Spool with Slot Orifices (IL)

If the check box Moving body removed, and the body movement is not simulated, then the overlap value is defined as:

where

If the check box Moving body is installed, and the body movement is simulated, then the overlap value is defined as:

where — moving the case in port CA.

The length of the camera is defined as:

where — the length of the camera at zero offset, the value of the parameter Chamber length at zero displacement.

The volume of the camera is:

where

The headrest with sharp edges

If for the parameter Edges geometry the value is set Sharp, then it is assumed that the spool edges are sharp.

The figure shows a spool valve with rectangular holes. Such holes are formed when there are slots around the circumference of the valve.

The area of the open hole is calculated as:

where

The hydraulic diameter is:

Overlap value limited between and the smaller of the values and , where — the value at which the area of the open hole becomes equal to the area of the rectangular slots:

where — the depth of the slots, the value of the parameter Depth of a slot.

Minimum overlap value It is usually zero, but it can be higher to simulate the leakage rate. Maximum overlap value It is usually very high (Inf), but a much lower value can be set to simulate an additional hole.

Flow coefficient calculated as:

where

The average density is calculated at an average pressure .

Expense ratio calculated as:

where

For meaning practically does not change. For low meaning it changes linearly with the change .

A reasonable value the default value is `1000'. However, for holes with complex (rough) geometry, it may be less than `50'. For very smooth geometry, it can be set to `50,000'.

The average fluid velocity is:

The volume consumption is:

where

The contribution to the flow due to the movement of the spool is calculated as:

where

The hydrodynamic force acting on the spool is determined by estimating the change in momentum. This force tends to close the valve. For a steady-state fluid flow, the hydrodynamic force is:

where — the angle of inclination of the jet, which is considered constant for a spool with sharp edges and is set in the parameter Jet angle.

Dependence of the hydrodynamic force from overlap It is defined as follows:

The force in the port RA is calculated taking into account the force in the port RB, the pressure force and the hydrodynamic force as:

the armrest with rounded edges

If for the parameter Edges geometry the value is set Rounded It is assumed that the edges of the spool are rounded and there is a diameter gap between the spool and the sleeve, which is a more realistic geometric model.

The rounding of the edges is determined by the following values:

If the overlap value is positive , then the flow is calculated as the flow through the hole, the area of which is:

The hydraulic diameter is:

Overlap value it is limited from above by the smaller of the values and , where — the value at which the area of the open hole becomes equal to the area of the rectangular slots:

where — the depth of the slots, the value of the parameter Depth of a slot.

Maximum overlap value It is usually very high (Inf), but a much lower value can be set to simulate an additional hole.

Flow coefficient calculated as:

where

The average density is calculated at an average pressure .

Expense ratio calculated as:

where

For meaning practically does not change. For low meaning it changes linearly with the change .

A reasonable value the default value is `1000'. However, for holes with complex (rough) geometry, it may be less than `50'. For very smooth geometry, it can be set to `50,000'.

The average fluid velocity is:

The volume consumption is:

where

With negative overlap the volume flow rate between the spool and the sleeve can be expressed as:

where — the continuity coefficient, which ensures the continuity of the flow.

The contribution to the flow due to the movement of the spool is calculated as:

where

The hydrodynamic force acting on the spool is determined by estimating the change in momentum. This force tends to close the valve. For a steady-state fluid flow, the hydrodynamic force is:

where — the angle of the jet.

The cosine of the jet angle is found by interpolating the experimental results shown in the figure below. Linear spline interpolation is used for this purpose.

Dependence of the hydrodynamic force from overlap It is defined as follows:

The force in the port RA is calculated taking into account the force in the port RB, the pressure force and the hydrodynamic force as:

If the check box is selected Moving body, and the hull movement is modeled, then the force at port CA is calculated based on the force at port CB: