Table of Contents
What is a convergent divergent nozzle?
This nozzle configuration is called a convergent-divergent, or CD, nozzle. In a CD nozzle, the hot exhaust leaves the combustion chamber and converges down to the minimum area, or throat, of the nozzle. The throat size is chosen to choke the flow and set the mass flow rate through the system.
What type of nozzle is used in a rocket?
Ramjets and rockets typically use a fixed convergent section followed by a fixed divergent section for the design of the nozzle. This nozzle configuration is called a convergent-divergent, or CD, nozzle. In a CD nozzle, the hot exhaust leaves the combustion chamber and converges down to the minimum area, or throat, of the nozzle.
How does the Mach number of a nozzle increase?
In a steady internal flow (like a nozzle) the Mach number can only reach 1 at a minimum in the cross-sectional area. When the nozzle isn’t choked, the flow through it is entirely subsonic and, if you lower the back pressure a little, the flow goes faster and the flow rate increases.
What is a CD nozzle?
A nozzle is a relatively simple device, just a specially shaped tube through which hot gases flow. Ramjets and rockets typically use a fixed convergent section followed by a fixed divergent section for the design of the nozzle. This nozzle configuration is called a convergent-divergent, or CD, nozzle.
When is the flow through the nozzle subsonic?
Figure 3a shows the flow through the nozzle when it is completely subsonic (i.e. the nozzle isn’t choked). The flow accelerates out of the chamber through the converging section, reaching its maximum (subsonic) speed at the throat.
What is the change in density in a supersonic flow?
But in supersonic flows, there are two changes; the velocity and the density. The equation: tells us that for M > 1, the change in density is much greater than the change in velocity. To conserve both mass and momentum in a supersonic flow, the velocity increases and the density decreases as the area is increased.