Just for the record, here's a chart of the Mizuno M19/R20 callibration points, and the Manufacturers spec.
The green triangles are the fan-law curves for this model's specification.
The red circles are for three sub-models. I am *presuming* they use the same fan assembly, and just have different power motors.
They comply reasonably well with the fan laws.
Can someone please check this data and calculations.
Here is the fan (and outlet tube) : https://www.lenr-forum.com/ima…caa43b99e97f1d5eb2b35.png
The fan spec is at https://www.sanyodenki.com/arc…_pdf/San_Ace_97BM33_E.pdfThe model number is 109BM12GC2-1
I have the radius of the output tube as 33 mm
The flow in M^3/minute and power are from the spec
I divide the flow by area to get m/minute and divide by 60 to get m/sec
Fan tube radius 33 mm 0.033 m
area m^2 0.003421
flow m^3/min 0.82
vel m/sec 3.99
I seem to have a Rossi/Prominent pump problem here : the specified maximum velocity is 3.99 m/sec but the calibration has a maximum of about 5.1 m/sec at 5.6 W (roughly ... read off my chart)
thank God (or Napoleon) for metric units.
I started my academic life with FPS. Then we switched to cgs. No, wait! MKS. Ooops : SI .... no wonder I can't remember any physical constants,
ps: But I prefer Imperial for human-scale ...
pps: My FIRST computer (Ferranti Perseus) had a mixed-radix MILL (arithmetic unit) .. so you could multiply stones,pounds, ounces by pounds, shillings, pence ... I have the manual.
Actually, Mizuno might find that a regulated flow water pump might do the job. I'll ship it to him (or a replicator) if they want.
RB asked me to post the FULL quote.
The warning about TURBULENT flows is at all velocities.
The warning about the HIGH flows (turbulent OR laminar) is NOT applicable.
ps : Life experience -- I've bought over $10M equipment based on specifications and acceptance tests (Including "latent defects"). One vendor had to "remove and replace" a system because it didn't perform within its "useful lifetime" (7 years).
I already paid for a Prominent pump. Because of my empathetic CONCERN about Rossi's flow rates.
Edit : You're welcome.
Are hotwire anemometers used in quantitative measurements of velocity,, in turbulent flows YES or NO?
You need to qualify your statements AF.
NO, by my references.
I almost married a pharmacist's daughter : does that count?
- When the direction of the airflow is known, choose a UNIdirectional probe.
- When the direction of the airflow is unknown or turbulent, choose an OMNIdirectional probe.
Of course, that instrument is beyond a "sparrow tears" budget.
[ I responded to the posts before seeing Alan Smith's notes.
ps : I understood that you endorsed my breaking out the calorimetric stuff into a separate thread ..
I have not other comment until you find the relevant in depth research papers supporting your BLACKBOX warning assertion.. pure rhetoric
Of course the black-box thing was pure rhetoric. At least THAT got through to you.
For engineering matters, I don't think there will be many. I'd look out for "best practices" etc. Not to mention proofs of negatives and all that.
So ... why don't YOU find a research paper showing that a single-wire (1D) hot-wire anemometer gives accurate QUANTITATIVE results for turbulent flow (Extra points : 2 to 3 diameters away from a major transition).
Edit : I see you found one. (Posted while I was composing)
Here's some background information on affinity laws : https://www.sciencedirect.com/…/engineering/affinity-law
eg The variation of pump performance with changes in speed also follows the affinity laws, but with a higher level of accuracy than do changes in impeller diameter.
ps "Concern" = "That's interesting .... "
AS I said before : Hot-wires and IR are great for DIFFERENTIAL analysis.
But *NOT* for quantitative.
what velocity is 5 mps in fpm?
It has a stable turbulent flow in 6,6 cm ID pipe.
What kind of care..?
Does this mean that hotwire anemometers should not be used for 5 mps in 6.6cm diameter pipe?
Yes or No?
Show a clear reference please and not foolish indirection..
This is timewasting
I have NO idea of what clarification you need beyond the reference I gave.
And yes : the length of the outlet pipe should be 14 diameters, ie 14*6.6 = 92.4 cm
(with the probe at 4 diameters = 27 cm from the end)
Recommendations (using Mizuno's fan) :
Make the outlet tube 15 diameters long, and measure 4 diameters from the outlet.
Use the RPM counter (unused yellow wire) rather than watts, so that the results are linear (rather than squared).
Correct the results for temperature.
As a general rule-of-thumb, conventional hot wire anemometry should not be used if the
local turbulence intensity is higher than about 35%, at least not for quantitative purposes.
Apart from the mix-up of velocity components (cross-talk), it is evident that a hot wire
can not distinguish between what is forward and backward, it behaves like a rectifier.
(Turbulence intensity is based on the transition from laminar to turbulent flow. Others have reported that the outlet is well into the turbulent flow domain )
See equations 18-19 :
The relative error increases quadratically with Tu. For Tu = 10% and H = 1.05, K = 0.20
the systematic error becomes +0.6%; +2.3% for Tu = 20%. Thus, to avoid excessive
systematic errors, it is essential to have low enough turbulence intensities. During velocity
calibrations, the rule-of-thumb is to have Tu < 5%, preferably Tu < 2%.
The relative error in using the approximations ve(t) = u(t) and q ....
instead directly proportional to the turbulence intensity. For Tu = 10%, with H and K
as above, the absolute value of the relative error is less than 3%.