Thứ Sáu, 31 tháng 3, 2017

Waching daily Mar 31 2017

Spice is nice,

You get spliced,

Pass the glitterstim,

Spice is nice,

It's a good laugh with giggledust.

What's Membrosia?

It's not spice, but it's so good,

It's addictive,

So will you (just) pass me some more.

The best spice comes from the spice mines of Kessel,

But the workers are more like slaves,

And the energy spiders could swallow you whole,

So I must confess, I'm unimpressed.

And as for this Killik milk, those big bugs,

It's rare and costs way too much.

But I'll go broke if I have to I swear,

Just for some more Membrosia!

I'm a bit high! I'm a bit high!

I'm a bit high!

Smuggler's Delight for some counter effects.

Yeah! Huh, come on! Yeah! Uhuh. All right. Come on.

You think I'm a glit(ter)biter,

Because of my addiction,

A little more glitterstim,

Won't make much a difference.

(So maybe) I can't stop myself now,

But maybe a little later,

I just need a bit more,

Just another fix.

Booster's Blue is so much better than Spliff, yes!

Have you tried the Milia Flower yet?

I'm addicted.

I'm addicted.

To Engspice!

Sweetspice!

Greespice!

(I'm) Addicted (and) I don't care.

Yeah!

Spice is nice,

You get spliced,

Pass the gli-itterstim,

Spice is nice,

It's a good laugh

With giggledust.

What's Membrosia?

It's not spice, but it's so good,

It's addictive,

So will you (just) pass me some more.

I want more.

I want more.

Spice!

Hey, what's up with that act, you can't even be timed with the last note!

Dude, I think they're high on spice.

Yeah, well if you ask me, they're always high on spice.

For more infomation >> SWTOR Cantina Music: Spice Is Nice (Gameplay Video Parody) - Duration: 3:34.

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SO THIS IS WHY EVERYONE LOVES THE WINTER XGAMES - Duration: 6:22.

Good Morning!

And welcome to Lillehammer.

It would be sweet if the bus was here, so that we can...

It's 10th of March,

and we are on our way to the slopes.

It's the Winter XGames,

and...

I'm a little hungover.

"you know you're hungover, when you have to pull out the handicap ramp."

On point today.

If you look at his profile pictures on facebook...

I open door for you.

New profile picture right here.

Hi, welcome to Lillehammer.

This is Erik.

We look pretty similar today.

It's because your stealing my style.

You're stealing my style.

Why does it smell like shit here?

We are on our way up to the top of the slopes.

I'm here with Stisema, who is playing on Saturday.

It's going to be awesome.

XGames. Beautiful weather.

Hafjell is looking good.

Erik Ruud here.

Lets run some cinematic, and enjoy the rest of the day!

Rull film!

For more infomation >> SO THIS IS WHY EVERYONE LOVES THE WINTER XGAMES - Duration: 6:22.

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Hydraulic modelling using Wanda - Duration: 33:58.

hi I Mike Crowley and today at fluid

mechanics I'm going to give an

introduction to the Wanda software tool.

Wonda is a software program for

modeling pipeline systems it's very good

at doing steady state and transient flow

analysis particularly of long pipe lines

and long pipeline systems today I'll

give an introduction to the user

interface and i'll show you how to build

a model using Wanda. I'll build a

model of two reservoirs connected with a

pipeline with a valve between them and

i'll show you what happens when you

close the valve when the flow is running

and you'll get a surge event or a water

hammer event in the pipeline I'll show

you how to do this shortly at fluid

mechanics.

So this is the user interface you're

presented with when you start. Here is

the working area where you're actually

going to build your model. Over here we

have a palette of components which will

build the model with and here is a

property window. Now within the palette

of components or shapes you have various

components we have tanks pumps all the

sort of basic sort of hydraulic

components that you you could want to

use. Within wonder I'm not going to be

going into this today but they have

other modules they can do heat transfer

and basically if we click on the tab for

that then those components for doing

heat transfer and they also have

components for doing more sophisticated

control systems but we're going to be

just dealing with the the Wonder liquid

components today. So we want to have two

tanks so the first thing we need to do

is select the tank or a reservoir in

this case so we're going to just use two

reservoirs at different heights and

we're going to connect them together. So

we just drag and drop the reservoir into

into the working space now as I said

we're going to have two reservoirs. So

just move that over a little bit. So I

just click click on another one and I'm

going to drag that over there. Now what

I'm going to do is have an undulating

pipe and in the middle of the pipe I'm

going to have a an air vent valve. So the

next thing we need to do is select a

pipe so this is the pipe component here

and we'll drag this in. Now we can we'll

be putting a profile in for that

pipeline in a minute and as it showing

how it goes up and down over Hills but

because as I say we want an air vent we

need to select two pipes and between the

two pipes will put the air vent.

Down here we have an air vent so I

think it's that one there. As you hover

over the the components it tells you

what they are. So this is what we want

so this is the the air vent and we're

going to need a valve at the end of the

pipeline because we're going to do a

simulation later on where we actually

close the valve. so that's the valve that

we're going to use.

Okay so they're the the basic components.

I think that's all we need to do this

this model. We now need to connect the

the components up so we go over here to

the connection and this basically

creates nodes between the various

components and we just connect them up

so I connect that to that that pipe to

that pipe. Clearly it doesn't

really matter too much where you put

things on the sheet. And we

then connect up the air vent in between

those two pipes there. I'll go back to

that mode so the first thing we need to

do is set up the tank. so we'll set up

that tank there and I say tank reservoir

as I said there's a couple of different

types of reservoir we can use this is

what we call an infinite area reservoir

so it doesn't matter how much fluid

fluid comes out of this reservoir the

level is always going to stay the same

there are other options this is a tank

with so if I put that in this has got a

limited area so effectively as the fluid

comes out of the tank the level would

start to drop but just to keep things

simple for the time being we'll just

we'll have a intimate area reservoir so

once we click on the component you'll

notice the property window comes alive

and start showing the options now this

property window is used for putting in

the parameters for that component and

after we've run the model will be able

to look at the results in this window as

well so most of the component we don't

need to do anything but the thing we do

need to say is the height of the

reservoir so I'm going to just for this

particular example put the height at 25

meters now we also need to set the

heights at the nodes between the

components okay and I'm going to set

that 25 meters actually you might say

well why why we're saying that and the

tank it took lemon's we could have set

that to a lower lower level you know the

outlet could be at the bottom of the

reservoir but just keeps things simple

I'm gonna set that to 25 meters to now

we've got the pipes here and the

valve now what we can do is some of the

values are going to be the same for all of

these three here so we've got the two

pipes and we've got the valve I mean as

you click on

components you'll see that different

parameters come up so there's the valve

there's the pipe okay but one thing I

know if I if I hold the shift key I can

select all three components together and

what you'll notice here is some of

the components some of them the names

are in red and some of them black and

what it means is when it's in red it

means that the values between the

different components is different so I'm

going t0. what we're going to do is

is the thing that we have the same for

all of them is the size so I'm going to

just say the the diameter for those and

we'll just set it for this example to

150 millimeters okay now if I set that

to 150mm you'll notice straightaway

that that's only set it for that

component there and the numbers come up

red that means that all the other the

other components have got different

values so what you can do is you got

that selected if you select that just

copies it through to the other ones

which is what you want which I which is

what I wanted to do now if i go back to

just selecting the pipes next for the

pipes i'm going to also set the wall

roughness and i'm going to set that to

one millimeter okay there are various

ways of working out friction.

the one I'm going to be

using as a Darcy formula with Colebrook-White

friction calculation now let's go

back to this pipe well actually what I'm

going to do is going to put a profile in

for the pipe okay so if i wanted to i

could just set the length of the pipe

and then it will just take the levels

from the nodes on either end but i'm not

going to do that what i'm going to do is

put a profile in so this is length hight

so then then what happens is you can go

down and we get a table a profile table

okay and we can put the the chainage in

and then we can put the the actual enter

the pipe in so basically we're going to

start off at this end of the pipe at 35

meters. So 0 chainage and it's 35

meters and then that just for this

example I would say at 3,000 meters

we're going to go down to

0 enter will come up with a new line

and then I put it 7,000 meters and we're

going to put in 10 meters in there so

basically the pipe starts off at 30

meters drops down to zero then comes

back up to 10 meters so what we need to

do then is put on that on that node

there we just put in the level that we

had for that which is going to be 10

meters we'll keep that the same kind of

it's different and then for this pipe

here I'm just going to put in that the

the the pipe length is

we're going to go pipe length it's gonna

be 6,000 meters okay the valve I think

we've set up most of the things we

need for the valve yeah we've got the

diameter its initial position is

100% in other words it's

opened the other thing we need to set is

this level here so basically the

level at this end of that pipe is 10

meters in the middle there so that pipe

is 10 meters of that end how we're going

to set it dropping down to 5 meters at

that end there five meters okay and

that's also going to be 5 meters on the

other end of that size of that valve and

I think we put in the head of that tank

no we didn't head it's 5 meters so we've

got a tank in fact what we can do is

going to turn on that on some of the

numbers so that tells us that it's at

five meters and I just put that up there

and that's the 25 meters and it will

come up show you what the value is

that's just by clicking on that tick

box there that I just shows you on there on

the chart go be a bit careful if you

start putting too much of these down

you'll end up with them a very cluttered

screen we're going to just initially run

a steady state case and what you can do

is as an option here disuse in other

words we can turn it off and we're going

to i'm just going to turn it off yes so

you notice it goes a bit greyed out so

it's not connected okay so we should now

be in a position to run a sort of a

steady state anaysis

on that on that model so let's go

often when you tried to run the model

first there's always some error but

let's justjust see what happens so I

just first of all look at the fluid

window so this tells you the fluids

property now the standard fluid they

uses water and that's exactly what I'm

going to use so I don't need to change

any of these parameters here but but

clearly you could put in various

properties if you want to for

different fluids oils etc. Now

the other thing I should perhaps point

out is there's two modes of operation on

this model and the defaults when you

first start a model is what they call

engineering mode okay and this is what

sort of recommended to start a model

often and basically this is just going

to give you the steady state steady

state results and it's it's easiest to

run it in there's less likely that

you're going to get there's less

information needed so the model is going

to run if you went to go for the

transient case you'd need to put all the

transit information in and it wouldn't

run so we should better run the model

now so we go to calculate steady state

so value of wall so if I obviously

missed out saying value of all roughness

is missing so let's just go back to that

component and I thought I'd put that in

already but I had an obviously

1 millimeter I'm sure I put it for that

one yeah that's that one's correct so

let's just calculate steady state

okay so I needed to set the

characteristic for this valve we're

going to set it to standard valve and

the type of valve is going to be a

butterfly valve so I think there

might be other types yes but we're just

gonna use a butterfly valve for this for

this case and diameter D so now let's

just try and run that model calculate

steady-state just asking me do I want to

save it and I just say just say use them

so that little click there said that its

run the model that little beep you heard

okay so if we look at some of these

results we can see the pressures at

various nodes and actually so I just

clicked on that node there and the

pressure there if you look there the

it's got a negative gauge pressure so

there's something not quite right with

the mod load of expected the pressure

there to be around about 0 gauge so I

suspect I've probably done something not

quite right so we got that height there

as 25 meters and the tank is 25 meters

but let's just quickly look at the

profile of the main yeah I started that

off at 30 meters so in other words the

inlet to the pipe is higher than the

tank which is not quite right so we put

that to 25 meters and now let's try

running the model again okay so I click

on that yeah so now clicked on there

that the pressure there is 0 and you

would expect the pressure at this end as

well to be 0 that's great so that that

looks okay so if we look at the profile

so what we can do is we can select a

pipe and we can look at the pressure

profile along the pipe which is this one

here and that's showing the pressure so

it starts off at 0 at the tank increases

as the level descends and then as a

level comes back up so the pressure

increases decreases again what's more

useful actually a better way to look at

is we can select the two pipes okay and

we can look at the pressure profile over

the whole main and that's what's

happening so basically as the level goes

down the pressure goes up and then at

the end it comes down or alternatively

normally you look in terms of head the

red line there is showing you the

profile of the main okay so that's

actually that the level of the main so

so initially it starts off at 25 meters

and if you remember the table we put it

it goes down 20 meters at 3,000 meters

along it comes back where the air valve

is up to 7,000 meters up to 10 and then

it goes back down to five at the end so

that's the the profile of the main and

this is showing you the head the total

header along the main as you'd expect it

because it's a it's got a constant

diameter pipe it just decreases

gradually to the end so that's the

steady-state case and of course you can

look at the flow velocities in the pipe

so we can look at the velocity obviously

the velocity in the pipe is going to be

the same all the way along because it's

just a steady state case 0.36 m/s

or it's probably got

discharged flow rate so actually the

flow rate along the main 23 cubic meters

an hour before we go on to look at the

transient case we need to put in the the

air valve now looking at this if we look

at the pressure at this point here the

pressure sorry the pressure is positive

so I don't think we're going to get any

air coming in and out of that Val but

but still we'll set up the air valve now

and we'll just say yes to that so we

do want to use it now. now I'll just go

through these air valve some of these

terms are a bit

not very obvious so first of all we need

to get the level right so it's 10 meters

there so we need to put the elevation of

the air valves so normally actually you

might put the elevation the air valve

slightly higher than the pipe itself

because it would be above the ground and

the pipe would be below it but I'll just

keep it the same the Laplace coefficenct

when I first start using the stuff I

found this a bit confusing what Laplace

me what they really mean by this is the

the the ratios of specific heat

capacities you know the CP over which is

1.4 for air okay ambient temperature

would you say 20 degrees inlet discharge

coefficient this is about how much the

the contraction as it goes through i

usually put 0.7 in and

0.7 for this as well inlet discharge

area okay so I'm just going to say that

this is based on a sort of a 70

millimeter valve and you need

to put this in m^2 you

could put it in mm^2

and put it in m^2 and it's I

think it's 3850e-6

meters squared okay 3850 that that's

basically a 70 millimeter valve. to the

minus 6 initial air volume so this is

the actual air volume that you've

actually got in the valve when you start

and it's going to be zero there's

usually with these air valve some sort

of residual volume left in there and

where the float goes and I need to put a

number in for that so I need to put a

volume for that and I'm going to put in

0.1 okay

I think that's all the parameters we

need for that we'll just check that now

that the model still runs before we move

on to the steady state okay so when I

run the model just then I got an error

signal I've got two screens here and on

the other screen it's come up with the

error error that's just showing an error

there and just looking at this thing I'm

not so what's so I think what's actually

wrong is this elevation I've got

actually its elevation offset not

elevation so so what I should have said

is the offset 0 so it sort will change

that 20 i think yeah that probably solve

the problem and it's just um model run

that again calculate steady oh yeah and

that worked or okay now so we can see

the pressures and everything in there

but if we should actually look at the

valve if we look down here the air flow

is 0 because there is no negative

pressure the pressure is positive at

that at that point because it's a

positive pressure so now we are ready to

go for the the transient case so we first

of all need to swap over modes so

initially we were doing this engineering

mode we now need to go to transient mode

okay if these two yes okay now one we go

to the transient mode what you'll find

is if we look at the the model there's

more parameters to put in particular for

the pipes so we need to put in some

information for the pipes and the thing

that we really need to do is is first of

all we need to set the mode that we're

going to use and we're going to talk

about water hammer or

surge you can there's a number of

ways you could model it water hammer is

is is the proper way to do it that's

using what they call the method of

characteristics to to work out the water

hammer wave speed now you can you can

specify wave speed I have done another

video on how you actually calculate the

wave speed in water hammer events and it

may be well looking at that if you

actually want to

work out how to calculate it you can

actually put in the physical parameters

of the wall thickness and that and

that's actually what I showed you in the

other show in the other video how to

calculate the wave speed or actually can

just specify what the wave speed is I

tend to prefer to just specify what the

wave speed is and we're going to set

both of them both pipes the same wave

speed and we're going to set it at a

typical sort of wave speed for a plastic pipe

would be about 1200 meters a second

actually how quite right

so 1,200 meter but I need to obviously

copy that across to the other one okay

and also that needs to be specified for

both of them so we're going to do it

that way ok so this uses a system called

the method of characteristics to plot

the progression of the wave speed the

wave front going along the pipe it

basically breaks the pipe up into small

sections and we have what's known as a

fixed stepped solver so actually if

we go up here we need to change the time

parameters so what we need to do is

the time step so we can set set how the

short of the time step we set the more

accurate the results are going to be I'm

going to set it to a time step of about

0.1s I think that's good enough

foot for what we need here and we can

run the model for say 200 seconds of

simulation time there are other methods

that other softwares use I have given a

demonstration on simulation X and

modelica modeling that uses a different

way of modeling the progression of

waves along a pipe it's not really as

accurate as the method of

characteristics for long pipes this is

by far the most accurate method of using

it other methods basically what they do

is split the pipe up again into small

sections which is what this does but

then they look at the bulk modulus of

the sections and

actually the wave speed sort of

propagates along the whole whole pipe

almost instantaneously so it doesn't

quite give you the same characteristics

definitely the method of characteristics

for long pipes is by far the best the

reason why other software you use a

different method is because they use

variable type step solvers MATLAB

Simulink sim hydraulics use that as well

in their in their software this does

require fixed step time solver of them okay so

let's try running the model now and see

what happens honor we need to fit all so

what we're going to do here now is we're

going to actually close the valve so

we've got a valve we've got the position

and what we're going to do is we're

going to set up a table of closing it

over a period of time initial position

is 100% use action table that's what

we're going to do yes so action table so

at time 0 the valve is going to be a

hundred percent open so we put one

hundred percent in there then at time

one second it's still going to be a

hundred percent so initially what I'm

going to do is initially for the first

one second this will this will provide

steady state conditions that we want and

then what will say is over say a period

of 20 seconds will close the valve will

save 30 seconds to start with and we'll

go down to zero and then at 200 seconds

which is the end of the run you will

still be 0 okay so that's going to give

you your profile of the valve closing so

that's just come across your screen so

effectively that's what we've got going

down to zero

let's try running that and see what

happens so we're now going to do this

the transient case so that has run I

think and what we can do is we can now

if we click on the valve we can look at

the discharge now that should give us

the discharge over time so what you can

see is is the valve closing. Now

actually this is the flow rate through

the valve and i'll just show something

else as well on this valve the position

so this is showing you the position and

actually what we can do is we can bring

the two graphs in together what if you

click on if you click and drag it in you

bring the two in together so the valve

is closing and actually what you find

with a butterfly valve which is typical

is that butterfly valves they don't

actually start to shut off the flow rate

until you've got to quite closed. so if i

can if i zoom into this zoom if we zoom

into this safe for the first 20 30

seconds you'll find that it's only when

you get to about 20 seconds which is

about sorry looking over this way sort

of when you get to about twenty-five

percent closed that the the flow rate

actually starts to drop off okay close

that down so what happens what's

happening to the pressure so we can look

at that point there and we can see the

pressure and this is a sort of a typical

surge analysis of water hammer event so

as you close the valve the pressure

builds up and actually it's on the

second thing that you get the highest

pressure in the system and then it's

slowly decays away over time let's just

have a look at the whole pipeline so we

can click both of those pipes

and we can actually look at the pressure

through the whole pipe now what this

tells you is this is giving you the

maximum and minimum pressure up over the

whole pipeline okay this is showing you

the centerline of the pipe or the

pressure for the centerline of the pipe

and going up and down this is the

minimum pressure that's the maximum

pressure now it's perhaps a bit more

useful to actually show what's happening

in the transient case so what you can do is

we'll bring down this time navigator bar

let's put onto the screen so just bring

it across and this this will allow you

to see what's actually happening to

think so what we do is we press the

start button and it basically runs

through the model and it tells you

what's actually actually happening.

okay so there we go this is showing you

the initial pressure the blue line is

the initial pressure in the pipeline and

as you can see as the valve closed at

the end so let's just stop that for a

second so if we go back we start again

so we're now up to nine seconds and not

much is happening this is because the

valve is just starting to close now

we're getting to sort of 20 seconds and

the valve is closing and the pressure at

the end of the pipe is starting to shoot

up as it closed down that pressure wave

is then moving all the way along the

pipe to the end and it's sort of like a

40 seconds it's getting to the end and

and now we can see what's happening over

a period of time as the pressure waves

fluctuate in the pipe okay that's

showing you what's happening I'm going

to speed it up a bit and you can see the

propagation of the wave over time that

will start to die down and eventually

you'll get to the final condition which

is well that's not quite the final

because I stopped it before it

completely settled but we can also look

at the pressure in at the point here and

that's the way the pressure at various

points okay so if I if I looked at that

other plot and plotted out that various

times this is what we would get

okay so looking at the pressure here.

This is showing you the pressure

characteristic we got for that valve

closing so let's see what we can do to

try and smooth that out a little bit so

what I'm going to do is I'm going to

freeze that screen and when we make the

changes we can you can see what happens

to it freeze all series okay I'm just

minimize that for a minute now we had

look at this valve and as I said the

valve as I showed previously it didn't

actually do any didn't actually help

reduce the flow until we got down to

about twenty-five percent so if we

rapidly close the valve term to

twenty-five percent and then do the rest

of it slowly I think that will help

quite a bit so what we'll do is I'll

change this time so if we say in two

seconds it closes so the first second it

closes really rapidly down to

twenty-five percent and then if I put in

that in 20 seconds it's now down to zero

percent so it's actually going to close

the last bit over a lot longer period of

time and then in 200 seconds it's down

to well it's still at zero percent okay

so that's that's that's what we're going

to do let's bring back that sorry let's

just over here the the graph so if I

bring back that graph and I'll run the

model calculate transient yes okay so

that's run

so if I now go back to this point here

and I take those pressure and I put that

onto that graph right well you can see

it's it's it's obviously gone down and

it's the pressure started to rise a bit

earlier because it's actually doing

something useful at the start now and

because the pressure rise because it was

actually the closure is over a longer

period of time the actual effective

pleasure along is over long a period of

time the surge pressures that rise have

been reduced and clearly I mean this is

quite a long pipeline so to have any

sort of effect i mean this this is that

it's got a length of 7,000 meters and

and that one there is forgot what was

that we put down so I that that that

pipe their length is seven sets that's

thirteen thousand meters so if we have

thirteen thousand meters and we got a

wave speed of 1200 so obviously so

that's going to be about 10s

so 20 seconds is sort of

basically the minimum that you would

need. At 20 seconds you're still going to

get significant surge so we need to sort

of which increase the speed or reduce

the increase the time to close to it for

about 40 seconds I think to make any

significant difference to this so let's

go back to the valve but at 40 seconds

okay that's where you run the model

hopefully should just put the model back

in so as you can see it's time to now

smooth it out more and we can just make

one more effort on that I mean I think

you need to 80 seconds with probability

about as good as you're going to get so

try 80 seconds in there plus 80 seconds

as we run the model so i think that's

about as good as you can get without

using sort of search or some sort of

damping system in there and if we look

at the profile of the flow rate through

there you go coming down nice and slowly

and if we look at the whole pipeline now

what's happening in the whole pipeline

the surge pressure should now be a lot

less over the whole pipeline and so so

we're not going up as high as we were

previously. So in summary Wonda is an

excellent program for doing surge

analysis on long pipelines and pipeline

systems it uses the method of

characteristics which is proven to be

the best method of solving surge

analysis particularly in long pipe lines

if you have any general questions then

please leave a comment on my website

blog and I will endeavor to answer them

there I cannot answer any questions

directly of our email but if you need

more detail advice or help on a surge

on a consultancy type

basis then please contact me my

contact details are on my website please

subscribe to my youtube channel i think

there is a link above over there

somewhere and please like my video if

you found it useful thank you for listen

that's it's a day form fluid mechanics

goodbye

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