Plug nozzle

Plug nozzles have applications in aircraft, rockets, and numerous other fluid flow devices.

A spring keeps the valve pressed against the opening under normal use, thereby providing a failsafe cut-off that stops the flow of water when the nozzle is dropped.

Normally this is shaped so that when the plug is pulled back toward the opening it both partially cuts off the water flow, as well as causing it to spread out to the widest possible angle.

When the trigger is pushed down further, the plug moves away from the opening, causing less blockage and disruption of the flow, ultimately allowing the water to form back into a stream.

The jet-engine plug nozzle has its origins in rocketry[2] but has also been studied over the years, but not used, for supersonic cruise aircraft such as the Boeing SST,[3] the proposed General Electric Variable Cycle Engine, with its acoustic plug nozzle,[4] and Concorde.

[7] A plug nozzle design evaluated at the National Gas Turbine Establishment[8] was rejected for the Concorde engine due to the weight penalty from the required variable features and concerns about adequate plug cooling during reheat operation.

It provided area control with relatively simple actuation and matched the annular shape of the turbine exhaust.