Case a: When the nozzle isn't choked, the flow in both sections of the • nozzle is subsonic. Case b: As the back pressure is lowered the flow speed increases • everywhere in the nozzle and eventually reaches the sonic speed (Mach 1) at the throat, but continues to be subsonic in the divergent part. Case c: further reduce in pressure will result in a supersonic flow in the • divergent part, but as the back pressure is not low enough the supersonic acceleration is terminated by a normal shock wave after which the flow will be subsonic. Case d: further decrease in the back pressure will result in the movement of • the normal shock to the nozzle exit. Case e: That is an under expanded nozzle. • Case f: The design point of the nozzle. The back pressure is low enough • such that the flow will be fully expanded and supersonic flow is generated. Case g: That is an over expanded nozzle. • Chapter Two Problem Description and Mathematical Formulation. - Problem description and boundary conditions. A quasi 1-D inviscid compressible flow through a converging-diverging nozzle (CD) is assumed to take place. The area of the nozzle varies according to equation (2).
• Case a: When the nozzle isn't choked, the flow in both sections of the nozzle is subsonic. • Case b: As the back pressure is lowered the flow speed increases everywhere in the nozzle and eventually reaches the sonic speed (Mach 1) at the throat, but continues to be subsonic in the divergent part. • Case c: further reduce in pressure will result in a supersonic flow in the divergent part, but as the back pressure is not low enough the supersonic acceleration is terminated by a normal shock wave after which the flow will be subsonic. • Case d: further decrease in the back pressure will result in the movement of the normal shock to the nozzle exit. • Case e: That is an under expanded nozzle. • Case f: The design point of the nozzle. The back pressure is low enough such that the flow will be fully expanded and supersonic flow is generated. • Case g: That is an over expanded nozzle. Chapter Two Problem Description and Mathematical Formulation. - Problem description and boundary conditions. A quasi 1-D inviscid compressible flow through a converging-diverging nozzle (CD) is assumed to take place. The area of the nozzle varies according to equation (2).
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