Hello I'm Francesca Furno
with Siemens PLM Software. Today I'm going to introduce to you a new
advanced developement regarding aeration within liquids.
LMS Imagine.Lab Hydraulics library has always taking into
account air either in a disolved or indisolved form depending on the
pressure level with respect to the saturation line.
Anyway today you have more option for aeration model in particular
you can take into account variable air amounts as the inputs of your
hydraulic systems and components, but you can also take into account
air dissolution and aeration dynamics by considering two differente time constants.
So these options are available in the fluid icon,
you have to look at the aeration group and you will find
in numeration parameter allowing you to select different type of aeration model.
So you can have the option gas transport
or a more complex option which is gas transport and dynamics, where you can
set time constants for aeration and dissolution dynamics.
In this video we will selected the option gas transport and dynamics, in order
to investigate the effect of air release and dissolution dynamics
on hydraulic pumps, in this particular case it will be a vane pump.
If you are interested in this topic and you would like to see also the effect of
a variable air amounts as input to hydraulic system
please watch the other video on the same topic.
The LMS Amesim animation tool allows you to visualise
the 3D geometry of the pump. In this case it's a vane pump and you can link a
simulation variables to the 3D objects in order to represent
the behavior of the components during the simulation.
Each chamber in between the external stator ring in a green color
the internal rotor in a light blue and two consecutive vanes
is alternativelly connected to the suction part in a blue color
or to the delivery port in red color.
The pressure level within the internal chambers depends on the
volume variation along
the revolution of the pump but also on the ports connection
to the suction and to the delivery, and finally also on the fluid
properties in particulary the bulk modulus which represent the
stiffness of the fluid. Fluid properties and then the bulk modulus
of the fluids depends on the air amount within the liquid.
So we will consider different dissolution time, we can access to it
through the icon on the fluid.
We will run some batch simulation and for investigation
purposes we will consider different dissolution times from tiny
values up to ten seconds. Looking at batch runs and simulation results
that have been saved in a plotter configuration, we see that increasing
the dissolution time from tiny values up to 10 seconds
lead to more air in undisovled form in the liquid and
consequently to lower bulk modulus. The bulk modulus as I have already said
is representing the compressibility of the fluid, so in more compressible fluid will
lead us to pressure evolution and in particular to pressure peaks which are lower
by increasing the dissolution time.
Pressure peaks are very important
for vibration and the NVH characteristics of the pumps,
consequently the dissolution time has to be investigated in order to improve
vibration and NVH issues.
We have seen that the dissolution time
affects pressure peaks inside internal chambers of the pump.
And we can also plot the total force due to the contribution of all chambers
acting on the stator ring. And the total force is consequently
also depending on the dissolution time
consequently also the position of the stator ring and consequently the
eccentricity of the pump is strongly affected by the dissolution time.
We can also plot the pressure peak as a function of the dissolution time
and also the mean force acting on the stator ring and increasing
the dissolution time we see that the pressure peak reduces
as that we have already seen before due to a higher compressibility of the fluid.
Not only also the mean force which is acting on the stator ring is
also changing and what is more important
it cannot course also its change sign that means that
the displacement control of the pump can change direction
in an unexpected way.
In conclusion new advanced aeration model allows customer
to represent the pressure peaks within positive displacement pumps
for any technology and also to represent the force acting
on the device for to the flow control regulation of the pump.
Thank you for watching, for more information please visit our website.