Mizuno Airflow Calorimetry

  • That can't be true. That's what anemometers are for


    Of course we could go back to pitot tubes.. in the process engineering dept in the 1980's we had about 10 of varying diameters and lengths..


    from 2m down to 10 cm.. S type and L-type.. and about 5 inclined manometers.. hotwire anemometers were a definite improvement.

  • It does work, perfectly. However what it calculated is not what you need to determine average airflow.


    We do not need to determine the average airflow. The flow rate is the same anywhere you measure it across the orifice. I am sure you know that, and I am sure you realize the average of 4.1, 4.1, 4.1, 4.1, 4.1 and 4.1 is 4.1. So, you are trolling and writing nonsense as usual.

  • I don't think that makes sense (turbulence is not stable directionally


    It does make sense... microscopic turbulence is stable directionally.. to a hot wire anemometer definitely.. unless there are temporal flow fluctuations

    as in the macroscopic swirling motion near the fan blades ..

    further away from the fan the flow profile stablilises..


    as studied in this research article.. by Abdul and Rahim 2007.

    FLOW MEASUREMENTS DOWNSTREAM OF AN AXIAL FLOW FAN INSIDE AN OUTDOOR AIR CONDITIONING UNIT.


    where they used an imaging system... smoke ? plus the de riguer hotwire anemometer




    Turbulence is a poorly understood term.


    For example.. the turbulence that Shane D might have often warned his passengers of

    is on a much large scale than the stable turbulent motion occurring on a microscopic scale near the skin of the aircraft.

    Perhaps THHnew needs to read up a bit on turbulence.

  • We do not need to determine the average airflow. The flow rate is the same anywhere you measure it across the orifice. I am sure you know that, and I am sure you realize the average of 4.1, 4.1, 4.1, 4.1, 4.1 and 4.1 is 4.1. So, you are trolling and writing nonsense as usual.


    Jed, you would be more respected here if you did not react in this way to my posts, based on what is usually (nearly always) a misunderstanding. And, while I am not much bothered, I feel it is impolite for you to continually misinterpret what I say, and based on this lack of understanding then (repeatedly) tell me that I am a lying troll.


    In this context what is relevant is the time-averaged flow velocity. You are totally missing the point thinking that the objection to HWAs relates to the spatial average over velocity profile. On the contrary, it relates to the temporal change in velocity (caused by turbulence). The issue is whether averaging the HWA output will deliver the correct (time-averaged) velocity. AF has given arguments that it does not always do this, based on the fact that averaging the magnitude of a vector is different averaging the component of a vector in a given direction. Although HWAs are not omnidirectional they do not correctly pick up just the parallel to pipe component of the velocity (pretty obviously).

  • In this context what is relevant is the time-averaged flow velocity. You are totally missing the point thinking that the objection to HWAs relates to the spatial average over velocity profile.


    As shown in the paper, and as I said, the flow velocity does not change over time. As I am sure you know. So, whether we are talking about measurements made over time, or measurements over space, the average of 4.1, 4.1, 4.1, 4.1, 4.1 and 4.1 is 4.1. As confirmed by two anemometers and countless calibrations. Again, you are posting bullshit.

  • In this context what is relevant is the time-averaged flow velocity

    Turbulence is a poorly understood term.


    For example.. the turbulence that Shane D might have often warned his passengers of often

    is on a much large scale than the stable turbulent motion occurring on a microscopic scale near the skin of the aircraft.

    Perhaps THHnew needs to read up a bit on turbulence.

    Read up a bit on turbulence please THHnew.

    stable turbulent profiles are temporally stable..

  • 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

    power 7.2

    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)

  • the specified maximum velocity is 3.99 m/sec but the calibration has a maximum of about 5.1 m/sec

    paradigmnoia bought a hotwire anemometer...and a fan, and measured 5m/s or so.


    he did spec calcs too where the spec conflicted with his measurement


    ask him to check


    he had no problems with the anemometry after his measurement

    and some education about anemometer traverses..

    until he invented another theory which was hair wrapped around the fan...


    forget the BS about the Rossi pump pls

  • Jed, you would be more respected here if you did not react in this way to my posts, based on what is usually (nearly always) a misunderstanding. And, while I am not much bothered, I feel it is impolite for you to continually misinterpret what I say, and based on this lack of understanding then (repeatedly) tell me that I am a lying troll.


    The problem is your troll like thinking and arguing.


    Please show why the calibration under your assumption is correct and then why all your objections are not seen in the calibration.


    But such arguments you never answer .. what confirms my & Jed's attitude.

  • @AF


    You got "vel m/sec 3.99". I haven't checked your calcs but I find this interesting. In FIg. 9 of the new Mizuno/Rothwell paper, this translates to an input power of ~3.6 W. Then on Figure 8, we see that there is a 'flyer' data point at that velocity, if one assumes the smooth line drawn on the Figure is correct. It is about 15% low. That makes me wonder if there is really a plateau in the data, up to higher input powers where it might suddenly jump up to the data regime shown at ~5 W input power. IOW, I am wondering if the smooth line is the correct model, and whether or not Figure 8 indicates some unexpected behavior on the part of the fan. Just something to consider.


    Edit: I should have added that if the line is right, the flyer point, being a real point, indicates that the 2sigma limits are something like +/- 30%, which suggests lots of variation in fan performance.

  • . . . indicates that the 2sigma limits are something like +/- 30%, which suggests lots of variation in fan performance.


    Since there is no measurable variation in fan performance, you are wrong.


    To put it another way: Who are we going to believe, you, or the two anemometers? With regard for the other blather from you and THH, should we believe you, or the 3 power meters? You, or the thermometers, thermocouples and RTDs?


    I think in experimental science we should go with the actual measured numbers from instruments, rather than handwaving and speculation.



  • The paper you link shows time-averaged velocity profiles downstream of the fan, which are, indeed, stable. It says nothing as to the instantaneous velocity - what is the level of high or low frequency turbulence - or how does the instantaneous direction of the velocity flow vary with time due to the tubulence.


    "Unless there are temporal flow fluctuations" well that is pretty well the definition of turbulence! In turbulent flow these exist, at many different time scales. All that is not seen when you look at time-averaged distributions.


    Normally it would not matter - but it means the average velocity results from an HWA cannot be relied upon, and will tend to under-read, in turbulent flow.

  • The problem is your troll like thinking and arguing.


    Please show why the calibration under your assumption is correct and then why all your objections are not seen in the calibration.


    But such arguments you never answer .. what confirms my & Jed's attitude.


    Wyttenbach I don't answer such questions because they misrepresent my views. In fact I have no idea what you are talking about: and am quite sure you have no idea what I have said.


    I make no assumption about whether calibration is correct or not. I merely point out that some system errors (like anenometer velocity) cancel when you use a control (calibration run with a known no-excess reactor) and some do not. I am stating the (obvious) fact that even if the anenometer results have some consistent error, the adjusted results (comparing active runs with a known power out calibration) should not be affected. However, I also point out, that reliance means it is important to establish that conditions when the control reactor and the active reactor arun are identical (so that in these two different cases the calorimeter losses are the same). You can look for either absolute excess heat, or excess over a control. Either one, proven, is enough. The two options require different things to be checked.


    It is for me most unfortunate when those contributing to these threads develop an adversarial attitude and find fault in what a given poster says because they assume (erroneously in this case) it must be on the "wrong side" of this debate rather than looking at and understanding substance.



  • (1) We don't know what the fan back-pressure is. If we assume (worst case) 0 then at 13.8V (max spec voltage) the fan delivers 0.9 m^3/min not 0.82. Having said that, it is sensitive to small amounts of back pressure, so I'd expect at this quite high air velocity that the spec 0.82 is more plausible, looking at the pressure vs speed figure.


    (2) It is possible that Mizuno drives this fan at higher voltages than the spec allows. Unwise, because it might get too hot and break.


    (3) The power required will depend on the back pressure, so I don't think we can conclude anything for sure from the specifications there.


    Even given this, I agree with you. That fan would have to be very highly over-driven to give a 27.5% increase in airflow, and the power used does not appear to be what there would be when over-driving it.

  • Actually, there are a couple of interesting items arising from the Figure Jed just posted. There are a couple of 'flyers' or 'outliers' based on the line drawn through the data, but I go back to my original question - Is the line right? If one fits a straight line to the data, the two outliers near the center-high end will be less so, but the point at low reactor T becomes way off. However, what if the correct 'line through the data' has a threshold response level, i.e. no signal (or just noise) until a particular value is reached (which would be the X axis intercept of the line)? That paints a different picture., and the points that define the lines are not well-replicated. I think it might be worth considering, but that's just me...