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- Index
K_bend
The K_Bend(rtod, alpha, Re) function returns the resistance coefficient for a bend given its bend radius to diameter ratio and the turning angle. Note that the function DuctBend_CL in the component library implements the dimensional version of this function.
Inputs:
RtoD = ratio of radius (R) to diameter (D)
alpha = bend turning angle (Degree or Radian)
Re = Reynolds number based on hydraulic diameter of duct (set to <0 if you do not want to implement a Reynolds number correction)
Example:
$UnitSystem SI C kPa Mass Degree
$VarInfo DELTAP units=Pa
$VarInfo h_L units=m
alpha = 45 [deg]
rtoD = 2 [-]
Re = 1e5 [-]
K = k_bend(rtoD,alpha, Re)
vel = 15 [m/s]
P = Po#
T = 20 [C]
F$ = 'Air'
rho=density(F$,P=P,T=T)
DELTAP = rho*vel^2/2*K
{Solution:
DELTAP=16.45 [Pa]
K=0.1214
}
Reference:
Legg, R., 2017, "Chapter 14: Ducted Air Systems" in Air Conditioning System Design, Butterworth-Heinemann,
Minor Losses Index