Instructables
Picture of Tesla turbine with hollow-axle exhaust
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Here are some photos of my modified Telsa turbine.  This is a primitive proof-of-concept prototype with 7 posterboard rotors, but it works surprisingly well.  The design allows 100% of the disc area to be used, and eliminates the turbulence from the exhaust passing through the plane of the rotors.  In the photos I am using a small electric motor as a dummy load to test self-starting.  Note the holes in the output shaft to allow exhaust to escape from that side also.  
It will work when powered by the exhaust from a vacuum cleaner (using a single-sided De Laval type nozzle) but was being tested with 50 psi of compressed air in the photos.  Nozzle in the photos was made from 3/8" OD (1/4" nominal) soft copper pipe.  Will take a video soon.