Fan volumetric speed

[pj47]

Good wiki, overall. Extremely helpful to me.

Regarding fan volume flow rates, the fan in the 991a does not run in open air. There's resistance to the flow. The correct comparison is to look at the fan curves (flow rate vs. static pressure). If the Sunon curve is always above the original fan curve, then it will provide more air.

Using the free air condition may or may not be accurate for which fan is better. Some fans have a lower free condition air flow, but better under resistance. It's likely the Sunon is better than the original fan, but you don't know for certain without the comparison.

Also, you have to look at the stall point of these axial fans and be certain you are operating above that point. See attached image.

Fans can be a bit confusing and complicated. With my 35 years experience in thermal engineering, I know it has caused some confusion to many people.

[rfrht]

Hello PJ47!

Thank you very much for your comments - I appreciate a lot the enlightment.

So I want now to add the following section. I'd love if you could vet it.

Fan Performance

Selecting a fan by solely relying its advertised airflow is plain bad practice. <YOUR NAME, callsign> brought to my attention that one should pay special attention to fan performance curves, because the fan will put some effort sucking the air through the vents, circulating through the radio and finally exhausting it - and not all fans behave the same when under load.

For the uninitiated, Static Pressure roughly translates to the effort that the fan puts to suck the air: The higher the static pressure, the more difficult to suck the air.

Considering the Panasonic fan datasheet Static Pressure x Airflow curves:

Panasonic fan Static Pressure vs Airflow curves

Now, from the SunOn fan datasheet:

SunOn fan Static Pressure vs Airflow curves

The selected SunOn fan for this project follows the curve number 2.

When comparing the curves, we can see that the SunOn curve number two outperforms in every aspect the Low and Middle curves of the Panasonic airflow curve - while Panasonic outperforms SunOn on its Standard (the top curve) while in high static pressures (high static pressure: congested environments, difficult to suck the air), while SunOn delivers a lot more air under lower static pressure.

It might be possible to infer that the SunOn will be on par with Panasonic fan performance when under heavy load, and exceedingly providing more airflow when the fan runs in lower speeds.

But... What about Noctua?

They don't disclose airflow curves for their product.

[rfrht]

@pj47 Can you please assess? And would appreciate your name / callsign to give credits. Thanks!

[pj47]

Hi Rodrigo, This is a great improvement. Well written! Thank you again for the 991a wiki. It’s been a fantastic help. I have only been a ham since January this year and got my 991a around May. The features were new to me and you bridged the gap between me and the manual. Thanks! Jim Petroski W8NRX

…

Sent from my iPhone On Nov 1, 2021, at 17:16, Rodrigo Freire ***@***.***> wrote:  Hello PJ47! Thank you very much for your comments - I appreciate a lot the enlightment. So I want now to add the following section. I'd love if you could vet it. Fan Performance Selecting a fan by solely relying its advertised airflow is plain bad practice. <YOUR NAME, callsign> brought to my attention that one should pay special attention to fan performance curves, because the fan will put some effort sucking the air through the vents, circulating through the radio and finally exhausting it - and not all fans behave the same when under load. Considering the Panasonic fan datasheet<https://www3.panasonic.biz/ac/cdn/e/fasys/component/fan_motor/catalog/fans_dc60_1b263-1e.pdf> Pressure x Airflow curves: [Panasonic fan Pressure vs Airflow curves]<https://user-images.githubusercontent.com/3044503/139742232-056dd52c-76e8-4309-9a98-b821fcf6f5b1.png> Panasonic fan Pressure vs Airflow curves Now, from the SunOn fan datasheet<https://www.sunon.com/eu/MANAGE/Docs/WEBCONT/Files/1236/Sunon%20DC%20Brushless%20Fan%20&%20Blower_(240-E).pdf>: [SunOn fan Pressure vs Airflow curves]<https://user-images.githubusercontent.com/3044503/139740316-56a8df34-0194-404d-9318-f264568771cf.png> SunOn fan Pressure vs Airflow curves The selected SunOn fan for this project follows the curve number 2. When comparing the curves, we can see that the SunOn curve number two outperforms in every aspect the Low and Middle curves of the Panasonic airflow curve - while Panasonic outperforms SunOn on its Standard (the top curve) while in high static pressures (high static pressure: congested environments, difficult to suck the air), while SunOn delivers a lot more air under lower static pressure. It might be possible to infer that the SunOn will be on par with Panasonic fan performance when under heavy load, and exceedingly providing more airflow when the fan runs in lower speeds. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub<#2 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ALCHYM7R7V57LT3MBZIWC2LUJ37SXANCNFSM5HEYVMYA>. Triage notifications on the go with GitHub Mobile for iOS<https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android<https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

[rfrht]

Thank you very much for the kind words, Jim! By the way, just wrote a new article, taking advantage of the writing streak.

Resolved by 817917d