Elbow (IH)#

The Elbow (IH) block describes the appropriate type of local resistance in the pipeline for an isothermal fluid.

When the Elbow Type parameter is set to Smoothly the resistance coefficient is calculated as (1):

(1)#\[ K = 30 \cdot f_{T} \cdot C_{angle}, \]

where:

f\(_T\) - dimensionless coefficient of friction, depending on the diameter of the elbow:

Elbow diameter, inch	0.5	0.75	1	1.25	1.5	2	2,5-3	4	5	6	8-10	12-16
Coefficient \(f_T\)	0.027	0.025	0.023	0.022	0.021	0.019	0.018	0.017	0.016	0.015	0.014	0.013

\(C_{angle}\) - correction factor for knee bending angle, which is calculated by formula (2):

(2)#\[ C_{angle}=0.0148\cdot θ−3.9716\cdot 10^{-5}\cdot θ^2, \]

where \(θ\) - is the bending angle of the knee in degrees.

When the Elbow Type parameter is set to Sharp-Edged the resistance coefficient K is calculated as follows:

α	0°	15°	30°	45°	60°	75°	90°
K	2f\(_T\)	4f\(_T\)	8f\(_T\)	15f\(_T\)	25f\(_T\)	40f\(_T\)	60f\(_T\)

(3)#\[ \dot m\:=\:A\:\cdot \:\sqrt{\frac{2\cdot \bar \rho}{K}}\:\cdot \:\frac{\Delta p}{(\Delta \rho^2+ \Delta \rho_{crit}^2)^{1/4}} \]

where:

\(A\) - cross-section areaof the elbow, [m\(^2\)];

\(\bar ρ\) - liquid density, [kg/m\(^3\)];

\(Δp\) - pressure difference across the elbow, [Pa].

\(Δp_{crit}\) - pressure difference across the elbow, [Pa].

The critical pressure drop \(Δp_{crit}\) is related to the critical Reynolds number Recrit at the boundary of laminar and turbulent flow zones (4):

(4)#\[ \Delta p_{crit}\:=\:\frac{\bar \rho}{2}\:\cdot \:K\:\cdot \:(\frac{\nu\:\cdot \:Re_{crit}}{D})^2 \]

where:

\(ν\) - fluid kinematic viscosity, [m\(^2\)/s];

\(Re_{crit}\) - critical Reynolds number, dimensionless value;

\(D\) - inner diameter of the elbow, [m].

1. Properties#

Property	Default value	Description	Units of measurement
Elbow Type: Smoothly; Sharp-Edged	Smoothly	-	-
Diameter	0.5	-	m
Critical Reynolds number	150	-	-
Angle	90	-	degrees

Parameters	Input/Output	Description	Units of measurement	Port type
Input	Input	-	-	Isothermal hydraulics
Output	Output	-	-	Isothermal hydraulics

In order to see the connection capabilities of the block, you need to go to page Description of block ports