All Things Chev

[rainsey]

MB, That is awsome how can I get hold of these and I will start filling them out

[rainsey]

Say, in regards to actually taking the measurements, I have had the orifice of the pressure intake at 90 degrees to the wind flow. Is this the correct way or should I face the orifice into the wind?

Kindest regards
Rainsey

[rainsey]

That is an awesome gadget Rainsey, please do keep us posted mate! Not to get you spending more money but it would be cool to see 2x cheapo mechanical temp guages zip tied along each hose reading the temps at each different pressure locations you test maybe? Once you've tested the outer bonnet pressure zones it would also show ambient temp wind incoming on the day of graphing data I'm thinking? Like Mythbusters I guess with their first 'control test' before all others :-)

I have an idea for the temp guage. I have an Autron ( now Redarc) Oil Pressure / Turbo Boost guage in the truck that has a digital temperature guage in it as well. I use it for monitoring outside temperature. I moved the probe the other day when I was sorting out my heating issue by measuring the under bonnet temp with it. I might be able to extend the cable and bring it up next to the pressure guage hose ....

You have me thinking

Kindest regards

Rainsey

[PeeBee]

[QUOTE=rainsey;717385]Say, in regards to actually taking the measurements, I have had the orifice of the pressure intake at 90 degrees to the wind flow. Is this the correct way or should I face the orifice into the wind?

Kindest regards
Rainsey[/QUOTE

Rainsey, you have to be careful with the actual set-up, as the DP device you have is really designed for ductwork in a closed system. I used to do this sort of 'stuff' on a daily basis 30 yrs ago, and have probably forgotten more than i should have, so i dived into one of my 'old head book', being a Ventilation handbook from the US Aircon Society and looked up the orientations. i might be going to sound like I'm telling you how to suck eggs but i don't have that agenda, nor do i know your background, so here goes.

1) there are 3 components of Pressure , TP-total pressure, SP - Static Pressure and VP - velocity pressure.

The static pressure is typically measured at the circumferential surface of a duct, at 90 deg to the airflow

The VP is measured with the device pointing directly into the flow/direction of the air stream. The TP is simply the summation of VP +SP. This can be on the inlet side or discharge side of the airflow generator - again this is basically non existent in our case, because we don't have a fan or pump shifting a volume of air down a duct - we have a vehicle pointed into the wind with airflow generating the flow but not as a fan would.

DP or differential pressure is more a measure of pressure drop across a resistance. In your case its the intercooler. Whats tricky is trying to equate 'flow' to pressure within a 'system' that is neither contained nor uniform - I am not sure I could draw a definitive conclusion to be honest. What you would perhaps be better doing is measuring VELOCITY, using a velometer. You can, from distant memory equate these pressure values to velocity however you need a closed system and need to know the temperature to convert the air to Standard CFM at 2o DegC. The temperature is easy enough, but the under bonnet zone could hardly be construed as a closed system from which the formulas would apply - so this won't work using the instrument you have.

Ok, so i have pissed all over your parade, and where to from here. i think its velocity, not pressure you want to profile. If you record velocity profiles in the locations mark has outlined, which is probably going to qualify you fro a financial grant in PHD studies, you will know where the airflow is, and be able to generate an airflow profile, which by definition can be linked to heat extraction due to erosion and convection.

How do you do this? Unfortunately I use a simple propeller bladed device that measures in M/S or F/sec but it does not data log. i am sure these are avail. but at a cost.

I hope this starts your thinking juices flowing, and happy to tear this apart to get to the end point we all want which is to understand the airflow into the bonnet area.

[rainsey]

[QUOTE=PBBIZ2;717396]

Say, in regards to actually taking the measurements, I have had the orifice of the pressure intake at 90 degrees to the wind flow. Is this the correct way or should I face the orifice into the wind?

Kindest regards
Rainsey[/QUOTE

Rainsey, you have to be careful with the actual set-up, as the DP device you have is really designed for ductwork in a closed system. I used to do this sort of 'stuff' on a daily basis 30 yrs ago, and have probably forgotten more than i should have, so i dived into one of my 'old head book', being a Ventilation handbook from the US Aircon Society and looked up the orientations. i might be going to sound like I'm telling you how to suck eggs but i don't have that agenda, nor do i know your background, so here goes.

1) there are 3 components of Pressure , TP-total pressure, SP - Static Pressure and VP - velocity pressure.

The static pressure is typically measured at the circumferential surface of a duct, at 90 deg to the airflow

The VP is measured with the device pointing directly into the flow/direction of the air stream. The TP is simply the summation of VP +SP. This can be on the inlet side or discharge side of the airflow generator - again this is basically non existent in our case, because we don't have a fan or pump shifting a volume of air down a duct - we have a vehicle pointed into the wind with airflow generating the flow but not as a fan would.

DP or differential pressure is more a measure of pressure drop across a resistance. In your case its the intercooler. Whats tricky is trying to equate 'flow' to pressure within a 'system' that is neither contained nor uniform - I am not sure I could draw a definitive conclusion to be honest. What you would perhaps be better doing is measuring VELOCITY, using a velometer. You can, from distant memory equate these pressure values to velocity however you need a closed system and need to know the temperature to convert the air to Standard CFM at 2o DegC. The temperature is easy enough, but the under bonnet zone could hardly be construed as a closed system from which the formulas would apply - so this won't work using the instrument you have.

Ok, so i have pissed all over your parade, and where to from here. i think its velocity, not pressure you want to profile. If you record velocity profiles in the locations mark has outlined, which is probably going to qualify you fro a financial grant in PHD studies, you will know where the airflow is, and be able to generate an airflow profile, which by definition can be linked to heat extraction due to erosion and convection.

How do you do this? Unfortunately I use a simple propeller bladed device that measures in M/S or F/sec but it does not data log. i am sure these are avail. but at a cost.

I hope this starts your thinking juices flowing, and happy to tear this apart to get to the end point we all want which is to understand the airflow into the bonnet area.

Hey, no problems pissing all over my parade as I am the first to admit that I have no friggin idea what the hell I am doing, but Im having fun doing it Most of the stuff you mentioned I have read in few documents I have got but to be truthful, I really dont know what I am reading.

I look at it this way, ill try something and post up the info, and more knowledgable people on the subject ( eg yourself) can critic it and in doing so, we eventually get an understanding as to what we should be seeing or doing. If I sit on my butt and do nothing, other than wasting forum space, no one learns anything, including myself.

The flow vs pressure conundrum has been playing on my mind since I thought I would tackle this. My background is in electrical engineering so hydraulics is to me more of a voodoo out there concept. Regardless, pondering all this is taking my mind off how much I am spending on the truck

Kindest regards

Rainsey

[rainsey]

[QUOTE=PBBIZ2;717396]

Say, in regards to actually taking the measurements, I have had the orifice of the pressure intake at 90 degrees to the wind flow. Is this the correct way or should I face the orifice into the wind?

Kindest regards
Rainsey[/QUOTE

Rainsey, you have to be careful with the actual set-up, as the DP device you have is really designed for ductwork in a closed system. I used to do this sort of 'stuff' on a daily basis 30 yrs ago, and have probably forgotten more than i should have, so i dived into one of my 'old head book', being a Ventilation handbook from the US Aircon Society and looked up the orientations. i might be going to sound like I'm telling you how to suck eggs but i don't have that agenda, nor do i know your background, so here goes.

1) there are 3 components of Pressure , TP-total pressure, SP - Static Pressure and VP - velocity pressure.

The static pressure is typically measured at the circumferential surface of a duct, at 90 deg to the airflow

The VP is measured with the device pointing directly into the flow/direction of the air stream. The TP is simply the summation of VP +SP. This can be on the inlet side or discharge side of the airflow generator - again this is basically non existent in our case, because we don't have a fan or pump shifting a volume of air down a duct - we have a vehicle pointed into the wind with airflow generating the flow but not as a fan would.

DP or differential pressure is more a measure of pressure drop across a resistance. In your case its the intercooler. Whats tricky is trying to equate 'flow' to pressure within a 'system' that is neither contained nor uniform - I am not sure I could draw a definitive conclusion to be honest. What you would perhaps be better doing is measuring VELOCITY, using a velometer. You can, from distant memory equate these pressure values to velocity however you need a closed system and need to know the temperature to convert the air to Standard CFM at 2o DegC. The temperature is easy enough, but the under bonnet zone could hardly be construed as a closed system from which the formulas would apply - so this won't work using the instrument you have.

Ok, so i have pissed all over your parade, and where to from here. i think its velocity, not pressure you want to profile. If you record velocity profiles in the locations mark has outlined, which is probably going to qualify you fro a financial grant in PHD studies, you will know where the airflow is, and be able to generate an airflow profile, which by definition can be linked to heat extraction due to erosion and convection.

How do you do this? Unfortunately I use a simple propeller bladed device that measures in M/S or F/sec but it does not data log. i am sure these are avail. but at a cost.

I hope this starts your thinking juices flowing, and happy to tear this apart to get to the end point we all want which is to understand the airflow into the bonnet area.

Hey,

I just had another thought. I dont give a rats what the actual pressure is. Im not measuring something with a view to setting a defined value. What I am after is the delta. The lowest value becomes the reference and all other measurements are taken off it.

I fully understand that a manometer is really meant for the duct work in a closed system, I used to use a Magnahealic in servicing dive regulators many moons back, its the same thing. if I was to create a defined input device, such as a length of tube and the manometer input goes into this, and this same device is then moved around the various parts of the vehicle, would I not be actually be measuring in a quasi closed system? This is no good for under the bonnet perse' but I am thinking more on the on bonnet pressure measurements?

Kindest regards

Rainsey

[PeeBee]

LOL, I love it. OK, keep the thought process rolling. What we have here simply does not fit into any boxes cleanly. I will have a think about your other post and see if I can value add or at least generate a direction to move forward.

[PeeBee]

[QUOTE=rainsey;717404]

Hey,

I just had another thought. I dont give a rats what the actual pressure is. Im not measuring something with a view to setting a defined value. What I am after is the delta. The lowest value becomes the reference and all other measurements are taken off it.

I fully understand that a manometer is really meant for the duct work in a closed system, I used to use a Magnahealic in servicing dive regulators many moons back, its the same thing. if I was to create a defined input device, such as a length of tube and the manometer input goes into this, and this same device is then moved around the various parts of the vehicle, would I not be actually be measuring in a quasi closed system? This is no good for under the bonnet perse' but I am thinking more on the on bonnet pressure measurements?

Kindest regards

Rainsey

OK, to generate DP you need flow and resistance. If you generate so much resistance in your hose, leading into the DP gauge and out of it, believe me we are moving into really sensitive stuff. I think what you will find is the pressure will ultimately be the same on both ends of the tube unless one end is clearly 'in the zone and the other is clearly out of it', without any external effect, such as turbulence and 'back pressure/negative pressure. I will chuck this around with some 'old heads' I know next week and see if what we are chasing is measurable. Right now I am unsure. I use magnohelics on dust collectors and baghouses. One side of the hose in in clean air/atmospheric and th other on the other side of the 'dirty filter membrane', hence DP is a simple representation, however the principal difference is that you generally have a mechanical device - a fan - pulling air thru the element. The pressure is usually positive on the dirty side and negative on the clean side, thus generating the DP. We are talking mbar and thats a fraction of a quarter of a poofteenth. I am just as keen to 'get somewhere rational with this' as i am poised to start chopping vents into my bonnet to relieve heat and generate flow.

[rainsey]

[QUOTE=PBBIZ2;717420]

OK, to generate DP you need flow and resistance. If you generate so much resistance in your hose, leading into the DP gauge and out of it, believe me we are moving into really sensitive stuff. I think what you will find is the pressure will ultimately be the same on both ends of the tube unless one end is clearly 'in the zone and the other is clearly out of it', without any external effect, such as turbulence and 'back pressure/negative pressure. I will chuck this around with some 'old heads' I know next week and see if what we are chasing is measurable. Right now I am unsure. I use magnohelics on dust collectors and baghouses. One side of the hose in in clean air/atmospheric and th other on the other side of the 'dirty filter membrane', hence DP is a simple representation, however the principal difference is that you generally have a mechanical device - a fan - pulling air thru the element. The pressure is usually positive on the dirty side and negative on the clean side, thus generating the DP. We are talking mbar and thats a fraction of a quarter of a poofteenth. I am just as keen to 'get somewhere rational with this' as i am poised to start chopping vents into my bonnet to relieve heat and generate flow.

And thus you have hit another thing that has been knocking on my frontal lobe since looking at this. The length of the tube from the point of measurement to the device measuring it.

I would perceive that the shorter the better. Air is a compressible medium hence if the pipe or hose front of the point of measurement is too long, what stops the air in the tube being compressed resulting in the endpoint not actually having any concernable change in pressure.

So if I have a meter long length of hose going to the pressure monitor, what's to say that the actual pressure at the end of the hose matched what is at the point of measurement?

An who said philosophy was not one of my strong points All whilst I'm watching American Horror Story


Sent from my iPad using Tapatalk HD

[PeeBee]

God, this is digging deep and on my third scotch and ice, its becoming difficult!!!

The air is only going to be compressed based on the flowrate down the tube and the resultant pressure - bearing in mind in this situation that pressure is simply system resistance as we don't have a positive compressive device like a fan or pump - itsd whatever air is flowing based on vehicle velocity into the end of the hose. Without a fan as such this is heading towards lab grade measurement device and well beyond what the mere mortal could afford.

If you had your DP device without a hose it will still detect the pressure difference, but may not indicate it unless the scale/sensitivity is correct, and unless the volume of air is significant you wont see the pressure build up in your compressible medium, so again, very small airflow is a problem. Its possible to detect very small pressure differences with a pitot tube, laid over on the side and measuring 'hundredths of an inch wg', but hard to steer down the road and not crash at the same time.

If this was water or incompressible we would be laughing for sure.

What you could do is measure the DP across the intercooler coil. The question then is whether this DP can be related to cooling capacity. The variables from a mechanical sense would be it the flow rate high enough butthe PD across the coil too great to effectively strip the heat out of the air, or is the flowrate too low to allow the coil to operate effectively. I dont know the answer as these are really design related issues - so in essence you need to find out the flow rate required, at what temperature range, the efficiency curve matches the intercooler at. The DP then is the design element that relates to the efficiency of the heat transfer device - I think thats clear??? So if the DP is too high the cooling effect is lower, if the differential temperature between the cooling air and the 'to be cooled air' is too close the efficiency drops also.End of the day its heat energy being transferred by whatever method is in play.

My glass is empty, going for a re-fill.