ANALYSIS OF FLOW CHARACTERISTICS OF DE LAVAL NOZZLE

A nozzle is a relatively simple device that consists of a specifically formed tube that allows hot gases to flow through it. However, the mathematics that describes the nozzle's operation necessitates some thought. Nozzles are available in a wide range of forms and sizes. A fixed geometry convergent nozzle is common on simple turbojets and turboprops. A co-annular nozzle is commonly used in turbofan engines. The core flow exits the central nozzle, while the annular nozzle exits the fan flow. The mixing of the two flows increases thrust, and these nozzles are also quieter than convergent nozzles. A variable geometry convergent-divergent CD nozzle is required for afterburning turbojets and turbofans. The flow in this nozzle first converges down to the smallest area, or throat, before expanding via the divergent segment to the right exit. These nozzles are heavier than fixed geometry nozzles because of the variable geometry, however variable geometry allows more efficient engine running across a larger airflow range than a conventional fixed nozzle. Nozzles are also used in rocket engines to accelerate hot exhaust and generate thrust. A fixed geometry CD nozzle is used in rocket engines, having a significantly greater divergent section than is required for a gas turbine.