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K_grad_exp_rect_free
The K_grad_exp_rect_free(A2overA1, theta) function returns the resistance coefficient for a gradual expansion with no discharge ducts given the ratio of the exit to inlet areas and the half angle. The correlation is for rectangular ducts. Note that the function DuctGradExpRectFree_CL in the component library implements the dimensional version of this function.
Inputs:
A2overA1 = ratio of downstream to upstream areas
theta = half angle (Degree or Radian)
Example:
$UnitSystem SI C kPa Degree
$VarInfo rho units=kg/m^3
$VarInfo DELTAP units=Pa
A2overA1=3
theta=8 [degree]
K = k_grad_exp_rect_free(A2overA1,theta)
vel = 15 [m/s]
P = Po#
T = 20 [C]
F$ = 'Air'
rho=density(F$,P=P,T=T)
DELTAP = rho*vel^2/2*K
{Solution:
DELTAP=53.21 [Pa]
K=0.3928
}
Reference:
Legg, R., 2017, "Chapter 14: Ducted Air Systems" in Air Conditioning System Design, Butterworth-Heinemann,
Minor Losses Index