why we use convergent nozzles for subsonic aircrafts... how we can reach supersonic speed using the c-divnozzl

Question

aeronautics---propulsion

Answer 1

The proper shape of a nozzle depends on the highest velocity desired, relative to the sonic velocity.
To accelerate a fluid we must use a converging nozzle at subsonic velocities and a diverging nozzle at supersonic velocities.
The highest velocity that can be achieved by a converging nozzle is sonic velocity, which will occur at the exit of the nozzle. If the converging nozzle is extended further which will decrease the area in hopes of accelerating the fluid to supersonic velocities, we will discover that it cannot be done.
Extending the nozzle further only moves the sonic cross section farther downstream.
In order to reach supersonic velocities, it is required to add a diverging section to the exit of a converging nozzle.
The reason for this is that when the fluid leaves the converging nozzle at sonic velocity, and enters the diverging section, there is a large decrease in density of the fluid which makes acceleration in the divergent section possible, so to achieve mach numbers >1, we must use a converging-diverging nozzle.
An example of this type of flow is is the flow of hot combustion gases thru a nozzle in a gas turbine.
This issue is really a lot more complicated however because if the back pressure at the outlet of the diverging section is too high you will still not be able to reach sonic velocities with a converging diverging nozzle.

The opposite process must occur in the engine inlet of a supersonic jet.

Answer 2

The theory of duct buzz was developed by myself and one other engineer, principle in the development and testing of the F-107. Duct buzz is a very destructive flight mode. I hardly recommend it when considering things I don't want to break. Duct buzz has believe it or not more than one primary source. Back-pressure variation is conducive to some of these sources. Thus, flying at Mach + we can indeed achieve a physical distinction between certain vital parts of aircraft normally best kept unified. As flight without certain parts actually physically attached to the plane can be detrimental to ones bank account, most pilots prefer to maintain a unified front with regard to such matters. They don't break the plane showing off. Gen. Wade Edward Hinson (AKA Sen. Wiener) NC BS PHOL (etc.)

Answer 3

The size of the nozzle is critical for producing maximum thrust.
The variable nozzle system is designed to match the thrust of the engine at any given power setting.

Answer 4

it is a fact of mach number
if mach number is less than unity,then it is a subsonic fluid flow,
so subsonic is possible with the help of convergent nozzles

we can reach supersonic(mach number >1),if the velocity of the aircraft isgreater than the velocity of air