Propeller Excitation and Response of 230000 TDW Tankers 



REPLY TO DISCUSSION 



Carl-Anders Johnsson 



Statens Skeppsprovningsanstalt 

 Goteborg, Sweden 



Thank you, Mr Huse, for your comments. We read your con- 

 tribution with interest and also with some relief, to get, without pay- 

 ing for it, a good investigation of the wall effect of a tunnel of similar 

 dimensions as that of SSPA. 



On trials we have several times observed that pressure fluc- 

 tuations certain up to 5-6 times blade frequency. Preliminary, it was 

 required to study the mechanism by which such components could be 

 included. 



The m term in Equations (15) and (16) of Appendix C however, 

 leads to large magnitudes of the component of that frequency, as the 

 corresponding inaccuracies in the Fourier term become significant. 

 Consequently, empirical damping of the signal was required ; for con- 

 venience the reduced frequency/oscillating blade relationship was 

 chosen as the "building brick". Presently, we terminate computations 

 at twice blade frequency and can neglect the method originally includ- 

 ed in the paper. 



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