mambo1988
Guest
rho1 è in g/mperic3 e nonk/s
paulpaul
Guest
first calculate the depression you need in the throat section to recall the liquid from the container! at this point remembers the preservation of energy in the mechanical form, transcrating (for the moment) the load losses and considering the incomprehensible steam:
cdc + gdz + dp/rho = dl - dla
dl = 0 (no work)
dla = 0 (no friction)
dz = 0 (horizontal tube)
rho = constant (incomprehensible flow)
cdc + dp/rho = 0 (horizontal tube springs)
apply and integrates between the mountain section ('1' and the gorge '2')
(p2-p1)/rho = 0
c1 = upstream speed, note
c2 = speed sez. throat, unknown
p1 = mountain pressure, note
p2 = pressure throat, note (see above)
rho = density, note
then applies continuity between the same sections:
♪
s1 = mountain section, note
s2 = throat section, unknown.
two unknowns, two equations: get s2 according to the other parameters
for the divergent section applies the same relationships: the total flow this time is that of the steam + the detergent, and impose on section 3 the atmospheric pressure. You should be able, I hope I didn't take a bark! :
you can then refine the calculation considering the pdc and steam as a compressible fluid. Try to see what you get out of this way
cdc + gdz + dp/rho = dl - dla
dl = 0 (no work)
dla = 0 (no friction)
dz = 0 (horizontal tube)
rho = constant (incomprehensible flow)
cdc + dp/rho = 0 (horizontal tube springs)
apply and integrates between the mountain section ('1' and the gorge '2')
(p2-p1)/rho = 0
c1 = upstream speed, note
c2 = speed sez. throat, unknown
p1 = mountain pressure, note
p2 = pressure throat, note (see above)
rho = density, note
then applies continuity between the same sections:
♪
s1 = mountain section, note
s2 = throat section, unknown.
two unknowns, two equations: get s2 according to the other parameters
for the divergent section applies the same relationships: the total flow this time is that of the steam + the detergent, and impose on section 3 the atmospheric pressure. You should be able, I hope I didn't take a bark! :
you can then refine the calculation considering the pdc and steam as a compressible fluid. Try to see what you get out of this way
mambo1988
Guest
then I made some calculations, as data I have:
p1=6 bar
S1=8,04*10^-6m^2;
v1=45,02 m/s
using the equation of bernoulli and the continuity of mass flow in 2 I get by imposing a p=0,3 bar:
v2=600 m/s
S2=0210-7 m2
Can I get such a high speed?? ? ?
paulpaul
Guest
It's possible!
On the contrary, I should have known from before considering the relationship between the mountain pressures and what you need to aspire the cleaner!
In this case the pressure you need is less than that critical, you can not ignore the compressibility of the fluid and your duct while always assuming convergent/divergent form will have the slightest pressure on the valley section and not in the throat section, where the speed is sonic. then recompress the fluid to the atmospheric pressure, slowing it down, with a further convergent/divergent. Are you sure the vapor output pressure is 6 bar? It seems so much....it would give rise to very high output speeds: I believe that 6 bar is the value present in boiler, which also works by accumulation, but that at the lance (usually the mixer is mounted on the handle) the pressure has already been reduced by a reducer... but I am not designer of this type of machine it is only a consideration!
commercially you can find objects similar to these
http://www.demaeng.com/dairy-agriculture-irrigation/venturi-injectors/c-series-injectors/These are for liquids, but if you do research I think you will find other similar devices for other fluids.
Hi.
On the contrary, I should have known from before considering the relationship between the mountain pressures and what you need to aspire the cleaner!
In this case the pressure you need is less than that critical, you can not ignore the compressibility of the fluid and your duct while always assuming convergent/divergent form will have the slightest pressure on the valley section and not in the throat section, where the speed is sonic. then recompress the fluid to the atmospheric pressure, slowing it down, with a further convergent/divergent. Are you sure the vapor output pressure is 6 bar? It seems so much....it would give rise to very high output speeds: I believe that 6 bar is the value present in boiler, which also works by accumulation, but that at the lance (usually the mixer is mounted on the handle) the pressure has already been reduced by a reducer... but I am not designer of this type of machine it is only a consideration!
commercially you can find objects similar to these
http://www.demaeng.com/dairy-agriculture-irrigation/venturi-injectors/c-series-injectors/These are for liquids, but if you do research I think you will find other similar devices for other fluids.
Hi.
PierArg
Guest
Did you see it was what I said? :finger::biggrin
I think you should also know the extent of detergent you need.... is a feature of the application.
mambo1988
Guest
then, since I am doing an internship at a firm on which I will do the thesis I would like to dimensional everything and realize it (because we have the possibility).
for the cleaner I thought of a kind of screw that regulates the flow of the detergent, (if I don't want detergent it just passes steam).
we say that with the following assumptions:
-Incomprehensible vapor
-other load losses
I managed to dimensional finding v2 about= 600 m/s and s2= 0.8 mm possible??? ? I imposed that in s2 there is a depression considering 0.3 bar
thanks for the help you are demonstrating
for the cleaner I thought of a kind of screw that regulates the flow of the detergent, (if I don't want detergent it just passes steam).
we say that with the following assumptions:
-Incomprehensible vapor
-other load losses
I managed to dimensional finding v2 about= 600 m/s and s2= 0.8 mm possible??? ? I imposed that in s2 there is a depression considering 0.3 bar
thanks for the help you are demonstrating
PierArg
Guest
according to me 600 m/s are a so many "too many".
Generally depression is 0.5 - 0.6....the 0.3 you imposed is too much.
the amount of detergent is the function of the mixture you have to make.
but what application is it?
attention that for speed of 600m/s you are in mach2 and follow the laws of the gas movement at supersonal speed...with all its theories.
paulpaul
Guest
Mambo
I also remind you that pressure in thermodynamic and fluid dynamic formulas must always be expressed as absolute pressures (except, of course, where pressure differences appear).
then on the exit section in the environment you have no zero but 1 bar (1,01325 bar if we want to be pinion).
with regard to the necessary p pressure I would operate so, neglecting the load losses in the liquid and the speed variations of the liquid itself and considering the reservoir of the atmospheric pressure liquid:
p = patm - rho(l)*g*h
patm = 1,01325 bar as mentioned before
rho(l) = liquid density
g = 9,81 m/s^2
h = lifting height
to consider possible baiting
I also remind you that pressure in thermodynamic and fluid dynamic formulas must always be expressed as absolute pressures (except, of course, where pressure differences appear).
then on the exit section in the environment you have no zero but 1 bar (1,01325 bar if we want to be pinion).
with regard to the necessary p pressure I would operate so, neglecting the load losses in the liquid and the speed variations of the liquid itself and considering the reservoir of the atmospheric pressure liquid:
p = patm - rho(l)*g*h
patm = 1,01325 bar as mentioned before
rho(l) = liquid density
g = 9,81 m/s^2
h = lifting height
to consider possible baiting
mambo1988
Guest
but theoretically if I consider the relative pressure (i.e. the ambient pressure 0 bar and consider a negative pressure =-0.5 in s2 (restrict section)) the calculations should not be equal? ?
the work proceeds but I still have many doubts. ..however thanks again to all.:biggrin:
also a necessary pressure that sucking the cleaner depends only on this formula??? or should I also consider viscosity, etc...
sodering steam as an incomprehensible fluid, does not lead me to excessive approximations??? also this convergent as the quantum in terms of length?
MBT
Guest
Million heaps!
If you have such high pressures, maybe instead of the actual venturi it is for you to agree to use an ejettore.http://it.wikipedia.org/wiki/eiettoreso you don't need to go under the atmospheric pressure in the choking
If you have such high pressures, maybe instead of the actual venturi it is for you to agree to use an ejettore.http://it.wikipedia.org/wiki/eiettoreso you don't need to go under the atmospheric pressure in the choking
mambo1988
Guest
It would be a great idea if I'm not mistaken is what uses the paint gun, but I prefer, if I can, a simple venturi for ease of realization of the piece.
I found section s2, but I don't know if the assumptions made are too approximate.
I found section s2, but I don't know if the assumptions made are too approximate.
MBT
Guest
And I understand, I...
but if with a venturi you have to reach the speed of light in order to have enough depression, the ease of realization you will also have it, but you fight with other difficulties!
load losses first, wears, noise, difficulty adjusting. . .
look that when superi mach 1 you have the sonic bang, that you repercussion on all the tubes and fluids contained in them!
but if with a venturi you have to reach the speed of light in order to have enough depression, the ease of realization you will also have it, but you fight with other difficulties!
load losses first, wears, noise, difficulty adjusting. . .
look that when superi mach 1 you have the sonic bang, that you repercussion on all the tubes and fluids contained in them!
MBT
Guest
de stage docet!
mambo1988
Guest
ook I understand, but in theory in reality the speed should not be lower??? I hypothesized an ideal fluid.
also the sonic speed should be for water-steam at 650 m/s??? If I'm not mistaken!...in my calculations I get a speed in s2 of about 550 m/s.
do you say that it is impossible to achieve such a system?
also the sonic speed should be for water-steam at 650 m/s??? If I'm not mistaken!...in my calculations I get a speed in s2 of about 550 m/s.
do you say that it is impossible to achieve such a system?
MBT
Guest
Great calm.. .
yours repair the maintenance of the customer, by means equally "heavy duty", only that to avoid you embarrassment do not let you know! :36_1_13::3553::36_1_15:
MBT
Guest
apart from that I should deal with (and it's not the case, today...) but if your speed is lower, your depression will also be lower
Besides, you have to try to avoid trans-sonic regimes. or pass by, or stay well below!
It's like walking on the street. Right is fine. Left is fine. If you walk in the middle, sooner or later they crush you like grapes!
The sound is the same. If you're in subsonic, it's okay. If you're in supersonic, it's okay. If you're in trans-sonic... sooner or later you end the grapes (modified city)
mambo1988
Guest
Mythical de laval and I'd even hugoniot... .