# Mechanical Engineering - Steam Nozzles and Turbines - Discussion

Discussion Forum : Steam Nozzles and Turbines - Section 1 (Q.No. 1)
1.
A nozzle is said to be a convergent nozzle
when the cross-section of the nozzle increases continuously from entrance to exit
when the cross-section of the nozzle decreases continuously from entrance to exit
when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
none of the above
Explanation:
No answer description is available. Let's discuss.
Discussion:
18 comments Page 1 of 2.

Imroz alam said:   3 years ago
Well said thanks @Imroz Alam.

Chakri said:   4 years ago
If pressure decreases then what about the velocity in the convergent nozzle?
(1)

Vivek said:   5 years ago
Well said, Thanks @Ssaikumar.

Kamlesh said:   5 years ago
Well said, Thanks @Saikumar.

Audut Hattale said:   6 years ago
Convergent Nozzle means decrease in cross-section gradually from entrance to exit.

Srinivasan said:   8 years ago
You explanation is very correct & good @Saikumar.

Arun said:   8 years ago
The area increase then the pressure decrease.

IND said:   8 years ago
Convergent Nozzle means decrease in cross-section gradually from entrance to exit.

Which is increase in cross section gradually from entrance to exit is called Divergent Nozzle.
(1)

SURYA said:   8 years ago
Convergence means gradually decrease area of flow line. That means answer should be B.

Saikumar said:   9 years ago
The pressure drops in a convergent nozzle because of the Bernoulli Principle.

A nozzle is a spout on the end of a hose or pipe used to control the movement of a fluid like water or air. A convergent nozzle is a nozzle that starts big and gets smaller-a decrease in cross-sectional area. 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. Some energy is in the random motion of molecules, which we observe as pressure. The energy in this random motion is converted into faster forward motion, known as stream flow. This change makes the pressure drop.

Pressure is inversely proportional to area, if everything else stays the same. In this case, the energy that causes pressure is converted to another type of energy, so both pressure and area decrease.