that takes one integral pressure transducer with its zeroing circuit and 

 measures a single pressure in sequence along the stern upper meridian. 



The pressure transducer used was designed for measuring low pressure up to 



3 

 0.2 psi (1.379 X 10 Pa). The zero-drift linearity, scanivalve, hystere- 

 sis, and pressure transducer with zeroing circuit were carefully checked 

 and the overall accuracy was found to be within 0.5 percent of the dynamic 

 pressure. 



A Prandtl-type static pressure probe of 0.123 in. (3.125 mm) diameter 

 with four equally spaced holes located three probe diameters after the 

 probe nose was used to measure the static pressure across the boundary 

 layer. By yawing the probe in the free stream, it was found that the 

 measured static pressure was insensitive to the probe angle up to a 5- 

 degree yaw. In all cases, the static pressure probe remained in alinement 

 by less than 5-degree yaw. 



The mean axial and radial velocities and the turbulence intensities 

 for the Reynolds stress calculations were measured by a TSI, Inc. Model 

 1241-20 "X" type hot-film probe. The probe elements are 0.002 in. (0.05 

 mm) in diameter with a sensing length of 0.04 in. (1.0 mm). The spacing 

 between the two cross elements is 0.04 in. (1.0 mm). A typical schematic 

 of the hot-film probe used is shown in Figure 2. A two-channel hot-wire 

 and hot-film anemometer with linearizers was used to monitor the response 

 of the hot-film probe. A temperature compensating sensor (probe) was used 

 with each hot-film element to regulate the operating temperature of the 

 sensor with the changes in air temperature. The "X" hot film and its 

 temperature-compensated sensor were calibrated together through the ex- 

 pected air temperature range and supplied with their individual lineariza- 

 tion polynomial coefficients at the factory. A single element TSI, Inc. 

 Model 1212-TI,5 hot-wire probe also was used to measure the velocity 

 distribution across the stern boundary layer. Two single-element TSI 

 (Model 1212) hot-wire probes with a 90-deg bend separated by a small radial 

 distance also were used to measure spatial correlation functions in the 

 thick boundary layer. 



