The document details a simulation investigation of separated nozzle flows, focusing on the behavior of a convergent-divergent nozzle and the effects of shock waves. It outlines the objectives, problem statements, CFD settings, and results, highlighting that shock-induced boundary-layer separation dominates under certain pressure conditions. The findings reveal a correlation between pressure ratios and Mach numbers, indicating the influence of nozzle design on efficiency.

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Assignment No. 11
Simulation Investigation of Separated Nozzle Flows
08.06.2021
Shivam Choubey
Student No: CFDB30321004

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Objective
• Simulate a convergent divergent nozzle and study the flow
behaviour.
• shock waves and compare with the experiment result.

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Problem Statement
Inlet Outlet
• During this simulation consider pressure inlet and outlet.
• To make nozzle Geomerty for simulation ,Used follwing point location.
• In fluid dynamics, boundary-layer separation is very normal condition, but this can be
Helpful to more system more efficient.
• nozzle separation is accompanied by an increase
in thrust efficiency .
polyline=true
1 0 35.2044 0
1 23.54 29.5402 0
1 50.4952 15.5194 0
1 60.8076 14.0462 0
1 61.722 14.1986 0
1 115.57 24.6888 0

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CFD Setting
Mesh Quality
Max skewness 0.8
Max Aspect ratio 13.279
Mesh statistics
No of nodes 24800
total volume 5.157356e+03
• Solver type – Density based solver
• K-e turbulence model ,Energy mode on
• Material – Air (Ideal gas)
• Inlet -Pressure based(Table 1 )
• Outlet –Pressure based (Table 1)
• Explict method used with underrelation
factor 0.7
• Fmg-initialization method used
• Number of iteration 4000.

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Table 1
Inlet Pressure (p1)
unit =bar
Outlet Pressure(p2) Pressure Ration(p1/p2)
1.4 1 1.4
1.8 1 1.8
2 1 2
3 1 3
3.4 1 3.4
5.4 1 5.4
8 1 8

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Results
Velocity Pressure
Experiment
Pressure Ration 1.4

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Results
Experiment
Pressure Ration 1.8
Pressure
Velocity
Experiment

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Results
Experiment
Pressure Ration 2
Experiment
Pressure
Velocity
Experiment

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Results
Experiment
Pressure Ration 3
Experiment
Pressure
Velocity
Experiment

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Results
Velocity Pressure
Experiment
Pressure Ration 5.4

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Results
Simulation Experiment
Experiment
Pressure Ration 2.4
0.567 in
56°
71°

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Mach Number
Pressure
ratio
Mach
Numbe
1.4 1.01
1.8 1.5
2 1.56
2.4 1.74
3 2.01
3.4 2.10
5.4 2.11
8.9 2.10

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Conclusion
• During simulation investigation of separated nozzle flows has been conducted. Results
indicate that the test nozzle was dominated by shock-induced boundary-layer separation
at over expanded off design conditions.
• From above simulation and experiment clearly shows that we can observe shock inside
nozzle till 3 Pressure ratio,Above that the shock wave generation is outside region.
• While developing pressure ratio also cause an increase in mach number and shock.

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References
• Experimental Investigation of Separated Nozzle Flows
Craig A. Hunter∗NASA Langley Research Center, Hampton, Virginia 23681