A1V1 = A2V2 (A :: Area, V :: Velocity).....(1); p + 1/2(rho)V^2 = const. (p :: pressure, Rho :: Density)...... (2); so, when there is an increase in cross sectional area, velocity decreases (Eq1) Decrease in velocity, increases pressure (Eq2) So pressure increases when velocity increases
S.F.E.E. is the "Grandmother" of Thermodynamics! You can apply with sufficient accuracy if you chose the location 1 far upstream and location far downstream; to avoid unsteadiness due to the pulsating action taking place due to the intermittent action (to-and-fro motion) of the piston. This is to avoid unsteadiness to justify "Steady" flow in the application of SFEE. While applying the SFEE to reciprocating pumps, you have to make the assumtions of no heat transfer and no change in internal energy. In doing so, you'll get the famous pump equation.
The 'dot' is put to indicate the time rate of flow ('rate' means speed). If there is no flow then there is no need to punt dot. Remember that using symbols, superscripts, subscripts, etc., are merely is a matter of convenience to express physical ideas and significance of certain terms and phenomena in terms of short-hand notation instead of using too many words or sentences. For example, the Newton's second law of motion is expressed by F = ma (i.e., the net force acting on a body of fixed or constant mass will always accelerate that mass. If there is no net force then 0 = ma or ma = 0. Since, in pure mathematics, if xy = 0, means either x = 0 or y = 0 or both are zero, which we apply to ma = 0. Since 'm' is not equal to 0, therefore, 'a' must be zero, which means if the mass has already been accelerated and is in motion will now move with a constant velocity (called terminal motion).
The work (or power) in the case of nozzles, diffusers, throttling or expansion devices, heat exchangers (boilers, condensers, evaporators, superheaters, economizers, pre-heaters, etc.) is zero simply because there are not moving parts. As far as the modelling of nozzles and diffusers is concerned, the heat transfer to or from the control surface is zero because either insulation is provided or very high speed flow through them, the surface area is relatively short/small so there is insufficient time for the control volume and its surroundings to exchange heat energy through the boundary (or control surface). That is why nozzles and diffusers are called adiabatic ducts. In actual circumstances, there are stray heat losses; no doubt. Remember that, more heat losses will affect (i) the exit kinetic energy in the case of nozzle (that will be reduced) and (ii) the pressure or enthalpy in the case of diffusers which will be reduced.
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Thanks for all your lessons so far, u are loved❤
Sir If we compare diverging nozzle and diffuser (having same shape ) why they work different . Explain sir
Thank you sir🙏❤️
thank you
sir if velocity increase than why pressure decrease?
it should be increase
A1V1 = A2V2 (A :: Area, V :: Velocity).....(1);
p + 1/2(rho)V^2 = const. (p :: pressure, Rho :: Density)...... (2);
so, when there is an increase in cross sectional area, velocity decreases (Eq1)
Decrease in velocity, increases pressure (Eq2)
So pressure increases when velocity increases
Mixardry thank you
Bernoulli equation.
th-cam.com/video/JFeQZeeGsdU/w-d-xo.html
Flow always happen higher pressure side to lower .but in diffuser how will pressure increase from low to higher.i dont understand please explain.
Sir can you recommend some link for these Explaination especially for SFEE for nozzle. I'm preparing for my assignment
Is Adiabatic process in nozzle sir
U r awesome sirji
Thanks for your videos. It is helping me a lot!
Thank you sir
Sir
Can we apply s.f.e.e on reciprocating pump?
No, it is an example of unsteady flow, but you can go for control volume approach.
S.F.E.E. is the "Grandmother" of Thermodynamics! You can apply with sufficient accuracy if you chose the location 1 far upstream and location far downstream; to avoid unsteadiness due to the pulsating action taking place due to the intermittent action (to-and-fro motion) of the piston. This is to avoid unsteadiness to justify "Steady" flow in the application of SFEE. While applying the SFEE to reciprocating pumps, you have to make the assumtions of no heat transfer and no change in internal energy. In doing so, you'll get the famous pump equation.
why there is no work done in case of nozzle?
No moving parts nd no heat is supplied or rejected
See my reply to Mr. Karan Singh Chouhan, who asked the same quation.
tq sir
Sir what is m raise to the dot
mass flow rate
The 'dot' is put to indicate the time rate of flow ('rate' means speed). If there is no flow then there is no need to punt dot. Remember that using symbols, superscripts, subscripts, etc., are merely is a matter of convenience to express physical ideas and significance of certain terms and phenomena in terms of short-hand notation instead of using too many words or sentences. For example, the Newton's second law of motion is expressed by F = ma (i.e., the net force acting on a body of fixed or constant mass will always accelerate that mass. If there is no net force then 0 = ma or ma = 0. Since, in pure mathematics, if xy = 0, means either x = 0 or y = 0 or both are zero, which we apply to ma = 0. Since 'm' is not equal to 0, therefore, 'a' must be zero, which means if the mass has already been accelerated and is in motion will now move with a constant velocity (called terminal motion).
why work is zero?
The work (or power) in the case of nozzles, diffusers, throttling or expansion devices, heat exchangers (boilers, condensers, evaporators, superheaters, economizers, pre-heaters, etc.) is zero simply because there are not moving parts. As far as the modelling of nozzles and diffusers is concerned, the heat transfer to or from the control surface is zero because either insulation is provided or very high speed flow through them, the surface area is relatively short/small so there is insufficient time for the control volume and its surroundings to exchange heat energy through the boundary (or control surface). That is why nozzles and diffusers are called adiabatic ducts. In actual circumstances, there are stray heat losses; no doubt. Remember that, more heat losses will affect (i) the exit kinetic energy in the case of nozzle (that will be reduced) and (ii) the pressure or enthalpy in the case of diffusers which will be reduced.
I think your explanation is not sufficient for me ..please relate nozzle and diffuser with mach number...then I will be satisfied
2nd diagram is nozzle
th-cam.com/video/JFeQZeeGsdU/w-d-xo.html