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April 3, 2016 | Author: | Posted in computer science, technology

Convergent and Divergent Nozzle

A convergent-divergent nozzle , also called De Laval nozzle , CD nozzle or con di nozzle , is a tube that is somewhat pinched in the middle so as to accelerate the flow of gas , which is passing through it . Since the gas flows symmetrically along the nozzle ‘s axis starting from the inlet to the exhaust , a constriction in the middle will produce a change in pressure and as well as in the velocity in to satisfy the law of conservation of Energy . As the gas , which emanated from the combustion [banner_entry_middle]

br chamber , enters the nozzle at subsonic velocities (velocity below the speed of sound ) with high pressure . As it reaches the nozzle throat it will be contracted down until it reaches sonic velocities . At this point the pressure will be reduced and as the gas leaves the nozzle throat , it will continue to expand and will reach supersonic velocity (velocities above the speed of sound ) since the cross sectional area of the nozzle increases . Important considerations in the analysis of gas flow in the CD nozzle includes that the gas is assumed to be ideal , the gas is at constant entropy , there is little amount of heat gained or lost or at all , the gas flow is constant , the behaviour of the gas flow is compressible , and the mass flow in the nozzle should be sufficient to produce supersonic flow

The CD nozzle is commonly located at the end of the combustion chamber and it controls the gas expansion at the exhaust to efficiently convert the energy at the combustion into thrust . By reaching sonic velocities at the nozzle throat , thrust is being produced and carried throughout the rest of the expansion cone . The two major configurations in the CD nozzle are submerged and external . In the submerged type the nozzle entry , the throat , and the exhaust parts are inside the combustion chamber . In the external type , all parts of the CD nozzle are entirely separated from the combustion chamber (see figure 1

The CD nozzle consists of three major sections : the convergent section where the subsonic gas flow will be accelerated thus reducing the pressure and increasing its kinetic energy the throat where it supports the transonic flow and the divergent section that furthers accelerate the supersonic flow and eventually matching the exit pressure to the outside pressure . If the two pressures do not matched , under a lower outside pressure the CD nozzle will create expansion waves and under a higher outside pressure the CD nozzle will create oblique shock wave

A carburettor is a mechanical device that combines or blends fuel and air for an internal combustion engine . The working principle of a carburettor is based on Bernoulli ‘s theorem that the pressure will be lower if the air moves faster . This principle is similar to CD nozzle wherein a constriction also exists . The carburettor mechanism is actuated by the throttle linkages which controls the flow of air intake to the engine . The speed… [banner_entry_footer]


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