462 MEASURING OF ATR. 



The dimensions of the Venturi were found by careful cali 

 Ijration with micrometer gauges to be : 



Upstream (Hameter : 9.9323 inches : A = 77.48 sq. inches 

 Throat diameter: 6.5003 inches: a = 33-i85 sq. inches 



The coefficient of contraction was taken as 0.99 instead of 

 0.985 as given for the inlet nozzles of tihe turl)o com])ressor test 

 because the Venturi had been designed for a capacity consider- 

 ably larger than that of the comi:)ressor under test. 



We can now comi)ilc taljlc XI which gi\es the result of the 

 calculation of the weight of air delivered per second. 



The same values of R and /\' are used here as found for 

 air of atmospheric pressure as no condensed w'ater vapour was 

 taken from the intercooler during the test. 



Table XII gives a comparison of the air taken in with the 

 air discharged in reference to the pressure at engine terminus. 



TABLE XII 



Test II IV V VI 



As mentioned before, the heating up of the air when flowing 

 into the c\lindcr may introduce an error into the comparison of 

 air taken in and air snit oul. ft is inleresling to find out what 

 increase- in leniiierature from suction cluunber to inside of cylinder 

 is necessar\ in order to explain the abo\-e discrepancies between 

 the measurements at air inlet and air discharge. 



