2D Free Jet Simulations (FLUENT)

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2D Free Jet Simulations (FLUENT)
Oct yan

Outline 2D Laminar Plane Jet 2D Laminar Round Jet
Theoretical Solutions Numerical Calculations (FLUENT code) Mean Stream Velocity Jet Half Width Momentum Thickness 2D Laminar Round Jet

2D Laminar Plane Jet ― Theoretical Solutions
Air emerges into a still air from a 2D slot at x=0 Constant momentum flux (J) at any cross section Spread at constant pressure (P = 1 bar) Red = 400 ( ux = 0.64 m/s） Temperature = 300 K ρ = kg/m3；ν = ×10-5 m2/s； Fig.1 Typical free 2D laminar plane jet streamline pattern Laminar Plane Jet (Schlichting 1933)

2D Laminar Plane Jet ― Numerical Calculations
Inlet velocity Wall Pressure outlet Symmetrical axis Interior Halved geometry

2D Laminar Plane Jet ― Numerical Calculations
Centerline Velocity( ) 𝒙 𝒖 𝒄 0.01 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 White’s book PDF page277 (J = )

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 20 x/d = 10 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 30 x/d = 40 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 60 x/d = 50 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 70 x/d = 80 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 90 x/d = 100 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Jet Half Width ( ) 𝒙/d 𝒓 𝟏/𝟐 /d 1 5 10 20 30 40 50 60 70 80 90 100 Half Width: Radial distance from the axis to the position at the which the absolute value of the axial velocity drops to half its value on the axis. The plot shows the relationship between jet half width and distance from the jet nozzle.

2D Laminar Plane Jet ― Numerical Calculations
Jet Self-similarity The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Momentum Thickness ( ) 𝒙 𝜽 0.01 e-4 0.05 e-4 0.1 e-3 0.2 e-3 0.3 e-3 0.4 e-3 0.5 e-3 0.6 e-3 0.7 e-3 0.8 e-3 0.9 e-2 1.0 e-3 Plot shows the changes in momentum thickness at different locations downstream of the jet.

Outline 2D Laminar Plane Jet 2D Laminar Round Jet
Theoretical Solutions Numerical Calculations (FLUENT code) Mean Stream Velocity Jet Half Width Momentum Thickness 2D Laminar Round Jet

2D Laminar Round Jet ― Theoretical Solutions
Air emerges into a still air from a circular orifice at x=0 Constant momentum flux (J) at any cross section Spread at constant pressure (P = 1 bar) Red = 400 ( u = 0.64 m/s） Temperature = 300 K ρ = 1.16 kg/m3；ν = 1.6×10-5 m2/s； Narrow Axisymmetric Jet (Schlichting 1933)

2D Laminar Round Jet ― Numerical Calculations
Inlet velocity Wall Pressure outlet Axial symmetirc Interior Halved geometry

2D Laminar Round Jet ― Numerical Calculations
Centerline Velocity( ) 𝒙 𝒖 𝒄 0.01 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

2D Laminar Round Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 20 x/d = 10 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 30 x/d = 40 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 60 x/d = 50 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 70 x/d = 80 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Plane Jet ― Numerical Calculations
Mean Stream Velocity ( ) x/d = 90 x/d = 100 The plot shows the flow profile along the radial direction of the flow.

2D Laminar Round Jet ― Numerical Calculations
Jet Half Width ( ) 𝒙/d 𝒓 𝟏/𝟐 /d 1 5 10 20 30 40 50 60 70 80 90 100 Half Width: Radial distance from the axis to the position at the which the absolute value of the axial velocity drops to half its value on the axis. The plot shows the relationship between jet half width and distance from the jet nozzle.

2D Laminar Round Jet ― Numerical Calculations
Jet Self-similarity The plot shows the flow profile along the radial direction of the flow.

2D Laminar Round Jet ― Numerical Calculations
Momentum Thickness ( ) 𝒙 𝜽/𝐝 1 e-2 5 e-1 10 e-1 20 e-1 30 e-1 40 e-1 50 e-1 60 e-1 70 e-1 80 e-1 90 e-1 100 e-1 Plot shows the changes in momentum thickness at different locations downstream of the jet.