Ball Poppet with Conical Seat (IL)

If the check box is Moving body removed, and the body movement is not simulated, then the ball lift is calculated as:

where

If the check box is Moving body is installed, and the body movement is simulated, then the ball lift is calculated as:

where — moving the case, which is inserted into the CA port.

The equations that the block uses depend on the model. Flow force model:

Equations for a simple model

The minimum flow area is determined by the curved surface of the truncated cone, as shown in the figure. It is assumed that this surface divides the area occupied by the liquid into two areas with different pressures. There is pressure on one of these areas. , and on the other — pressure . This assumption is reasonable if the lift of the ball is small compared to the diameter of the saddle. If the rise of the ball is large, it is obvious that at some point the smallest limitation will be the area of the neck.

The condition must be met:

In case of violation of this condition, the ball will not be able to rest on the conical seat.

If this condition is violated, then it is considered that the saddle is round as in the block. Ball Poppet with Sharp Edge Seat (IL). Make sure that the condition is not violated.

The area of the hole is defined as:

where

The hydraulic diameter is calculated as:

The active diameter is calculated as:

Note that the value used for , limited between and the smaller of the values and , where — this is the lifting value at which the calculated area becomes equal to the area of the neck:

Meaning Always more .

Usually the value is it is zero, but it can be set higher to simulate the leakage rate. Meaning it is usually very high (for example, Inf), but a much lower value can be set to simulate an additional hole.

Liquid volume , the pressure in which is equal to the pressure , additional to the volume when the valve is closed, is calculated as:

The value of the additional volume it is important when calculating pressure dynamics (frequency analysis).

The derivative of the additional volume by calculated as:

If the check box Moving body removed, the volume of liquid that is discharged into port B is calculated as:

where — parameter value Volume at port B corresponding to zero lift.

And the volume of liquid that is discharged into port A is calculated as:

where — parameter value Volume at port A corresponding to zero lift.

If the check box Moving body installed:

where — the diameter of the conical seat on the side of the ball, the value of the parameter Seat cylinder diameter.

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

If the check box Moving body if withdrawn, the volume costs in ports B and A are calculated as:

where

If the check box Moving body installed:

where

The hydrodynamic force 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:

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

where — parameter value Lift corresponding to minimum area.

The power in port RA is calculated as:

where — the power that enters the RB port.

If the check box is selected Moving body, and the hull movement is modeled, then the force in the port CA is calculated as:

where

Equations for the model adjusted for the effective pressure area coefficient

Model Corrected by effective pressure area factor differs from Simple the fact that the value of the active diameter and the hydrodynamic force is calculated taking into account the type of flow (laminar or turbulent).

This section contains the equations for calculating the adjusted parameters, the remaining parameters are calculated in the same way as for the model. Simple.

Active diameter defined as:

Active area defined as:

Real active area depends on the type of flow (laminar or turbulent):

In these formulas — parameter value Turbulent effective pressure area factor.

The hydrodynamic force also varies depending on the velocity of the liquid at the inlet and outlet of the hole.:

where

The power in port RA is calculated as:

where — the power that enters the RB port.

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

where

Equations with modification of calculation of active areas upstream

Model Advanced active area differs from Simple by calculating the active areas (minimum and maximum) upstream.

This section contains the equations for calculating the adjusted parameters, the remaining parameters are calculated in the same way as for the model. Simple.

The maximum active area upstream is calculated as:

The minimum active area upstream is calculated as follows:

The active area upstream is calculated as:

It should be noted that the calculation performed is valid only for the incoming jet and is not valid for the outgoing jet. Therefore, the updraft must be on the side of the saddle. Then the power in the port RA is calculated as:

where — the active diameter calculated from the value of the active area upstream .

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

where