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Pressure Loss Across Louvers Equation and Calculator

Fluids Flow Design and Engineering
Hydraulic Pneumatic Design Engineering

Head or pressure loss coefficient and head (pressure) loss of a fluid in across angled louvers inside a pipe equation and calculator.

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Preview: Pressure loss coefficient and head (pressure) loss across louvers calculator

The heat flow (q) from the plate is calculated as:

h_L = k_loss x (u_m² / (2 x g) )

Where k_loss is the head loss coefficient, u_m is the flow velocity in the pipe, and g is the gravitational acceleration. k_loss is dependant on the Reynolds Number Re . If Re is smaller than or equal to 50, then (1 - 50 / Re) is taken to be zero:

Where k_qu is a function of the angle and the number of  louvers based on a table of values (see table below), and Re is the Reynolds Number and is calculated as:

Re = u_m x D_h / v

Where:

N = Number of Louvers
A = Angle of louvers
a = Width (m)
g = 9.80665 m/s²
u_m = Flow Velocity in tube (m/s)
v = Kinematic Velocity (kg/m-s)
D_h = hydraulic diameter of the tube (m) - A square cross section has a hydraulic diameter equal to the width of the tube.
k_qu = Angle vs Number of louver constant - see table below

k_qu

↑ No. Louvers ↓	← Angle →
	0	10	20	30	40	50	60	70	80
2	0.07	0.4	1.10	2.20	5.50	11.5	30.0	80.0	300.0
3	0.14	0.25	0.80	2.00	4.50	10.0	20.0	40.0	140.0
4	0.12	0.22	0.73	1.70	4.00	8.00	14.0	30.0	110.0
5	0.15	0.20	0.65	1.50	3.00	7.00	13.0	35.0	70.0
6	0.20	0.35	1.00	2.30	4.80	8.50	16.0	35.0	150.0

References

Idel'chik, I E. and Fried, Erwin., Flow Resistance, a Design Guide for Engineers , Taylor & Francis, Washington D.C. 1989. p 306.