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Finally got around to making coolant flow "sensors". (Used existing 3/4" cu pipe with wells for temperature sensors. Maybe a bad idea because of the restriction may not make it true 0.75" ID.)

Trying to calibrate pressure sensors.
Have a hose with water. Connect to vacuum and pressure ports of sensor when water is level. When I raise one end of the hose to get a 20" difference between the two water levels, is that 10" or 20" H2O?

Yesterday I filled a 5 gal bucket through the sensors, timing it to 9 gal/min. Pressure readout indicated what I had previously gotten as 35.25" H2O.
Something is obviously wrong. Perhaps the 35.25" H2O was really half of that?

Moving on. Trying to make a formula to convert inH2O to Gal/min.
h_w _{(in H2O)} = 0.186 (v_fpm / 60)²� � where v_fpm = velocity (ft/min).
Vfpm = 60 * Sqrt(Hw / 0.186)
231 cuIn / gallon.
Area of 3/4" pipe: 0.44 sq in.
231/0.44 = 525" or 44 feet/min for 1 Gal/min flow.
So gal/min = 60 * Sqrt(Hw / 0.186) / 44
60 * Sqrt(20" / 0.186) / 44 ~ 13.6 gal/min. Close to Steve's 16 gal/min through 0.8" pipe.

Anyone seeing a mistake here?

Need to repeat my filling 5 gal bucket through sensors test, but need to get my pressure sensor calibration right first.

Finn

On 8/21/2021 12:15 PM, Steven W. Boese SBoese@uwyo.edu wrote:

Finn,

20" of water column corresponded to 16 gal/min through a 0.8" dia tube.� Coolant delta T is based on measurements in my plane. Typically, I see about 10 deg F delta T at a cruise power setting.

If I remember correctly, Bill Shertz made water pump flow rate measurements with a system he set up for this purpose.

Steve Boese��

From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Sent: Saturday, August 21, 2021 6:04 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Coolant flow sensors
�

Thank you Steve. Exactly what I need. I can make those.

What were the approximate pressures?

On a related note, what is the 15F coolant temp deltas you mention based on?
35 gpm coolant flow cooling 180 HP?

I keep wondering where the 35 gpm comes from.

Mainly by reducing oil cooler exit air area, I'm now down to 200F @130 mph @ about 4,000' density altitude and 70F OAT. Can climb at full power to about 1,500' on a 85F day (keeping speed at 110-120 mph). Only small incremental improvements so far.. Looking for that magic change that will lower that to 180F.

After working with air flow, I think I'll now circle back to coolant flow. Coolant delta over right rad still higher than left rad. Am thinking of hooking up a garden hose to rad inputs and see how quickly 5 gal buckets will fill up from each rad output But 35 gpm is a lot more than a garde
n hose can supply?

But flow sensors should give better real world results..

Finn
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