Why does velocity increases in divergent nozzle?
In divergent portion of nozzle , specific volume of fluid increases at a higher rate than the crossectional area along the divergent portion. So to maintain constant mass flow rate (M=A*V*density), velocity of flow increases reaching Mach numbers greater than one.
Does the fluid pressure increase or decrease as fluid speed increases?
Bernoulli’s Principle states that as the speed of a moving fluid increases, the pressure within the fluid decreases.
What happens when supersonic flow comes across a divergent nozzle?
When supersonic flow comes across a divergent nozzle, its density reduces. Therefore, it accelerates, keeping mass flow rate constant. The nozzle has three parts: a convergent part, a throat and a divergent part. For the entire flow through the nozzle, the mass is conserved.
Why does the pressure decrease in a convergent nozzle?
In a convergent nozzle, there is an increase in velocity and a decrease in pressure, but we know that pressure is inversely proportional to area. Then why is this pressure decreased in convergent nozzle, although there is a decrease in area? The pressure drops in a convergent nozzle because of the Bernoulli Principle.
Why does the nozzle speed up as the fluid enters?
As a fluid enters the smaller cross-section, it has to speed up due to the conservation of mass. To maintain a constant amount of fluid moving through the restricted portion of the nozzle, the fluid must move faster. The energy to make this fluid speed up has to come from somewhere.
How does area affect the speed of a supersonic flow?
On the other hand, if the converging section is small enough so that the flow chokes in the throat, then a slight increase in area causes the flow to go supersonic. For a supersonic flow (M > 1) the term multiplying velocity change is negative (1 – M^2 < 0). Then an increase in the area (dA > 0) produces an increase in the velocity (dV > 0).