Setting Stopping Criteria for the Reference Simulation

In addition to Fixed Steps stopping criterion, you can monitor some key quantities such as the mass flow rate and the total pressure ratio to assess the convergence of the air flow in the compressor. In the smart sweep study in Design Manager, each run (other than the first) reuses the results from the previous run. Therefore, defining stopping criteria that are based on physical quantities can reduce the design run time.

In the simulation, you create two reports that calculate the following quantities:
  • Corrected Mass Flow Rate at Stator Outlet—entire mass flow rate at stator outlet multiplied with a turbomachinery correction factor. The number of stator blades 46 is also multiplied. See Corrected Mass Flow Rate.
  • Rotor Total Pressure Ratio—mass flow averaged pressure at rotor outlet (the interface between rotor and stator) divided by mass flow averaged pressure at rotor inlet. This value indicates that the total pressure increases in the rotor stage.
  • Stage Total Pressure Ratio—mass flow averaged pressure at stator outlet divided by mass flow averaged pressure at rotor inlet. This quantity is required as a smart sweep response.
  1. To create a monitor stopping criterion from the Corrected Mass Flow Rate at Stator Outlet:
    1. To create a report for the mass flow rate at stator outlet, right-click Report node and select Flow / Energy > Mass Flow.
    2. Select the Mass Flow 1 node and set Parts to Regions > StatorPassage > Boundaries > Outlet.
    3. Rename the Mass Flow 1 report to StatorOutletMassFlow.
    4. To create the following two mass flow averaged quantities, right-click twice Report and select Flow / Energy > Mass Flow Averaged.
    5. Define the two reports as follows:
      Report Name Rename To Properties Values
      Mass Flow Averaged 1 RotorInletTotalPressure Field Function Absolute Total Pressure
      Parts Regions > RotorPassage > Boundaries > Inlet
      Mass Flow Averaged 2 RotorInletTotalTemperature Field Function Total Temperature > Lab Reference Frame
      Parts Regions > RotorPassage > Boundaries > Inlet
    6. To create two global parameters, right-click the Automation > Parameters node and select New > Scalar.
    7. Define the two global parameters as follows:
      Parameter Name Rename To Properties Values
      Scalar Pref Value 101325
      Dimensions Pressure
      Scalar 2 Tref Value 288.1
      Dimensions Temperature
    8. To create a field function for the correction factor, right-click the Automation > Field Functions node and select New > Scalar.
    9. Define the field function as follows:
      Function Name Rename to Properties Values
      User Field Function 1 MassFlowCorrectionFactor Function Name MassFlowCorrectionFactor
      Dimensions Dimensionless
      Definition (sqrt(${RotorInletTotalTemperatureReport}/${Tref})/(${RotorInletTotalPressureReport}/${Pref}))
    10. To create the report for the corrected mass flow at the stator outlet, right-click the Report node and select User > Expression.
    11. Set the new report as follows:
      Report Name Rename To Properties Values
      Expression 1 CorrectedStatorOutletMassFlow Definition ${StatorOutletMassFlowReport}*46*${MassFlowCorrectionFactor}

      Here the corrected stator outlet mass flow is calculated for the full-scaled model. 46 is the number of stator blades.
      Dimensions Mass/Time
    12. To create a monitor from the report, right-click the CorrectedStatorOutletMassFlow report and select Create Monitor From Report.
    13. Right-click the Monitors > CorrectedStatorOutletMassFlow Monitor node and select Create Stopping Criterion from Monitor.
    14. Select the Stopping Criteria > CorrectedStatorOutletMassFlow Monitor Criterion node and set the properties as follows:
      Node Properties Values
      CorrectedStatorOutletMassFlow Monitor Criterion Criterion Option Asymptotic
      Logical Rule And
      Asymptotic Limit Refresh Sampling ✓
      |Max-Min| 1.0E-5
      Number of Samples 100
      Normalized ✓
  2. To create a monitor stopping criterion from the Rotor Total Pressure Ratio:
    1. To create a mass flow averaged pressure at rotor outlet, right-click the Report node and select Flow / Energy > Mass Flow Averaged.
    2. Define the new report as follows:
      Report Name Rename To Properties Values
      Mass Flow Averaged 1 RotorOutletTotalPressure Field Function Absolute Total Pressure
      Parts Regions > RotorPassage > Boundaries > Int_1[RotorPassage/StatorPassage]

      This boundary is the place when the flow leaves the rotor region—the interface between rotor and stator.
    3. To create a report for the rotor total pressure ratio, right-click the Report node and select User > Expression.
    4. Set the new report as follows:
      Report Name Rename To Properties Values
      Expression 1 RotorTotalPressureRatio Definition ${RotorOutletTotalPressureReport}/${RotorInletTotalPressureReport}
      Dimensions Dimensionless
    5. To create a monitor from the report, right-click the RotorTotalPressureRatio report and select Create Monitor From Report.
    6. Right-click the Monitors > RotorTotalPressureRatio Monitor node and select Create Stopping Criterion from Monitor.
    7. Select the Stopping Criteria > RotorTotalPressureRatio Monitor Criterion node and set the properties as follows:
      Node Properties Values
      RotorTotalPressureRatio Monitor Criterion Criterion Option Asymptotic
      Logical Rule And
      Asymptotic Limit Refresh Sampling ✓
      |Max-Min| 1.0E-5
      Number of Samples 100
      Normalized ✓
After defining the two monitor stopping criteria, you limit the iteration number of each run to 5000.
  1. Select the Stopping Criteria > Fixed Steps node and set Fixed Steps to 5000 and activate Enabled.
  2. To create the Stage Total Pressure Ratio report as a design response in the smart sweep study:
    1. To create a mass flow averaged pressure at stator outlet, right-click the Report node and select Flow / Energy > Mass Flow Averaged.
    2. Define the new report as follows:
      Report Name Rename To Properties Values
      Mass Flow Averaged 1 StatorOutletTotalPressure Field Function Absolute Total Pressure
      Parts Regions > StatorPassage > Boundaries > Outlet
    3. To create a report for the stage total pressure ratio, right-click the Report node and select User > Expression.
    4. Set the new report as follows:
      Report Name Rename To Properties Values
      Expression 1 StageTotalPressureRatio Definition ${StatorOutletTotalPressureReport}/${RotorInletTotalPressureReport}
      Dimensions Dimensionless
  3. Save the reference simulation.