TABLE 3 - LOCATIONS OF HOT FILM GAGES 



Location 



Nondimensiona! Axial Distance from Model 



z orepoint to Hot Fi 



m Gages - 



x/D 



4620-1 



4620-2 



4620-3 



4620-4 



4620-5 



4620-6 



4620-7 



4620-8 



4620-9 



1 



0.16 



0.29 



0.29 



0.29 



0.30 



0.41 



0.13 



0.05 



0.06 



2 



0.37 



0.45 



0.45 



0.47 



0.42 



0.52 



0.21 



0.17 



0.14 



3 



0.49 



0.61 



0.61 



0.65 



0.54 



0.62 



0.34 



0.29 



0.27 



4 



0.57 



0.86 



0.81 



1.26 



0.75 



0.72 



0.54 



0.46 



0.39 



5 



0.81 



0.98 



1.02 



1.59 





0.82 





0.66 



0.59 



6 



1.22 



1.42 



1.59 



1.91 





1.02 









7 



1.63 



2.04 



1.71 



2.24 





1.23 









8 



2.78 



2.94 



1.87 



3.64 













9 







2.04 















The hot film probes were made by Lingtronics Laboratory. The active elements 

 (platinum) were approximately 1.6 mm long, fixed to one end of a Pyrex cylinder 12.7 mm in 

 length and 2.4 mm in diameter. The cylinders were carefully mounted in predrilled holes in 

 the model surfaces and were held in place with rubber cement. Any ridge between the model 

 surface and the probes was held to less than 0.025 mm, and the holes in the model were 

 drilled perpendicular to the surface ±0.50 deg. As a further precaution, each probe was 

 located along a different meridian streamline, to avoid possible spurious signals which might 

 result from tripping of turbulence by probes, located at successively further forward positions. 



Five channels of instrumentation were available and interchangeable between hot films, 

 allowing the five most significant probes to be activated during a given run. Each channel 

 consisted of an anemometer, linearizer, oscilloscope, and attentuator. For each speed, 20-s 

 samples of hot film output were recorded on tape. The output of each channel was kept 

 close to but less than the 1.4-V overload capacity of the recorder by adjusting the overheat 

 ratios of the films, the linearizer amplifiers, and the attenuators. Overheat ratios were kept 

 between 1.035 and 1.050 for most of the tests; however, for some of the low-speed runs, 

 slightly higher ratios were needed. Since these adjustments had to be made quickly as the 

 carriage moved down the basin, no record of amplifications or overheat ratios could be kept. 

 Thus, the information obtained from the hot films was primarily qualitative and was used to 

 determine the nature of the flow at the hot film locations. Figure 6 shows one channel of 

 the instrumentation. 



