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From: "Marc Wiese" <cardmarc@charter.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: Turbochargers for 200 hp airflow rates for turbonormalizing
Date: Thu, 1 Nov 2007 16:33:43 -0500
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this data from lyc 10360 A1B  turbo (normalized) charged,  ~ 200 hp
engine...)
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Induction Air Temperature?

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Gents:

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What temperature rise do you typically see across your turbo?

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[At my typical cruise of 16,500 or 17,500 I typically see IAT of about=20

177 F at 28.5" and 2550 RPM, flowing about 10 GPH.]

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After putting the IAT probe in, I've observed the temperature on four=20

flights.  Running at 25/25, the IAT is 160F to 170F, ~110F above ambient =


(50F to 60F), at 10,500 and 11,500.  Temperature drops at lower power=20

settings, same altitude and external temperature.  I think I saw about=20

140F when I pulled the power back to21" in some turbulence.  That=20

doesn't seem right - if the turbo is matched to the airflow, I think=20

delta T should be mostly a function of the pressure rise and less so the =


work input (exhaust volume through turbo, which I assume would scale=20

roughly 1:3 with intake flow), so I would not expect a significant=20

temperature change with throttle position, only with altitude.=20

Obviously I'm wrong.   An adiabatic rise would be ~65F to 95F depending=20

on the controller setpoint. (That's 13" to 19" rise, for a setpoint of=20

32" to 38" Hg.)

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[It's going to be more than adiabatic, 'cause the compressor is far from =


an ideally efficient machine. There have been two iterations now toward=20

higher efficiency... first, TurboFlite started using a different=20

compressor unit that was a bit more efficient at our operating point.=20

And now TATI is considering using the same turbo that's used in the=20

Cirrus install... an even more efficient unit.  As far as the throttle=20

change correlation, remember that your increasing mass flow through the=20

machine, and hence moving the turbine and compressors along their =
curves...]


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Marc Wiese, 20B and 94 13B t engines=20