Page 8 - Air and Gas Drilling Manual

List of Symbols

a = eccentricity, ft
a a = constant
A b = cross-sectional area of the inside of the blooey line, ft 2
A bi = cross-sectional area of the single drill bit orifice, ft 2
A dci = cross-sectional area of inside of the drill collars, ft 2
= constant
a i
A n = total cross-sectional area of flow through drill bit nozzles, ft 2
A o = total cross-sectional area of flow through the drill bit open orifices, ft 2
A tn = total nozzle flow area, ft 2
c = clearance volume ratio
C = fluid flow loss coefficient for drill bit orifices or nozzles
D = inside diameter (or hydraulic diameter) of the pressure conduit, ft
dι = inside diameter of drill pipe body lumped geometry in openhole
section, in
Dι = inside diameter of drill pipe body lumped geometry in openhole

section, ft
d 1 = outer diameter of the rotary cylinder, ft
d 2 = inside diameter of the cylindrical housing, ft
D ani = annulus inside diameter, ft
d ani = annulus inside diameter, in
D ano = annulus outside diameter, ft
d ano = annulus outside diameter, in

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