RCAIDE.Library.Methods.Powertrain.Converters.Turbine.compute_turbine_performance

compute_turbine_performance#

compute_turbine_performance(turbine, conditions)[source]#

Computes turbine performance parameters based on input conditions and component characteristics.

Parameters:

  • turbine (RCAIDE.Library.Components.Powertrain.Converters.Turbine) –

    Turbine component with the following attributes:
    • tagstr

      Identifier for the turbine

    • working_fluidData
      Working fluid object with methods to compute properties
      • compute_gammafunction

        Computes ratio of specific heats

      • compute_cpfunction

        Computes specific heat at constant pressure

      • compute_Rfunction

        Computes gas constant

    • mechanical_efficiencyfloat

      Mechanical efficiency [unitless]

    • polytropic_efficiencyfloat

      Polytropic efficiency [unitless]

  • conditions (RCAIDE.Framework.Mission.Common.Conditions) –

    Flight conditions with:
    • energyData
      Energy conditions
      • convertersdict
        Converter energy conditions indexed by tag
        • inputsData
          Input conditions
          • static_temperaturearray_like

            Static temperature [K]

          • static_pressurearray_like

            Static pressure [Pa]

          • mach_numberarray_like

            Mach number [unitless]

          • stagnation_temperaturearray_like

            Entering stagnation temperature [K]

          • stagnation_pressurearray_like

            Entering stagnation pressure [Pa]

          • bypass_ratioarray_like

            Bypass ratio [unitless]

          • fuel_to_air_ratioarray_like

            Fuel-to-air ratio [unitless]

          • compressorData
            Compressor data
            • work_donearray_like

              Compressor work [J/(kg/s)]

            • external_shaft_work_donearray_like

              Shaft power off take [J/(kg/s)]

          • fanData
            Fan data
            • work_donearray_like

              Fan work done [J/(kg/s)]

Returns:

Results are stored in conditions.energy.converters[turbine.tag].outputs:
  • stagnation_pressurearray_like

    Exiting stagnation pressure [Pa]

  • stagnation_temperaturearray_like

    Exiting stagnation temperature [K]

  • stagnation_enthalpyarray_like

    Exiting stagnation enthalpy [J/kg]

  • static_temperaturearray_like

    Exiting static temperature [K]

  • static_pressurearray_like

    Exiting static pressure [Pa]

  • mach_numberarray_like

    Exiting Mach number [unitless]

  • gas_constantarray_like

    Gas constant [J/(kg·K)]

  • pressure_ratioarray_like

    Pressure ratio across turbine [unitless]

  • temperature_ratioarray_like

    Temperature ratio across turbine [unitless]

  • gammaarray_like

    Ratio of specific heats [unitless]

  • cparray_like

    Specific heat at constant pressure [J/(kg·K)]

Return type:

None

Notes

This function calculates the performance of a turbine by computing the energy extraction required to drive the compressor, fan, and any external power loads. It then determines the resulting thermodynamic properties at the turbine exit.

The computation follows these steps:

  1. Extract turbine parameters and working fluid properties

  2. Compute the working fluid properties (gamma, Cp, R) at inlet conditions

  3. Calculate the energy drop across the turbine based on compressor/fan work and mechanical efficiency

  4. Compute the exit stagnation temperature, enthalpy, and pressure

  5. Calculate the exit static temperature and pressure

  6. Compute performance ratios (pressure ratio, temperature ratio)

  7. Store all results in the conditions data structure

Major Assumptions

  • Constant polytropic efficiency throughout the turbine

  • Constant pressure ratio across the turbine

  • The working fluid behaves as a perfect gas

  • Mechanical losses are accounted for through a constant efficiency factor

Theory The energy balance across the turbine is:

\[\Delta h_t = -\frac{1}{1+f} \cdot \frac{W_{comp} + W_{ext} + \alpha W_{fan}}{\eta_{mech}}\]
where:

  • \(\Delta h_t\) is the enthalpy drop across the turbine

  • \(f\) is the fuel-to-air ratio

  • \(W_{comp}\) is the compressor work

  • \(W_{ext}\) is the external shaft work

  • \(W_{fan}\) is the fan work

  • \(\alpha\) is the bypass ratio

  • \(\eta_{mech}\) is the mechanical efficiency

The exit stagnation temperature is:

\[T_{t,out} = T_{t,in} + \frac{\Delta h_t}{C_p}\]

The exit stagnation pressure is calculated using the polytropic efficiency:

\[P_{t,out} = P_{t,in} \cdot \left(\frac{T_{t,out}}{T_{t,in}}\right)^{\frac{\gamma}{(\gamma-1)\eta_{poly}}}\]

References

[1] Mattingly, J.D., “Elements of Gas Turbine Propulsion”, AIAA Education Series, 2005

See also

RCAIDE.Library.Methods.Powertrain.Converters.Compressor.compute_compressor_performance, RCAIDE.Library.Methods.Powertrain.Converters.Fan.compute_fan_performance