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Did multiple engine runs. Unfortunately the pressure sensors max out at 2800-2600 RPM. (That RPM limit appears to drop as air gets out of system.) From calibration with garden hose that's about 9 - 10 gal/min (per radiator). Fortunately flow through radiators appears balanced within 5% or less.
If the flow is linear with RPM, that would be more than 45 gal/min at 6500 RPM. That's a big if. I guess I really need to get pressure sensors that will let me measure flows at 6,500 RPM or higher (50 gal/min or higher) and/or remake my flow sensors for bigger ID and less restriction, to make sure that coolant flow is not a limiting factor so I can concentrate on airflow. ID of the flow sensor makes big difference in produced pressure from flow because area is proportional to radius squared.

Looking at Ed's Cooling spreadsheet (attached), I'm wondering if the spreadsheet would be any different for the Renesis.
The Coolant Cp makes a big difference for adequate cooling.

Finn

On 2/20/2022 12:34 PM, Finn Lassen finn.lassen@verizon.net wrote:

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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Attachment: Cooling.xls

(154K)

Attachment: CoolantFlowSensor.xls

(28K)