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## Fw: Tesla Turbine recalculation

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• the following information was offered by harryc@ontarioeast.net copied ... From: Harry Valentine To: tesla-owner@yahoogroups.com Sent: Sunday, March 09, 2003
Message 1 of 1 , Mar 9, 2003
the following information was offered by harryc@... copied
----- Original Message -----
Sent: Sunday, March 09, 2003 3:56 PM
Subject: Tesla Turbine recalculation

This may be of interest to your group

I have recalculated some data pertaining to my recent article re using a steam driven Tesla turbine in a modern railway concept steam locomotive, at webpage:

For calculation purposes, a Tesla stack of 30-discs were used, where the main inter-active surface areas would be between 2-ft radius and 3-ft radius, with 0.25"-spacing between discs. The total effective area would be 900-sq.ft and the active inter-disc volume would be 2.4-cu-ft, with a hydraulic radius of 0.4898". The calculated back-pressure for a steam density of 0.25-lb/cu-ft and an average swirl velocity of 2500-ft/sec at 2.5-ft radius, was 114-psia.

The Mach 2 inlet pressure was 129.7-psia at 400-deg F (from a boiler delivering 1000-psia at 1000-deg F). For a maximum avarage relative velocity (between steam swirl and discs) at 2.5-ft radius of 1000-ft/sec, the Reynold's # worls out to (0.25 x 1000 x 0.4898/12)/(3.56E10-7). This last figure is the dynamic steam viscosity at 400-deg F. The Reynolds # works out to 2.866E10+7, which yields a friction drag coefficient of 0.002.

Calculating maximum power, based on 35,000-Hp coming from the boiler, with average relative steam velocity at 1,000-ft/sec at 2.5-ft.

Drag= (1/2gravity) x(V-squared * density * area * drag coeff)
=6987-lbf at 2.5-ft radius at 4800RPM. This calculates to 15,880-Hp, or 45% of the horsepower energy in  the steam leaving the boiler. As the mass flowrate is reduced, the relative velocity decreases and the drag factor increase by 25%, using flat-plate boundary layer theory. This means that at a relative velocity of 500-ft/sec, the Tesla discs would still deliver around 4900-Hp at 4800-RPM and still with little change in efficiency.

I'm not into the metaphysics of the Tesla engine, however, I'd find single pass efficiencies of around 28% to 32% to be more acceptable.

Regards,

Harry
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