Setting up the Injector

For a charge-motion simulation, you set up an injector using the Injector Engine Part, which provides a template for defining the geometry and physics of the injector and its nozzles. You can create single-nozzle or multi-nozzle injectors. Cylinder sector models require a single-nozzle injector.

By default, Simcenter STAR-CCM+ In-cylinder injects the fuel using a hollow/solid cone injector. If you selected the Huh Atomization model in Setting the Engine Models, Simcenter STAR-CCM+ In-cylinder uses a nozzle injector instead.

For multiple injectors, Simcenter STAR-CCM+ In-cylinder injects the same fuel for all injectors.

To create an injector:

  1. Right-click the Engine node and select Create Injector.
    The Edit tab displays the injector template. The Graphics window updates and shows a preview of the injector. By default, the injector is centered in the cylinder head.
To position the injector:
  1. In the Geometry tab, set Injector Origin and Injector Direction in the Coordinate System of your choice.
    The injector coordinate system is displayed in the Graphics window as X_ref, Y_ref, Z_ref.
  2. To preview the injector in the Graphics window, click Update at the bottom of the dialog.
    Simcenter STAR-CCM+ In-cylinder updates the position and orientation of the injector.
By default, Simcenter STAR-CCM+ In-cylinder creates a single-nozzle injector.

To set up the nozzle for a single-nozzle injector:

  1. Set Nozzle Origin Reference and Nozzle Target Reference in the coordinate systems of your choice.
    The coordinate systems for the nozzle origin reference and the nozzle target reference are displayed in the Graphics window as X_org, Y_org, Z_org and X_trg, Y_trg, Z_trg, respectively.
    Example:

    If the coordinate systems are placed on top of each other, the display order in the Graphics window is as follows:
    1. X_ref, Y_ref, Z_ref
    2. X_org, Y_org, Z_org
    3. X_trg, Y_trg, Z_trg
  2. To rotate the nozzle around the injector axis, set Nozzle Rotation Offset to the required rotation offset angle.
    Note that nozzle rotation is not supported for cylinder sector models.
  3. Click Update.
    Simcenter STAR-CCM+ In-cylinder updates the position and orientation of the nozzle accordingly.
For a multi-nozzle injector, you use the default nozzle as reference nozzle. Simcenter STAR-CCM+ In-cylinder automatically duplicates the reference nozzle and sweeps the duplicates around the injector axis. The angular distance between the nozzles is given by α = 360 ⁢ deg ⁡ n , where n is the number of nozzles.

To set up the nozzles for a multi-nozzle injector:

  1. Set up the reference nozzle as described in Steps 4 and 5.
  2. Set Number of Nozzles as required.
  3. Click Update
    For a half engine model with a multi-nozzle injector, if you specify an even number of nozzles, Simcenter STAR-CCM+ In-cylinder automatically applies a Nozzle Rotation Offset of | α r o t | = α 2 . This auto-calculation of the rotation offset angle avoids that nozzles are created on the symmetry plane.
If the auto-calculated rotation offset angle does not suit your requirements, you can overwrite the value accordingly:
  1. Set Nozzle Rotation Offset as required and click Apply.
To characterize the nozzle flow:
  1. Depending on the injector type, in the Per Nozzle group-box set the following properties:
    Injector TypeProperties
    Hollow/Solid Cone Injector
    • Area Ratio
    • Hydraulic Diameter
    • Inner Cone Angle—for a solid spray cone, set this property to 0.
    • Outer Cone Angle
    Nozzle Injector
    • Discharge Coefficient
    • Diameter
    • Length
    • Form Loss Coefficient
    • Dissipation Rate Coefficient
  2. Click Apply.
For more information, see Engine Reference—Injector Geometry.

To set the physics conditions for the injector:

  1. Click the Physics tab.
  2. Set the mass flow rate of the injected fuel depending on how the data for the mass flow rate are available:
    Mass Flow Rate DataProcedure
    Tabular data
    1. Make sure that Mass Flow Rate is set to Table.
    2. Next to the File drop-down menu, click Import.
    3. In the Import Table dialog, navigate to the folder that contains the table.
    4. Select the file and click Open.

      In the Graphics window, a plot opens that displays the mass flow rate as a function of crank angle.

    5. Set the following table properties:
      • Time / Crank Angle
      • Mass Flow Rate Column
      • Time / Crank Angle Units
      • Mass Flow Rate Units
    Constant value
    1. Set Mass Flow Rate to Stepped Constant.
    2. Below the Mass Flow Rate property, in the text-box, set the constant fuel mass flow rate.
    3. Set the following properties:
      • Start of Injection
      • End of Injection
    4. Click Update.

      In the Graphics window, a plot opens that displays the stepped mass flow rate profile as a function of crank angle.

  3. To shift the mass flow rate profile along the crank angle axis or the time axis, respectively, set the following properties:
    • [injector] : Injection Crank Angle Anchor
    • [injector] : Injection Time Anchor
    • [injector] : Injection Crank Angle Target

    where [injector] is the name of the injector.

  4. For solid cone and hollow cone injectors, if you want to increase the sample density at the centerlines of the nozzles, set Cone Angle Sampling Polynomial Exponent to an integer value larger than 1. A value of 1 corresponds to a uniform distribution.
  5. Set the fuel temperature depending on how the data for the temperature are available:
    Fuel Temperature DataProcedure
    Tabular data
    1. Set Fuel Temperature to Table.
    2. Depending on whether the temperature data are described in the same or in a separate table as the mass flow rate data, do one of the following:
      • If the temperature data are described in the same table, select the previously imported table from the File drop-down menu.
      • If the temperature data are described in a separate table, import the table as described for the mass flow rate table using the Import button next to the File drop-down menu below the Fuel Temperature property.

      The plot in the Graphics window displays the fuel temperature curve.

    3. Set the following table properties:
      • Time / Crank Angle
      • Fuel Temperature Column
      • Time / Crank Angle Units
      • Fuel Temperature Units
    Constant value
    1. Set Fuel Temperature to Constant.
    2. Below the Fuel Temperature property, in the text-box, set the temperature of your fuel.
  6. For a nozzle injector, the diameter of the injected fuel droplets corresponds to the nozzle diameter as specified in Step 11. For a hollow/solid cone injector, set the droplet diameter of the injected fuel droplets depending on how the data for the droplet diameter are available:
    Droplet Diameter DataProcedure
    Tabular data
    1. Depending on the function that the tabular data describe, set Droplet Diameter to one of the following:
      • For a cumulative distribution function, set CDF Table.
      • For a probability density function, set PDF Table.
    2. Depending on whether the diameter data are described in the same or in a separate table as the mass flow rate and temperature data, do one of the following:
      • If the droplet diameter data are described in the same table, select the previously imported table from the File drop-down menu.
      • If the droplet diameter data are described in a separate table, import the table as described for the mass flow rate table using the Import button next to the File drop-down menu below the Droplet Diameter property.
    3. Set Data to the table header that contains the particle diameter in m.

    The plot in the Graphics window displays the cumulative distribution function or the probability density function for the droplet diameter, respectively.

    Rosin-Rammler distribution function
    1. Set Droplet Diameter to Rosin-Rammler.
    2. Set the following properties:
      • Minimum Diameter
      • Maximum Diameter
      • Sauter Mean Diameter
      • Exponent
    Constant value
    1. Set Droplet Diameter to Constant.
    2. Below the Droplet Diameter property, in the text-box, set the diameter of the injected droplets.
  7. Click Update, then OK.
    For more information, see Engine Reference—Injector Physics.
    Simcenter STAR-CCM+ In-cylinder adds the Engine > [injector] node to the tree. The nozzles of the injector are listed as sub-nodes Nozzle 1 to Nozzle [n], respectively.

    For a half engine model, warning triangles indicate the nozzles that are positioned outside the fluid domain.



    注Do not delete these nozzles—they are used to calculate the correct mass flow rates for the nozzles inside the fluid domain.
For a multi-nozzle injector, all nozzles own the same Geometry properties as the reference nozzle by default.

To adjust the Geometry settings for a specific nozzle inside the fluid domain:

  1. Right-click the respective Engine > [injector] > Nozzle [n] node and select Edit.
  2. In the Injector Nozzle : Nozzle [n] dialog, adjust the settings, such as the Nozzle Origin or the Nozzle Target, according to your needs.
    The coordinate systems for the nozzle origin and the nozzle target are displayed in the Graphics window as X_org, Y_org, Z_org and X_trg, Y_trg, Z_trg, respectively.
  3. Click Apply, then Close.
To create an additional nozzle for the injector:
  1. Right-click the Engine > [injector] node and select Add Nozzle.
To delete a nozzle of the injector:
  1. Right-click the respective Engine > [injector] > Nozzle [n] node and select Delete.