ABSTRACT 



Experiments are described in which the pressure distribu- 

 tion on two model controllable-pitch propellers was measured. 

 The pressure was measured at 40 locations on the blade surface 

 with the propeller operating in both uniform and inclined flow. 

 The discussion of the experimental technique includes a de- 

 scription of the hardware and data analysis systems. 



The accuracy of the measured pressures was comparable to 

 the measured calibration accuracy, excluding unexpected loading 

 effects observed on some of the gages. 



The measured mean pressure distributions produced fair 

 correlation with predictions based on equivalent two-dimensional 

 blade-section methods at the design advance coefficient. The 

 measured pressure coefficients at certain blade locations were 

 observed to be dependent upon Reynolds number for a given advance 

 coefficient. Boundary-layer separation is thought to have 

 caused the Reynolds-number effect. These viscous effects were 

 greater than previously anticipated. 



The variation of the mean pressure distributions with 

 advance coefficient produced the expected trends. At a given 

 location, C generally varied linearly with advance coefficient 



with increased sensitivity toward the leading edge. 



Measurements of the unsteady pressure were performed with 

 the propeller shaft inclined 7.5 degrees to the flow direction. 

 Quasi-steady predictions of the fluctuating pressures under- 

 estimated the measured values by 30 percent to 50 percent, 

 but generally followed the measured fluctuating pressure 

 distribution along the chord. Over a range of advance 

 coefficients, the quasi-steady predictions matched the general 

 trends in the measured fluctuating pressures. 



ADMINISTRATIVE INFORMATION 

 The work reported herein was funded by the Naval Sea Systems Command (NAVSEA 

 05R), Task Area S0379-SL001, Task 19977. The work was performed at the David W. 

 Taylor Naval Ship Research and Development Center (DTNSRDC) under Work Units 1544-296 

 and 1544-350. 



