One would assume that it wouldn't need clarification that the circumstance of a car on a track doing a standing 1.5 mile run would not be in a confined box where the air would eventually come up to temperature. I guess it depends on whether the intent of an answer is to discuss air temps on above a hot track on a mild sunny day or to maybe find any possible hole in the question.

The original question is a very real situation. While particulate, moisture, unusual gasses, or a pot hanging over the track would obviously impact any exacting measurements, they are not really relevant to the concept of the general question.

EDIT: After looking at the responses I see that asking this type of question on this forum was a mistake. Kindly withdrawn.

[narly1]

EDIT: After looking at the responses I see that asking this type of question on this forum was a mistake. Kindly withdrawn.

Perhaps within the context of what this forum is about (FFR cars).

But that being said asking a well thought out and worded question in the presence of a polite and intelligent audience is never a mistake.

Earl

[J R Jones]

You ended an earlier technical discussion here stating that you "wrote the book" on that topic, so I await your new book on this subject to hit the shelves.

[mikeinatlanta]

You ended an earlier technical discussion here stating that you "wrote the book" on that topic, so I await your new book on this subject to hit the shelves.

It was more like a couple of books on that topic (composites repair). Just another book to some and "the" book to others. :)

[Hoooper]

How closely are we following the car in front?

[Presto51]

First let me say that I don't have a question needing an answer. This is posted solely because I find the subject fascinating. I spend hours thinking about this stuff.

It's a nice calm 75 degree sunny day at high noon. The track temperature is 115. While moving, what is the temperature of the air going into your oil cooler scoop 8" off the track? Same question for your radiator inlet 18" and your hood scoop 30" off the track. Please try and substantiate any opinion.

Don't forget to factor in barometric pressure.

Ron

[Ford & Jeep Fan]

First let me say that I don't have a question needing an answer. This is posted solely because I find the subject fascinating. I spend hours thinking about this stuff.

It's a nice calm 75 degree sunny day at high noon. The track temperature is 115. While moving, what is the temperature of the air going into your oil cooler scoop 8" off the track? Same question for your radiator inlet 18" and your hood scoop 30" off the track. Please try and substantiate any opinion.

wind is everything in this question. Air is a fluid and as such is at the whim of the winds. On a full sun day the difference between track and grass infield will be more. THe color of track surface will have and effect as well. The darker the blacktop the more radiant heat it will absorb.