1. Institute of Fluid-Flow Machinery,Polish Academy of Sciences,Fiszera 14 Street,Gdansk 80-231, Polande-mail: pbaginski@imp.gda.pl
2. Institute of Fluid-Flow Machinery,Polish Academy of Sciences,Fiszera 14 Street,Gdansk 80-231, Polande-mail: slawomir.banaszek@imp.gda.pl