23.3.5 Point Properties for Cone Injections

In 3D problems, you can define a hollow or solid cone of particle streams using the cone or solid-cone injection type, respectively. For both types of cone injections, the inputs are as follows:

• position

  Set the coordinates of the origin of the spray cone in the X-, Y-, and Z-Position fields.

• diameter

  Set the diameter of the particles in the stream in the Diameter field.

• temperature

  Set the temperature of the streams in the Temperature field.

• axis

  Set the $x$, $y$, and $z$ components of the vector defining the cone's axis in the X-Axis, Y-Axis, and Z-Axis fields.

• velocity

  Set the velocity magnitude of the particle streams that will be oriented along the specified spray cone angle in the Velocity Mag. field.

• cone angle

  Set the included half-angle, $\theta$, of the hollow spray cone in the Cone Angle field, as shown in Figure  23.3.4.

  Figure 23.3.4: Cone Half Angle and Radius

  

• radius

  A nonzero inner radius can be specified to model injectors that do not emanate from a single point. Set the radius $r$ (defined as shown in Figure  23.3.4) in the Radius field. The particles will be distributed about the axis with the specified radius.

• swirl fraction (hollow cone only)

  Set the fraction of the velocity magnitude to go into the swirling component of the flow in the Swirl Fraction field. The direction of the swirl component is defined using the right-hand rule about the axis (a negative value for the swirl fraction can be used to reverse the swirl direction).

• mass flow rate

  For coupled calculations, set the total mass flow rate for the streams in the spray cone in the Total Flow Rate field.

The distribution of the particle streams for the solid cone injection is random, as seen in Figure  23.3.3. Furthermore, duplicating this injection may not necessarily result in the same distribution, at the same location.

For transient calculations, the spatial distribution of streams at the initial injection location is recalculated at each time step. Sampling different possible trajectories allows a more accurate representation of a solid cone using fewer computational parcels. For steady state calculations, the trajectories are initialized one time and kept the same for subsequent DPM iterations. The trajectories are recalculated when a change in the Injections dialog box occurs or when a case and data file are saved. If the residuals and solution change when a small change is made to the injection or when a case and data file are saved, it may mean that there are not enough trajectories being used to represent the solid cone with sufficient accuracy.

Note that you may want to define multiple spray cones emanating from the same initial location in order to specify a size known distribution of the spray or to include a known range of cone angles.

For the massless particle type, you will only need to define position, axis, cone angle and radius. The particle velocities are set by the solver equal to the velocity of the continuous phase at the injection points.