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Department of Mechanical Engineering

SDT Fan Alone RANS Simulation Using SU2

Nuo Li , Sheryl M. Grace

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Department of Mechanical Engineering, Boston University

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SDT Baseline vane placement

Fan configuration

Hughes et al. “Fan Noise Source Diagnostic Test-Rotor Alone Aerodynamic Performance Results” 2002

NASA SDT rig Configuration

  • 22 fan blades
  • 22-inch fan diameter
  • Measured data:
    • Far-field noise
    • Stator unsteady pressure
    • LDV wake fields
    • HW wake fields

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Department of Mechanical Engineering

Outline

Method

  • Simulation domain & boundary conditions
  • Mesh
  • Solver configuration

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Results

  • Qualitative flow field comparisons
  • Quantitative mean passage comparisons
  • Circumferential averaged value comparisons

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Conclusions

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SDT Baseline vane placement

Simulation domain and boundary conditions

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  • Single passage
  • Rotor-alone
  • Rotating frame

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SDT Baseline vane placement

Simulation domain and boundary conditions

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  • Single passage
  • Rotor-alone
  • Rotating frame

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SDT Baseline vane placement

Simulation domain and boundary conditions

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Inlet:

Giles total pressure & total temperature

(ambient condition)

Outlet:

Giles static pressure

(calculated from fan pressure ratio and isentropic relation)

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SDT Baseline vane placement

Simulation domain and boundary conditions

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Passage boundaries:

periodic

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SDT Baseline vane placement

Simulation domain and boundary conditions

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Blade:

zero heat flux non-slip rotating

Spinner:

zero heat flux non-slip rotating

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SDT Baseline vane placement

Simulation domain and boundary conditions

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Shroud:

zero heat flux non-slip shroud condition

Downstream hub:

zero heat flux non-slip shroud condition

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SDT Baseline vane placement

Mesh

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  • 5.8M grid points created using Pointwise
  • 12-block structured grid

(treated as 1 unstructured block in SU2)

Shroud mesh near LE

Blade surface

Tip gap surface

Tip gap: 0.02” (0.5mm)

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SDT Baseline vane placement

Solver configuration

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  • Turbulence model: SST 2003m
  • Turbulent convective scheme:

2nd order upwind MUSCL

  • Time discretization: Euler implicit
  • Slope limiter: Venkat-wall distance

Turbulence modeling

  • Solver type: RANS
  • Convective scheme: 2nd order upwind Roe-MUSCL
  • Time discretization: Euler implicit
  • 2nd order slope limiter: Venkatakrishnan-Wang
  • CFL number: 10-100 adaptive

Flow solver configuration

Initial and boundary conditions

  • Initial Mach number: 0.271
  • Initial static pressure: 96.3 kPa, temperature: 284K
  • Inlet total pressure: 101.3 kPa, outlet static pressure: 103.7 kPa
  • Dynamic mesh angular velocity: -817.76 Rad/s
  • Turbulence intensity: 1%, turbulent viscosity ratio: 1

Needed to avoid divergence

 

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SDT Baseline vane placement

Hot-wire survey locations

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Station 1

(HW1)

Station 2

(HW2)

 

 

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Method

  • Simulation domain & boundary conditions
  • Mesh
  • Solver configuration

​

Results

​

  • Qualitative flow field comparisons
  • Quantitative mean passage comparisons
  • Circumferential averaged value comparisons

​

Conclusions

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Outline

SU2 Solution

Calculated inlet mass flow (x22 passages)

Calculated outlet mass flow (x22 passages)

Total pressure ratio

58.31 lbm/s 

58.34 lbm/s 

1.155

Experiment

Mass flow

Total pressure ratio

58.3 lbm/s

1.16

*Convergence residual criterion: 1E-9 Rho

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Streamwise velocity fields comparison

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SU2

Measured

 

Boundary layer not measured by HW

Quantitatively in good agreement with HW

Top row:

HW1 location

Bottom row:

HW2 location

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Mid-span mean passage comparison

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Top row:

HW1 location

Bottom row:

HW2 location

Axial velocity

TKE

Velocity deficit and wake TKE are in good agreement with the experiment

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Required values for acoustic model

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RANS-informed cascade interaction noise model

Rotor

Stator

 

Flow quantities needed as functions of radial location:

  • Streamwise velocity
  • Axial velocity
  • Turbulence intensity
  • Turbulence length scale

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Circumferential averaged comparison at HW2 location

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Streamwise velocity

RMS velocity

Turbulence length scale

 

 

 

 

 

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Lessons learned

For this particular application:

  • Y+ <= 1 is needed
  • Large element length ratio should be avoided
  • Wall distance-based limiter is needed for turbulence model.
  • Most stable with CFL number from 10~100, small initial CFL (like 1) causes numerical issues
  • Inlet turbulent viscosity ratio > 10 causes numerical issue

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Conclusions

Acknowledgement

 

Julian Winkler,

Craig Aaron Reimann,

Dmytro Voytovych,

Jeff Mendoza

From RTRC

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Additional slides

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Circumferential averaged comparison at HW1 location

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Streamwise velocity

RMS velocity

Turbulence length scale

 

 

 

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Turbulent kinetic energy comparisons

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SU2

Measured

Top row:

HW1 location

Bottom row:

HW2 location

 

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Previous validation

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Li, N., Wachtmann, B., Ramsarran, T., Winkler, J., Reimann, C. A., Voytovych, D., Mendoza, J., and Grace, S. M., “Fan-stage broadband interaction noise trends,” AIAA Paper No. 2022-2884, 2022. doi:10.2514/6.2022-2884.

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SU2 solver configuration

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SU2 solver configuration part 1

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SU2 solver configuration part 2

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