Operating Parameters

The operating parameters pertaining to the Gear template involve the time definition for the simulation, pump configuration, angular velocity definitions for pump rotation and other advanced/extended settings (see Figure 6.156).

Figure 6.156 - Gear model-Operating parameters

Time Definition

This provides the following ways to specify the size and number of time steps for the external gear pump simulation (see Figure 6.156):

Revolutions: A single revolution corresponds to a pump rotation of 360 degrees. The parameters required under this Time Definition are:

Number of Revolutions: The number of pump revolutions to be simulated.
Time Steps Per Drive Gear Tooth Rotation: The number of time steps taken to move the drive gear through one pocket (angle between the tips of two drive gear teeth).

The magnitude of the time-step size (s) and the angle of rotation (deg) depend on the Time Steps Per Drive Gear Tooth Rotation and the Number of Drive Gear Teeth as follows:

	6.15
	6.16

For a Time Definition of Revolutions, the Number of Time Steps is computed as follows:

6.17

Pockets:A method of Time Definition that uses the angle from one inner tooth to the next to determine the size and number of time steps. A single pocket corresponds to a rotation equal to the average angle between blades, based on 360 degrees divided by the user specified Number of Inner Teeth. The parameters specified under this Time Definition are:

Number of Pockets: This dictates the amount of rotation based on the angle between two inner teeth.
Time Steps Per Drive Gear Tooth Rotation

Figure 6.157 - Pocket-Gear

For a Time Definition of Pockets, the Number of Time Steps is computed as follows:

6.18

Note: The number of pockets corresponds to the number of inner teeth.

Total Time Steps: Total number of time steps for a given simulation. The following parameters are specified for this Time Definition:

Time Steps Per Drive Gear Tooth Rotation
Number of Time Steps (in the Simulation Panel)

For a Time Definition of Total Time Steps, the Simulation Time (Duration) is computed as follows:

6.19

Note:

If the Number of Time Steps is displayed in Blue, it means that it is set and controlled elsewhere and cannot be changed in the Simulation Panel.
The setting of the Time Definition in the Model Tab of Properties Panel and in the Simulation Panel are slaved to each other, such that changing the value in one panel, changes the value in the other.
If multiple templates are active, the Gear module must be set as the Reference Pump for the Time Definition option to be displayed.

Pump Configuration

This contains parameters pertaining to the geometry of the external gear pump (see Figure 6.156). The inputs such as Number of Drive Gear Teeth, Number of Slave Gear Teeth, Drive Gear Center, Slave Gear Center and Feature Angle are same as those defined in the mesher.

Angular Velocity Definition

This contains parameters pertaining to the rotation of the pump. The parameters defined under the Angular Velocity Definition are: Rotational Direction, Rotational Speed and Rotational Axis Vector see Figure 6.143.

Note: A variable Rotational Speed can be specified using the Expression Editor.

Cluster Method

This method controls the axial grid distribution in the drive and slave gears using the following methods:

Linear Distribution gives a uniform cell spacing.
Symmetric Clustering(1-2) stretches the mesh towards or away from the top and bottom of the drive and slave gears in the axial direction depending on the value entered for Cluster Mesh in Axial Direction(1-2). The original distribution gives a uniform cell spacing. The values entered must be between 1.0 and 2.0.

Figure 6.158 - Gear-Cluster method

Figure 6.159 - Helix angle

Helix Angle

This allows to specify the angle between the gear teeth axial inclination and the gear axis. During mesh generation, the Helix Angle (see, Figure 6.159) is used to specify the correct slant of the gear teeth whereas, the CAD Surfaces are used as bounds for the mesh to obtain a water-tight volume.