Bavin, Vashkevich, and Miniovich 



aonstatlonary circulation 

 quasi -steady clrculati 



6 5 il i 2 



Fig. 3 - Effect of flow nonuniformity on pressures 

 due to loading: 1, first harmonic; 2, second har- 

 monic; 3, first harmonic for the case of a circum- 

 ferentially uniform flow 



The dashed lines in Fig. 3 correspond to the case when circulation around 

 the blade of a propeller operating in a wake was calculated by means of the 

 quasi- steady theory. It can be seen that percentagewise this method gives over- 

 estimated values of second-harmonic amplitudes, whereas the amplitudes of the 

 first harmonic of the pressure remain almost the same as those corresponding 

 to the nonstationary circulation. The conclusion that the amplitudes of higher 

 pressure harmonics are overestimated when making use of quasi-steady circu- 

 lation was confirmed by some other calculations. 



It should be noted that for lightly and moderately loaded propellers the 

 effect of nonuniform inflow conditions on the total pressure (both loading and 

 thickness constituents) should be less pronounced than that on the loading- 

 associated pressures only. For higher propeller loadings (bp > i) the total 

 pressure practically is equal to its loading component. 



Calculations of propeller- induced pressures for different wakes have shown 

 that the maximum pressure amplitudes at some points of the hull surface can be 



10 



