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MapleSim Hydraulics Library from Modelon

Poppet Lift Cone  Ball poppet lift with conical seat

This is a template model for a poppet lift with conical seat.

Flow Area

When the poppet is far from the seat, the flowarea between the two chambers is limited by the area between the seat-side rod and the seat.

As the poppet moves nearer, the flow area is limited by the seat and the poppet. The flow area is the area of a truncated cone with base radius s, top radius a, and slant height h,

A=πs+ah

s=a+Xcosθ2

h=Xcosθ

with a constant.  See the following figure.

Hydraulic Diameter

The hydraulic diameter is D=4AP where P is the wetted perimeter and A is the flow area. The wetted perimeter for the poppet lift with conical seat is P=2π2a+Xcosθ2

Chamber Volumes

The chamber volumes V1 (poppet side) and V2 (seat side) are calculated using the following quantities: The initial volume (when the poppet lift is closed) on both poppet side (V01) and seat side (V02) are known.

The seat side volume is

V2={V02XXminV02XArod2+VcapR,a+VconeVsliceotherwise

where XXmin is the distance the poppet has been lifted from its initial position.

V1 is calculated from the relationship V1+V2=V01+V02XXminArod2Arod1.

Implementation

This model calculates the volumes on both sides of the poppet lift, the mass flow between the two sides and the force f. Pressure is calculated in volume components connected to connector portA and portA1.

Connections

Name

Description

Modelica ID

supportA

 

supportA

supportB

 

supportB

flangeA

 

flangeA

flangeB

 

flangeB

oil

Fluid property model

oil

portA

 

portA

portA1

 

portA1

Parameters

General Parameters

Name

Default

Units

Description

Modelica ID

L

 

m

Element length

L

reverse

false

 

Reverse the sign convention, see documentation for details

reverse

R

0.1

m

Poppet radius

R

θ

[1]

rad

Conical seat/poppet angle

theta

r

0.05

m

Throat radius

r

Rrod1

 

m

Rod radius, poppet side

Rrod_1

Rrod2

 

m

Rod radius, seat side

Rrod_2

lift0

0

m

Poppet lift in neutral position

lift_0

piston

L

m

Piston length

l_piston

V1

[2]

m3

Volume, poppet side, when closed valve

V01

V2

[2]

m3

Volume, seat side, when closed valve

V02

Xmin

0

m

minimum distance between poppet center and seat in basic case, otherwise set as 0

Xmin

transition type

1

 

Type of transition

TransitionType

k1

10

 

Laminar part of flow model

k1

k2

2.04

 

Turbulent part of flow model

k2

Cdmax

0.7

 

Discharge coefficient

Cdmax

λc

14

 

Critical flow number

lambdac

Xmaxstart

r

 

 

XmaxStart

Xmaxnom

0.001Xmaxstart

 

 

XmaxNominal

ΔTsystem

0

K

Temperature offset from system temperature

dT_system

[1] 0.25π

[2] 2.0πLR2

Constant Parameters

Name

Default

Units

Description

Modelica ID

Aflowmax

[1]

m2

Maximum flow area

flowareamax

Arod1

[2]

m2

Rod area, poppet side

Arod_1

Arod2

[3]

m2

Rod area, seat side

Arod_2

X0

lift0+Xmin

m

distance from seat to poppet center

X_0

[1] πr2Arod2_

[2] πRrod12

[3] πRrod22

See Also

Elements, MapleSim Hydraulics Library from Modelon Overview


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