Hello I’m’ Francesca Furno with Siemens PLM Software.
Today I’m going to introduce you with advanced developments regarding aeration within liquids.
LMS Imagine.Lab hydraulic libraries have always taken into account air within liquids
either in dissolved and undissolved form depending on the pressure level
with respect to the saturation line.
Anyway, today you have more options available in the fluid icon
and this option allow you to consider different effects,
so for example variable air amounts as inputs to your hydraulic systems and components
but also dynamics for areation and dissolution which are represented by time constants.
New areation models are available in fluid properties models.
So click here in the icon, you will access to the areation group
and in particular you have an enumeration corresponding to air and dissolution.
You have several options: gas transport, and gas transport and dynamics
where you can change for example your time constants.
In this video we will select the gas transport option
and we will consider an hydraulic valvetrain with variable air as inputs to the valvetrain.
If you are interested in this topic and in particular to air release and dissolution dynamics,
you can also watch the second video on the same topic.
Today we are considering an hydraulic valvetrain with a rockerarm configuration.
LMS Imagine.Lab Amesim animation tool allow you to represent the working principle of the system.
In particular, you can link simulation variables to 3D objects
in order to visualize the motion of each element.
In particular, you have a rotating camshaft pushing a rocker arm
in charge of transforming the rotating motion into a linear motion of a piston.
The piston is compressing and decompressing an hydraulic chamber
which is transferring the motion to the engine valves.
The fluid compressibility in a collapsing chamber is very important regarding the dynamics of the system
and in particular the delay and lifts of the engine valves.
The lubrication circuit is supplying the hydraulic valvetrain
and is represented as a source of constant pressure at 3.5 bars,
a constant temperature for simplicity, but a variable air amount.
This is due to the fact that during the working cycle of the vehicle,
the lubrication circuit is more and more areating.
Then we want to consider an increase of areation as boundary condition for the hydraulic valvetrain.
In order to consider a variable amount of air inside the hydraulic system,
we need to select the gas transport option within the fluid model.
Consequently we need to provide with a variable signal a variable amount of air as input.
In this example we will apply to the system a variable total gas amount and an undissolved gas amount
which is corresponding to a volumetric percentage of air from about 0 up to 30%.
During the simulation, the air will be transferred from the inlet up to the final linear actuator
which is finally the engine valve.
The air will reach the final collapsing chamber with a certain delay.
We can then have a look at the void content into the collapsing chamber.
This amount of air is increasing during the simulation,
meaning that the compressibility of the chamber is also increasing.
Consequently we have a weaker transfer of the motion from the camshaft to engine valve.
If we consider several engine cycles, we can use a specific LMS Amesim facility which is the modulo plot.
Within this tool, we keep constant the camshaft speed and the supplied pressure
but we provide a variable amount of air.
We can check the valve lift during several working cycles.
In particular, we see that with an increasing amount of air,
the engine valve lift is decreasing due to a higher compressibility in the collapsing chamber.
In conclusion, new advanced areation models allow users to consider variable air amounts
as inputs to hydraulic systems, and allow to optimize either the design or the control strategies
also in worst case conditions for the system behavior.
Thank you for watching. For more information please visit our website.