Mechanical Losses

The user can specify drivetrain mechanical losses either as a lookup table of torque, ShaftInputTorqueVsResistingTorque, or as a table of power, ShaftInputPowerVsPowerLoss. Both options have an additional option to make it a function of shaft speed: ShaftSpeedVsShaftInputTorqueVsResistingTorque and ShaftSpeedVsShaftInputPowerVsPowerLoss. Effectively making it a two-dimensional lookup table. In all cases the losses are referred to the low-speed shaft. Loss values will be linearly interpolated from the specified table.

The option to express losses in terms of power has been provided for convenience, since data is sometimes provided in this form. However this model is inappropriate at low rotational speeds. If any calculations at low-speed are to be carried out, including start-ups, shut-downs, idling, or parked simulations with slipping brake, then it is advisable to recalculate the losses in terms of torque.

In the Bladed model, the mechanical losses are applied as friction at the position of the shaft brake. If the brake is on the high-speed shaft, the loss torque is scaled appropriately using the GearboxRatio.

ShaftInputTorqueVsResistingTorque

A line or row in a lookup table, specifying a value of ResistingTorque for a specified ShaftInputTorque.

The ShaftInputTorqueVsResistingTorque has two properties:

• ShaftInputTorque: The input torque of the low-speed shaft.
• ResistingTorque: The torque acting in opposition to the shaft's rotation.

Example of a ShaftInputTorqueVsResistingTorque type Losses:

"Losses": {
  "ShaftInputTorqueVsResistingTorque": [
    {
      "ShaftInputTorque": 0.0,
      "ResistingTorque": 23000.0
    },
    {
      "ShaftInputTorque": 960000.0,
      "ResistingTorque": 37000.0
    },
    {
      "ShaftInputTorque": 1280000.0,
      "ResistingTorque": 49000.0
    }
  ]
},

ShaftSpeedVsShaftInputTorqueVsResistingTorque

A line or row in a lookup table, specifying a value of PowerLoss for a specified ShaftSpeed.

The ShaftSpeedVsShaftInputTorqueVsResistingTorque has two properties:

• ShaftSpeed: The rotational velocity of the low-speed shaft in radians per second.
• ShaftInputTorqueVsResistingTorque: The torque acting in opposition to the shaft's rotation.

Example of a ShaftSpeedVsShaftInputTorqueVsResistingTorque type Losses:

"Losses": {
  "ShaftSpeedVsShaftInputTorqueVsResistingTorque": [
    {
      "ShaftSpeed": 1.0,
      "ShaftInputTorqueVsResistingTorque": [
        {
          "ShaftInputTorque": 0.0,
          "ResistingTorque": 23000.0
        },
        {
          "ShaftInputTorque": 960000.0,
          "ResistingTorque": 37000.0
        },
        {
          "ShaftInputTorque": 1280000.0,
          "ResistingTorque": 49000.0
        }
      ]
    },
    {
      "ShaftSpeed": 1.2,
      "ShaftInputTorqueVsResistingTorque": [
        {
          "ShaftInputTorque": 0.0,
          "ResistingTorque": 25000.0
        },
        {
          "ShaftInputTorque": 970000.0,
          "ResistingTorque": 38000.0
        },
        {
          "ShaftInputTorque": 1300000.0,
          "ResistingTorque": 50000.0
        }
      ]
    }
  ]
},

ShaftInputPowerVsPowerLoss

A line or row in a lookup table, specifying a value of PowerLoss for a specified ShaftSpeed.

The ShaftInputPowerVsPowerLoss has two properties:

• ShaftInputPower: The input power of the low-speed shaft.
• PowerLoss: The power lost through internal friction throughout the drivetrain.

Example of a ShaftInputPowerVsPowerLoss type Losses:

"Losses": {
  "ShaftInputPowerVsPowerLoss": [
    {
      "ShaftInputPower": 9600.0,
      "PowerLoss": 230.0
    },
    {
      "ShaftInputPower": 12800.0,
      "PowerLoss": 370.0
    },
    {
      "ShaftInputPower": 15100.0,
      "PowerLoss": 490.0
    }
  ]
},

ShaftSpeedVsShaftInputPowerVsPowerLoss

A line or row in a lookup table, specifying a value of PowerLoss for a specified ShaftSpeed.

The ShaftSpeedVsShaftInputPowerVsPowerLoss has two properties:

• ShaftSpeed: The rotational velocity of the low-speed shaft in radians per second.
• ShaftInputPowerVsPowerLoss: The power lost through internal friction throughout the drivetrain.

Example of a ShaftSpeedVsShaftInputPowerVsPowerLoss type Losses:

"Losses": {
  "ShaftSpeedVsShaftInputPowerVsPowerLoss": [
    {
      "ShaftSpeed": 1.0,
      "ShaftInputPowerVsPowerLoss": [
      {
        "ShaftInputPower": 9600.0,
        "PowerLoss": 230.0
      },
      {
        "ShaftInputPower": 12800.0,
        "PowerLoss": 370.0
      },
      {
        "ShaftInputPower": 15100.0,
        "PowerLoss": 490.0
      }
      ]
    },
    {
      "ShaftSpeed": 1.2,
      "ShaftInputPowerVsPowerLoss": [
      {
        "ShaftInputPower": 9800.0,
        "PowerLoss": 250.0
      },
      {
        "ShaftInputPower": 13200.0,
        "PowerLoss": 470.0
      },
      {
        "ShaftInputPower": 15100.0,
        "PowerLoss": 490.0
      }
      ]
    }
  ]
},