How to Calculate and Solve for Pressure Gradient | Polymer & Textile

The image above represents pressure gradient.

To compute for pressure gradient, four essential parameters are needed and these parameters are value (α), viscosity (μ), screw rotation speed (N) and proportionality constant that depends on screw geometry (B).

The formula for calculating pressure gradient:

ΔP = αμN / B

Where;

ΔP = Pressure Gradient
α = Value
μ = Viscosity
N = Screw Rotation Speed
B = Proportionality Constant that Depends on Screw Geometry

Let’s solve an example;
Find the pressure gradient when the value is 2, viscosity is 9, screw rotation speed is 20 and proportionality constant that depends on screw geometry is 24.

This implies that;

α = Value = 2
μ = Viscosity = 9
N = Screw Rotation Speed = 20
B = Proportionality Constant that Depends on Screw Geometry = 24

ΔP = αμN / B
ΔP = (2)(9)(20) / 24
ΔP = 360 / 24
ΔP = 15

Therefore, the pressure gradient is 15.

Calculating the Value when the Pressure Gradient, Viscosity, Screw Rotation Speed and Proportionality Constant that Depends on Screw Geometry is Given.

α = ΔP x B / μN

Where;

α = Value
ΔP = Pressure Gradient
μ = Viscosity
N = Screw Rotation Speed
B = Proportionality Constant that Depends on Screw Geometry

Let’s solve an example;
Find the value when the pressure gradient is 20, viscosity is 5, screw rotation speed is 11 and the proportionality constant that depends on screw geometry is 7.

This implies that;

ΔP = Pressure Gradient = 20
μ = Viscosity = 5
N = Screw Rotation Speed = 11
B = Proportionality Constant that Depends on Screw Geometry = 7

α = ΔP x B / μN
α = 20 x 7 / (5)(11)
α = 140 / 55
α = 2.54

Therefore, the value is 2.54.

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