Orifice in tube

[jfholm]

Thanks for your input maineSS. I too have wondered about the plate effects on the stream. So I shall take the time to test that out.
I guess you could call me one of those handymen. I will say this, when I read posts I could not car less who posts them or what motives etc they may have. I look and the information within that post and then I decide if it contains theories that I have not considered. You have mentioned a couple of things that have interested me.

Of course the orifice plate has an effect on the "stream" (actually air flow). That is what it is supposed to do. If you understand airflow and measuring it the orifice creates the pressure differential between the upper chamber and the lower chamber when flowing through your tested item (cylinder head etc.). This is what you measure to determine what your flow is. Of course it has an effect on the airflow, it is supposed to! It is also probably the best way to measure airflow in a rough environment that most of us flow in. The LFE is really great but costs much more than I can afford and is not good in dirty environments.

John

[RandyW.]

Just curious if you build the performance trends EZ bench the parts list says use pvc pipe. How do they get around the problems of flowing in a pipe, just curious.

[larrycavan]

Don't know what's happening exactly, it seems if you exceed a certain time, you're automatically logged out, and lose your post. I'm going to try posting/editing as I write instead of waiting till the end...

Let's start at "Inside, you will have a region of organized flow between the inlet and orifice, surrounded by a "tube" of recirculating air trapped within the confines of the box. It's similar to what you'll see in a river- downstream flow is out in the main channel, eddies and backflow close to the banks. "Orifice in a box" looks like "orifice in a tube"- it seems quite doubtful the ideal sideways flow into the orifice will occur in a box that's not room-sized.

Rick mentions placing a baffle before the orifice to prevent the incoming jet from the settling box from disrupting orifice inflow. This is a great example of "settling boxes" not settling much of anything- the jet from the bore adapter simply reforms at the exit of the settling box. When the jet hits this wall, the flow will have to boil up over it and fall down the other side. When a moving fluid drops abruptly from a higher elevation to a lower one, a cavity forms between the flow and the drop. This cavity is occupied by a turbulent roller of constantly changing size. What we end up with is a highly turbulent, pulsating flow directly in front of the orifice. You'll get the same effect if you hang the baffle from the top, side, whatever- forcing the flow to make a 90 deg turn will generate lots of turbulence in an area you really don't want it in. If you think I'm being overly dramatic, just make one wall of the box transparent, add smoke or streamers, and enjoy the show. The turbulence caused by PVC pipe irregularities will be minor by comparison.

PVC pipe has certain other qualities. It doesn't leak, and a tube equalizes stresses much better than boxlike shapes- which is why pressure-resistant items like cannon barrels and submarines tend to be totally tubular. For flowbench construction, it means no painting, no painstaking joinery, no leak chasing. You don't have to glue the joints- just run a bead of silicone round the cuff after the pipe is inserted, and cut it with a razor if later disassembly is required.

So far, Ive not heard any compelling reasons to abandon my wicked tubular ways, which have served my friend well these past 20+ years- he's made a lot of horsepower with his bench. I think a lot of your visitors are resistant to buying a set of plans when flowbench construction info is widespread nowdays- times have changed. Just about anything can be made to work, after a fashion, and you won't convert these people to customers by telling them their ideas are wrong (even if they are totally whacked out). What the handymen are really looking for is something they can't make themselves, and can't be downloaded for free- computerized data aquisition and data management. People don't want to squint at manometers trying to interpret flow readings, and customers aren't impressed by a couple lines of handwritten data. Expectations are higher today.

Now the companies that serve this market are into the "system" approach, where both hardware and software have to be bought from one company, and you need to spend ~ $1000 to to get a functional system. This is OK for business users who need out-of-the-box performance, and can write the cost off as a tax expense. This market has gotten smaller in the past few years due to economic issues, and trying to enter it against companies who've had 20 years to gain position will be a hard row to hoe. I would think about making a digital manometer/software package that would more versatile and less costly than Superflow, Audie, or Performance Trends. If your manometer will plug and play with the "Big 3" software, and your software will play with their hardware, AND offer options like high-depression flow measurement, floating depression, fixed depression, beta ratio selection, the Big 3's customers wil start getting interested. If it costs $100 less, the Big 3 will begin to have a problem with customer retention. The experimenter crowd will also show interest, as you'd be the only game in town catering to their needs. Development in this direction will likely be much more rewarding than selling plans.

You come across like somebody that "thinks" they know all about what performance improvement businesses need in order to be successful. ie. your last 2 paragraphs. On what first hand knowledge do you derive such a conclusion? Are you in or somehow have ties to someone in the business?

It's good for someone to challenge an opinion or an accepted standard / method / device. However, it appears to me that there's something between the lines. The "hidden agenda". I suspect this is about more than an orifice in a pipe vs an orifice in a cabinet.

Your comments on Bruce's business are rather poor etiquette IMO. We've had some great debates over the years but there are boundaries for behavior. This place isn't just another shoot your mouth off kind of a forum like so many are these days. We're a pretty tightly knitted bunch of people who respect each other, even when we disagree. Some of us go back 7 or 8 years together on this forum. You have no idea how many people we've helped to build successful flow benches. You come along and think that in a few opinionated paragraphs that you'll lay that all to waste. Think again......

'nough said

[1960FL]

David I will take this in parts,

Don't know what's happening exactly, it seems if you exceed a certain time, you're automatically logged out, and lose your post. I'm going to try posting/editing as I write instead of waiting till the end... .

I have reviewed your posts and see where you might be having trouble it appears you are using a public computer (extreme randomness in IP Address) and this is often a situation with these types of public system configurations. Are you using a computer at a public or institutional facility in Biddeford? As I suggested before compose your longer messages in a text editor then just cut and past.

Let's start at "Inside, you will have a region of organized flow between the inlet and orifice, surrounded by a "tube" of recirculating air trapped within the confines of the box. It's similar to what you'll see in a river- downstream flow is out in the main channel, eddies and backflow close to the banks. "Orifice in a box" looks like "orifice in a tube"- it seems quite doubtful the ideal sideways flow into the orifice will occur in a box that's not room-sized. .

Orifice in a box is an orifice in a tube but designed to have a beta ratio high enough to have little or no effect. In fact flow in the box is like flow in the river except it is flow in a river approaching a DAM or Black Hole depending on flow direction. The air is turbulent and slowing in speed in either chamber working toward rest (as the pressure differential changes) when it then organizes as it begins its journey toward the pressure differential, the internal orifice is a restriction that causes the increase/decrease in pressure between the two chambers. I do find it funny though that this design without extreme calibration using simple water gauges and a orifice CD derived form a book from the turn of the century can mathematically perform in a linear manor with accuracy within a couple percent of theoretical calculation. ????? When calibrated properly it can perform within 1 to 2% across an entire orifice range.

Again no one is telling you not to build your orifice in a tube, or maybe you are just looking to validate a purchase of product or a business, or even equipment you have.

Rick mentions placing a baffle before the orifice to prevent the incoming jet from the settling box from disrupting orifice inflow. This is a great example of "settling boxes" not settling much of anything- the jet from the bore adapter simply reforms at the exit of the settling box. When the jet hits this wall, the flow will have to boil up over it and fall down the other side. When a moving fluid drops abruptly from a higher elevation to a lower one, a cavity forms between the flow and the drop. This cavity is occupied by a turbulent roller of constantly changing size. What we end up with is a highly turbulent, pulsating flow directly in front of the orifice. You'll get the same effect if you hang the baffle from the top, side, whatever- forcing the flow to make a 90 deg turn will generate lots of turbulence in an area you really don't want it in. If you think I'm being overly dramatic, just make one wall of the box transparent, add smoke or streamers, and enjoy the show. The turbulence caused by PVC pipe irregularities will be minor by comparison.

PVC pipe has certain other qualities. It doesn't leak, and a tube equalizes stresses much better than boxlike shapes- which is why pressure-resistant items like cannon barrels and submarines tend to be totally tubular. For flowbench construction, it means no painting, no painstaking joinery, no leak chasing. You don't have to glue the joints- just run a bead of silicone round the cuff after the pipe is inserted, and cut it with a razor if later disassembly is required. .

One expects the air entering the BOX to be turbulent but the abrupt pressure changes begin to have and effect on this air causing mass chaos which in turn is similar to stagnant air. Unlike in a smaller pipe this air is not focused down steam it is migrating toward the pressure differential. If you want a good show take a wadd of ones and go watch the girls dance.

If you want to see the air as it approaches the orifice adhere streamers around the internal orifice on the side the air is approaching from and see what happens. Remember we do not care in the least what the air in the chamber is doing, only that the air approaching the orifice is at or near full flow.

Oh and yes I agree if you are looking to build something to test a 100” + an easy rout is pipe but you better glue it and understand the math and limitations of each flow element.

So far, Ive not heard any compelling reasons to abandon my wicked tubular ways, which have served my friend well these past 20+ years- he's made a lot of horsepower with his bench. I think a lot of your visitors are resistant to buying a set of plans when flowbench construction info is widespread nowdays- times have changed. Just about anything can be made to work, after a fashion, and you won't convert these people to customers by telling them their ideas are wrong (even if they are totally whacked out). What the handymen are really looking for is something they can't make themselves, and can't be downloaded for free- computerized data aquisition and data management. People don't want to squint at manometers trying to interpret flow readings, and customers aren't impressed by a couple lines of handwritten data. Expectations are higher today. .

No one on this forum will tell any one to abandon a project unless they truly do not understand what they are dealing with. Most will recommend buying the plans as it is an easy proven way to get us motorheads where we want to be and that is working or racing our Sh_t. All the information and a lot of knowledge is here on the forum but no one is going to do your homework for you, you do have to read.

Now the companies that serve this market are into the "system" approach, where both hardware and software have to be bought from one company, and you need to spend ~ $1000 to to get a functional system. This is OK for business users who need out-of-the-box performance, and can write the cost off as a tax expense. This market has gotten smaller in the past few years due to economic issues, and trying to enter it against companies who've had 20 years to gain position will be a hard row to hoe. I would think about making a digital manometer/software package that would more versatile and less costly than Superflow, Audie, or Performance Trends. If your manometer will plug and play with the "Big 3" software, and your software will play with their hardware, AND offer options like high-depression flow measurement, floating depression, fixed depression, beta ratio selection, the Big 3's customers wil start getting interested. If it costs $100 less, the Big 3 will begin to have a problem with customer retention. The experimenter crowd will also show interest, as you'd be the only game in town catering to their needs. Development in this direction will likely be much more rewarding than selling plans.

David, You have been poking a wound since you first posted here with obviously an underlying agenda of either self promotion or intentional discrediting of what goes on here on the forum. If you want controversy I say go play on YB if you want to talk flow benches and what you are going to build you are in the right place. If you do actually read the forum you will see we embrace many designs (follow the ivenhoee thread) and I only dispute self promoted theories of over discussed authors of books that tell us to purchase off the shelf parts to make more horsepower. Oh and did I mention he even gives Audie a BJ for a device he shows is off 12% against the BSI.

If your friend makes good power it is not from his flowbench but from what he learned about airflow, flowbenches have NO ability to make power they can only help you lean and validate your changes, Pito, Orifice in Pipe, Orifice in a Bax, Mass Air, FLE. These are all just tools.

FREE, LOL I am still waiting on a check I was promised 4 years ago, the only thing free is Knowledge. OH and did I mention that for FREE you can read the Flow Bench Tech forum and by the time you are done you should have enough knowledge to build a repeatable flowbench see it’s free. And yes I do understand you have to pay for plans to get access to the Secret hand shake club, but then the only thing in there is stuff about a design that is all wrong.

Business; Ahhhh Based on what I know about capitalism and business I would say I got a pretty good handle on it, I have three comments on what you have to say. One if you do not like how PTS/FBT works, design a flowbench, design a digital monometer or computer controlled interface, start a forum and have at it, that my son is the beauty of The American Dream. Free Enterprise. Two, If you are looking for “open source”, this is the place take charge start a thread start your designs and we all will contribute and embrace. Three, if you are of the current more youthful modern ilk you could then maybe start and Occupy Super Flow Movement.

In closing David, here on the forum we encourage good discussion and education, we all seam to value learning and sir you may have a lot to offer us here, but when you walk up to the cage and poke the lion with a stick you should expect the result. Share, Add Value contribute and you will find a good group of people.

Good day,

Rick

[Bakerlite]

Thanks for your input maineSS. I too have wondered about the plate effects on the stream. So I shall take the time to test that out.
I guess you could call me one of those handymen. I will say this, when I read posts I could not car less who posts them or what motives etc they may have. I look and the information within that post and then I decide if it contains theories that I have not considered. You have mentioned a couple of things that have interested me.

Of course the orifice plate has an effect on the "stream" (actually air flow). That is what it is supposed to do. If you understand airflow and measuring it the orifice creates the pressure differential between the upper chamber and the lower chamber when flowing through your tested item (cylinder head etc.). This is what you measure to determine what your flow is. Of course it has an effect on the airflow, it is supposed to! It is also probably the best way to measure airflow in a rough environment that most of us flow in. The LFE is really great but costs much more than I can afford and is not good in dirty environments.

John

Ah, yes I already know all that. What I'm talking about are the variables. Like size ,thickness, shape, position etc in relation to the cabinet size.

[1960FL]

Bakerlite,

Ok, orifice (Strange for this thread) for what we do should be no more than .125" thick if a square edge and no more than .250" for a sharp edge. Most of us use .125 sharp edge plates but once you understand CD and how your plates work there is nothing wrong with using a .125 machined square edge plate as you can flow in both directions without having to turn it over. Note sharp edge plates of the same ID will flow slightly more as there CD will be slightly higher but at this point we are splitting hairs.

Box dimensions and orientation the orifice should be centered in the dividing board the internal box dimensions (4 Walls) should be such that the maximum potential flow internal orifice diameter to a wall ration makes a beta ratio no bigger than .200. I/e lets say your bench was going to use a 10" delta P across the orifice and you wanted to be able to flow up to 500CFM the internal orifice would have to be able to flow 500 plus cfm so lets say 553 cfm, this means at max flow you are not exceeding the capability of the internal plate and your DP wont max out. A 553 cfm plate at 10DP would put you around 3.65" id for the orifice at a CD of .60 . So if we take 3.65/.200 we want the box to be no smaller than 18.25" square inside dimension. Now remember the lower the beta ratio the more linear the flow output will follow theoretical, so in this case i would go to something like 20"X20"x20" and your beta will be at .185 making the correction at max flow less than .5cfm. The fact is the bigger (within reason) and more symmetrical you make the to "Recovery Chambers" the more stable the air and the reading.

All that said if the chamber gets to big the responsiveness of the data acquisition slows.


Hope this helps,

Rick

[Tony]

And to duplicate that with an orifice in a pipe design, might realistically require placing a 3.65 inch orifice in maybe a 20 inch diameter pipe.

[jfholm]

Thanks for your input maineSS. I too have wondered about the plate effects on the stream. So I shall take the time to test that out.
I guess you could call me one of those handymen. I will say this, when I read posts I could not car less who posts them or what motives etc they may have. I look and the information within that post and then I decide if it contains theories that I have not considered. You have mentioned a couple of things that have interested me.

Of course the orifice plate has an effect on the "stream" (actually air flow). That is what it is supposed to do. If you understand airflow and measuring it the orifice creates the pressure differential between the upper chamber and the lower chamber when flowing through your tested item (cylinder head etc.). This is what you measure to determine what your flow is. Of course it has an effect on the airflow, it is supposed to! It is also probably the best way to measure airflow in a rough environment that most of us flow in. The LFE is really great but costs much more than I can afford and is not good in dirty environments.

John

Ah, yes I already know all that. What I'm talking about are the variables. Like size ,thickness, shape, position etc in relation to the cabinet size.

Also those same variables you talk about are there when you use the orifice in a tube. But you introduce another variable when installing the orifice in a tube and that is if the tube is not large enough the CD of your orifice is increased as the orifice approaches the size of the tube. So in practice to maintain the same beta ratio so the CD will be the same for all your orifices then you need to have a different size tube for every orifice you use.

[maineSS]

Well... this is interesting. It seems others have questions about "Orifice in a Tube".

After I did the shop vac test, I wondered about the chamber size of the PTS design. Now a 20" cube will place the orifice 10" from the incoming jet from the "settling box". If you place your hand 10" from the nozzle of a shop vac, you'll see the jet hasn't lost much at 10", no wonder Rick mentioned placing a secondary divider in front of the jet. Place your hand where this divider might be- say 5" out- and block 2/3 of the stream so the jet has to jump over it. Feel the turbulence over the back of your hand- think 5" is enough space to quiet that down so lovely sideways flow into the orifice can take place? Probably not- the problem is one of scale. You need a MUCH larger box size compared to jet size to get quiescent orifice flow conditions. In an earlier post, Rick mentioned placing a bureau in a room in front of a window as an example for a leafblower jet- that's about the right size. His comment about large chambers being slower to "see" flow changes is also correct- which is one reason why room-size chambers are totally impractical in real life. Practically sized chambers are going to have turbulence directly in front of the orifice with a baffle, which means orifice flow conditions will differ from ideal (just like a tube). There is a way to slow the jet in a small box without generating high turbulence levels so sideways inflow can take place, but after recent experiences here, I'm not going to reveal it just yet. If certain gentlemen are as talented at design as they are at uninformed and incorrect speculation, they should be able to figure out how it's done.

When I first posted, I was aware of the Beta Ratio, as it's found in more fully-developed flow equations, but I was unsure at just what percentage it started becoming PRACTICALLY important. My experience suggests 50%, but then there's the possibility of my flow straightener position skewing things. So, to get back on course here, is anyone aware of any studies, tech journal articles, published thesis, etc. covering actual experimental work in this area?

[Brucepts]

Do you find it amazing that someone could develope a set of plans not supported by research nor a thesis?

Do you know how many of my of PTS designs have been built, analyzed and are in use in a college environment? Let's add trade and high schools plus college senior projects?

Doubt you will have an answer for that question.

this forum is probably the best place for flow bench research