The coefficient of drag, CD, is determined using the dimensionless parameter, Re, and the
approximated range taken from documented experimental data. Equations 2.2 and 2.3
show the Reynold's number relation and the approximated value of CD based on the
expected flow velocity range.
Re pVD (2.2)
CD =1, for 10,000 < Re < 200,000 (2.3)
D represents the diameter of the tube. Fluid properties of the flowing current including
density and absolute viscosity, [t, are determined from documented values at a
temperature of 200 C (Fox & McDonald, 1999).
2.2 Non-wrinkled Inflatable Theory
Figure 2.3 shows the assumed stress distribution for a non-wrinkled inflated beam
subject to a bending moment.
Urn
-0
Figure 2.3 Stress distribution in tube subject to bending moment
Comer & Levy (1963) defined the stress distribution in this unwrinkled inflated circular-
cylindrical beam using Equation 2.4.
co (1 + cos ) O-m(1- cos 0)
S= (2.4)
2 2