Investigation enables more accurate prediction of coolant flows within internally cooled turbine blades and vanes. The data is applicable for predicting flows in complex flow passages

Metger, G. W.

Rhode, J. E.

Richards, H. T.

English

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April 1970	 Brief 70-10062 
NASA TECH BRIEF 
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be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
....... . 
Discharge Coefficients for Thick-Plate Orifices 
Experimental discharge coefficients have been 
obtained for thick-plate orifices with approaching 
airflow perpendicular or inclined to the orifice axis. 
Other variables investigated were flow temperature 
and pressure; orifice pressure differential; approach 
Mach number; orifice diameter, thickness, and inlet 
edge radius; orifice surface finish; interference of 
multiple orifices; and approach passage geometry and 
length. 
This investigation was undertaken to enable more 
accurate prediction of coolant flows within internally 
cooled turbine blades and vanes. The data should 
have broad applicability for predicting flows in de-
signs where flow passages become comparatively 
complex. 
The discharge coefficients (ratio of actual flow to 
ideal flow) were correlated with a velocity-head 
parameter which consisted of the ratio of the velocity 
head of the flow though the orifice to the velocity 
head of the flow approaching the orifice axis for 
various approach Mach numbers. The discharge 
coefficients were found to be dependent on the angle 
between the approaching flow and the axis of the 
orifice; on the ratio of the orifice thickness to orifice 
diameter; and on the inlet edge radius of the orifice. 
Also, the discharge coefficients were found to depend 
strongly on the approach Mach number and static 
pressure difference across the orifice. The effects of 
flow temperature and pressure levels, orifice surface 
finish, multiple orifice interference, and approach 
passage geometry and length on discharge coefficients 
were found to be negligible for the cases considered. 
The geometry of the main flow duct in all cases but 
one was a 0.25 in.-diameter tube. (The exception was 
a rectangular cross-section main duct used to inves-
tigate the effect of curvature of the upstream face of
the orifice.) The orifice thickness varied from 0.06 
to 0.25 in. and the orifice diameters varied from 0.059 
to 0.128 in. The inlet edge of the orifice was varied 
from a sharp corner to 0.030 in. radius. The main 
duct inlet airflow Mach number was varied from 0 to 
0.65, static pressure was varied from 20.0 to 80.0 psia, 
and the temperature was varied from ambient to 
approximately 1000°F. Orifices with axes at 45° and 
90° angles to the main duct flow were investigated. 
Notes: 
1. The following documentation may be obtained 
from:
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.65) 
Reference: 
NASA-TN-D-5467 (N69-38012), Dis- 
charge Coefficients for Thick Plate Ori-
fices with Approach Flow Perpendicular 
and Inclined to the Orifice Axis 
2. Questions concerning this innovation may be 
directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B70-10062 
Patent status: 
No patent action is contemplated by NASA. 
Source: J. E. Rhode, H. T. Richards, 
and G. W. Metger 
Lewis Research Center 
(LEW-11067) 
Category 06 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned .rights.
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Discharge coefficients for thick-plate orifices

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