Spool with Beveled Edge (IL)

A spool valve with a beveled edge.

blockType: EngeeFluids.IsothermalLiquid.DesignComponents.Spools.BeveledEdge

Spool with Beveled Edge (IL)

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Valves & Orifices/Spools & Poppets/Fixed Body/Spool with Beveled Edge (IL)

Spool with Beveled Edge with Moving Body (IL)

Path in the library:

/Physical Modeling/Fluids/Isothermal Liquid/Valves & Orifices/Spools & Poppets/Moving Body/Spool with Beveled Edge with Moving Body (IL)

Description

Block Spool with Beveled Edge (IL) It is a one-dimensional movement of a spool with a beveled edge in a sleeve with a gap between the spool and the sleeve.

The resulting force acting on the spool is due to the force applied at the port RA, the pressure force at the port B, and the viscous friction caused by the Poiseuille effect and the Couette effect (if the Couette effect is taken into account).

The movement and speed of the rod are transmitted to the RB port. There are no restrictions on the displacement value in the block, but restrictions can be provided by an attached block using end stops (Translational Hard Stop).

If the check box is selected Moving body, then the block is implemented Spool with Beveled Edge with Moving Body (IL) and the body movement is simulated. In this case, the displacement and speed of the case are transmitted to the CB port. There are no restrictions on the displacement value in the block, but restrictions can be provided by an attached block using end stops.

The overlap is calculated based on these displacements relative to the overlap corresponding to the zero offset. .

The flow rate is calculated based on the movement of the spool.

The area of the open hole is a variable related to the movement of the spool and the movement of the housing, if it is modeled.

Sometimes it is useful to limit the hole area to the maximum value. The maximum opening area is determined by the corresponding overlap value — a parameter Underlap corresponding to maximum area. The default value means that there are no restrictions on the area. This value is independent of any movement restrictions applied by other attached mechanical units. The maximum area can be used to simulate the flow area adjacent to the opening when the valve is wide open.

In addition, the flow area should not exceed the annular area determined by the diameter of the spool and stem.

The beveled edge of the spool is determined by the following parameters:

— chamfer length Bevel length, which is limited by the distance between the edges of the spool ;
— chamfer depth Bevel depth, which is limited by the diameters of the spool and rod;
— the number of chamfers along the edge of the spool Number of bevels.

The equations

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

where

— the overlap corresponding to the zero offset, the value of the parameter Underlap corresponding to zero displacement;
— moving the spool in port RB.

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

where — moving the case in the CB port.

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.

Camera volume calculated as

where

— diameter of the spool;
— diameter of the stem.

Effective cross-sectional area It is calculated from the projection of the body edge onto the chamfer plane. Based on this, the minimum area shown in the figure is obtained.

spool with beveled edge il 2 en

When calculating the cross-sectional area, the following restrictions are taken into account:

the vertical area corresponding to the segment area obtained from the current segment of the chamfer angle :
the area of the neck that limits the total flow area:

Flow coefficient calculated as

where

— pressure difference between ports;
— hydraulic diameter;
— kinematic viscosity;
— the average density of the liquid.

Expense ratio calculated as

where

— maximum flow rate, parameter value Maximum flow coefficient;
— critical flow coefficient, parameter value Critical flow number.

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

A reasonable value the default is 1000. However, for holes with complex (rough) geometry, it may be smaller. 50. For very smooth geometry, it can be set to 50000.

The average fluid velocity is

Consumption is determined by the following factors:

by opening the metering edge under conditions of positive overlap ( ):

where
- — the area of the passage hole;
- — the density of the liquid at atmospheric pressure;
leaks in negative overlap conditions ( ). The leakage rate is calculated using a typical laminar flow equation for annular holes with eccentricity:

where
- — the absolute average viscosity of the liquid;
- — diametrical gap, parameter value Clearance on diameter; it should be borne in mind that for diametrical gaps more than 60 microns of leakage should be overestimated;
- — relative eccentricity, parameter value Eccentricity ratio, which is defined as the ratio of eccentricity and half of the diametrical gap:
  
  The value of the relative eccentricity should be from 0 before 1.
- and shown in the picture.
  
  The considered leakage length is limited by the distance between the edges of the spool .

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

where — the speed of the spool movement.

The power in port RB is calculated as

where

— power on port RA;
— the pressure force on the port B acting on the area of the neck;
— the force of viscous friction.

If the check box Moving body removed, the viscous friction force is defined as

If the check box Moving body If established, then the viscous friction force is defined as

In these equations:

— the length of viscous friction:

In case of leakage, this length is limited by the distance between the edges of the spool ;
— the ratio of the viscous friction areas, which reduces the involved area of the spool by subtracting the chamfer area:

where
- — the current area of the spool:
- — the current chamfer area for :

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

where — the force of viscous friction on the body, which is determined only for leakage (negative overlap) and is calculated as

Ports

Conserving

# A — Isothermal liquid port
Isothermal liquid

Details

The isothermal liquid port corresponding to the inlet or outlet.

Program usage name

port_a

# B — Isothermal liquid port
Isothermal liquid

Details

The isothermal liquid port corresponding to the inlet or outlet.

Program usage name

port_b

# RA — stock
translational mechanics

Details

Mechanical translational port corresponding to the rod.

Program usage name

rod_flange_a

# RB — stock
translational mechanics

Details

Mechanical translational port corresponding to the rod.

Program usage name

rod_flange_b

# CA — housing
translational mechanics

Details

Mechanical translational port corresponding to the body.

Dependencies

To use this port, check the box Moving body.

Program usage name

case_flange_a

# CB — housing
translational mechanics

Details

Mechanical translational port corresponding to the body.

Dependencies

To use this port, check the box Moving body.

Program usage name

case_flange_b

Parameters

Main

# Opening orientation — the direction of movement of the spool corresponding to the opening of the hole
Positive relative rod displacement opens orifice | Negative relative rod displacement opens orifice

Details

The direction of movement of the element corresponding to the opening of the hole:

Positive orientation Positive relative rod displacement opens orifice means that the positive movement of the spool opens the hole.;
The negative direction Negative relative rod displacement opens orifice this means that the negative movement of the spool opens the hole.

Values	`Positive relative rod displacement opens orifice` \| `Negative relative rod displacement opens orifice`
Default value	`Positive relative rod displacement opens orifice`
Program usage name	`opening_orientation`
Evaluatable	No

Parameters

# Moving body — movable housing

Details

Select this option if you are modeling a movable enclosure.

If the flag is unchecked, it is assumed that the body is stationary.

Default value	`—`
Program usage name	`moving_case`
Evaluatable	No

# Couette effect — the Couette effect

Details

Checking this box means that the Couette effect is taken into account, that is, the contribution of the Couette current to the force of internal friction.

Default value	`true (switched on)`
Program usage name	`couette_effect`
Evaluatable	No

# Number of bevels — number of chamfers

Details

The number of chamfers along the spool edge.

Default value	`2`
Program usage name	`bevel_count`
Evaluatable	Yes

# Spool diameter — diameter of the spool
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The diameter of the spool must be larger than the diameter of the stem.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`10.0 mm`
Program usage name	`spool_diameter`
Evaluatable	Yes

# Rod diameter — stem diameter
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The diameter of the rod.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`5.0 mm`
Program usage name	`rod_diameter`
Evaluatable	Yes

# Bevel length — chamfer length
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The chamfer length cannot be greater than the distance between the edges of the spool .

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`4.0 mm`
Program usage name	`bevel_length`
Evaluatable	Yes

# Bevel depth — chamfer depth
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The depth of the chamfer is limited by the diameters of the spool and rod.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`2.0 mm`
Program usage name	`bevel_depth`
Evaluatable	Yes

# Chamber length at zero displacement — camera length at zero offset
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The length of the camera at zero offset (within the calculated camera volume).

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.0 mm`
Program usage name	`chamber_length_offset`
Evaluatable	Yes

Underlap Definition

# Underlap corresponding to zero displacement — overlap corresponding to the zero offset
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The overlap corresponding to the zero offset.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.0 mm`
Program usage name	`offset`
Evaluatable	Yes

# Underlap corresponding to maximum area — overlap corresponding to the maximum area
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The overlap corresponding to the maximum opening area.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`Inf mm`
Program usage name	`orifice_opening_at_max_area`
Evaluatable	Yes

Leakages on the Spool

# Clearance on diameter — diametrical gap
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The diameter gap between the spool and the housing. It should be borne in mind that for diametrical gaps more than 60 microns of leakage should be overestimated.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.003 mm`
Program usage name	`clearance`
Evaluatable	Yes

# Eccentricity ratio — relative eccentricity

Details

The relative eccentricity of 0 before 1.

Default value	`0.0`
Program usage name	`eccentricity_ratio`
Evaluatable	Yes

# Edge-to-edge distance — edge-to-edge distance
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

Edge-to-edge distance , which limits the length of the leak.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`10.0 mm`
Program usage name	`spool_length`
Evaluatable	Yes

Flow Coefficient Law

# Maximum flow coefficient — maximum flow rate

Details

The maximum flow rate affects the flow rate/pressure drop characteristics in the orifice. For most applications, this value can be left at the default.

Default value	`0.7`
Program usage name	`C_q_max`
Evaluatable	Yes

# Critical flow number — critical flow coefficient

Details

The critical flow coefficient affects the flow rate/pressure drop characteristics in the orifice. For most applications, this value can be left at the default.

Default value	`100.0`
Program usage name	`critical_flow_number`
Evaluatable	Yes

Initial Conditions

# Initial rod displacement — initial displacement of the rod
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The initial displacement of the rod.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.0 mm`
Program usage name	`rod_displacement_start`
Evaluatable	Yes

# Initial case displacement — initial displacement of the body
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The initial displacement of the body.

Dependencies

To use this option, check the box Moving body.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`0.0 mm`
Program usage name	`case_displacement_start`
Evaluatable	Yes