cacciatorino
Guest
If by renewable we mean the biodiesel that causes deforestation and hungers the poorest in Latin America, the budget becomes questionable....:frown:
Goticaa85M
Guest
I work on those shipyards, with power turbines at 6 stages, have always been realized by fiat avio, since the 70s.
the pinion, instead, treats the same machine, at least for the gas generator part, but the complete with a 2-stage power turbine.
snaroz
Guest
but in a car turbine the speed of exhaust gases at the entrance is greater than that at the exit? I mean, are the exhaust gases "frenated" by the turbine? and if the exhaust gases were really braked by the presence of the turbine, should the engine performance not worsen? or perhaps the fact of sending compressed air to the motor allows not only to cancel the loss of performance due to the presence of the turbine (which brakes the gases), but even to increase the overall performance?
Thanks
Thanks
MBT
Guest
in fact the turbine "frena" the motor.
Similarly the volumetric compressor "rub" energy to the motor.
but what "even" inside the engine makes you recover it with great interests... ;-)
Similarly the volumetric compressor "rub" energy to the motor.
but what "even" inside the engine makes you recover it with great interests... ;-)
snaroz
Guest
Hello, guys, I wanted to know: When talking about pressure fluids (such as compressed air, pressure oil etc...) is a high-speed particle flow? and the task of the impeller of a centrifugal compressor is to raise the speed of the incoming fluid (which means putting it in pressure)? Thank you so much!
PierArg
Guest
Not usually.
the air is compressed by the turbo compressor because you need more mass flow in the combustion chamber... consequently, to make it stand in more, it compresses and increases the pressure.
idem for oil.
note: wrong conception of the use of the word "high pressure washing".
surely you will have happened to go to a car wash "do it yourself" and read: washing with high pressure water.
It's true, the high pressure is there, but it's in the tube of the spear. the one that arrives at the stain is ambient pressure water that has transformed the pressure in speed thanks to the nozzle.
should call it "high-energy kinetic washing."
Excuse my digression from mental deviation.
the air is compressed by the turbo compressor because you need more mass flow in the combustion chamber... consequently, to make it stand in more, it compresses and increases the pressure.
idem for oil.
note: wrong conception of the use of the word "high pressure washing".
surely you will have happened to go to a car wash "do it yourself" and read: washing with high pressure water.
It's true, the high pressure is there, but it's in the tube of the spear. the one that arrives at the stain is ambient pressure water that has transformed the pressure in speed thanks to the nozzle.
should call it "high-energy kinetic washing."
Excuse my digression from mental deviation.
zeigs
Guest
quoto pierarg: pressure is a "static" feature, in practice I can have a steady fluid and keep it in pressure. in practice is a macroscopic effect of particle movement (such as temperature). then I can transform this potential energy into kinetics (by means of the nozzle) and hence the relationship greater pressure (before the nozzle)-> higher speed (after the nozzle).
in the centrifugal compressor in reality I have that in the impeller I give kinetic energy, in the form of speed (the blades "light" the particles), then it is in the coclea (I hope it is the right term) that this energy transforms it into pressure, slowing it and making it increase pressure (a little like the water of the spear on the hand gives me a feeling of pressure, when in reality the water is not in pressure, but only fast,
in the centrifugal compressor in reality I have that in the impeller I give kinetic energy, in the form of speed (the blades "light" the particles), then it is in the coclea (I hope it is the right term) that this energy transforms it into pressure, slowing it and making it increase pressure (a little like the water of the spear on the hand gives me a feeling of pressure, when in reality the water is not in pressure, but only fast,
snaroz
Guest
I have not understood guys
in 8 bar domestic compressors it is commonly said: "the air pressure coming out of the tube is 8 bar." in autotraction compressors I often read phrases like: "The air fired from the turbo comes out at the pressure of 1 bar." ..or "home tap water comes out at about 2-3 bar". phrases of this type have put in crisis my previous concept of pressure and have made me associate it to fluids that move at high speed. so I see the pressure as a concept both "static" (pressure of a fluid in a cylinder), but also as "dynamic".
I see an air compressor (which is centrifugal or piston) simply as an "air particles accelerator".
thanks for your explanations!
in 8 bar domestic compressors it is commonly said: "the air pressure coming out of the tube is 8 bar." in autotraction compressors I often read phrases like: "The air fired from the turbo comes out at the pressure of 1 bar." ..or "home tap water comes out at about 2-3 bar". phrases of this type have put in crisis my previous concept of pressure and have made me associate it to fluids that move at high speed. so I see the pressure as a concept both "static" (pressure of a fluid in a cylinder), but also as "dynamic".
I see an air compressor (which is centrifugal or piston) simply as an "air particles accelerator".
thanks for your explanations!
PierArg
Guest
point 1:
a fluid moves thanks to the pressure difference. It is not said that a pressure fluid should be static.
for example suppose a plant where water circulates at 100 bar. after 10 meters and some discontinuities will have suffered load losses that will bring the fluid to 99,5 bar.
the fluid is under pressure and still moves.
point2:
home water coming out of the tap is atmospheric pressure while in the tap is at 2-3 bar.
what comes out is water with kinetic energy equal to what is obtained by turning 2-3 pressure bar through the tap diffuser
a fluid moves thanks to the pressure difference. It is not said that a pressure fluid should be static.
for example suppose a plant where water circulates at 100 bar. after 10 meters and some discontinuities will have suffered load losses that will bring the fluid to 99,5 bar.
the fluid is under pressure and still moves.
point2:
home water coming out of the tap is atmospheric pressure while in the tap is at 2-3 bar.
what comes out is water with kinetic energy equal to what is obtained by turning 2-3 pressure bar through the tap diffuser
paulpaul
Guest
exact, although in reality this is true only for zero-reaction-grade machines, those in which the static pressure change (more correctly than static thalpy) is concentrated all in the diffuser (for compressors) or in the distributor (for turbines). normally in centrifugal compressors a part of the compression is actually carried out by the impeller.
snaroz
Guest
we take a very powerful hairdryer or fan: air fired from these devices is high pressure, but it is not compressed. Is that right?
PierArg
Guest
no, if he hears you fulvio, he makes you banish (snake!).
once in a discussion he tried to explain the difference between a fan and a compressor.
the fan does not generate a deltap
once in a discussion he tried to explain the difference between a fan and a compressor.
the fan does not generate a deltap
PierArg
Guest
Accommodation:
http://www.cad3d.it/forum1/showthread.php?t=18446&highlight=differenza+ventilatore+compressoreread what writes lightning at post 3 and 5.
http://www.cad3d.it/forum1/showthread.php?t=18446&highlight=differenza+ventilatore+compressoreread what writes lightning at post 3 and 5.
paulpaul
Guest
interesting discussion that I had lost! of the rest I am a novice of the forum! :smile:
Ing Italy
Guest
odour that a fan does not generate a deltp comes to me new...in reality I would say that a fan provides mainly static pressure load and a negligible dynamic pressure load (they also confirm the programs for fans with prevalence curves)...the question is that the static pressure load that generates is much lower than the pressure load generated by a compressor: to give an idea a fan works with compression ratio of about 1.01 and a compressor with 1.2 more or less. this difference causes the air flow that passes through a fan to be considered incomprehensible. This reasoning on the motion inside the channel palare then it is obvious that if the air in mandate is present in the atmosphere then the static load is canceled and becomes all dynamic but only because there is the energy transformation from pressure to kinetic energy or potential but the original energy is of pressure
paulpaul
Guest
Bye-bye!
I agree with the lightning post here:smile:
a fan generates a predominantly dynamic prevalence (they are used to accelerate an aeriform, so as to let him win just the load losses or the pressurizing or depressurizing slightly closed environments).
somewhere some author even said that an operating machine can be called fan (and not compressor) if its static prevalence is less than 1/10 of the total prevalence.
in fact they are usually without diffuser, because the purpose is not to elevate the pressure but to "accelerate" the fluid. Obviously, you will also have an increase in static pressure downstream of the machine if this is placed in a pipeline that as such has load losses.
manufacturers in fact normally provide total deltap diagrams - flow rate. but we typically talk about some tens or pmax a few hundred mmh2o!
the fact that fans are more "accelerant" machines than "diffondents" makes to them very low reaction degrees (the relative speeds in input and output are practically equal, as well as the speed of drag).
a compressor, however, as you rightly said, if free in the atmosphere does not generate static prevalence if not the one necessary to allow the only transfer of the fluid from the aspiration to the mandate. only that a compressor, once put in a conduit, is able (for construction) to support much greater prevalences (also depends on the type of machine!) than those related to load losses, typically comparable by a fan: i.e. the particular process in which the compressor is inserted.
I agree with the lightning post here:smile:
a fan generates a predominantly dynamic prevalence (they are used to accelerate an aeriform, so as to let him win just the load losses or the pressurizing or depressurizing slightly closed environments).
somewhere some author even said that an operating machine can be called fan (and not compressor) if its static prevalence is less than 1/10 of the total prevalence.
in fact they are usually without diffuser, because the purpose is not to elevate the pressure but to "accelerate" the fluid. Obviously, you will also have an increase in static pressure downstream of the machine if this is placed in a pipeline that as such has load losses.
manufacturers in fact normally provide total deltap diagrams - flow rate. but we typically talk about some tens or pmax a few hundred mmh2o!
the fact that fans are more "accelerant" machines than "diffondents" makes to them very low reaction degrees (the relative speeds in input and output are practically equal, as well as the speed of drag).
a compressor, however, as you rightly said, if free in the atmosphere does not generate static prevalence if not the one necessary to allow the only transfer of the fluid from the aspiration to the mandate. only that a compressor, once put in a conduit, is able (for construction) to support much greater prevalences (also depends on the type of machine!) than those related to load losses, typically comparable by a fan: i.e. the particular process in which the compressor is inserted.
Ing Italy
Guest
hi paul!in this case I disagree with you:
allego:
http://www.manualihoepli.it/media/doc/pr217.pdf (linea dei carichi fig.)
_ (load line p.390)
http://www.dynair.it/catalogocompleto/ita/pdf/intro.pdf (paragraph 1.4)
Good morning!
allego:
http://www.manualihoepli.it/media/doc/pr217.pdf (linea dei carichi fig.)
_ (load line p.390)
http://www.dynair.it/catalogocompleto/ita/pdf/intro.pdf (paragraph 1.4)
Good morning!
paulpaul
Guest
a little healthy comparison doesn't hurt anyone! :smile:
Helps to spread doubts on both sides!
As the question is perhaps more academic than practical, I think we are turning around the same thing more or less: the sense of my earlier intervention was to say that a fan mainly gives kinetic energy to the fluid (so dynamic pressure) for "geometria" of the blade itself. to underline that the desired effect is the increase in dynamic pressure, these machines are not usually equipped with diffused palettes downstream of the impeller, if the spiral wanted of centrifugal fans is excluded, whose function is above all to collect the fluid and "canal" it in a duct, and in which a certain static pressure recovery is carried out at the expense of the dynamic pressure.
If the fan is inextricted in a conduit that has load losses, we will have a "matching" between machine and circuit where the total pressure in static and dynamic will be divided according to both the characteristics of the circuit and the machine.
On the other hand, a dynamic compressor stage has a rotoric scaffolding already having a degree of reaction not negligible, thus operating a certain compression already on the rotor (by slowing the fluid): but, above all, it presents the downstream static scaffolding expressly designed to further slow the fluid and give it pressure.
it turns out that, when a compressor is placed in a conduit, it is able to support a static deltap decidedly higher than that of the fan that, at most, can transfer in static all the total pressure in case limit in which the fluid is arrested (and it is spoken of a few hundred mmh2o).
I repeat, it is a rather academic question: there are "sufficient" spreads for fans with prevails almost from compressors! for certain machines there can actually be an overlap! :smile:
Helps to spread doubts on both sides!
As the question is perhaps more academic than practical, I think we are turning around the same thing more or less: the sense of my earlier intervention was to say that a fan mainly gives kinetic energy to the fluid (so dynamic pressure) for "geometria" of the blade itself. to underline that the desired effect is the increase in dynamic pressure, these machines are not usually equipped with diffused palettes downstream of the impeller, if the spiral wanted of centrifugal fans is excluded, whose function is above all to collect the fluid and "canal" it in a duct, and in which a certain static pressure recovery is carried out at the expense of the dynamic pressure.
If the fan is inextricted in a conduit that has load losses, we will have a "matching" between machine and circuit where the total pressure in static and dynamic will be divided according to both the characteristics of the circuit and the machine.
On the other hand, a dynamic compressor stage has a rotoric scaffolding already having a degree of reaction not negligible, thus operating a certain compression already on the rotor (by slowing the fluid): but, above all, it presents the downstream static scaffolding expressly designed to further slow the fluid and give it pressure.
it turns out that, when a compressor is placed in a conduit, it is able to support a static deltap decidedly higher than that of the fan that, at most, can transfer in static all the total pressure in case limit in which the fluid is arrested (and it is spoken of a few hundred mmh2o).
I repeat, it is a rather academic question: there are "sufficient" spreads for fans with prevails almost from compressors! for certain machines there can actually be an overlap! :smile: