The turbine drum will probably work if you can get it spinning very freely. Spinup time will be dreadful though. How would you make the turbine blades? Might be possible to get some flat plates cut with slots to slide the blades in at each end, with some thin ti for the blades. If you make the nozzle for the fan/compressor the same size as the blades you might be able to improve the efficiency a bit by focusing all the air. Needs a small gap between nozzle and blades too. Jamie's idea of using venturi nozzles might help too.